text: /* Common target dependent code for GDB on ARM systems.
  
     Copyright (C) 1988-2017 Free Software Foundation, Inc.
  
     This file is part of GDB.
  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 3 of the License, or
     (at your option) any later version.
  
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
  
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  
  #include "defs.h"
  
  #include <ctype.h>		/* XXX for isupper ().  */
  
  #include "frame.h"
  #include "inferior.h"
  #include "infrun.h"
  #include "gdbcmd.h"
  #include "gdbcore.h"
  #include "dis-asm.h"		/* For register styles.  */
  #include "regcache.h"
  #include "reggroups.h"
  #include "doublest.h"
  #include "value.h"
  #include "arch-utils.h"
  #include "osabi.h"
  #include "frame-unwind.h"
  #include "frame-base.h"
  #include "trad-frame.h"
  #include "objfiles.h"
  #include "dwarf2-frame.h"
  #include "gdbtypes.h"
  #include "prologue-value.h"
  #include "remote.h"
  #include "target-descriptions.h"
  #include "user-regs.h"
  #include "observer.h"
  
  #include "arch/arm.h"
  #include "arch/arm-get-next-pcs.h"
  #include "arm-tdep.h"
  #include "gdb/sim-arm.h"
  
  #include "elf-bfd.h"
  #include "coff/internal.h"
  #include "elf/arm.h"
  
  #include "vec.h"
  
  #include "record.h"
  #include "record-full.h"
  
  #include "features/arm-with-m.c"
  #include "features/arm-with-m-fpa-layout.c"
  #include "features/arm-with-m-vfp-d16.c"
  #include "features/arm-with-iwmmxt.c"
  #include "features/arm-with-vfpv2.c"
  #include "features/arm-with-vfpv3.c"
  #include "features/arm-with-neon.c"
  
  static int arm_debug;
  
  /* Macros for setting and testing a bit in a minimal symbol that marks
     it as Thumb function.  The MSB of the minimal symbol's "info" field
     is used for this purpose.
  
     MSYMBOL_SET_SPECIAL	Actually sets the "special" bit.
     MSYMBOL_IS_SPECIAL   Tests the "special" bit in a minimal symbol.  */
  
  #define MSYMBOL_SET_SPECIAL(msym)				\
  	MSYMBOL_TARGET_FLAG_1 (msym) = 1
  
  #define MSYMBOL_IS_SPECIAL(msym)				\
  	MSYMBOL_TARGET_FLAG_1 (msym)
  
  /* Per-objfile data used for mapping symbols.  */
  static const struct objfile_data *arm_objfile_data_key;
  
  struct arm_mapping_symbol
  {
    bfd_vma value;
    char type;
  };
  typedef struct arm_mapping_symbol arm_mapping_symbol_s;
  DEF_VEC_O(arm_mapping_symbol_s);
  
  struct arm_per_objfile
  {
    VEC(arm_mapping_symbol_s) **section_maps;
  };
  
  /* The list of available "set arm ..." and "show arm ..." commands.  */
  static struct cmd_list_element *setarmcmdlist = NULL;
  static struct cmd_list_element *showarmcmdlist = NULL;
  
  /* The type of floating-point to use.  Keep this in sync with enum
     arm_float_model, and the help string in _initialize_arm_tdep.  */
  static const char *const fp_model_strings[] =
  {
    "auto",
    "softfpa",
    "fpa",
    "softvfp",
    "vfp",
    NULL
  };
  
  /* A variable that can be configured by the user.  */
  static enum arm_float_model arm_fp_model = ARM_FLOAT_AUTO;
  static const char *current_fp_model = "auto";
  
  /* The ABI to use.  Keep this in sync with arm_abi_kind.  */
  static const char *const arm_abi_strings[] =
  {
    "auto",
    "APCS",
    "AAPCS",
    NULL
  };
  
  /* A variable that can be configured by the user.  */
  static enum arm_abi_kind arm_abi_global = ARM_ABI_AUTO;
  static const char *arm_abi_string = "auto";
  
  /* The execution mode to assume.  */
  static const char *const arm_mode_strings[] =
    {
      "auto",
      "arm",
      "thumb",
      NULL
    };
  
  static const char *arm_fallback_mode_string = "auto";
  static const char *arm_force_mode_string = "auto";
  
  /* Internal override of the execution mode.  -1 means no override,
     0 means override to ARM mode, 1 means override to Thumb mode.
     The effect is the same as if arm_force_mode has been set by the
     user (except the internal override has precedence over a user's
     arm_force_mode override).  */
  static int arm_override_mode = -1;
  
  /* Number of different reg name sets (options).  */
  static int num_disassembly_options;
  
  /* The standard register names, and all the valid aliases for them.  Note
     that `fp', `sp' and `pc' are not added in this alias list, because they
     have been added as builtin user registers in
     std-regs.c:_initialize_frame_reg.  */
  static const struct
  {
    const char *name;
    int regnum;
  } arm_register_aliases[] = {
    /* Basic register numbers.  */
    { "r0", 0 },
    { "r1", 1 },
    { "r2", 2 },
    { "r3", 3 },
    { "r4", 4 },
    { "r5", 5 },
    { "r6", 6 },
    { "r7", 7 },
    { "r8", 8 },
    { "r9", 9 },
    { "r10", 10 },
    { "r11", 11 },
    { "r12", 12 },
    { "r13", 13 },
    { "r14", 14 },
    { "r15", 15 },
    /* Synonyms (argument and variable registers).  */
    { "a1", 0 },
    { "a2", 1 },
    { "a3", 2 },
    { "a4", 3 },
    { "v1", 4 },
    { "v2", 5 },
    { "v3", 6 },
    { "v4", 7 },
    { "v5", 8 },
    { "v6", 9 },
    { "v7", 10 },
    { "v8", 11 },
    /* Other platform-specific names for r9.  */
    { "sb", 9 },
    { "tr", 9 },
    /* Special names.  */
    { "ip", 12 },
    { "lr", 14 },
    /* Names used by GCC (not listed in the ARM EABI).  */
    { "sl", 10 },
    /* A special name from the older ATPCS.  */
    { "wr", 7 },
  };
  
  static const char *const arm_register_names[] =
  {"r0",  "r1",  "r2",  "r3",	/*  0  1  2  3 */
   "r4",  "r5",  "r6",  "r7",	/*  4  5  6  7 */
   "r8",  "r9",  "r10", "r11",	/*  8  9 10 11 */
   "r12", "sp",  "lr",  "pc",	/* 12 13 14 15 */
   "f0",  "f1",  "f2",  "f3",	/* 16 17 18 19 */
   "f4",  "f5",  "f6",  "f7",	/* 20 21 22 23 */
   "fps", "cpsr" };		/* 24 25       */
  
  /* Valid register name styles.  */
  static const char **valid_disassembly_styles;
  
  /* Disassembly style to use. Default to "std" register names.  */
  static const char *disassembly_style;
  
  /* This is used to keep the bfd arch_info in sync with the disassembly
     style.  */
  static void set_disassembly_style_sfunc(char *, int,
  					 struct cmd_list_element *);
  static void set_disassembly_style (void);
  
  static void convert_from_extended (const struct floatformat *, const void *,
  				   void *, int);
  static void convert_to_extended (const struct floatformat *, void *,
  				 const void *, int);
  
  static enum register_status arm_neon_quad_read (struct gdbarch *gdbarch,
  						struct regcache *regcache,
  						int regnum, gdb_byte *buf);
  static void arm_neon_quad_write (struct gdbarch *gdbarch,
  				 struct regcache *regcache,
  				 int regnum, const gdb_byte *buf);
  
  static CORE_ADDR
    arm_get_next_pcs_syscall_next_pc (struct arm_get_next_pcs *self);
  
  
  /* get_next_pcs operations.  */
  static struct arm_get_next_pcs_ops arm_get_next_pcs_ops = {
    arm_get_next_pcs_read_memory_unsigned_integer,
    arm_get_next_pcs_syscall_next_pc,
    arm_get_next_pcs_addr_bits_remove,
    arm_get_next_pcs_is_thumb,
    NULL,
  };
  
  struct arm_prologue_cache
  {
    /* The stack pointer at the time this frame was created; i.e. the
       caller's stack pointer when this function was called.  It is used
       to identify this frame.  */
    CORE_ADDR prev_sp;
  
    /* The frame base for this frame is just prev_sp - frame size.
       FRAMESIZE is the distance from the frame pointer to the
       initial stack pointer.  */
  
    int framesize;
  
    /* The register used to hold the frame pointer for this frame.  */
    int framereg;
  
    /* Saved register offsets.  */
    struct trad_frame_saved_reg *saved_regs;
  };
  
  static CORE_ADDR arm_analyze_prologue (struct gdbarch *gdbarch,
  				       CORE_ADDR prologue_start,
  				       CORE_ADDR prologue_end,
  				       struct arm_prologue_cache *cache);
  
  /* Architecture version for displaced stepping.  This effects the behaviour of
     certain instructions, and really should not be hard-wired.  */
  
  #define DISPLACED_STEPPING_ARCH_VERSION		5
  
  /* Set to true if the 32-bit mode is in use.  */
  
  int arm_apcs_32 = 1;
  
  /* Return the bit mask in ARM_PS_REGNUM that indicates Thumb mode.  */
  
  int
  arm_psr_thumb_bit (struct gdbarch *gdbarch)
  {
    if (gdbarch_tdep (gdbarch)->is_m)
      return XPSR_T;
    else
      return CPSR_T;
  }
  
  /* Determine if the processor is currently executing in Thumb mode.  */
  
  int
  arm_is_thumb (struct regcache *regcache)
  {
    ULONGEST cpsr;
    ULONGEST t_bit = arm_psr_thumb_bit (get_regcache_arch (regcache));
  
    cpsr = regcache_raw_get_unsigned (regcache, ARM_PS_REGNUM);
  
    return (cpsr & t_bit) != 0;
  }
  
  /* Determine if FRAME is executing in Thumb mode.  */
  
  int
  arm_frame_is_thumb (struct frame_info *frame)
  {
    CORE_ADDR cpsr;
    ULONGEST t_bit = arm_psr_thumb_bit (get_frame_arch (frame));
  
    /* Every ARM frame unwinder can unwind the T bit of the CPSR, either
       directly (from a signal frame or dummy frame) or by interpreting
       the saved LR (from a prologue or DWARF frame).  So consult it and
       trust the unwinders.  */
    cpsr = get_frame_register_unsigned (frame, ARM_PS_REGNUM);
  
    return (cpsr & t_bit) != 0;
  }
  
  /* Callback for VEC_lower_bound.  */
  
  static inline int
  arm_compare_mapping_symbols (const struct arm_mapping_symbol *lhs,
  			     const struct arm_mapping_symbol *rhs)
  {
    return lhs->value < rhs->value;
  }
  
  /* Search for the mapping symbol covering MEMADDR.  If one is found,
     return its type.  Otherwise, return 0.  If START is non-NULL,
     set *START to the location of the mapping symbol.  */
  
  static char
  arm_find_mapping_symbol (CORE_ADDR memaddr, CORE_ADDR *start)
  {
    struct obj_section *sec;
  
    /* If there are mapping symbols, consult them.  */
    sec = find_pc_section (memaddr);
    if (sec != NULL)
      {
        struct arm_per_objfile *data;
        VEC(arm_mapping_symbol_s) *map;
        struct arm_mapping_symbol map_key = { memaddr - obj_section_addr (sec),
  					    0 };
        unsigned int idx;
  
        data = (struct arm_per_objfile *) objfile_data (sec->objfile,
  						      arm_objfile_data_key);
        if (data != NULL)
  	{
  	  map = data->section_maps[sec->the_bfd_section->index];
  	  if (!VEC_empty (arm_mapping_symbol_s, map))
  	    {
  	      struct arm_mapping_symbol *map_sym;
  
  	      idx = VEC_lower_bound (arm_mapping_symbol_s, map, &map_key,
  				     arm_compare_mapping_symbols);
  
  	      /* VEC_lower_bound finds the earliest ordered insertion
  		 point.  If the following symbol starts at this exact
  		 address, we use that; otherwise, the preceding
  		 mapping symbol covers this address.  */
  	      if (idx < VEC_length (arm_mapping_symbol_s, map))
  		{
  		  map_sym = VEC_index (arm_mapping_symbol_s, map, idx);
  		  if (map_sym->value == map_key.value)
  		    {
  		      if (start)
  			*start = map_sym->value + obj_section_addr (sec);
  		      return map_sym->type;
  		    }
  		}
  
  	      if (idx > 0)
  		{
  		  map_sym = VEC_index (arm_mapping_symbol_s, map, idx - 1);
  		  if (start)
  		    *start = map_sym->value + obj_section_addr (sec);
  		  return map_sym->type;
  		}
  	    }
  	}
      }
  
    return 0;
  }
  
  /* Determine if the program counter specified in MEMADDR is in a Thumb
     function.  This function should be called for addresses unrelated to
     any executing frame; otherwise, prefer arm_frame_is_thumb.  */
  
  int
  arm_pc_is_thumb (struct gdbarch *gdbarch, CORE_ADDR memaddr)
  {
    struct bound_minimal_symbol sym;
    char type;
    struct displaced_step_closure* dsc
      = get_displaced_step_closure_by_addr(memaddr);
  
    /* If checking the mode of displaced instruction in copy area, the mode
       should be determined by instruction on the original address.  */
    if (dsc)
      {
        if (debug_displaced)
  	fprintf_unfiltered (gdb_stdlog,
  			    "displaced: check mode of %.8lx instead of %.8lx\n",
  			    (unsigned long) dsc->insn_addr,
  			    (unsigned long) memaddr);
        memaddr = dsc->insn_addr;
      }
  
    /* If bit 0 of the address is set, assume this is a Thumb address.  */
    if (IS_THUMB_ADDR (memaddr))
      return 1;
  
    /* Respect internal mode override if active.  */
    if (arm_override_mode != -1)
      return arm_override_mode;
  
    /* If the user wants to override the symbol table, let him.  */
    if (strcmp (arm_force_mode_string, "arm") == 0)
      return 0;
    if (strcmp (arm_force_mode_string, "thumb") == 0)
      return 1;
  
    /* ARM v6-M and v7-M are always in Thumb mode.  */
    if (gdbarch_tdep (gdbarch)->is_m)
      return 1;
  
    /* If there are mapping symbols, consult them.  */
    type = arm_find_mapping_symbol (memaddr, NULL);
    if (type)
      return type == 't';
  
    /* Thumb functions have a "special" bit set in minimal symbols.  */
    sym = lookup_minimal_symbol_by_pc (memaddr);
    if (sym.minsym)
      return (MSYMBOL_IS_SPECIAL (sym.minsym));
  
    /* If the user wants to override the fallback mode, let them.  */
    if (strcmp (arm_fallback_mode_string, "arm") == 0)
      return 0;
    if (strcmp (arm_fallback_mode_string, "thumb") == 0)
      return 1;
  
    /* If we couldn't find any symbol, but we're talking to a running
       target, then trust the current value of $cpsr.  This lets
       "display/i $pc" always show the correct mode (though if there is
       a symbol table we will not reach here, so it still may not be
       displayed in the mode it will be executed).  */
    if (target_has_registers)
      return arm_frame_is_thumb (get_current_frame ());
  
    /* Otherwise we're out of luck; we assume ARM.  */
    return 0;
  }
  
  /* Determine if the address specified equals any of these magic return
     values, called EXC_RETURN, defined by the ARM v6-M and v7-M
     architectures.
  
     From ARMv6-M Reference Manual B1.5.8
     Table B1-5 Exception return behavior
  
     EXC_RETURN    Return To        Return Stack
     0xFFFFFFF1    Handler mode     Main
     0xFFFFFFF9    Thread mode      Main
     0xFFFFFFFD    Thread mode      Process
  
     From ARMv7-M Reference Manual B1.5.8
     Table B1-8 EXC_RETURN definition of exception return behavior, no FP
  
     EXC_RETURN    Return To        Return Stack
     0xFFFFFFF1    Handler mode     Main
     0xFFFFFFF9    Thread mode      Main
     0xFFFFFFFD    Thread mode      Process
  
     Table B1-9 EXC_RETURN definition of exception return behavior, with
     FP
  
     EXC_RETURN    Return To        Return Stack    Frame Type
     0xFFFFFFE1    Handler mode     Main            Extended
     0xFFFFFFE9    Thread mode      Main            Extended
     0xFFFFFFED    Thread mode      Process         Extended
     0xFFFFFFF1    Handler mode     Main            Basic
     0xFFFFFFF9    Thread mode      Main            Basic
     0xFFFFFFFD    Thread mode      Process         Basic
  
     For more details see "B1.5.8 Exception return behavior"
     in both ARMv6-M and ARMv7-M Architecture Reference Manuals.  */
  
  static int
  arm_m_addr_is_magic (CORE_ADDR addr)
  {
    switch (addr)
      {
        /* Values from Tables in B1.5.8 the EXC_RETURN definitions of
  	 the exception return behavior.  */
        case 0xffffffe1:
        case 0xffffffe9:
        case 0xffffffed:
        case 0xfffffff1:
        case 0xfffffff9:
        case 0xfffffffd:
  	/* Address is magic.  */
  	return 1;
  
        default:
  	/* Address is not magic.  */
  	return 0;
      }
  }
  
  /* Remove useless bits from addresses in a running program.  */
  static CORE_ADDR
  arm_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR val)
  {
    /* On M-profile devices, do not strip the low bit from EXC_RETURN
       (the magic exception return address).  */
    if (gdbarch_tdep (gdbarch)->is_m
        && arm_m_addr_is_magic (val))
      return val;
  
    if (arm_apcs_32)
      return UNMAKE_THUMB_ADDR (val);
    else
      return (val & 0x03fffffc);
  }
  
  /* Return 1 if PC is the start of a compiler helper function which
     can be safely ignored during prologue skipping.  IS_THUMB is true
     if the function is known to be a Thumb function due to the way it
     is being called.  */
  static int
  skip_prologue_function (struct gdbarch *gdbarch, CORE_ADDR pc, int is_thumb)
  {
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    struct bound_minimal_symbol msym;
  
    msym = lookup_minimal_symbol_by_pc (pc);
    if (msym.minsym != NULL
        && BMSYMBOL_VALUE_ADDRESS (msym) == pc
        && MSYMBOL_LINKAGE_NAME (msym.minsym) != NULL)
      {
        const char *name = MSYMBOL_LINKAGE_NAME (msym.minsym);
  
        /* The GNU linker's Thumb call stub to foo is named
  	 __foo_from_thumb.  */
        if (strstr (name, "_from_thumb") != NULL)
  	name += 2;
  
        /* On soft-float targets, __truncdfsf2 is called to convert promoted
  	 arguments to their argument types in non-prototyped
  	 functions.  */
        if (startswith (name, "__truncdfsf2"))
  	return 1;
        if (startswith (name, "__aeabi_d2f"))
  	return 1;
  
        /* Internal functions related to thread-local storage.  */
        if (startswith (name, "__tls_get_addr"))
  	return 1;
        if (startswith (name, "__aeabi_read_tp"))
  	return 1;
      }
    else
      {
        /* If we run against a stripped glibc, we may be unable to identify
  	 special functions by name.  Check for one important case,
  	 __aeabi_read_tp, by comparing the *code* against the default
  	 implementation (this is hand-written ARM assembler in glibc).  */
  
        if (!is_thumb
  	  && read_memory_unsigned_integer (pc, 4, byte_order_for_code)
  	     == 0xe3e00a0f /* mov r0, #0xffff0fff */
  	  && read_memory_unsigned_integer (pc + 4, 4, byte_order_for_code)
  	     == 0xe240f01f) /* sub pc, r0, #31 */
  	return 1;
      }
  
    return 0;
  }
  
  /* Extract the immediate from instruction movw/movt of encoding T.  INSN1 is
     the first 16-bit of instruction, and INSN2 is the second 16-bit of
     instruction.  */
  #define EXTRACT_MOVW_MOVT_IMM_T(insn1, insn2) \
    ((bits ((insn1), 0, 3) << 12)               \
     | (bits ((insn1), 10, 10) << 11)           \
     | (bits ((insn2), 12, 14) << 8)            \
     | bits ((insn2), 0, 7))
  
  /* Extract the immediate from instruction movw/movt of encoding A.  INSN is
     the 32-bit instruction.  */
  #define EXTRACT_MOVW_MOVT_IMM_A(insn) \
    ((bits ((insn), 16, 19) << 12) \
     | bits ((insn), 0, 11))
  
  /* Decode immediate value; implements ThumbExpandImmediate pseudo-op.  */
  
  static unsigned int
  thumb_expand_immediate (unsigned int imm)
  {
    unsigned int count = imm >> 7;
  
    if (count < 8)
      switch (count / 2)
        {
        case 0:
  	return imm & 0xff;
        case 1:
  	return (imm & 0xff) | ((imm & 0xff) << 16);
        case 2:
  	return ((imm & 0xff) << 8) | ((imm & 0xff) << 24);
        case 3:
  	return (imm & 0xff) | ((imm & 0xff) << 8)
  		| ((imm & 0xff) << 16) | ((imm & 0xff) << 24);
        }
  
    return (0x80 | (imm & 0x7f)) << (32 - count);
  }
  
  /* Return 1 if the 16-bit Thumb instruction INSN restores SP in
     epilogue, 0 otherwise.  */
  
  static int
  thumb_instruction_restores_sp (unsigned short insn)
  {
    return (insn == 0x46bd  /* mov sp, r7 */
  	  || (insn & 0xff80) == 0xb000  /* add sp, imm */
  	  || (insn & 0xfe00) == 0xbc00);  /* pop <registers> */
  }
  
  /* Analyze a Thumb prologue, looking for a recognizable stack frame
     and frame pointer.  Scan until we encounter a store that could
     clobber the stack frame unexpectedly, or an unknown instruction.
     Return the last address which is definitely safe to skip for an
     initial breakpoint.  */
  
  static CORE_ADDR
  thumb_analyze_prologue (struct gdbarch *gdbarch,
  			CORE_ADDR start, CORE_ADDR limit,
  			struct arm_prologue_cache *cache)
  {
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    int i;
    pv_t regs[16];
    struct pv_area *stack;
    struct cleanup *back_to;
    CORE_ADDR offset;
    CORE_ADDR unrecognized_pc = 0;
  
    for (i = 0; i < 16; i++)
      regs[i] = pv_register (i, 0);
    stack = make_pv_area (ARM_SP_REGNUM, gdbarch_addr_bit (gdbarch));
    back_to = make_cleanup_free_pv_area (stack);
  
    while (start < limit)
      {
        unsigned short insn;
  
        insn = read_memory_unsigned_integer (start, 2, byte_order_for_code);
  
        if ((insn & 0xfe00) == 0xb400)		/* push { rlist } */
  	{
  	  int regno;
  	  int mask;
  
  	  if (pv_area_store_would_trash (stack, regs[ARM_SP_REGNUM]))
  	    break;
  
  	  /* Bits 0-7 contain a mask for registers R0-R7.  Bit 8 says
  	     whether to save LR (R14).  */
  	  mask = (insn & 0xff) | ((insn & 0x100) << 6);
  
  	  /* Calculate offsets of saved R0-R7 and LR.  */
  	  for (regno = ARM_LR_REGNUM; regno >= 0; regno--)
  	    if (mask & (1 << regno))
  	      {
  		regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM],
  						       -4);
  		pv_area_store (stack, regs[ARM_SP_REGNUM], 4, regs[regno]);
  	      }
  	}
        else if ((insn & 0xff80) == 0xb080)	/* sub sp, #imm */
  	{
  	  offset = (insn & 0x7f) << 2;		/* get scaled offset */
  	  regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM],
  						 -offset);
  	}
        else if (thumb_instruction_restores_sp (insn))
  	{
  	  /* Don't scan past the epilogue.  */
  	  break;
  	}
        else if ((insn & 0xf800) == 0xa800)	/* add Rd, sp, #imm */
  	regs[bits (insn, 8, 10)] = pv_add_constant (regs[ARM_SP_REGNUM],
  						    (insn & 0xff) << 2);
        else if ((insn & 0xfe00) == 0x1c00	/* add Rd, Rn, #imm */
  	       && pv_is_register (regs[bits (insn, 3, 5)], ARM_SP_REGNUM))
  	regs[bits (insn, 0, 2)] = pv_add_constant (regs[bits (insn, 3, 5)],
  						   bits (insn, 6, 8));
        else if ((insn & 0xf800) == 0x3000	/* add Rd, #imm */
  	       && pv_is_register (regs[bits (insn, 8, 10)], ARM_SP_REGNUM))
  	regs[bits (insn, 8, 10)] = pv_add_constant (regs[bits (insn, 8, 10)],
  						    bits (insn, 0, 7));
        else if ((insn & 0xfe00) == 0x1800	/* add Rd, Rn, Rm */
  	       && pv_is_register (regs[bits (insn, 6, 8)], ARM_SP_REGNUM)
  	       && pv_is_constant (regs[bits (insn, 3, 5)]))
  	regs[bits (insn, 0, 2)] = pv_add (regs[bits (insn, 3, 5)],
  					  regs[bits (insn, 6, 8)]);
        else if ((insn & 0xff00) == 0x4400	/* add Rd, Rm */
  	       && pv_is_constant (regs[bits (insn, 3, 6)]))
  	{
  	  int rd = (bit (insn, 7) << 3) + bits (insn, 0, 2);
  	  int rm = bits (insn, 3, 6);
  	  regs[rd] = pv_add (regs[rd], regs[rm]);
  	}
        else if ((insn & 0xff00) == 0x4600)	/* mov hi, lo or mov lo, hi */
  	{
  	  int dst_reg = (insn & 0x7) + ((insn & 0x80) >> 4);
  	  int src_reg = (insn & 0x78) >> 3;
  	  regs[dst_reg] = regs[src_reg];
  	}
        else if ((insn & 0xf800) == 0x9000)	/* str rd, [sp, #off] */
  	{
  	  /* Handle stores to the stack.  Normally pushes are used,
  	     but with GCC -mtpcs-frame, there may be other stores
  	     in the prologue to create the frame.  */
  	  int regno = (insn >> 8) & 0x7;
  	  pv_t addr;
  
  	  offset = (insn & 0xff) << 2;
  	  addr = pv_add_constant (regs[ARM_SP_REGNUM], offset);
  
  	  if (pv_area_store_would_trash (stack, addr))
  	    break;
  
  	  pv_area_store (stack, addr, 4, regs[regno]);
  	}
        else if ((insn & 0xf800) == 0x6000)	/* str rd, [rn, #off] */
  	{
  	  int rd = bits (insn, 0, 2);
  	  int rn = bits (insn, 3, 5);
  	  pv_t addr;
  
  	  offset = bits (insn, 6, 10) << 2;
  	  addr = pv_add_constant (regs[rn], offset);
  
  	  if (pv_area_store_would_trash (stack, addr))
  	    break;
  
  	  pv_area_store (stack, addr, 4, regs[rd]);
  	}
        else if (((insn & 0xf800) == 0x7000	/* strb Rd, [Rn, #off] */
  		|| (insn & 0xf800) == 0x8000)	/* strh Rd, [Rn, #off] */
  	       && pv_is_register (regs[bits (insn, 3, 5)], ARM_SP_REGNUM))
  	/* Ignore stores of argument registers to the stack.  */
  	;
        else if ((insn & 0xf800) == 0xc800	/* ldmia Rn!, { registers } */
  	       && pv_is_register (regs[bits (insn, 8, 10)], ARM_SP_REGNUM))
  	/* Ignore block loads from the stack, potentially copying
  	   parameters from memory.  */
  	;
        else if ((insn & 0xf800) == 0x9800	/* ldr Rd, [Rn, #immed] */
  	       || ((insn & 0xf800) == 0x6800	/* ldr Rd, [sp, #immed] */
  		   && pv_is_register (regs[bits (insn, 3, 5)], ARM_SP_REGNUM)))
  	/* Similarly ignore single loads from the stack.  */
  	;
        else if ((insn & 0xffc0) == 0x0000	/* lsls Rd, Rm, #0 */
  	       || (insn & 0xffc0) == 0x1c00)	/* add Rd, Rn, #0 */
  	/* Skip register copies, i.e. saves to another register
  	   instead of the stack.  */
  	;
        else if ((insn & 0xf800) == 0x2000)	/* movs Rd, #imm */
  	/* Recognize constant loads; even with small stacks these are necessary
  	   on Thumb.  */
  	regs[bits (insn, 8, 10)] = pv_constant (bits (insn, 0, 7));
        else if ((insn & 0xf800) == 0x4800)	/* ldr Rd, [pc, #imm] */
  	{
  	  /* Constant pool loads, for the same reason.  */
  	  unsigned int constant;
  	  CORE_ADDR loc;
  
  	  loc = start + 4 + bits (insn, 0, 7) * 4;
  	  constant = read_memory_unsigned_integer (loc, 4, byte_order);
  	  regs[bits (insn, 8, 10)] = pv_constant (constant);
  	}
        else if (thumb_insn_size (insn) == 4) /* 32-bit Thumb-2 instructions.  */
  	{
  	  unsigned short inst2;
  
  	  inst2 = read_memory_unsigned_integer (start + 2, 2,
  						byte_order_for_code);
  
  	  if ((insn & 0xf800) == 0xf000 && (inst2 & 0xe800) == 0xe800)
  	    {
  	      /* BL, BLX.  Allow some special function calls when
  		 skipping the prologue; GCC generates these before
  		 storing arguments to the stack.  */
  	      CORE_ADDR nextpc;
  	      int j1, j2, imm1, imm2;
  
  	      imm1 = sbits (insn, 0, 10);
  	      imm2 = bits (inst2, 0, 10);
  	      j1 = bit (inst2, 13);
  	      j2 = bit (inst2, 11);
  
  	      offset = ((imm1 << 12) + (imm2 << 1));
  	      offset ^= ((!j2) << 22) | ((!j1) << 23);
  
  	      nextpc = start + 4 + offset;
  	      /* For BLX make sure to clear the low bits.  */
  	      if (bit (inst2, 12) == 0)
  		nextpc = nextpc & 0xfffffffc;
  
  	      if (!skip_prologue_function (gdbarch, nextpc,
  					   bit (inst2, 12) != 0))
  		break;
  	    }
  
  	  else if ((insn & 0xffd0) == 0xe900    /* stmdb Rn{!},
  						   { registers } */
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    {
  	      pv_t addr = regs[bits (insn, 0, 3)];
  	      int regno;
  
  	      if (pv_area_store_would_trash (stack, addr))
  		break;
  
  	      /* Calculate offsets of saved registers.  */
  	      for (regno = ARM_LR_REGNUM; regno >= 0; regno--)
  		if (inst2 & (1 << regno))
  		  {
  		    addr = pv_add_constant (addr, -4);
  		    pv_area_store (stack, addr, 4, regs[regno]);
  		  }
  
  	      if (insn & 0x0020)
  		regs[bits (insn, 0, 3)] = addr;
  	    }
  
  	  else if ((insn & 0xff50) == 0xe940	/* strd Rt, Rt2,
  						   [Rn, #+/-imm]{!} */
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    {
  	      int regno1 = bits (inst2, 12, 15);
  	      int regno2 = bits (inst2, 8, 11);
  	      pv_t addr = regs[bits (insn, 0, 3)];
  
  	      offset = inst2 & 0xff;
  	      if (insn & 0x0080)
  		addr = pv_add_constant (addr, offset);
  	      else
  		addr = pv_add_constant (addr, -offset);
  
  	      if (pv_area_store_would_trash (stack, addr))
  		break;
  
  	      pv_area_store (stack, addr, 4, regs[regno1]);
  	      pv_area_store (stack, pv_add_constant (addr, 4),
  			     4, regs[regno2]);
  
  	      if (insn & 0x0020)
  		regs[bits (insn, 0, 3)] = addr;
  	    }
  
  	  else if ((insn & 0xfff0) == 0xf8c0	/* str Rt,[Rn,+/-#imm]{!} */
  		   && (inst2 & 0x0c00) == 0x0c00
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    {
  	      int regno = bits (inst2, 12, 15);
  	      pv_t addr = regs[bits (insn, 0, 3)];
  
  	      offset = inst2 & 0xff;
  	      if (inst2 & 0x0200)
  		addr = pv_add_constant (addr, offset);
  	      else
  		addr = pv_add_constant (addr, -offset);
  
  	      if (pv_area_store_would_trash (stack, addr))
  		break;
  
  	      pv_area_store (stack, addr, 4, regs[regno]);
  
  	      if (inst2 & 0x0100)
  		regs[bits (insn, 0, 3)] = addr;
  	    }
  
  	  else if ((insn & 0xfff0) == 0xf8c0	/* str.w Rt,[Rn,#imm] */
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    {
  	      int regno = bits (inst2, 12, 15);
  	      pv_t addr;
  
  	      offset = inst2 & 0xfff;
  	      addr = pv_add_constant (regs[bits (insn, 0, 3)], offset);
  
  	      if (pv_area_store_would_trash (stack, addr))
  		break;
  
  	      pv_area_store (stack, addr, 4, regs[regno]);
  	    }
  
  	  else if ((insn & 0xffd0) == 0xf880	/* str{bh}.w Rt,[Rn,#imm] */
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    /* Ignore stores of argument registers to the stack.  */
  	    ;
  
  	  else if ((insn & 0xffd0) == 0xf800	/* str{bh} Rt,[Rn,#+/-imm] */
  		   && (inst2 & 0x0d00) == 0x0c00
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    /* Ignore stores of argument registers to the stack.  */
  	    ;
  
  	  else if ((insn & 0xffd0) == 0xe890	/* ldmia Rn[!],
  						   { registers } */
  		   && (inst2 & 0x8000) == 0x0000
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    /* Ignore block loads from the stack, potentially copying
  	       parameters from memory.  */
  	    ;
  
  	  else if ((insn & 0xffb0) == 0xe950	/* ldrd Rt, Rt2,
  						   [Rn, #+/-imm] */
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    /* Similarly ignore dual loads from the stack.  */
  	    ;
  
  	  else if ((insn & 0xfff0) == 0xf850	/* ldr Rt,[Rn,#+/-imm] */
  		   && (inst2 & 0x0d00) == 0x0c00
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    /* Similarly ignore single loads from the stack.  */
  	    ;
  
  	  else if ((insn & 0xfff0) == 0xf8d0	/* ldr.w Rt,[Rn,#imm] */
  		   && pv_is_register (regs[bits (insn, 0, 3)], ARM_SP_REGNUM))
  	    /* Similarly ignore single loads from the stack.  */
  	    ;
  
  	  else if ((insn & 0xfbf0) == 0xf100	/* add.w Rd, Rn, #imm */
  		   && (inst2 & 0x8000) == 0x0000)
  	    {
  	      unsigned int imm = ((bits (insn, 10, 10) << 11)
  				  | (bits (inst2, 12, 14) << 8)
  				  | bits (inst2, 0, 7));
  
  	      regs[bits (inst2, 8, 11)]
  		= pv_add_constant (regs[bits (insn, 0, 3)],
  				   thumb_expand_immediate (imm));
  	    }
  
  	  else if ((insn & 0xfbf0) == 0xf200	/* addw Rd, Rn, #imm */
  		   && (inst2 & 0x8000) == 0x0000)
  	    {
  	      unsigned int imm = ((bits (insn, 10, 10) << 11)
  				  | (bits (inst2, 12, 14) << 8)
  				  | bits (inst2, 0, 7));
  
  	      regs[bits (inst2, 8, 11)]
  		= pv_add_constant (regs[bits (insn, 0, 3)], imm);
  	    }
  
  	  else if ((insn & 0xfbf0) == 0xf1a0	/* sub.w Rd, Rn, #imm */
  		   && (inst2 & 0x8000) == 0x0000)
  	    {
  	      unsigned int imm = ((bits (insn, 10, 10) << 11)
  				  | (bits (inst2, 12, 14) << 8)
  				  | bits (inst2, 0, 7));
  
  	      regs[bits (inst2, 8, 11)]
  		= pv_add_constant (regs[bits (insn, 0, 3)],
  				   - (CORE_ADDR) thumb_expand_immediate (imm));
  	    }
  
  	  else if ((insn & 0xfbf0) == 0xf2a0	/* subw Rd, Rn, #imm */
  		   && (inst2 & 0x8000) == 0x0000)
  	    {
  	      unsigned int imm = ((bits (insn, 10, 10) << 11)
  				  | (bits (inst2, 12, 14) << 8)
  				  | bits (inst2, 0, 7));
  
  	      regs[bits (inst2, 8, 11)]
  		= pv_add_constant (regs[bits (insn, 0, 3)], - (CORE_ADDR) imm);
  	    }
  
  	  else if ((insn & 0xfbff) == 0xf04f)	/* mov.w Rd, #const */
  	    {
  	      unsigned int imm = ((bits (insn, 10, 10) << 11)
  				  | (bits (inst2, 12, 14) << 8)
  				  | bits (inst2, 0, 7));
  
  	      regs[bits (inst2, 8, 11)]
  		= pv_constant (thumb_expand_immediate (imm));
  	    }
  
  	  else if ((insn & 0xfbf0) == 0xf240)	/* movw Rd, #const */
  	    {
  	      unsigned int imm
  		= EXTRACT_MOVW_MOVT_IMM_T (insn, inst2);
  
  	      regs[bits (inst2, 8, 11)] = pv_constant (imm);
  	    }
  
  	  else if (insn == 0xea5f		/* mov.w Rd,Rm */
  		   && (inst2 & 0xf0f0) == 0)
  	    {
  	      int dst_reg = (inst2 & 0x0f00) >> 8;
  	      int src_reg = inst2 & 0xf;
  	      regs[dst_reg] = regs[src_reg];
  	    }
  
  	  else if ((insn & 0xff7f) == 0xf85f)	/* ldr.w Rt,<label> */
  	    {
  	      /* Constant pool loads.  */
  	      unsigned int constant;
  	      CORE_ADDR loc;
  
  	      offset = bits (inst2, 0, 11);
  	      if (insn & 0x0080)
  		loc = start + 4 + offset;
  	      else
  		loc = start + 4 - offset;
  
  	      constant = read_memory_unsigned_integer (loc, 4, byte_order);
  	      regs[bits (inst2, 12, 15)] = pv_constant (constant);
  	    }
  
  	  else if ((insn & 0xff7f) == 0xe95f)	/* ldrd Rt,Rt2,<label> */
  	    {
  	      /* Constant pool loads.  */
  	      unsigned int constant;
  	      CORE_ADDR loc;
  
  	      offset = bits (inst2, 0, 7) << 2;
  	      if (insn & 0x0080)
  		loc = start + 4 + offset;
  	      else
  		loc = start + 4 - offset;
  
  	      constant = read_memory_unsigned_integer (loc, 4, byte_order);
  	      regs[bits (inst2, 12, 15)] = pv_constant (constant);
  
  	      constant = read_memory_unsigned_integer (loc + 4, 4, byte_order);
  	      regs[bits (inst2, 8, 11)] = pv_constant (constant);
  	    }
  
  	  else if (thumb2_instruction_changes_pc (insn, inst2))
  	    {
  	      /* Don't scan past anything that might change control flow.  */
  	      break;
  	    }
  	  else
  	    {
  	      /* The optimizer might shove anything into the prologue,
  		 so we just skip what we don't recognize.  */
  	      unrecognized_pc = start;
  	    }
  
  	  start += 2;
  	}
        else if (thumb_instruction_changes_pc (insn))
  	{
  	  /* Don't scan past anything that might change control flow.  */
  	  break;
  	}
        else
  	{
  	  /* The optimizer might shove anything into the prologue,
  	     so we just skip what we don't recognize.  */
  	  unrecognized_pc = start;
  	}
  
        start += 2;
      }
  
    if (arm_debug)
      fprintf_unfiltered (gdb_stdlog, "Prologue scan stopped at %s\n",
  			paddress (gdbarch, start));
  
    if (unrecognized_pc == 0)
      unrecognized_pc = start;
  
    if (cache == NULL)
      {
        do_cleanups (back_to);
        return unrecognized_pc;
      }
  
    if (pv_is_register (regs[ARM_FP_REGNUM], ARM_SP_REGNUM))
      {
        /* Frame pointer is fp.  Frame size is constant.  */
        cache->framereg = ARM_FP_REGNUM;
        cache->framesize = -regs[ARM_FP_REGNUM].k;
      }
    else if (pv_is_register (regs[THUMB_FP_REGNUM], ARM_SP_REGNUM))
      {
        /* Frame pointer is r7.  Frame size is constant.  */
        cache->framereg = THUMB_FP_REGNUM;
        cache->framesize = -regs[THUMB_FP_REGNUM].k;
      }
    else
      {
        /* Try the stack pointer... this is a bit desperate.  */
        cache->framereg = ARM_SP_REGNUM;
        cache->framesize = -regs[ARM_SP_REGNUM].k;
      }
  
    for (i = 0; i < 16; i++)
      if (pv_area_find_reg (stack, gdbarch, i, &offset))
        cache->saved_regs[i].addr = offset;
  
    do_cleanups (back_to);
    return unrecognized_pc;
  }
  
  
  /* Try to analyze the instructions starting from PC, which load symbol
     __stack_chk_guard.  Return the address of instruction after loading this
     symbol, set the dest register number to *BASEREG, and set the size of
     instructions for loading symbol in OFFSET.  Return 0 if instructions are
     not recognized.  */
  
  static CORE_ADDR
  arm_analyze_load_stack_chk_guard(CORE_ADDR pc, struct gdbarch *gdbarch,
  				 unsigned int *destreg, int *offset)
  {
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    int is_thumb = arm_pc_is_thumb (gdbarch, pc);
    unsigned int low, high, address;
  
    address = 0;
    if (is_thumb)
      {
        unsigned short insn1
  	= read_memory_unsigned_integer (pc, 2, byte_order_for_code);
  
        if ((insn1 & 0xf800) == 0x4800) /* ldr Rd, #immed */
  	{
  	  *destreg = bits (insn1, 8, 10);
  	  *offset = 2;
  	  address = (pc & 0xfffffffc) + 4 + (bits (insn1, 0, 7) << 2);
  	  address = read_memory_unsigned_integer (address, 4,
  						  byte_order_for_code);
  	}
        else if ((insn1 & 0xfbf0) == 0xf240) /* movw Rd, #const */
  	{
  	  unsigned short insn2
  	    = read_memory_unsigned_integer (pc + 2, 2, byte_order_for_code);
  
  	  low = EXTRACT_MOVW_MOVT_IMM_T (insn1, insn2);
  
  	  insn1
  	    = read_memory_unsigned_integer (pc + 4, 2, byte_order_for_code);
  	  insn2
  	    = read_memory_unsigned_integer (pc + 6, 2, byte_order_for_code);
  
  	  /* movt Rd, #const */
  	  if ((insn1 & 0xfbc0) == 0xf2c0)
  	    {
  	      high = EXTRACT_MOVW_MOVT_IMM_T (insn1, insn2);
  	      *destreg = bits (insn2, 8, 11);
  	      *offset = 8;
  	      address = (high << 16 | low);
  	    }
  	}
      }
    else
      {
        unsigned int insn
  	= read_memory_unsigned_integer (pc, 4, byte_order_for_code);
  
        if ((insn & 0x0e5f0000) == 0x041f0000) /* ldr Rd, [PC, #immed] */
  	{
  	  address = bits (insn, 0, 11) + pc + 8;
  	  address = read_memory_unsigned_integer (address, 4,
  						  byte_order_for_code);
  
  	  *destreg = bits (insn, 12, 15);
  	  *offset = 4;
  	}
        else if ((insn & 0x0ff00000) == 0x03000000) /* movw Rd, #const */
  	{
  	  low = EXTRACT_MOVW_MOVT_IMM_A (insn);
  
  	  insn
  	    = read_memory_unsigned_integer (pc + 4, 4, byte_order_for_code);
  
  	  if ((insn & 0x0ff00000) == 0x03400000) /* movt Rd, #const */
  	    {
  	      high = EXTRACT_MOVW_MOVT_IMM_A (insn);
  	      *destreg = bits (insn, 12, 15);
  	      *offset = 8;
  	      address = (high << 16 | low);
  	    }
  	}
      }
  
    return address;
  }
  
  /* Try to skip a sequence of instructions used for stack protector.  If PC
     points to the first instruction of this sequence, return the address of
     first instruction after this sequence, otherwise, return original PC.
  
     On arm, this sequence of instructions is composed of mainly three steps,
       Step 1: load symbol __stack_chk_guard,
       Step 2: load from address of __stack_chk_guard,
       Step 3: store it to somewhere else.
  
     Usually, instructions on step 2 and step 3 are the same on various ARM
     architectures.  On step 2, it is one instruction 'ldr Rx, [Rn, #0]', and
     on step 3, it is also one instruction 'str Rx, [r7, #immd]'.  However,
     instructions in step 1 vary from different ARM architectures.  On ARMv7,
     they are,
  
  	movw	Rn, #:lower16:__stack_chk_guard
  	movt	Rn, #:upper16:__stack_chk_guard
  
     On ARMv5t, it is,
  
  	ldr	Rn, .Label
  	....
  	.Lable:
  	.word	__stack_chk_guard
  
     Since ldr/str is a very popular instruction, we can't use them as
     'fingerprint' or 'signature' of stack protector sequence.  Here we choose
     sequence {movw/movt, ldr}/ldr/str plus symbol __stack_chk_guard, if not
     stripped, as the 'fingerprint' of a stack protector cdoe sequence.  */
  
  static CORE_ADDR
  arm_skip_stack_protector(CORE_ADDR pc, struct gdbarch *gdbarch)
  {
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    unsigned int basereg;
    struct bound_minimal_symbol stack_chk_guard;
    int offset;
    int is_thumb = arm_pc_is_thumb (gdbarch, pc);
    CORE_ADDR addr;
  
    /* Try to parse the instructions in Step 1.  */
    addr = arm_analyze_load_stack_chk_guard (pc, gdbarch,
  					   &basereg, &offset);
    if (!addr)
      return pc;
  
    stack_chk_guard = lookup_minimal_symbol_by_pc (addr);
    /* ADDR must correspond to a symbol whose name is __stack_chk_guard.
       Otherwise, this sequence cannot be for stack protector.  */
    if (stack_chk_guard.minsym == NULL
        || !startswith (MSYMBOL_LINKAGE_NAME (stack_chk_guard.minsym), "__stack_chk_guard"))
     return pc;
  
    if (is_thumb)
      {
        unsigned int destreg;
        unsigned short insn
  	= read_memory_unsigned_integer (pc + offset, 2, byte_order_for_code);
  
        /* Step 2: ldr Rd, [Rn, #immed], encoding T1.  */
        if ((insn & 0xf800) != 0x6800)
  	return pc;
        if (bits (insn, 3, 5) != basereg)
  	return pc;
        destreg = bits (insn, 0, 2);
  
        insn = read_memory_unsigned_integer (pc + offset + 2, 2,
  					   byte_order_for_code);
        /* Step 3: str Rd, [Rn, #immed], encoding T1.  */
        if ((insn & 0xf800) != 0x6000)
  	return pc;
        if (destreg != bits (insn, 0, 2))
  	return pc;
      }
    else
      {
        unsigned int destreg;
        unsigned int insn
  	= read_memory_unsigned_integer (pc + offset, 4, byte_order_for_code);
  
        /* Step 2: ldr Rd, [Rn, #immed], encoding A1.  */
        if ((insn & 0x0e500000) != 0x04100000)
  	return pc;
        if (bits (insn, 16, 19) != basereg)
  	return pc;
        destreg = bits (insn, 12, 15);
        /* Step 3: str Rd, [Rn, #immed], encoding A1.  */
        insn = read_memory_unsigned_integer (pc + offset + 4,
  					   4, byte_order_for_code);
        if ((insn & 0x0e500000) != 0x04000000)
  	return pc;
        if (bits (insn, 12, 15) != destreg)
  	return pc;
      }
    /* The size of total two instructions ldr/str is 4 on Thumb-2, while 8
       on arm.  */
    if (is_thumb)
      return pc + offset + 4;
    else
      return pc + offset + 8;
  }
  
  /* Advance the PC across any function entry prologue instructions to
     reach some "real" code.
  
     The APCS (ARM Procedure Call Standard) defines the following
     prologue:
  
     mov          ip, sp
     [stmfd       sp!, {a1,a2,a3,a4}]
     stmfd        sp!, {...,fp,ip,lr,pc}
     [stfe        f7, [sp, #-12]!]
     [stfe        f6, [sp, #-12]!]
     [stfe        f5, [sp, #-12]!]
     [stfe        f4, [sp, #-12]!]
     sub fp, ip, #nn @@ nn == 20 or 4 depending on second insn.  */
  
  static CORE_ADDR
  arm_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
  {
    CORE_ADDR func_addr, limit_pc;
  
    /* See if we can determine the end of the prologue via the symbol table.
       If so, then return either PC, or the PC after the prologue, whichever
       is greater.  */
    if (find_pc_partial_function (pc, NULL, &func_addr, NULL))
      {
        CORE_ADDR post_prologue_pc
  	= skip_prologue_using_sal (gdbarch, func_addr);
        struct compunit_symtab *cust = find_pc_compunit_symtab (func_addr);
  
        if (post_prologue_pc)
  	post_prologue_pc
  	  = arm_skip_stack_protector (post_prologue_pc, gdbarch);
  
  
        /* GCC always emits a line note before the prologue and another
  	 one after, even if the two are at the same address or on the
  	 same line.  Take advantage of this so that we do not need to
  	 know every instruction that might appear in the prologue.  We
  	 will have producer information for most binaries; if it is
  	 missing (e.g. for -gstabs), assuming the GNU tools.  */
        if (post_prologue_pc
  	  && (cust == NULL
  	      || COMPUNIT_PRODUCER (cust) == NULL
  	      || startswith (COMPUNIT_PRODUCER (cust), "GNU ")
  	      || startswith (COMPUNIT_PRODUCER (cust), "clang ")))
  	return post_prologue_pc;
  
        if (post_prologue_pc != 0)
  	{
  	  CORE_ADDR analyzed_limit;
  
  	  /* For non-GCC compilers, make sure the entire line is an
  	     acceptable prologue; GDB will round this function's
  	     return value up to the end of the following line so we
  	     can not skip just part of a line (and we do not want to).
  
  	     RealView does not treat the prologue specially, but does
  	     associate prologue code with the opening brace; so this
  	     lets us skip the first line if we think it is the opening
  	     brace.  */
  	  if (arm_pc_is_thumb (gdbarch, func_addr))
  	    analyzed_limit = thumb_analyze_prologue (gdbarch, func_addr,
  						     post_prologue_pc, NULL);
  	  else
  	    analyzed_limit = arm_analyze_prologue (gdbarch, func_addr,
  						   post_prologue_pc, NULL);
  
  	  if (analyzed_limit != post_prologue_pc)
  	    return func_addr;
  
  	  return post_prologue_pc;
  	}
      }
  
    /* Can't determine prologue from the symbol table, need to examine
       instructions.  */
  
    /* Find an upper limit on the function prologue using the debug
       information.  If the debug information could not be used to provide
       that bound, then use an arbitrary large number as the upper bound.  */
    /* Like arm_scan_prologue, stop no later than pc + 64.  */
    limit_pc = skip_prologue_using_sal (gdbarch, pc);
    if (limit_pc == 0)
      limit_pc = pc + 64;          /* Magic.  */
  
  
    /* Check if this is Thumb code.  */
    if (arm_pc_is_thumb (gdbarch, pc))
      return thumb_analyze_prologue (gdbarch, pc, limit_pc, NULL);
    else
      return arm_analyze_prologue (gdbarch, pc, limit_pc, NULL);
  }
  
  /* *INDENT-OFF* */
  /* Function: thumb_scan_prologue (helper function for arm_scan_prologue)
     This function decodes a Thumb function prologue to determine:
       1) the size of the stack frame
       2) which registers are saved on it
       3) the offsets of saved regs
       4) the offset from the stack pointer to the frame pointer
  
     A typical Thumb function prologue would create this stack frame
     (offsets relative to FP)
       old SP ->	24  stack parameters
  		20  LR
  		16  R7
       R7 ->       0  local variables (16 bytes)
       SP ->     -12  additional stack space (12 bytes)
     The frame size would thus be 36 bytes, and the frame offset would be
     12 bytes.  The frame register is R7.
     
     The comments for thumb_skip_prolog() describe the algorithm we use
     to detect the end of the prolog.  */
  /* *INDENT-ON* */
  
  static void
  thumb_scan_prologue (struct gdbarch *gdbarch, CORE_ADDR prev_pc,
  		     CORE_ADDR block_addr, struct arm_prologue_cache *cache)
  {
    CORE_ADDR prologue_start;
    CORE_ADDR prologue_end;
  
    if (find_pc_partial_function (block_addr, NULL, &prologue_start,
  				&prologue_end))
      {
        /* See comment in arm_scan_prologue for an explanation of
  	 this heuristics.  */
        if (prologue_end > prologue_start + 64)
  	{
  	  prologue_end = prologue_start + 64;
  	}
      }
    else
      /* We're in the boondocks: we have no idea where the start of the
         function is.  */
      return;
  
    prologue_end = min (prologue_end, prev_pc);
  
    thumb_analyze_prologue (gdbarch, prologue_start, prologue_end, cache);
  }
  
  /* Return 1 if the ARM instruction INSN restores SP in epilogue, 0
     otherwise.  */
  
  static int
  arm_instruction_restores_sp (unsigned int insn)
  {
    if (bits (insn, 28, 31) != INST_NV)
      {
        if ((insn & 0x0df0f000) == 0x0080d000
  	  /* ADD SP (register or immediate).  */
  	  || (insn & 0x0df0f000) == 0x0040d000
  	  /* SUB SP (register or immediate).  */
  	  || (insn & 0x0ffffff0) == 0x01a0d000
  	  /* MOV SP.  */
  	  || (insn & 0x0fff0000) == 0x08bd0000
  	  /* POP (LDMIA).  */
  	  || (insn & 0x0fff0000) == 0x049d0000)
  	  /* POP of a single register.  */
  	return 1;
      }
  
    return 0;
  }
  
  /* Analyze an ARM mode prologue starting at PROLOGUE_START and
     continuing no further than PROLOGUE_END.  If CACHE is non-NULL,
     fill it in.  Return the first address not recognized as a prologue
     instruction.
  
     We recognize all the instructions typically found in ARM prologues,
     plus harmless instructions which can be skipped (either for analysis
     purposes, or a more restrictive set that can be skipped when finding
     the end of the prologue).  */
  
  static CORE_ADDR
  arm_analyze_prologue (struct gdbarch *gdbarch,
  		      CORE_ADDR prologue_start, CORE_ADDR prologue_end,
  		      struct arm_prologue_cache *cache)
  {
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    int regno;
    CORE_ADDR offset, current_pc;
    pv_t regs[ARM_FPS_REGNUM];
    struct pv_area *stack;
    struct cleanup *back_to;
    CORE_ADDR unrecognized_pc = 0;
  
    /* Search the prologue looking for instructions that set up the
       frame pointer, adjust the stack pointer, and save registers.
  
       Be careful, however, and if it doesn't look like a prologue,
       don't try to scan it.  If, for instance, a frameless function
       begins with stmfd sp!, then we will tell ourselves there is
       a frame, which will confuse stack traceback, as well as "finish" 
       and other operations that rely on a knowledge of the stack
       traceback.  */
  
    for (regno = 0; regno < ARM_FPS_REGNUM; regno++)
      regs[regno] = pv_register (regno, 0);
    stack = make_pv_area (ARM_SP_REGNUM, gdbarch_addr_bit (gdbarch));
    back_to = make_cleanup_free_pv_area (stack);
  
    for (current_pc = prologue_start;
         current_pc < prologue_end;
         current_pc += 4)
      {
        unsigned int insn
  	= read_memory_unsigned_integer (current_pc, 4, byte_order_for_code);
  
        if (insn == 0xe1a0c00d)		/* mov ip, sp */
  	{
  	  regs[ARM_IP_REGNUM] = regs[ARM_SP_REGNUM];
  	  continue;
  	}
        else if ((insn & 0xfff00000) == 0xe2800000	/* add Rd, Rn, #n */
  	       && pv_is_register (regs[bits (insn, 16, 19)], ARM_SP_REGNUM))
  	{
  	  unsigned imm = insn & 0xff;                   /* immediate value */
  	  unsigned rot = (insn & 0xf00) >> 7;           /* rotate amount */
  	  int rd = bits (insn, 12, 15);
  	  imm = (imm >> rot) | (imm << (32 - rot));
  	  regs[rd] = pv_add_constant (regs[bits (insn, 16, 19)], imm);
  	  continue;
  	}
        else if ((insn & 0xfff00000) == 0xe2400000	/* sub Rd, Rn, #n */
  	       && pv_is_register (regs[bits (insn, 16, 19)], ARM_SP_REGNUM))
  	{
  	  unsigned imm = insn & 0xff;                   /* immediate value */
  	  unsigned rot = (insn & 0xf00) >> 7;           /* rotate amount */
  	  int rd = bits (insn, 12, 15);
  	  imm = (imm >> rot) | (imm << (32 - rot));
  	  regs[rd] = pv_add_constant (regs[bits (insn, 16, 19)], -imm);
  	  continue;
  	}
        else if ((insn & 0xffff0fff) == 0xe52d0004)	/* str Rd,
  							   [sp, #-4]! */
  	{
  	  if (pv_area_store_would_trash (stack, regs[ARM_SP_REGNUM]))
  	    break;
  	  regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM], -4);
  	  pv_area_store (stack, regs[ARM_SP_REGNUM], 4,
  			 regs[bits (insn, 12, 15)]);
  	  continue;
  	}
        else if ((insn & 0xffff0000) == 0xe92d0000)
  	/* stmfd sp!, {..., fp, ip, lr, pc}
  	   or
  	   stmfd sp!, {a1, a2, a3, a4}  */
  	{
  	  int mask = insn & 0xffff;
  
  	  if (pv_area_store_would_trash (stack, regs[ARM_SP_REGNUM]))
  	    break;
  
  	  /* Calculate offsets of saved registers.  */
  	  for (regno = ARM_PC_REGNUM; regno >= 0; regno--)
  	    if (mask & (1 << regno))
  	      {
  		regs[ARM_SP_REGNUM]
  		  = pv_add_constant (regs[ARM_SP_REGNUM], -4);
  		pv_area_store (stack, regs[ARM_SP_REGNUM], 4, regs[regno]);
  	      }
  	}
        else if ((insn & 0xffff0000) == 0xe54b0000	/* strb rx,[r11,#-n] */
  	       || (insn & 0xffff00f0) == 0xe14b00b0	/* strh rx,[r11,#-n] */
  	       || (insn & 0xffffc000) == 0xe50b0000)	/* str  rx,[r11,#-n] */
  	{
  	  /* No need to add this to saved_regs -- it's just an arg reg.  */
  	  continue;
  	}
        else if ((insn & 0xffff0000) == 0xe5cd0000	/* strb rx,[sp,#n] */
  	       || (insn & 0xffff00f0) == 0xe1cd00b0	/* strh rx,[sp,#n] */
  	       || (insn & 0xffffc000) == 0xe58d0000)	/* str  rx,[sp,#n] */
  	{
  	  /* No need to add this to saved_regs -- it's just an arg reg.  */
  	  continue;
  	}
        else if ((insn & 0xfff00000) == 0xe8800000	/* stm Rn,
  							   { registers } */
  	       && pv_is_register (regs[bits (insn, 16, 19)], ARM_SP_REGNUM))
  	{
  	  /* No need to add this to saved_regs -- it's just arg regs.  */
  	  continue;
  	}
        else if ((insn & 0xfffff000) == 0xe24cb000)	/* sub fp, ip #n */
  	{
  	  unsigned imm = insn & 0xff;			/* immediate value */
  	  unsigned rot = (insn & 0xf00) >> 7;		/* rotate amount */
  	  imm = (imm >> rot) | (imm << (32 - rot));
  	  regs[ARM_FP_REGNUM] = pv_add_constant (regs[ARM_IP_REGNUM], -imm);
  	}
        else if ((insn & 0xfffff000) == 0xe24dd000)	/* sub sp, sp #n */
  	{
  	  unsigned imm = insn & 0xff;			/* immediate value */
  	  unsigned rot = (insn & 0xf00) >> 7;		/* rotate amount */
  	  imm = (imm >> rot) | (imm << (32 - rot));
  	  regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM], -imm);
  	}
        else if ((insn & 0xffff7fff) == 0xed6d0103	/* stfe f?,
  							   [sp, -#c]! */
  	       && gdbarch_tdep (gdbarch)->have_fpa_registers)
  	{
  	  if (pv_area_store_would_trash (stack, regs[ARM_SP_REGNUM]))
  	    break;
  
  	  regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM], -12);
  	  regno = ARM_F0_REGNUM + ((insn >> 12) & 0x07);
  	  pv_area_store (stack, regs[ARM_SP_REGNUM], 12, regs[regno]);
  	}
        else if ((insn & 0xffbf0fff) == 0xec2d0200	/* sfmfd f0, 4,
  							   [sp!] */
  	       && gdbarch_tdep (gdbarch)->have_fpa_registers)
  	{
  	  int n_saved_fp_regs;
  	  unsigned int fp_start_reg, fp_bound_reg;
  
  	  if (pv_area_store_would_trash (stack, regs[ARM_SP_REGNUM]))
  	    break;
  
  	  if ((insn & 0x800) == 0x800)		/* N0 is set */
  	    {
  	      if ((insn & 0x40000) == 0x40000)	/* N1 is set */
  		n_saved_fp_regs = 3;
  	      else
  		n_saved_fp_regs = 1;
  	    }
  	  else
  	    {
  	      if ((insn & 0x40000) == 0x40000)	/* N1 is set */
  		n_saved_fp_regs = 2;
  	      else
  		n_saved_fp_regs = 4;
  	    }
  
  	  fp_start_reg = ARM_F0_REGNUM + ((insn >> 12) & 0x7);
  	  fp_bound_reg = fp_start_reg + n_saved_fp_regs;
  	  for (; fp_start_reg < fp_bound_reg; fp_start_reg++)
  	    {
  	      regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM], -12);
  	      pv_area_store (stack, regs[ARM_SP_REGNUM], 12,
  			     regs[fp_start_reg++]);
  	    }
  	}
        else if ((insn & 0xff000000) == 0xeb000000 && cache == NULL) /* bl */
  	{
  	  /* Allow some special function calls when skipping the
  	     prologue; GCC generates these before storing arguments to
  	     the stack.  */
  	  CORE_ADDR dest = BranchDest (current_pc, insn);
  
  	  if (skip_prologue_function (gdbarch, dest, 0))
  	    continue;
  	  else
  	    break;
  	}
        else if ((insn & 0xf0000000) != 0xe0000000)
  	break;			/* Condition not true, exit early.  */
        else if (arm_instruction_changes_pc (insn))
  	/* Don't scan past anything that might change control flow.  */
  	break;
        else if (arm_instruction_restores_sp (insn))
  	{
  	  /* Don't scan past the epilogue.  */
  	  break;
  	}
        else if ((insn & 0xfe500000) == 0xe8100000	/* ldm */
  	       && pv_is_register (regs[bits (insn, 16, 19)], ARM_SP_REGNUM))
  	/* Ignore block loads from the stack, potentially copying
  	   parameters from memory.  */
  	continue;
        else if ((insn & 0xfc500000) == 0xe4100000
  	       && pv_is_register (regs[bits (insn, 16, 19)], ARM_SP_REGNUM))
  	/* Similarly ignore single loads from the stack.  */
  	continue;
        else if ((insn & 0xffff0ff0) == 0xe1a00000)
  	/* MOV Rd, Rm.  Skip register copies, i.e. saves to another
  	   register instead of the stack.  */
  	continue;
        else
  	{
  	  /* The optimizer might shove anything into the prologue, if
  	     we build up cache (cache != NULL) from scanning prologue,
  	     we just skip what we don't recognize and scan further to
  	     make cache as complete as possible.  However, if we skip
  	     prologue, we'll stop immediately on unrecognized
  	     instruction.  */
  	  unrecognized_pc = current_pc;
  	  if (cache != NULL)
  	    continue;
  	  else
  	    break;
  	}
      }
  
    if (unrecognized_pc == 0)
      unrecognized_pc = current_pc;
  
    if (cache)
      {
        int framereg, framesize;
  
        /* The frame size is just the distance from the frame register
  	 to the original stack pointer.  */
        if (pv_is_register (regs[ARM_FP_REGNUM], ARM_SP_REGNUM))
  	{
  	  /* Frame pointer is fp.  */
  	  framereg = ARM_FP_REGNUM;
  	  framesize = -regs[ARM_FP_REGNUM].k;
  	}
        else
  	{
  	  /* Try the stack pointer... this is a bit desperate.  */
  	  framereg = ARM_SP_REGNUM;
  	  framesize = -regs[ARM_SP_REGNUM].k;
  	}
  
        cache->framereg = framereg;
        cache->framesize = framesize;
  
        for (regno = 0; regno < ARM_FPS_REGNUM; regno++)
  	if (pv_area_find_reg (stack, gdbarch, regno, &offset))
  	  cache->saved_regs[regno].addr = offset;
      }
  
    if (arm_debug)
      fprintf_unfiltered (gdb_stdlog, "Prologue scan stopped at %s\n",
  			paddress (gdbarch, unrecognized_pc));
  
    do_cleanups (back_to);
    return unrecognized_pc;
  }
  
  static void
  arm_scan_prologue (struct frame_info *this_frame,
  		   struct arm_prologue_cache *cache)
  {
    struct gdbarch *gdbarch = get_frame_arch (this_frame);
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
    CORE_ADDR prologue_start, prologue_end;
    CORE_ADDR prev_pc = get_frame_pc (this_frame);
    CORE_ADDR block_addr = get_frame_address_in_block (this_frame);
  
    /* Assume there is no frame until proven otherwise.  */
    cache->framereg = ARM_SP_REGNUM;
    cache->framesize = 0;
  
    /* Check for Thumb prologue.  */
    if (arm_frame_is_thumb (this_frame))
      {
        thumb_scan_prologue (gdbarch, prev_pc, block_addr, cache);
        return;
      }
  
    /* Find the function prologue.  If we can't find the function in
       the symbol table, peek in the stack frame to find the PC.  */
    if (find_pc_partial_function (block_addr, NULL, &prologue_start,
  				&prologue_end))
      {
        /* One way to find the end of the prologue (which works well
           for unoptimized code) is to do the following:
  
  	    struct symtab_and_line sal = find_pc_line (prologue_start, 0);
  
  	    if (sal.line == 0)
  	      prologue_end = prev_pc;
  	    else if (sal.end < prologue_end)
  	      prologue_end = sal.end;
  
  	 This mechanism is very accurate so long as the optimizer
  	 doesn't move any instructions from the function body into the
  	 prologue.  If this happens, sal.end will be the last
  	 instruction in the first hunk of prologue code just before
  	 the first instruction that the scheduler has moved from
  	 the body to the prologue.
  
  	 In order to make sure that we scan all of the prologue
  	 instructions, we use a slightly less accurate mechanism which
  	 may scan more than necessary.  To help compensate for this
  	 lack of accuracy, the prologue scanning loop below contains
  	 several clauses which'll cause the loop to terminate early if
  	 an implausible prologue instruction is encountered.
  
  	 The expression
  
  	      prologue_start + 64
  
  	 is a suitable endpoint since it accounts for the largest
  	 possible prologue plus up to five instructions inserted by
  	 the scheduler.  */
  
        if (prologue_end > prologue_start + 64)
  	{
  	  prologue_end = prologue_start + 64;	/* See above.  */
  	}
      }
    else
      {
        /* We have no symbol information.  Our only option is to assume this
  	 function has a standard stack frame and the normal frame register.
  	 Then, we can find the value of our frame pointer on entrance to
  	 the callee (or at the present moment if this is the innermost frame).
  	 The value stored there should be the address of the stmfd + 8.  */
        CORE_ADDR frame_loc;
        LONGEST return_value;
  
        frame_loc = get_frame_register_unsigned (this_frame, ARM_FP_REGNUM);
        if (!safe_read_memory_integer (frame_loc, 4, byte_order, &return_value))
          return;
        else
          {
            prologue_start = gdbarch_addr_bits_remove
  			     (gdbarch, return_value) - 8;
            prologue_end = prologue_start + 64;	/* See above.  */
          }
      }
  
    if (prev_pc < prologue_end)
      prologue_end = prev_pc;
  
    arm_analyze_prologue (gdbarch, prologue_start, prologue_end, cache);
  }
  
  static struct arm_prologue_cache *
  arm_make_prologue_cache (struct frame_info *this_frame)
  {
    int reg;
    struct arm_prologue_cache *cache;
    CORE_ADDR unwound_fp;
  
    cache = FRAME_OBSTACK_ZALLOC (struct arm_prologue_cache);
    cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
  
    arm_scan_prologue (this_frame, cache);
  
    unwound_fp = get_frame_register_unsigned (this_frame, cache->framereg);
    if (unwound_fp == 0)
      return cache;
  
    cache->prev_sp = unwound_fp + cache->framesize;
  
    /* Calculate actual addresses of saved registers using offsets
       determined by arm_scan_prologue.  */
    for (reg = 0; reg < gdbarch_num_regs (get_frame_arch (this_frame)); reg++)
      if (trad_frame_addr_p (cache->saved_regs, reg))
        cache->saved_regs[reg].addr += cache->prev_sp;
  
    return cache;
  }
  
  /* Implementation of the stop_reason hook for arm_prologue frames.  */
  
  static enum unwind_stop_reason
  arm_prologue_unwind_stop_reason (struct frame_info *this_frame,
  				 void **this_cache)
  {
    struct arm_prologue_cache *cache;
    CORE_ADDR pc;
  
    if (*this_cache == NULL)
      *this_cache = arm_make_prologue_cache (this_frame);
    cache = (struct arm_prologue_cache *) *this_cache;
  
    /* This is meant to halt the backtrace at "_start".  */
    pc = get_frame_pc (this_frame);
    if (pc <= gdbarch_tdep (get_frame_arch (this_frame))->lowest_pc)
      return UNWIND_OUTERMOST;
  
    /* If we've hit a wall, stop.  */
    if (cache->prev_sp == 0)
      return UNWIND_OUTERMOST;
  
    return UNWIND_NO_REASON;
  }
  
  /* Our frame ID for a normal frame is the current function's starting PC
     and the caller's SP when we were called.  */
  
  static void
  arm_prologue_this_id (struct frame_info *this_frame,
  		      void **this_cache,
  		      struct frame_id *this_id)
  {
    struct arm_prologue_cache *cache;
    struct frame_id id;
    CORE_ADDR pc, func;
  
    if (*this_cache == NULL)
      *this_cache = arm_make_prologue_cache (this_frame);
    cache = (struct arm_prologue_cache *) *this_cache;
  
    /* Use function start address as part of the frame ID.  If we cannot
       identify the start address (due to missing symbol information),
       fall back to just using the current PC.  */
    pc = get_frame_pc (this_frame);
    func = get_frame_func (this_frame);
    if (!func)
      func = pc;
  
    id = frame_id_build (cache->prev_sp, func);
    *this_id = id;
  }
  
  static struct value *
  arm_prologue_prev_register (struct frame_info *this_frame,
  			    void **this_cache,
  			    int prev_regnum)
  {
    struct gdbarch *gdbarch = get_frame_arch (this_frame);
    struct arm_prologue_cache *cache;
  
    if (*this_cache == NULL)
      *this_cache = arm_make_prologue_cache (this_frame);
    cache = (struct arm_prologue_cache *) *this_cache;
  
    /* If we are asked to unwind the PC, then we need to return the LR
       instead.  The prologue may save PC, but it will point into this
       frame's prologue, not the next frame's resume location.  Also
       strip the saved T bit.  A valid LR may have the low bit set, but
       a valid PC never does.  */
    if (prev_regnum == ARM_PC_REGNUM)
      {
        CORE_ADDR lr;
  
        lr = frame_unwind_register_unsigned (this_frame, ARM_LR_REGNUM);
        return frame_unwind_got_constant (this_frame, prev_regnum,
  					arm_addr_bits_remove (gdbarch, lr));
      }
  
    /* SP is generally not saved to the stack, but this frame is
       identified by the next frame's stack pointer at the time of the call.
       The value was already reconstructed into PREV_SP.  */
    if (prev_regnum == ARM_SP_REGNUM)
      return frame_unwind_got_constant (this_frame, prev_regnum, cache->prev_sp);
  
    /* The CPSR may have been changed by the call instruction and by the
       called function.  The only bit we can reconstruct is the T bit,
       by checking the low bit of LR as of the call.  This is a reliable
       indicator of Thumb-ness except for some ARM v4T pre-interworking
       Thumb code, which could get away with a clear low bit as long as
       the called function did not use bx.  Guess that all other
       bits are unchanged; the condition flags are presumably lost,
       but the processor status is likely valid.  */
    if (prev_regnum == ARM_PS_REGNUM)
      {
        CORE_ADDR lr, cpsr;
        ULONGEST t_bit = arm_psr_thumb_bit (gdbarch);
  
        cpsr = get_frame_register_unsigned (this_frame, prev_regnum);
        lr = frame_unwind_register_unsigned (this_frame, ARM_LR_REGNUM);
        if (IS_THUMB_ADDR (lr))
  	cpsr |= t_bit;
        else
  	cpsr &= ~t_bit;
        return frame_unwind_got_constant (this_frame, prev_regnum, cpsr);
      }
  
    return trad_frame_get_prev_register (this_frame, cache->saved_regs,
  				       prev_regnum);
  }
  
  struct frame_unwind arm_prologue_unwind = {
    NORMAL_FRAME,
    arm_prologue_unwind_stop_reason,
    arm_prologue_this_id,
    arm_prologue_prev_register,
    NULL,
    default_frame_sniffer
  };
  
  /* Maintain a list of ARM exception table entries per objfile, similar to the
     list of mapping symbols.  We only cache entries for standard ARM-defined
     personality routines; the cache will contain only the frame unwinding
     instructions associated with the entry (not the descriptors).  */
  
  static const struct objfile_data *arm_exidx_data_key;
  
  struct arm_exidx_entry
  {
    bfd_vma addr;
    gdb_byte *entry;
  };
  typedef struct arm_exidx_entry arm_exidx_entry_s;
  DEF_VEC_O(arm_exidx_entry_s);
  
  struct arm_exidx_data
  {
    VEC(arm_exidx_entry_s) **section_maps;
  };
  
  static void
  arm_exidx_data_free (struct objfile *objfile, void *arg)
  {
    struct arm_exidx_data *data = (struct arm_exidx_data *) arg;
    unsigned int i;
  
    for (i = 0; i < objfile->obfd->section_count; i++)
      VEC_free (arm_exidx_entry_s, data->section_maps[i]);
  }
  
  static inline int
  arm_compare_exidx_entries (const struct arm_exidx_entry *lhs,
  			   const struct arm_exidx_entry *rhs)
  {
    return lhs->addr < rhs->addr;
  }
  
  static struct obj_section *
  arm_obj_section_from_vma (struct objfile *objfile, bfd_vma vma)
  {
    struct obj_section *osect;
  
    ALL_OBJFILE_OSECTIONS (objfile, osect)
      if (bfd_get_section_flags (objfile->obfd,
  			       osect->the_bfd_section) & SEC_ALLOC)
        {
  	bfd_vma start, size;
  	start = bfd_get_section_vma (objfile->obfd, osect->the_bfd_section);
  	size = bfd_get_section_size (osect->the_bfd_section);
  
  	if (start <= vma && vma < start + size)
  	  return osect;
        }
  
    return NULL;
  }
  
  /* Parse contents of exception table and exception index sections
     of OBJFILE, and fill in the exception table entry cache.
  
     For each entry that refers to a standard ARM-defined personality
     routine, extract the frame unwinding instructions (from either
     the index or the table section).  The unwinding instructions
     are normalized by:
      - extracting them from the rest of the table data
      - converting to host endianness
      - appending the implicit 0xb0 ("Finish") code
  
     The extracted and normalized instructions are stored for later
     retrieval by the arm_find_exidx_entry routine.  */
   
  static void
  arm_exidx_new_objfile (struct objfile *objfile)
  {
    struct cleanup *cleanups;
    struct arm_exidx_data *data;
    asection *exidx, *extab;
    bfd_vma exidx_vma = 0, extab_vma = 0;
    bfd_size_type exidx_size = 0, extab_size = 0;
    gdb_byte *exidx_data = NULL, *extab_data = NULL;
    LONGEST i;
  
    /* If we've already touched this file, do nothing.  */
    if (!objfile || objfile_data (objfile, arm_exidx_data_key) != NULL)
      return;
    cleanups = make_cleanup (null_cleanup, NULL);
  
    /* Read contents of exception table and index.  */
    exidx = bfd_get_section_by_name (objfile->obfd, ELF_STRING_ARM_unwind);
    if (exidx)
      {
        exidx_vma = bfd_section_vma (objfile->obfd, exidx);
        exidx_size = bfd_get_section_size (exidx);
        exidx_data = (gdb_byte *) xmalloc (exidx_size);
        make_cleanup (xfree, exidx_data);
  
        if (!bfd_get_section_contents (objfile->obfd, exidx,
  				     exidx_data, 0, exidx_size))
  	{
  	  do_cleanups (cleanups);
  	  return;
  	}
      }
  
    extab = bfd_get_section_by_name (objfile->obfd, ".ARM.extab");
    if (extab)
      {
        extab_vma = bfd_section_vma (objfile->obfd, extab);
        extab_size = bfd_get_section_size (extab);
        extab_data = (gdb_byte *) xmalloc (extab_size);
        make_cleanup (xfree, extab_data);
  
        if (!bfd_get_section_contents (objfile->obfd, extab,
  				     extab_data, 0, extab_size))
  	{
  	  do_cleanups (cleanups);
  	  return;
  	}
      }
  
    /* Allocate exception table data structure.  */
    data = OBSTACK_ZALLOC (&objfile->objfile_obstack, struct arm_exidx_data);
    set_objfile_data (objfile, arm_exidx_data_key, data);
    data->section_maps = OBSTACK_CALLOC (&objfile->objfile_obstack,
  				       objfile->obfd->section_count,
  				       VEC(arm_exidx_entry_s) *);
  
    /* Fill in exception table.  */
    for (i = 0; i < exidx_size / 8; i++)
      {
        struct arm_exidx_entry new_exidx_entry;
        bfd_vma idx = bfd_h_get_32 (objfile->obfd, exidx_data + i * 8);
        bfd_vma val = bfd_h_get_32 (objfile->obfd, exidx_data + i * 8 + 4);
        bfd_vma addr = 0, word = 0;
        int n_bytes = 0, n_words = 0;
        struct obj_section *sec;
        gdb_byte *entry = NULL;
  
        /* Extract address of start of function.  */
        idx = ((idx & 0x7fffffff) ^ 0x40000000) - 0x40000000;
        idx += exidx_vma + i * 8;
  
        /* Find section containing function and compute section offset.  */
        sec = arm_obj_section_from_vma (objfile, idx);
        if (sec == NULL)
  	continue;
        idx -= bfd_get_section_vma (objfile->obfd, sec->the_bfd_section);
  
        /* Determine address of exception table entry.  */
        if (val == 1)
  	{
  	  /* EXIDX_CANTUNWIND -- no exception table entry present.  */
  	}
        else if ((val & 0xff000000) == 0x80000000)
  	{
  	  /* Exception table entry embedded in .ARM.exidx
  	     -- must be short form.  */
  	  word = val;
  	  n_bytes = 3;
  	}
        else if (!(val & 0x80000000))
  	{
  	  /* Exception table entry in .ARM.extab.  */
  	  addr = ((val & 0x7fffffff) ^ 0x40000000) - 0x40000000;
  	  addr += exidx_vma + i * 8 + 4;
  
  	  if (addr >= extab_vma && addr + 4 <= extab_vma + extab_size)
  	    {
  	      word = bfd_h_get_32 (objfile->obfd,
  				   extab_data + addr - extab_vma);
  	      addr += 4;
  
  	      if ((word & 0xff000000) == 0x80000000)
  		{
  		  /* Short form.  */
  		  n_bytes = 3;
  		}
  	      else if ((word & 0xff000000) == 0x81000000
  		       || (word & 0xff000000) == 0x82000000)
  		{
  		  /* Long form.  */
  		  n_bytes = 2;
  		  n_words = ((word >> 16) & 0xff);
  		}
  	      else if (!(word & 0x80000000))
  		{
  		  bfd_vma pers;
  		  struct obj_section *pers_sec;
  		  int gnu_personality = 0;
  
  		  /* Custom personality routine.  */
  		  pers = ((word & 0x7fffffff) ^ 0x40000000) - 0x40000000;
  		  pers = UNMAKE_THUMB_ADDR (pers + addr - 4);
  
  		  /* Check whether we've got one of the variants of the
  		     GNU personality routines.  */
  		  pers_sec = arm_obj_section_from_vma (objfile, pers);
  		  if (pers_sec)
  		    {
  		      static const char *personality[] = 
  			{
  			  "__gcc_personality_v0",
  			  "__gxx_personality_v0",
  			  "__gcj_personality_v0",
  			  "__gnu_objc_personality_v0",
  			  NULL
  			};
  
  		      CORE_ADDR pc = pers + obj_section_offset (pers_sec);
  		      int k;
  
  		      for (k = 0; personality[k]; k++)
  			if (lookup_minimal_symbol_by_pc_name
  			      (pc, personality[k], objfile))
  			  {
  			    gnu_personality = 1;
  			    break;
  			  }
  		    }
  
  		  /* If so, the next word contains a word count in the high
  		     byte, followed by the same unwind instructions as the
  		     pre-defined forms.  */
  		  if (gnu_personality
  		      && addr + 4 <= extab_vma + extab_size)
  		    {
  		      word = bfd_h_get_32 (objfile->obfd,
  					   extab_data + addr - extab_vma);
  		      addr += 4;
  		      n_bytes = 3;
  		      n_words = ((word >> 24) & 0xff);
  		    }
  		}
  	    }
  	}
  
        /* Sanity check address.  */
        if (n_words)
  	if (addr < extab_vma || addr + 4 * n_words > extab_vma + extab_size)
  	  n_words = n_bytes = 0;
  
        /* The unwind instructions reside in WORD (only the N_BYTES least
  	 significant bytes are valid), followed by N_WORDS words in the
  	 extab section starting at ADDR.  */
        if (n_bytes || n_words)
  	{
  	  gdb_byte *p = entry
  	    = (gdb_byte *) obstack_alloc (&objfile->objfile_obstack,
  					  n_bytes + n_words * 4 + 1);
  
  	  while (n_bytes--)
  	    *p++ = (gdb_byte) ((word >> (8 * n_bytes)) & 0xff);
  
  	  while (n_words--)
  	    {
  	      word = bfd_h_get_32 (objfile->obfd,
  				   extab_data + addr - extab_vma);
  	      addr += 4;
  
  	      *p++ = (gdb_byte) ((word >> 24) & 0xff);
  	      *p++ = (gdb_byte) ((word >> 16) & 0xff);
  	      *p++ = (gdb_byte) ((word >> 8) & 0xff);
  	      *p++ = (gdb_byte) (word & 0xff);
  	    }
  
  	  /* Implied "Finish" to terminate the list.  */
  	  *p++ = 0xb0;
  	}
  
        /* Push entry onto vector.  They are guaranteed to always
  	 appear in order of increasing addresses.  */
        new_exidx_entry.addr = idx;
        new_exidx_entry.entry = entry;
        VEC_safe_push (arm_exidx_entry_s,
  		     data->section_maps[sec->the_bfd_section->index],
  		     &new_exidx_entry);
      }
  
    do_cleanups (cleanups);
  }
  
  /* Search for the exception table entry covering MEMADDR.  If one is found,
     return a pointer to its data.  Otherwise, return 0.  If START is non-NULL,
     set *START to the start of the region covered by this entry.  */
  
  static gdb_byte *
  arm_find_exidx_entry (CORE_ADDR memaddr, CORE_ADDR *start)
  {
    struct obj_section *sec;
  
    sec = find_pc_section (memaddr);
    if (sec != NULL)
      {
        struct arm_exidx_data *data;
        VEC(arm_exidx_entry_s) *map;
        struct arm_exidx_entry map_key = { memaddr - obj_section_addr (sec), 0 };
        unsigned int idx;
  
        data = ((struct arm_exidx_data *)
  	      objfile_data (sec->objfile, arm_exidx_data_key));
        if (data != NULL)
  	{
  	  map = data->section_maps[sec->the_bfd_section->index];
  	  if (!VEC_empty (arm_exidx_entry_s, map))
  	    {
  	      struct arm_exidx_entry *map_sym;
  
  	      idx = VEC_lower_bound (arm_exidx_entry_s, map, &map_key,
  				     arm_compare_exidx_entries);
  
  	      /* VEC_lower_bound finds the earliest ordered insertion
  		 point.  If the following symbol starts at this exact
  		 address, we use that; otherwise, the preceding
  		 exception table entry covers this address.  */
  	      if (idx < VEC_length (arm_exidx_entry_s, map))
  		{
  		  map_sym = VEC_index (arm_exidx_entry_s, map, idx);
  		  if (map_sym->addr == map_key.addr)
  		    {
  		      if (start)
  			*start = map_sym->addr + obj_section_addr (sec);
  		      return map_sym->entry;
  		    }
  		}
  
  	      if (idx > 0)
  		{
  		  map_sym = VEC_index (arm_exidx_entry_s, map, idx - 1);
  		  if (start)
  		    *start = map_sym->addr + obj_section_addr (sec);
  		  return map_sym->entry;
  		}
  	    }
  	}
      }
  
    return NULL;
  }
  
  /* Given the current frame THIS_FRAME, and its associated frame unwinding
     instruction list from the ARM exception table entry ENTRY, allocate and
     return a prologue cache structure describing how to unwind this frame.
  
     Return NULL if the unwinding instruction list contains a "spare",
     "reserved" or "refuse to unwind" instruction as defined in section
     "9.3 Frame unwinding instructions" of the "Exception Handling ABI
     for the ARM Architecture" document.  */
  
  static struct arm_prologue_cache *
  arm_exidx_fill_cache (struct frame_info *this_frame, gdb_byte *entry)
  {
    CORE_ADDR vsp = 0;
    int vsp_valid = 0;
  
    struct arm_prologue_cache *cache;
    cache = FRAME_OBSTACK_ZALLOC (struct arm_prologue_cache);
    cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
  
    for (;;)
      {
        gdb_byte insn;
  
        /* Whenever we reload SP, we actually have to retrieve its
  	 actual value in the current frame.  */
        if (!vsp_valid)
  	{
  	  if (trad_frame_realreg_p (cache->saved_regs, ARM_SP_REGNUM))
  	    {
  	      int reg = cache->saved_regs[ARM_SP_REGNUM].realreg;
  	      vsp = get_frame_register_unsigned (this_frame, reg);
  	    }
  	  else
  	    {
  	      CORE_ADDR addr = cache->saved_regs[ARM_SP_REGNUM].addr;
  	      vsp = get_frame_memory_unsigned (this_frame, addr, 4);
  	    }
  
  	  vsp_valid = 1;
  	}
  
        /* Decode next unwind instruction.  */
        insn = *entry++;
  
        if ((insn & 0xc0) == 0)
  	{
  	  int offset = insn & 0x3f;
  	  vsp += (offset << 2) + 4;
  	}
        else if ((insn & 0xc0) == 0x40)
  	{
  	  int offset = insn & 0x3f;
  	  vsp -= (offset << 2) + 4;
  	}
        else if ((insn & 0xf0) == 0x80)
  	{
  	  int mask = ((insn & 0xf) << 8) | *entry++;
  	  int i;
  
  	  /* The special case of an all-zero mask identifies
  	     "Refuse to unwind".  We return NULL to fall back
  	     to the prologue analyzer.  */
  	  if (mask == 0)
  	    return NULL;
  
  	  /* Pop registers r4..r15 under mask.  */
  	  for (i = 0; i < 12; i++)
  	    if (mask & (1 << i))
  	      {
  	        cache->saved_regs[4 + i].addr = vsp;
  		vsp += 4;
  	      }
  
  	  /* Special-case popping SP -- we need to reload vsp.  */
  	  if (mask & (1 << (ARM_SP_REGNUM - 4)))
  	    vsp_valid = 0;
  	}
        else if ((insn & 0xf0) == 0x90)
  	{
  	  int reg = insn & 0xf;
  
  	  /* Reserved cases.  */
  	  if (reg == ARM_SP_REGNUM || reg == ARM_PC_REGNUM)
  	    return NULL;
  
  	  /* Set SP from another register and mark VSP for reload.  */
  	  cache->saved_regs[ARM_SP_REGNUM] = cache->saved_regs[reg];
  	  vsp_valid = 0;
  	}
        else if ((insn & 0xf0) == 0xa0)
  	{
  	  int count = insn & 0x7;
  	  int pop_lr = (insn & 0x8) != 0;
  	  int i;
  
  	  /* Pop r4..r[4+count].  */
  	  for (i = 0; i <= count; i++)
  	    {
  	      cache->saved_regs[4 + i].addr = vsp;
  	      vsp += 4;
  	    }
  
  	  /* If indicated by flag, pop LR as well.  */
  	  if (pop_lr)
  	    {
  	      cache->saved_regs[ARM_LR_REGNUM].addr = vsp;
  	      vsp += 4;
  	    }
  	}
        else if (insn == 0xb0)
  	{
  	  /* We could only have updated PC by popping into it; if so, it
  	     will show up as address.  Otherwise, copy LR into PC.  */
  	  if (!trad_frame_addr_p (cache->saved_regs, ARM_PC_REGNUM))
  	    cache->saved_regs[ARM_PC_REGNUM]
  	      = cache->saved_regs[ARM_LR_REGNUM];
  
  	  /* We're done.  */
  	  break;
  	}
        else if (insn == 0xb1)
  	{
  	  int mask = *entry++;
  	  int i;
  
  	  /* All-zero mask and mask >= 16 is "spare".  */
  	  if (mask == 0 || mask >= 16)
  	    return NULL;
  
  	  /* Pop r0..r3 under mask.  */
  	  for (i = 0; i < 4; i++)
  	    if (mask & (1 << i))
  	      {
  		cache->saved_regs[i].addr = vsp;
  		vsp += 4;
  	      }
  	}
        else if (insn == 0xb2)
  	{
  	  ULONGEST offset = 0;
  	  unsigned shift = 0;
  
  	  do
  	    {
  	      offset |= (*entry & 0x7f) << shift;
  	      shift += 7;
  	    }
  	  while (*entry++ & 0x80);
  
  	  vsp += 0x204 + (offset << 2);
  	}
        else if (insn == 0xb3)
  	{
  	  int start = *entry >> 4;
  	  int count = (*entry++) & 0xf;
  	  int i;
  
  	  /* Only registers D0..D15 are valid here.  */
  	  if (start + count >= 16)
  	    return NULL;
  
  	  /* Pop VFP double-precision registers D[start]..D[start+count].  */
  	  for (i = 0; i <= count; i++)
  	    {
  	      cache->saved_regs[ARM_D0_REGNUM + start + i].addr = vsp;
  	      vsp += 8;
  	    }
  
  	  /* Add an extra 4 bytes for FSTMFDX-style stack.  */
  	  vsp += 4;
  	}
        else if ((insn & 0xf8) == 0xb8)
  	{
  	  int count = insn & 0x7;
  	  int i;
  
  	  /* Pop VFP double-precision registers D[8]..D[8+count].  */
  	  for (i = 0; i <= count; i++)
  	    {
  	      cache->saved_regs[ARM_D0_REGNUM + 8 + i].addr = vsp;
  	      vsp += 8;
  	    }
  
  	  /* Add an extra 4 bytes for FSTMFDX-style stack.  */
  	  vsp += 4;
  	}
        else if (insn == 0xc6)
  	{
  	  int start = *entry >> 4;
  	  int count = (*entry++) & 0xf;
  	  int i;
  
  	  /* Only registers WR0..WR15 are valid.  */
  	  if (start + count >= 16)
  	    return NULL;
  
  	  /* Pop iwmmx registers WR[start]..WR[start+count].  */
  	  for (i = 0; i <= count; i++)
  	    {
  	      cache->saved_regs[ARM_WR0_REGNUM + start + i].addr = vsp;
  	      vsp += 8;
  	    }
  	}
        else if (insn == 0xc7)
  	{
  	  int mask = *entry++;
  	  int i;
  
  	  /* All-zero mask and mask >= 16 is "spare".  */
  	  if (mask == 0 || mask >= 16)
  	    return NULL;
  
  	  /* Pop iwmmx general-purpose registers WCGR0..WCGR3 under mask.  */
  	  for (i = 0; i < 4; i++)
  	    if (mask & (1 << i))
  	      {
  		cache->saved_regs[ARM_WCGR0_REGNUM + i].addr = vsp;
  		vsp += 4;
  	      }
  	}
        else if ((insn & 0xf8) == 0xc0)
  	{
  	  int count = insn & 0x7;
  	  int i;
  
  	  /* Pop iwmmx registers WR[10]..WR[10+count].  */
  	  for (i = 0; i <= count; i++)
  	    {
  	      cache->saved_regs[ARM_WR0_REGNUM + 10 + i].addr = vsp;
  	      vsp += 8;
  	    }
  	}
        else if (insn == 0xc8)
  	{
  	  int start = *entry >> 4;
  	  int count = (*entry++) & 0xf;
  	  int i;
  
  	  /* Only registers D0..D31 are valid.  */
  	  if (start + count >= 16)
  	    return NULL;
  
  	  /* Pop VFP double-precision registers
  	     D[16+start]..D[16+start+count].  */
  	  for (i = 0; i <= count; i++)
  	    {
  	      cache->saved_regs[ARM_D0_REGNUM + 16 + start + i].addr = vsp;
  	      vsp += 8;
  	    }
  	}
        else if (insn == 0xc9)
  	{
  	  int start = *entry >> 4;
  	  int count = (*entry++) & 0xf;
  	  int i;
  
  	  /* Pop VFP double-precision registers D[start]..D[start+count].  */
  	  for (i = 0; i <= count; i++)
  	    {
  	      cache->saved_regs[ARM_D0_REGNUM + start + i].addr = vsp;
  	      vsp += 8;
  	    }
  	}
        else if ((insn & 0xf8) == 0xd0)
  	{
  	  int count = insn & 0x7;
  	  int i;
  
  	  /* Pop VFP double-precision registers D[8]..D[8+count].  */
  	  for (i = 0; i <= count; i++)
  	    {
  	      cache->saved_regs[ARM_D0_REGNUM + 8 + i].addr = vsp;
  	      vsp += 8;
  	    }
  	}
        else
  	{
  	  /* Everything else is "spare".  */
  	  return NULL;
  	}
      }
  
    /* If we restore SP from a register, assume this was the frame register.
       Otherwise just fall back to SP as frame register.  */
    if (trad_frame_realreg_p (cache->saved_regs, ARM_SP_REGNUM))
      cache->framereg = cache->saved_regs[ARM_SP_REGNUM].realreg;
    else
      cache->framereg = ARM_SP_REGNUM;
  
    /* Determine offset to previous frame.  */
    cache->framesize
      = vsp - get_frame_register_unsigned (this_frame, cache->framereg);
  
    /* We already got the previous SP.  */
    cache->prev_sp = vsp;
  
    return cache;
  }
  
  /* Unwinding via ARM exception table entries.  Note that the sniffer
     already computes a filled-in prologue cache, which is then used
     with the same arm_prologue_this_id and arm_prologue_prev_register
     routines also used for prologue-parsing based unwinding.  */
  
  static int
  arm_exidx_unwind_sniffer (const struct frame_unwind *self,
  			  struct frame_info *this_frame,
  			  void **this_prologue_cache)
  {
    struct gdbarch *gdbarch = get_frame_arch (this_frame);
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    CORE_ADDR addr_in_block, exidx_region, func_start;
    struct arm_prologue_cache *cache;
    gdb_byte *entry;
  
    /* See if we have an ARM exception table entry covering this address.  */
    addr_in_block = get_frame_address_in_block (this_frame);
    entry = arm_find_exidx_entry (addr_in_block, &exidx_region);
    if (!entry)
      return 0;
  
    /* The ARM exception table does not describe unwind information
       for arbitrary PC values, but is guaranteed to be correct only
       at call sites.  We have to decide here whether we want to use
       ARM exception table information for this frame, or fall back
       to using prologue parsing.  (Note that if we have DWARF CFI,
       this sniffer isn't even called -- CFI is always preferred.)
  
       Before we make this decision, however, we check whether we
       actually have *symbol* information for the current frame.
       If not, prologue parsing would not work anyway, so we might
       as well use the exception table and hope for the best.  */
    if (find_pc_partial_function (addr_in_block, NULL, &func_start, NULL))
      {
        int exc_valid = 0;
  
        /* If the next frame is "normal", we are at a call site in this
  	 frame, so exception information is guaranteed to be valid.  */
        if (get_next_frame (this_frame)
  	  && get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME)
  	exc_valid = 1;
  
        /* We also assume exception information is valid if we're currently
  	 blocked in a system call.  The system library is supposed to
  	 ensure this, so that e.g. pthread cancellation works.  */
        if (arm_frame_is_thumb (this_frame))
  	{
  	  LONGEST insn;
  
  	  if (safe_read_memory_integer (get_frame_pc (this_frame) - 2, 2,
  					byte_order_for_code, &insn)
  	      && (insn & 0xff00) == 0xdf00 /* svc */)
  	    exc_valid = 1;
  	}
        else
  	{
  	  LONGEST insn;
  
  	  if (safe_read_memory_integer (get_frame_pc (this_frame) - 4, 4,
  					byte_order_for_code, &insn)
  	      && (insn & 0x0f000000) == 0x0f000000 /* svc */)
  	    exc_valid = 1;
  	}
  	
        /* Bail out if we don't know that exception information is valid.  */
        if (!exc_valid)
  	return 0;
  
       /* The ARM exception index does not mark the *end* of the region
  	covered by the entry, and some functions will not have any entry.
  	To correctly recognize the end of the covered region, the linker
  	should have inserted dummy records with a CANTUNWIND marker.
  
  	Unfortunately, current versions of GNU ld do not reliably do
  	this, and thus we may have found an incorrect entry above.
  	As a (temporary) sanity check, we only use the entry if it
  	lies *within* the bounds of the function.  Note that this check
  	might reject perfectly valid entries that just happen to cover
  	multiple functions; therefore this check ought to be removed
  	once the linker is fixed.  */
        if (func_start > exidx_region)
  	return 0;
      }
  
    /* Decode the list of unwinding instructions into a prologue cache.
       Note that this may fail due to e.g. a "refuse to unwind" code.  */
    cache = arm_exidx_fill_cache (this_frame, entry);
    if (!cache)
      return 0;
  
    *this_prologue_cache = cache;
    return 1;
  }
  
  struct frame_unwind arm_exidx_unwind = {
    NORMAL_FRAME,
    default_frame_unwind_stop_reason,
    arm_prologue_this_id,
    arm_prologue_prev_register,
    NULL,
    arm_exidx_unwind_sniffer
  };
  
  static struct arm_prologue_cache *
  arm_make_epilogue_frame_cache (struct frame_info *this_frame)
  {
    struct arm_prologue_cache *cache;
    int reg;
  
    cache = FRAME_OBSTACK_ZALLOC (struct arm_prologue_cache);
    cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
  
    /* Still rely on the offset calculated from prologue.  */
    arm_scan_prologue (this_frame, cache);
  
    /* Since we are in epilogue, the SP has been restored.  */
    cache->prev_sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM);
  
    /* Calculate actual addresses of saved registers using offsets
       determined by arm_scan_prologue.  */
    for (reg = 0; reg < gdbarch_num_regs (get_frame_arch (this_frame)); reg++)
      if (trad_frame_addr_p (cache->saved_regs, reg))
        cache->saved_regs[reg].addr += cache->prev_sp;
  
    return cache;
  }
  
  /* Implementation of function hook 'this_id' in
     'struct frame_uwnind' for epilogue unwinder.  */
  
  static void
  arm_epilogue_frame_this_id (struct frame_info *this_frame,
  			    void **this_cache,
  			    struct frame_id *this_id)
  {
    struct arm_prologue_cache *cache;
    CORE_ADDR pc, func;
  
    if (*this_cache == NULL)
      *this_cache = arm_make_epilogue_frame_cache (this_frame);
    cache = (struct arm_prologue_cache *) *this_cache;
  
    /* Use function start address as part of the frame ID.  If we cannot
       identify the start address (due to missing symbol information),
       fall back to just using the current PC.  */
    pc = get_frame_pc (this_frame);
    func = get_frame_func (this_frame);
    if (func == 0)
      func = pc;
  
    (*this_id) = frame_id_build (cache->prev_sp, pc);
  }
  
  /* Implementation of function hook 'prev_register' in
     'struct frame_uwnind' for epilogue unwinder.  */
  
  static struct value *
  arm_epilogue_frame_prev_register (struct frame_info *this_frame,
  				  void **this_cache, int regnum)
  {
    if (*this_cache == NULL)
      *this_cache = arm_make_epilogue_frame_cache (this_frame);
  
    return arm_prologue_prev_register (this_frame, this_cache, regnum);
  }
  
  static int arm_stack_frame_destroyed_p_1 (struct gdbarch *gdbarch,
  					  CORE_ADDR pc);
  static int thumb_stack_frame_destroyed_p (struct gdbarch *gdbarch,
  					  CORE_ADDR pc);
  
  /* Implementation of function hook 'sniffer' in
     'struct frame_uwnind' for epilogue unwinder.  */
  
  static int
  arm_epilogue_frame_sniffer (const struct frame_unwind *self,
  			    struct frame_info *this_frame,
  			    void **this_prologue_cache)
  {
    if (frame_relative_level (this_frame) == 0)
      {
        struct gdbarch *gdbarch = get_frame_arch (this_frame);
        CORE_ADDR pc = get_frame_pc (this_frame);
  
        if (arm_frame_is_thumb (this_frame))
  	return thumb_stack_frame_destroyed_p (gdbarch, pc);
        else
  	return arm_stack_frame_destroyed_p_1 (gdbarch, pc);
      }
    else
      return 0;
  }
  
  /* Frame unwinder from epilogue.  */
  
  static const struct frame_unwind arm_epilogue_frame_unwind =
  {
    NORMAL_FRAME,
    default_frame_unwind_stop_reason,
    arm_epilogue_frame_this_id,
    arm_epilogue_frame_prev_register,
    NULL,
    arm_epilogue_frame_sniffer,
  };
  
  /* Recognize GCC's trampoline for thumb call-indirect.  If we are in a
     trampoline, return the target PC.  Otherwise return 0.
  
     void call0a (char c, short s, int i, long l) {}
  
     int main (void)
     {
       (*pointer_to_call0a) (c, s, i, l);
     }
  
     Instead of calling a stub library function  _call_via_xx (xx is
     the register name), GCC may inline the trampoline in the object
     file as below (register r2 has the address of call0a).
  
     .global main
     .type main, %function
     ...
     bl .L1
     ...
     .size main, .-main
  
     .L1:
     bx r2
  
     The trampoline 'bx r2' doesn't belong to main.  */
  
  static CORE_ADDR
  arm_skip_bx_reg (struct frame_info *frame, CORE_ADDR pc)
  {
    /* The heuristics of recognizing such trampoline is that FRAME is
       executing in Thumb mode and the instruction on PC is 'bx Rm'.  */
    if (arm_frame_is_thumb (frame))
      {
        gdb_byte buf[2];
  
        if (target_read_memory (pc, buf, 2) == 0)
  	{
  	  struct gdbarch *gdbarch = get_frame_arch (frame);
  	  enum bfd_endian byte_order_for_code
  	    = gdbarch_byte_order_for_code (gdbarch);
  	  uint16_t insn
  	    = extract_unsigned_integer (buf, 2, byte_order_for_code);
  
  	  if ((insn & 0xff80) == 0x4700)  /* bx <Rm> */
  	    {
  	      CORE_ADDR dest
  		= get_frame_register_unsigned (frame, bits (insn, 3, 6));
  
  	      /* Clear the LSB so that gdb core sets step-resume
  		 breakpoint at the right address.  */
  	      return UNMAKE_THUMB_ADDR (dest);
  	    }
  	}
      }
  
    return 0;
  }
  
  static struct arm_prologue_cache *
  arm_make_stub_cache (struct frame_info *this_frame)
  {
    struct arm_prologue_cache *cache;
  
    cache = FRAME_OBSTACK_ZALLOC (struct arm_prologue_cache);
    cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
  
    cache->prev_sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM);
  
    return cache;
  }
  
  /* Our frame ID for a stub frame is the current SP and LR.  */
  
  static void
  arm_stub_this_id (struct frame_info *this_frame,
  		  void **this_cache,
  		  struct frame_id *this_id)
  {
    struct arm_prologue_cache *cache;
  
    if (*this_cache == NULL)
      *this_cache = arm_make_stub_cache (this_frame);
    cache = (struct arm_prologue_cache *) *this_cache;
  
    *this_id = frame_id_build (cache->prev_sp, get_frame_pc (this_frame));
  }
  
  static int
  arm_stub_unwind_sniffer (const struct frame_unwind *self,
  			 struct frame_info *this_frame,
  			 void **this_prologue_cache)
  {
    CORE_ADDR addr_in_block;
    gdb_byte dummy[4];
    CORE_ADDR pc, start_addr;
    const char *name;
  
    addr_in_block = get_frame_address_in_block (this_frame);
    pc = get_frame_pc (this_frame);
    if (in_plt_section (addr_in_block)
        /* We also use the stub winder if the target memory is unreadable
  	 to avoid having the prologue unwinder trying to read it.  */
        || target_read_memory (pc, dummy, 4) != 0)
      return 1;
  
    if (find_pc_partial_function (pc, &name, &start_addr, NULL) == 0
        && arm_skip_bx_reg (this_frame, pc) != 0)
      return 1;
  
    return 0;
  }
  
  struct frame_unwind arm_stub_unwind = {
    NORMAL_FRAME,
    default_frame_unwind_stop_reason,
    arm_stub_this_id,
    arm_prologue_prev_register,
    NULL,
    arm_stub_unwind_sniffer
  };
  
  /* Put here the code to store, into CACHE->saved_regs, the addresses
     of the saved registers of frame described by THIS_FRAME.  CACHE is
     returned.  */
  
  static struct arm_prologue_cache *
  arm_m_exception_cache (struct frame_info *this_frame)
  {
    struct gdbarch *gdbarch = get_frame_arch (this_frame);
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
    struct arm_prologue_cache *cache;
    CORE_ADDR unwound_sp;
    LONGEST xpsr;
  
    cache = FRAME_OBSTACK_ZALLOC (struct arm_prologue_cache);
    cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
  
    unwound_sp = get_frame_register_unsigned (this_frame,
  					    ARM_SP_REGNUM);
  
    /* The hardware saves eight 32-bit words, comprising xPSR,
       ReturnAddress, LR (R14), R12, R3, R2, R1, R0.  See details in
       "B1.5.6 Exception entry behavior" in
       "ARMv7-M Architecture Reference Manual".  */
    cache->saved_regs[0].addr = unwound_sp;
    cache->saved_regs[1].addr = unwound_sp + 4;
    cache->saved_regs[2].addr = unwound_sp + 8;
    cache->saved_regs[3].addr = unwound_sp + 12;
    cache->saved_regs[12].addr = unwound_sp + 16;
    cache->saved_regs[14].addr = unwound_sp + 20;
    cache->saved_regs[15].addr = unwound_sp + 24;
    cache->saved_regs[ARM_PS_REGNUM].addr = unwound_sp + 28;
  
    /* If bit 9 of the saved xPSR is set, then there is a four-byte
       aligner between the top of the 32-byte stack frame and the
       previous context's stack pointer.  */
    cache->prev_sp = unwound_sp + 32;
    if (safe_read_memory_integer (unwound_sp + 28, 4, byte_order, &xpsr)
        && (xpsr & (1 << 9)) != 0)
      cache->prev_sp += 4;
  
    return cache;
  }
  
  /* Implementation of function hook 'this_id' in
     'struct frame_uwnind'.  */
  
  static void
  arm_m_exception_this_id (struct frame_info *this_frame,
  			 void **this_cache,
  			 struct frame_id *this_id)
  {
    struct arm_prologue_cache *cache;
  
    if (*this_cache == NULL)
      *this_cache = arm_m_exception_cache (this_frame);
    cache = (struct arm_prologue_cache *) *this_cache;
  
    /* Our frame ID for a stub frame is the current SP and LR.  */
    *this_id = frame_id_build (cache->prev_sp,
  			     get_frame_pc (this_frame));
  }
  
  /* Implementation of function hook 'prev_register' in
     'struct frame_uwnind'.  */
  
  static struct value *
  arm_m_exception_prev_register (struct frame_info *this_frame,
  			       void **this_cache,
  			       int prev_regnum)
  {
    struct arm_prologue_cache *cache;
  
    if (*this_cache == NULL)
      *this_cache = arm_m_exception_cache (this_frame);
    cache = (struct arm_prologue_cache *) *this_cache;
  
    /* The value was already reconstructed into PREV_SP.  */
    if (prev_regnum == ARM_SP_REGNUM)
      return frame_unwind_got_constant (this_frame, prev_regnum,
  				      cache->prev_sp);
  
    return trad_frame_get_prev_register (this_frame, cache->saved_regs,
  				       prev_regnum);
  }
  
  /* Implementation of function hook 'sniffer' in
     'struct frame_uwnind'.  */
  
  static int
  arm_m_exception_unwind_sniffer (const struct frame_unwind *self,
  				struct frame_info *this_frame,
  				void **this_prologue_cache)
  {
    CORE_ADDR this_pc = get_frame_pc (this_frame);
  
    /* No need to check is_m; this sniffer is only registered for
       M-profile architectures.  */
  
    /* Check if exception frame returns to a magic PC value.  */
    return arm_m_addr_is_magic (this_pc);
  }
  
  /* Frame unwinder for M-profile exceptions.  */
  
  struct frame_unwind arm_m_exception_unwind =
  {
    SIGTRAMP_FRAME,
    default_frame_unwind_stop_reason,
    arm_m_exception_this_id,
    arm_m_exception_prev_register,
    NULL,
    arm_m_exception_unwind_sniffer
  };
  
  static CORE_ADDR
  arm_normal_frame_base (struct frame_info *this_frame, void **this_cache)
  {
    struct arm_prologue_cache *cache;
  
    if (*this_cache == NULL)
      *this_cache = arm_make_prologue_cache (this_frame);
    cache = (struct arm_prologue_cache *) *this_cache;
  
    return cache->prev_sp - cache->framesize;
  }
  
  struct frame_base arm_normal_base = {
    &arm_prologue_unwind,
    arm_normal_frame_base,
    arm_normal_frame_base,
    arm_normal_frame_base
  };
  
  /* Assuming THIS_FRAME is a dummy, return the frame ID of that
     dummy frame.  The frame ID's base needs to match the TOS value
     saved by save_dummy_frame_tos() and returned from
     arm_push_dummy_call, and the PC needs to match the dummy frame's
     breakpoint.  */
  
  static struct frame_id
  arm_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
  {
    return frame_id_build (get_frame_register_unsigned (this_frame,
  						      ARM_SP_REGNUM),
  			 get_frame_pc (this_frame));
  }
  
  /* Given THIS_FRAME, find the previous frame's resume PC (which will
     be used to construct the previous frame's ID, after looking up the
     containing function).  */
  
  static CORE_ADDR
  arm_unwind_pc (struct gdbarch *gdbarch, struct frame_info *this_frame)
  {
    CORE_ADDR pc;
    pc = frame_unwind_register_unsigned (this_frame, ARM_PC_REGNUM);
    return arm_addr_bits_remove (gdbarch, pc);
  }
  
  static CORE_ADDR
  arm_unwind_sp (struct gdbarch *gdbarch, struct frame_info *this_frame)
  {
    return frame_unwind_register_unsigned (this_frame, ARM_SP_REGNUM);
  }
  
  static struct value *
  arm_dwarf2_prev_register (struct frame_info *this_frame, void **this_cache,
  			  int regnum)
  {
    struct gdbarch * gdbarch = get_frame_arch (this_frame);
    CORE_ADDR lr, cpsr;
    ULONGEST t_bit = arm_psr_thumb_bit (gdbarch);
  
    switch (regnum)
      {
      case ARM_PC_REGNUM:
        /* The PC is normally copied from the return column, which
  	 describes saves of LR.  However, that version may have an
  	 extra bit set to indicate Thumb state.  The bit is not
  	 part of the PC.  */
        lr = frame_unwind_register_unsigned (this_frame, ARM_LR_REGNUM);
        return frame_unwind_got_constant (this_frame, regnum,
  					arm_addr_bits_remove (gdbarch, lr));
  
      case ARM_PS_REGNUM:
        /* Reconstruct the T bit; see arm_prologue_prev_register for details.  */
        cpsr = get_frame_register_unsigned (this_frame, regnum);
        lr = frame_unwind_register_unsigned (this_frame, ARM_LR_REGNUM);
        if (IS_THUMB_ADDR (lr))
  	cpsr |= t_bit;
        else
  	cpsr &= ~t_bit;
        return frame_unwind_got_constant (this_frame, regnum, cpsr);
  
      default:
        internal_error (__FILE__, __LINE__,
  		      _("Unexpected register %d"), regnum);
      }
  }
  
  static void
  arm_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
  			   struct dwarf2_frame_state_reg *reg,
  			   struct frame_info *this_frame)
  {
    switch (regnum)
      {
      case ARM_PC_REGNUM:
      case ARM_PS_REGNUM:
        reg->how = DWARF2_FRAME_REG_FN;
        reg->loc.fn = arm_dwarf2_prev_register;
        break;
      case ARM_SP_REGNUM:
        reg->how = DWARF2_FRAME_REG_CFA;
        break;
      }
  }
  
  /* Implement the stack_frame_destroyed_p gdbarch method.  */
  
  static int
  thumb_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
  {
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    unsigned int insn, insn2;
    int found_return = 0, found_stack_adjust = 0;
    CORE_ADDR func_start, func_end;
    CORE_ADDR scan_pc;
    gdb_byte buf[4];
  
    if (!find_pc_partial_function (pc, NULL, &func_start, &func_end))
      return 0;
  
    /* The epilogue is a sequence of instructions along the following lines:
  
      - add stack frame size to SP or FP
      - [if frame pointer used] restore SP from FP
      - restore registers from SP [may include PC]
      - a return-type instruction [if PC wasn't already restored]
  
      In a first pass, we scan forward from the current PC and verify the
      instructions we find as compatible with this sequence, ending in a
      return instruction.
  
      However, this is not sufficient to distinguish indirect function calls
      within a function from indirect tail calls in the epilogue in some cases.
      Therefore, if we didn't already find any SP-changing instruction during
      forward scan, we add a backward scanning heuristic to ensure we actually
      are in the epilogue.  */
  
    scan_pc = pc;
    while (scan_pc < func_end && !found_return)
      {
        if (target_read_memory (scan_pc, buf, 2))
  	break;
  
        scan_pc += 2;
        insn = extract_unsigned_integer (buf, 2, byte_order_for_code);
  
        if ((insn & 0xff80) == 0x4700)  /* bx <Rm> */
  	found_return = 1;
        else if (insn == 0x46f7)  /* mov pc, lr */
  	found_return = 1;
        else if (thumb_instruction_restores_sp (insn))
  	{
  	  if ((insn & 0xff00) == 0xbd00)  /* pop <registers, PC> */
  	    found_return = 1;
  	}
        else if (thumb_insn_size (insn) == 4)  /* 32-bit Thumb-2 instruction */
  	{
  	  if (target_read_memory (scan_pc, buf, 2))
  	    break;
  
  	  scan_pc += 2;
  	  insn2 = extract_unsigned_integer (buf, 2, byte_order_for_code);
  
  	  if (insn == 0xe8bd)  /* ldm.w sp!, <registers> */
  	    {
  	      if (insn2 & 0x8000)  /* <registers> include PC.  */
  		found_return = 1;
  	    }
  	  else if (insn == 0xf85d  /* ldr.w <Rt>, [sp], #4 */
  		   && (insn2 & 0x0fff) == 0x0b04)
  	    {
  	      if ((insn2 & 0xf000) == 0xf000) /* <Rt> is PC.  */
  		found_return = 1;
  	    }
  	  else if ((insn & 0xffbf) == 0xecbd  /* vldm sp!, <list> */
  		   && (insn2 & 0x0e00) == 0x0a00)
  	    ;
  	  else
  	    break;
  	}
        else
  	break;
      }
  
    if (!found_return)
      return 0;
  
    /* Since any instruction in the epilogue sequence, with the possible
       exception of return itself, updates the stack pointer, we need to
       scan backwards for at most one instruction.  Try either a 16-bit or
       a 32-bit instruction.  This is just a heuristic, so we do not worry
       too much about false positives.  */
  
    if (pc - 4 < func_start)
      return 0;
    if (target_read_memory (pc - 4, buf, 4))
      return 0;
  
    insn = extract_unsigned_integer (buf, 2, byte_order_for_code);
    insn2 = extract_unsigned_integer (buf + 2, 2, byte_order_for_code);
  
    if (thumb_instruction_restores_sp (insn2))
      found_stack_adjust = 1;
    else if (insn == 0xe8bd)  /* ldm.w sp!, <registers> */
      found_stack_adjust = 1;
    else if (insn == 0xf85d  /* ldr.w <Rt>, [sp], #4 */
  	   && (insn2 & 0x0fff) == 0x0b04)
      found_stack_adjust = 1;
    else if ((insn & 0xffbf) == 0xecbd  /* vldm sp!, <list> */
  	   && (insn2 & 0x0e00) == 0x0a00)
      found_stack_adjust = 1;
  
    return found_stack_adjust;
  }
  
  static int
  arm_stack_frame_destroyed_p_1 (struct gdbarch *gdbarch, CORE_ADDR pc)
  {
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    unsigned int insn;
    int found_return;
    CORE_ADDR func_start, func_end;
  
    if (!find_pc_partial_function (pc, NULL, &func_start, &func_end))
      return 0;
  
    /* We are in the epilogue if the previous instruction was a stack
       adjustment and the next instruction is a possible return (bx, mov
       pc, or pop).  We could have to scan backwards to find the stack
       adjustment, or forwards to find the return, but this is a decent
       approximation.  First scan forwards.  */
  
    found_return = 0;
    insn = read_memory_unsigned_integer (pc, 4, byte_order_for_code);
    if (bits (insn, 28, 31) != INST_NV)
      {
        if ((insn & 0x0ffffff0) == 0x012fff10)
  	/* BX.  */
  	found_return = 1;
        else if ((insn & 0x0ffffff0) == 0x01a0f000)
  	/* MOV PC.  */
  	found_return = 1;
        else if ((insn & 0x0fff0000) == 0x08bd0000
  	  && (insn & 0x0000c000) != 0)
  	/* POP (LDMIA), including PC or LR.  */
  	found_return = 1;
      }
  
    if (!found_return)
      return 0;
  
    /* Scan backwards.  This is just a heuristic, so do not worry about
       false positives from mode changes.  */
  
    if (pc < func_start + 4)
      return 0;
  
    insn = read_memory_unsigned_integer (pc - 4, 4, byte_order_for_code);
    if (arm_instruction_restores_sp (insn))
      return 1;
  
    return 0;
  }
  
  /* Implement the stack_frame_destroyed_p gdbarch method.  */
  
  static int
  arm_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
  {
    if (arm_pc_is_thumb (gdbarch, pc))
      return thumb_stack_frame_destroyed_p (gdbarch, pc);
    else
      return arm_stack_frame_destroyed_p_1 (gdbarch, pc);
  }
  
  /* When arguments must be pushed onto the stack, they go on in reverse
     order.  The code below implements a FILO (stack) to do this.  */
  
  struct stack_item
  {
    int len;
    struct stack_item *prev;
    gdb_byte *data;
  };
  
  static struct stack_item *
  push_stack_item (struct stack_item *prev, const gdb_byte *contents, int len)
  {
    struct stack_item *si;
    si = XNEW (struct stack_item);
    si->data = (gdb_byte *) xmalloc (len);
    si->len = len;
    si->prev = prev;
    memcpy (si->data, contents, len);
    return si;
  }
  
  static struct stack_item *
  pop_stack_item (struct stack_item *si)
  {
    struct stack_item *dead = si;
    si = si->prev;
    xfree (dead->data);
    xfree (dead);
    return si;
  }
  
  
  /* Return the alignment (in bytes) of the given type.  */
  
  static int
  arm_type_align (struct type *t)
  {
    int n;
    int align;
    int falign;
  
    t = check_typedef (t);
    switch (TYPE_CODE (t))
      {
      default:
        /* Should never happen.  */
        internal_error (__FILE__, __LINE__, _("unknown type alignment"));
        return 4;
  
      case TYPE_CODE_PTR:
      case TYPE_CODE_ENUM:
      case TYPE_CODE_INT:
      case TYPE_CODE_FLT:
      case TYPE_CODE_SET:
      case TYPE_CODE_RANGE:
      case TYPE_CODE_REF:
      case TYPE_CODE_CHAR:
      case TYPE_CODE_BOOL:
        return TYPE_LENGTH (t);
  
      case TYPE_CODE_ARRAY:
        if (TYPE_VECTOR (t))
  	{
  	  /* Use the natural alignment for vector types (the same for
  	     scalar type), but the maximum alignment is 64-bit.  */
  	  if (TYPE_LENGTH (t) > 8)
  	    return 8;
  	  else
  	    return TYPE_LENGTH (t);
  	}
        else
  	return arm_type_align (TYPE_TARGET_TYPE (t));
      case TYPE_CODE_COMPLEX:
        return arm_type_align (TYPE_TARGET_TYPE (t));
  
      case TYPE_CODE_STRUCT:
      case TYPE_CODE_UNION:
        align = 1;
        for (n = 0; n < TYPE_NFIELDS (t); n++)
  	{
  	  falign = arm_type_align (TYPE_FIELD_TYPE (t, n));
  	  if (falign > align)
  	    align = falign;
  	}
        return align;
      }
  }
  
  /* Possible base types for a candidate for passing and returning in
     VFP registers.  */
  
  enum arm_vfp_cprc_base_type
  {
    VFP_CPRC_UNKNOWN,
    VFP_CPRC_SINGLE,
    VFP_CPRC_DOUBLE,
    VFP_CPRC_VEC64,
    VFP_CPRC_VEC128
  };
  
  /* The length of one element of base type B.  */
  
  static unsigned
  arm_vfp_cprc_unit_length (enum arm_vfp_cprc_base_type b)
  {
    switch (b)
      {
      case VFP_CPRC_SINGLE:
        return 4;
      case VFP_CPRC_DOUBLE:
        return 8;
      case VFP_CPRC_VEC64:
        return 8;
      case VFP_CPRC_VEC128:
        return 16;
      default:
        internal_error (__FILE__, __LINE__, _("Invalid VFP CPRC type: %d."),
  		      (int) b);
      }
  }
  
  /* The character ('s', 'd' or 'q') for the type of VFP register used
     for passing base type B.  */
  
  static int
  arm_vfp_cprc_reg_char (enum arm_vfp_cprc_base_type b)
  {
    switch (b)
      {
      case VFP_CPRC_SINGLE:
        return 's';
      case VFP_CPRC_DOUBLE:
        return 'd';
      case VFP_CPRC_VEC64:
        return 'd';
      case VFP_CPRC_VEC128:
        return 'q';
      default:
        internal_error (__FILE__, __LINE__, _("Invalid VFP CPRC type: %d."),
  		      (int) b);
      }
  }
  
  /* Determine whether T may be part of a candidate for passing and
     returning in VFP registers, ignoring the limit on the total number
     of components.  If *BASE_TYPE is VFP_CPRC_UNKNOWN, set it to the
     classification of the first valid component found; if it is not
     VFP_CPRC_UNKNOWN, all components must have the same classification
     as *BASE_TYPE.  If it is found that T contains a type not permitted
     for passing and returning in VFP registers, a type differently
     classified from *BASE_TYPE, or two types differently classified
     from each other, return -1, otherwise return the total number of
     base-type elements found (possibly 0 in an empty structure or
     array).  Vector types are not currently supported, matching the
     generic AAPCS support.  */
  
  static int
  arm_vfp_cprc_sub_candidate (struct type *t,
  			    enum arm_vfp_cprc_base_type *base_type)
  {
    t = check_typedef (t);
    switch (TYPE_CODE (t))
      {
      case TYPE_CODE_FLT:
        switch (TYPE_LENGTH (t))
  	{
  	case 4:
  	  if (*base_type == VFP_CPRC_UNKNOWN)
  	    *base_type = VFP_CPRC_SINGLE;
  	  else if (*base_type != VFP_CPRC_SINGLE)
  	    return -1;
  	  return 1;
  
  	case 8:
  	  if (*base_type == VFP_CPRC_UNKNOWN)
  	    *base_type = VFP_CPRC_DOUBLE;
  	  else if (*base_type != VFP_CPRC_DOUBLE)
  	    return -1;
  	  return 1;
  
  	default:
  	  return -1;
  	}
        break;
  
      case TYPE_CODE_COMPLEX:
        /* Arguments of complex T where T is one of the types float or
  	 double get treated as if they are implemented as:
  
  	 struct complexT
  	 {
  	   T real;
  	   T imag;
  	 };
  
        */
        switch (TYPE_LENGTH (t))
  	{
  	case 8:
  	  if (*base_type == VFP_CPRC_UNKNOWN)
  	    *base_type = VFP_CPRC_SINGLE;
  	  else if (*base_type != VFP_CPRC_SINGLE)
  	    return -1;
  	  return 2;
  
  	case 16:
  	  if (*base_type == VFP_CPRC_UNKNOWN)
  	    *base_type = VFP_CPRC_DOUBLE;
  	  else if (*base_type != VFP_CPRC_DOUBLE)
  	    return -1;
  	  return 2;
  
  	default:
  	  return -1;
  	}
        break;
  
      case TYPE_CODE_ARRAY:
        {
  	if (TYPE_VECTOR (t))
  	  {
  	    /* A 64-bit or 128-bit containerized vector type are VFP
  	       CPRCs.  */
  	    switch (TYPE_LENGTH (t))
  	      {
  	      case 8:
  		if (*base_type == VFP_CPRC_UNKNOWN)
  		  *base_type = VFP_CPRC_VEC64;
  		return 1;
  	      case 16:
  		if (*base_type == VFP_CPRC_UNKNOWN)
  		  *base_type = VFP_CPRC_VEC128;
  		return 1;
  	      default:
  		return -1;
  	      }
  	  }
  	else
  	  {
  	    int count;
  	    unsigned unitlen;
  
  	    count = arm_vfp_cprc_sub_candidate (TYPE_TARGET_TYPE (t),
  						base_type);
  	    if (count == -1)
  	      return -1;
  	    if (TYPE_LENGTH (t) == 0)
  	      {
  		gdb_assert (count == 0);
  		return 0;
  	      }
  	    else if (count == 0)
  	      return -1;
  	    unitlen = arm_vfp_cprc_unit_length (*base_type);
  	    gdb_assert ((TYPE_LENGTH (t) % unitlen) == 0);
  	    return TYPE_LENGTH (t) / unitlen;
  	  }
        }
        break;
  
      case TYPE_CODE_STRUCT:
        {
  	int count = 0;
  	unsigned unitlen;
  	int i;
  	for (i = 0; i < TYPE_NFIELDS (t); i++)
  	  {
  	    int sub_count = 0;
  
  	    if (!field_is_static (&TYPE_FIELD (t, i)))
  	      sub_count = arm_vfp_cprc_sub_candidate (TYPE_FIELD_TYPE (t, i),
  						      base_type);
  	    if (sub_count == -1)
  	      return -1;
  	    count += sub_count;
  	  }
  	if (TYPE_LENGTH (t) == 0)
  	  {
  	    gdb_assert (count == 0);
  	    return 0;
  	  }
  	else if (count == 0)
  	  return -1;
  	unitlen = arm_vfp_cprc_unit_length (*base_type);
  	if (TYPE_LENGTH (t) != unitlen * count)
  	  return -1;
  	return count;
        }
  
      case TYPE_CODE_UNION:
        {
  	int count = 0;
  	unsigned unitlen;
  	int i;
  	for (i = 0; i < TYPE_NFIELDS (t); i++)
  	  {
  	    int sub_count = arm_vfp_cprc_sub_candidate (TYPE_FIELD_TYPE (t, i),
  							base_type);
  	    if (sub_count == -1)
  	      return -1;
  	    count = (count > sub_count ? count : sub_count);
  	  }
  	if (TYPE_LENGTH (t) == 0)
  	  {
  	    gdb_assert (count == 0);
  	    return 0;
  	  }
  	else if (count == 0)
  	  return -1;
  	unitlen = arm_vfp_cprc_unit_length (*base_type);
  	if (TYPE_LENGTH (t) != unitlen * count)
  	  return -1;
  	return count;
        }
  
      default:
        break;
      }
  
    return -1;
  }
  
  /* Determine whether T is a VFP co-processor register candidate (CPRC)
     if passed to or returned from a non-variadic function with the VFP
     ABI in effect.  Return 1 if it is, 0 otherwise.  If it is, set
     *BASE_TYPE to the base type for T and *COUNT to the number of
     elements of that base type before returning.  */
  
  static int
  arm_vfp_call_candidate (struct type *t, enum arm_vfp_cprc_base_type *base_type,
  			int *count)
  {
    enum arm_vfp_cprc_base_type b = VFP_CPRC_UNKNOWN;
    int c = arm_vfp_cprc_sub_candidate (t, &b);
    if (c <= 0 || c > 4)
      return 0;
    *base_type = b;
    *count = c;
    return 1;
  }
  
  /* Return 1 if the VFP ABI should be used for passing arguments to and
     returning values from a function of type FUNC_TYPE, 0
     otherwise.  */
  
  static int
  arm_vfp_abi_for_function (struct gdbarch *gdbarch, struct type *func_type)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
    /* Variadic functions always use the base ABI.  Assume that functions
       without debug info are not variadic.  */
    if (func_type && TYPE_VARARGS (check_typedef (func_type)))
      return 0;
    /* The VFP ABI is only supported as a variant of AAPCS.  */
    if (tdep->arm_abi != ARM_ABI_AAPCS)
      return 0;
    return gdbarch_tdep (gdbarch)->fp_model == ARM_FLOAT_VFP;
  }
  
  /* We currently only support passing parameters in integer registers, which
     conforms with GCC's default model, and VFP argument passing following
     the VFP variant of AAPCS.  Several other variants exist and
     we should probably support some of them based on the selected ABI.  */
  
  static CORE_ADDR
  arm_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
  		     struct regcache *regcache, CORE_ADDR bp_addr, int nargs,
  		     struct value **args, CORE_ADDR sp, int struct_return,
  		     CORE_ADDR struct_addr)
  {
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
    int argnum;
    int argreg;
    int nstack;
    struct stack_item *si = NULL;
    int use_vfp_abi;
    struct type *ftype;
    unsigned vfp_regs_free = (1 << 16) - 1;
  
    /* Determine the type of this function and whether the VFP ABI
       applies.  */
    ftype = check_typedef (value_type (function));
    if (TYPE_CODE (ftype) == TYPE_CODE_PTR)
      ftype = check_typedef (TYPE_TARGET_TYPE (ftype));
    use_vfp_abi = arm_vfp_abi_for_function (gdbarch, ftype);
  
    /* Set the return address.  For the ARM, the return breakpoint is
       always at BP_ADDR.  */
    if (arm_pc_is_thumb (gdbarch, bp_addr))
      bp_addr |= 1;
    regcache_cooked_write_unsigned (regcache, ARM_LR_REGNUM, bp_addr);
  
    /* Walk through the list of args and determine how large a temporary
       stack is required.  Need to take care here as structs may be
       passed on the stack, and we have to push them.  */
    nstack = 0;
  
    argreg = ARM_A1_REGNUM;
    nstack = 0;
  
    /* The struct_return pointer occupies the first parameter
       passing register.  */
    if (struct_return)
      {
        if (arm_debug)
  	fprintf_unfiltered (gdb_stdlog, "struct return in %s = %s\n",
  			    gdbarch_register_name (gdbarch, argreg),
  			    paddress (gdbarch, struct_addr));
        regcache_cooked_write_unsigned (regcache, argreg, struct_addr);
        argreg++;
      }
  
    for (argnum = 0; argnum < nargs; argnum++)
      {
        int len;
        struct type *arg_type;
        struct type *target_type;
        enum type_code typecode;
        const bfd_byte *val;
        int align;
        enum arm_vfp_cprc_base_type vfp_base_type;
        int vfp_base_count;
        int may_use_core_reg = 1;
  
        arg_type = check_typedef (value_type (args[argnum]));
        len = TYPE_LENGTH (arg_type);
        target_type = TYPE_TARGET_TYPE (arg_type);
        typecode = TYPE_CODE (arg_type);
        val = value_contents (args[argnum]);
  
        align = arm_type_align (arg_type);
        /* Round alignment up to a whole number of words.  */
        align = (align + INT_REGISTER_SIZE - 1) & ~(INT_REGISTER_SIZE - 1);
        /* Different ABIs have different maximum alignments.  */
        if (gdbarch_tdep (gdbarch)->arm_abi == ARM_ABI_APCS)
  	{
  	  /* The APCS ABI only requires word alignment.  */
  	  align = INT_REGISTER_SIZE;
  	}
        else
  	{
  	  /* The AAPCS requires at most doubleword alignment.  */
  	  if (align > INT_REGISTER_SIZE * 2)
  	    align = INT_REGISTER_SIZE * 2;
  	}
  
        if (use_vfp_abi
  	  && arm_vfp_call_candidate (arg_type, &vfp_base_type,
  				     &vfp_base_count))
  	{
  	  int regno;
  	  int unit_length;
  	  int shift;
  	  unsigned mask;
  
  	  /* Because this is a CPRC it cannot go in a core register or
  	     cause a core register to be skipped for alignment.
  	     Either it goes in VFP registers and the rest of this loop
  	     iteration is skipped for this argument, or it goes on the
  	     stack (and the stack alignment code is correct for this
  	     case).  */
  	  may_use_core_reg = 0;
  
  	  unit_length = arm_vfp_cprc_unit_length (vfp_base_type);
  	  shift = unit_length / 4;
  	  mask = (1 << (shift * vfp_base_count)) - 1;
  	  for (regno = 0; regno < 16; regno += shift)
  	    if (((vfp_regs_free >> regno) & mask) == mask)
  	      break;
  
  	  if (regno < 16)
  	    {
  	      int reg_char;
  	      int reg_scaled;
  	      int i;
  
  	      vfp_regs_free &= ~(mask << regno);
  	      reg_scaled = regno / shift;
  	      reg_char = arm_vfp_cprc_reg_char (vfp_base_type);
  	      for (i = 0; i < vfp_base_count; i++)
  		{
  		  char name_buf[4];
  		  int regnum;
  		  if (reg_char == 'q')
  		    arm_neon_quad_write (gdbarch, regcache, reg_scaled + i,
  					 val + i * unit_length);
  		  else
  		    {
  		      xsnprintf (name_buf, sizeof (name_buf), "%c%d",
  				 reg_char, reg_scaled + i);
  		      regnum = user_reg_map_name_to_regnum (gdbarch, name_buf,
  							    strlen (name_buf));
  		      regcache_cooked_write (regcache, regnum,
  					     val + i * unit_length);
  		    }
  		}
  	      continue;
  	    }
  	  else
  	    {
  	      /* This CPRC could not go in VFP registers, so all VFP
  		 registers are now marked as used.  */
  	      vfp_regs_free = 0;
  	    }
  	}
  
        /* Push stack padding for dowubleword alignment.  */
        if (nstack & (align - 1))
  	{
  	  si = push_stack_item (si, val, INT_REGISTER_SIZE);
  	  nstack += INT_REGISTER_SIZE;
  	}
        
        /* Doubleword aligned quantities must go in even register pairs.  */
        if (may_use_core_reg
  	  && argreg <= ARM_LAST_ARG_REGNUM
  	  && align > INT_REGISTER_SIZE
  	  && argreg & 1)
  	argreg++;
  
        /* If the argument is a pointer to a function, and it is a
  	 Thumb function, create a LOCAL copy of the value and set
  	 the THUMB bit in it.  */
        if (TYPE_CODE_PTR == typecode
  	  && target_type != NULL
  	  && TYPE_CODE_FUNC == TYPE_CODE (check_typedef (target_type)))
  	{
  	  CORE_ADDR regval = extract_unsigned_integer (val, len, byte_order);
  	  if (arm_pc_is_thumb (gdbarch, regval))
  	    {
  	      bfd_byte *copy = (bfd_byte *) alloca (len);
  	      store_unsigned_integer (copy, len, byte_order,
  				      MAKE_THUMB_ADDR (regval));
  	      val = copy;
  	    }
  	}
  
        /* Copy the argument to general registers or the stack in
  	 register-sized pieces.  Large arguments are split between
  	 registers and stack.  */
        while (len > 0)
  	{
  	  int partial_len = len < INT_REGISTER_SIZE ? len : INT_REGISTER_SIZE;
  	  CORE_ADDR regval
  	    = extract_unsigned_integer (val, partial_len, byte_order);
  
  	  if (may_use_core_reg && argreg <= ARM_LAST_ARG_REGNUM)
  	    {
  	      /* The argument is being passed in a general purpose
  		 register.  */
  	      if (byte_order == BFD_ENDIAN_BIG)
  		regval <<= (INT_REGISTER_SIZE - partial_len) * 8;
  	      if (arm_debug)
  		fprintf_unfiltered (gdb_stdlog, "arg %d in %s = 0x%s\n",
  				    argnum,
  				    gdbarch_register_name
  				      (gdbarch, argreg),
  				    phex (regval, INT_REGISTER_SIZE));
  	      regcache_cooked_write_unsigned (regcache, argreg, regval);
  	      argreg++;
  	    }
  	  else
  	    {
  	      gdb_byte buf[INT_REGISTER_SIZE];
  
  	      memset (buf, 0, sizeof (buf));
  	      store_unsigned_integer (buf, partial_len, byte_order, regval);
  
  	      /* Push the arguments onto the stack.  */
  	      if (arm_debug)
  		fprintf_unfiltered (gdb_stdlog, "arg %d @ sp + %d\n",
  				    argnum, nstack);
  	      si = push_stack_item (si, buf, INT_REGISTER_SIZE);
  	      nstack += INT_REGISTER_SIZE;
  	    }
  	      
  	  len -= partial_len;
  	  val += partial_len;
  	}
      }
    /* If we have an odd number of words to push, then decrement the stack
       by one word now, so first stack argument will be dword aligned.  */
    if (nstack & 4)
      sp -= 4;
  
    while (si)
      {
        sp -= si->len;
        write_memory (sp, si->data, si->len);
        si = pop_stack_item (si);
      }
  
    /* Finally, update teh SP register.  */
    regcache_cooked_write_unsigned (regcache, ARM_SP_REGNUM, sp);
  
    return sp;
  }
  
  
  /* Always align the frame to an 8-byte boundary.  This is required on
     some platforms and harmless on the rest.  */
  
  static CORE_ADDR
  arm_frame_align (struct gdbarch *gdbarch, CORE_ADDR sp)
  {
    /* Align the stack to eight bytes.  */
    return sp & ~ (CORE_ADDR) 7;
  }
  
  static void
  print_fpu_flags (struct ui_file *file, int flags)
  {
    if (flags & (1 << 0))
      fputs_filtered ("IVO ", file);
    if (flags & (1 << 1))
      fputs_filtered ("DVZ ", file);
    if (flags & (1 << 2))
      fputs_filtered ("OFL ", file);
    if (flags & (1 << 3))
      fputs_filtered ("UFL ", file);
    if (flags & (1 << 4))
      fputs_filtered ("INX ", file);
    fputc_filtered ('\n', file);
  }
  
  /* Print interesting information about the floating point processor
     (if present) or emulator.  */
  static void
  arm_print_float_info (struct gdbarch *gdbarch, struct ui_file *file,
  		      struct frame_info *frame, const char *args)
  {
    unsigned long status = get_frame_register_unsigned (frame, ARM_FPS_REGNUM);
    int type;
  
    type = (status >> 24) & 127;
    if (status & (1 << 31))
      fprintf_filtered (file, _("Hardware FPU type %d\n"), type);
    else
      fprintf_filtered (file, _("Software FPU type %d\n"), type);
    /* i18n: [floating point unit] mask */
    fputs_filtered (_("mask: "), file);
    print_fpu_flags (file, status >> 16);
    /* i18n: [floating point unit] flags */
    fputs_filtered (_("flags: "), file);
    print_fpu_flags (file, status);
  }
  
  /* Construct the ARM extended floating point type.  */
  static struct type *
  arm_ext_type (struct gdbarch *gdbarch)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  
    if (!tdep->arm_ext_type)
      tdep->arm_ext_type
        = arch_float_type (gdbarch, -1, "builtin_type_arm_ext",
  			 floatformats_arm_ext);
  
    return tdep->arm_ext_type;
  }
  
  static struct type *
  arm_neon_double_type (struct gdbarch *gdbarch)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  
    if (tdep->neon_double_type == NULL)
      {
        struct type *t, *elem;
  
        t = arch_composite_type (gdbarch, "__gdb_builtin_type_neon_d",
  			       TYPE_CODE_UNION);
        elem = builtin_type (gdbarch)->builtin_uint8;
        append_composite_type_field (t, "u8", init_vector_type (elem, 8));
        elem = builtin_type (gdbarch)->builtin_uint16;
        append_composite_type_field (t, "u16", init_vector_type (elem, 4));
        elem = builtin_type (gdbarch)->builtin_uint32;
        append_composite_type_field (t, "u32", init_vector_type (elem, 2));
        elem = builtin_type (gdbarch)->builtin_uint64;
        append_composite_type_field (t, "u64", elem);
        elem = builtin_type (gdbarch)->builtin_float;
        append_composite_type_field (t, "f32", init_vector_type (elem, 2));
        elem = builtin_type (gdbarch)->builtin_double;
        append_composite_type_field (t, "f64", elem);
  
        TYPE_VECTOR (t) = 1;
        TYPE_NAME (t) = "neon_d";
        tdep->neon_double_type = t;
      }
  
    return tdep->neon_double_type;
  }
  
  /* FIXME: The vector types are not correctly ordered on big-endian
     targets.  Just as s0 is the low bits of d0, d0[0] is also the low
     bits of d0 - regardless of what unit size is being held in d0.  So
     the offset of the first uint8 in d0 is 7, but the offset of the
     first float is 4.  This code works as-is for little-endian
     targets.  */
  
  static struct type *
  arm_neon_quad_type (struct gdbarch *gdbarch)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  
    if (tdep->neon_quad_type == NULL)
      {
        struct type *t, *elem;
  
        t = arch_composite_type (gdbarch, "__gdb_builtin_type_neon_q",
  			       TYPE_CODE_UNION);
        elem = builtin_type (gdbarch)->builtin_uint8;
        append_composite_type_field (t, "u8", init_vector_type (elem, 16));
        elem = builtin_type (gdbarch)->builtin_uint16;
        append_composite_type_field (t, "u16", init_vector_type (elem, 8));
        elem = builtin_type (gdbarch)->builtin_uint32;
        append_composite_type_field (t, "u32", init_vector_type (elem, 4));
        elem = builtin_type (gdbarch)->builtin_uint64;
        append_composite_type_field (t, "u64", init_vector_type (elem, 2));
        elem = builtin_type (gdbarch)->builtin_float;
        append_composite_type_field (t, "f32", init_vector_type (elem, 4));
        elem = builtin_type (gdbarch)->builtin_double;
        append_composite_type_field (t, "f64", init_vector_type (elem, 2));
  
        TYPE_VECTOR (t) = 1;
        TYPE_NAME (t) = "neon_q";
        tdep->neon_quad_type = t;
      }
  
    return tdep->neon_quad_type;
  }
  
  /* Return the GDB type object for the "standard" data type of data in
     register N.  */
  
  static struct type *
  arm_register_type (struct gdbarch *gdbarch, int regnum)
  {
    int num_regs = gdbarch_num_regs (gdbarch);
  
    if (gdbarch_tdep (gdbarch)->have_vfp_pseudos
        && regnum >= num_regs && regnum < num_regs + 32)
      return builtin_type (gdbarch)->builtin_float;
  
    if (gdbarch_tdep (gdbarch)->have_neon_pseudos
        && regnum >= num_regs + 32 && regnum < num_regs + 32 + 16)
      return arm_neon_quad_type (gdbarch);
  
    /* If the target description has register information, we are only
       in this function so that we can override the types of
       double-precision registers for NEON.  */
    if (tdesc_has_registers (gdbarch_target_desc (gdbarch)))
      {
        struct type *t = tdesc_register_type (gdbarch, regnum);
  
        if (regnum >= ARM_D0_REGNUM && regnum < ARM_D0_REGNUM + 32
  	  && TYPE_CODE (t) == TYPE_CODE_FLT
  	  && gdbarch_tdep (gdbarch)->have_neon)
  	return arm_neon_double_type (gdbarch);
        else
  	return t;
      }
  
    if (regnum >= ARM_F0_REGNUM && regnum < ARM_F0_REGNUM + NUM_FREGS)
      {
        if (!gdbarch_tdep (gdbarch)->have_fpa_registers)
  	return builtin_type (gdbarch)->builtin_void;
  
        return arm_ext_type (gdbarch);
      }
    else if (regnum == ARM_SP_REGNUM)
      return builtin_type (gdbarch)->builtin_data_ptr;
    else if (regnum == ARM_PC_REGNUM)
      return builtin_type (gdbarch)->builtin_func_ptr;
    else if (regnum >= ARRAY_SIZE (arm_register_names))
      /* These registers are only supported on targets which supply
         an XML description.  */
      return builtin_type (gdbarch)->builtin_int0;
    else
      return builtin_type (gdbarch)->builtin_uint32;
  }
  
  /* Map a DWARF register REGNUM onto the appropriate GDB register
     number.  */
  
  static int
  arm_dwarf_reg_to_regnum (struct gdbarch *gdbarch, int reg)
  {
    /* Core integer regs.  */
    if (reg >= 0 && reg <= 15)
      return reg;
  
    /* Legacy FPA encoding.  These were once used in a way which
       overlapped with VFP register numbering, so their use is
       discouraged, but GDB doesn't support the ARM toolchain
       which used them for VFP.  */
    if (reg >= 16 && reg <= 23)
      return ARM_F0_REGNUM + reg - 16;
  
    /* New assignments for the FPA registers.  */
    if (reg >= 96 && reg <= 103)
      return ARM_F0_REGNUM + reg - 96;
  
    /* WMMX register assignments.  */
    if (reg >= 104 && reg <= 111)
      return ARM_WCGR0_REGNUM + reg - 104;
  
    if (reg >= 112 && reg <= 127)
      return ARM_WR0_REGNUM + reg - 112;
  
    if (reg >= 192 && reg <= 199)
      return ARM_WC0_REGNUM + reg - 192;
  
    /* VFP v2 registers.  A double precision value is actually
       in d1 rather than s2, but the ABI only defines numbering
       for the single precision registers.  This will "just work"
       in GDB for little endian targets (we'll read eight bytes,
       starting in s0 and then progressing to s1), but will be
       reversed on big endian targets with VFP.  This won't
       be a problem for the new Neon quad registers; you're supposed
       to use DW_OP_piece for those.  */
    if (reg >= 64 && reg <= 95)
      {
        char name_buf[4];
  
        xsnprintf (name_buf, sizeof (name_buf), "s%d", reg - 64);
        return user_reg_map_name_to_regnum (gdbarch, name_buf,
  					  strlen (name_buf));
      }
  
    /* VFP v3 / Neon registers.  This range is also used for VFP v2
       registers, except that it now describes d0 instead of s0.  */
    if (reg >= 256 && reg <= 287)
      {
        char name_buf[4];
  
        xsnprintf (name_buf, sizeof (name_buf), "d%d", reg - 256);
        return user_reg_map_name_to_regnum (gdbarch, name_buf,
  					  strlen (name_buf));
      }
  
    return -1;
  }
  
  /* Map GDB internal REGNUM onto the Arm simulator register numbers.  */
  static int
  arm_register_sim_regno (struct gdbarch *gdbarch, int regnum)
  {
    int reg = regnum;
    gdb_assert (reg >= 0 && reg < gdbarch_num_regs (gdbarch));
  
    if (regnum >= ARM_WR0_REGNUM && regnum <= ARM_WR15_REGNUM)
      return regnum - ARM_WR0_REGNUM + SIM_ARM_IWMMXT_COP0R0_REGNUM;
  
    if (regnum >= ARM_WC0_REGNUM && regnum <= ARM_WC7_REGNUM)
      return regnum - ARM_WC0_REGNUM + SIM_ARM_IWMMXT_COP1R0_REGNUM;
  
    if (regnum >= ARM_WCGR0_REGNUM && regnum <= ARM_WCGR7_REGNUM)
      return regnum - ARM_WCGR0_REGNUM + SIM_ARM_IWMMXT_COP1R8_REGNUM;
  
    if (reg < NUM_GREGS)
      return SIM_ARM_R0_REGNUM + reg;
    reg -= NUM_GREGS;
  
    if (reg < NUM_FREGS)
      return SIM_ARM_FP0_REGNUM + reg;
    reg -= NUM_FREGS;
  
    if (reg < NUM_SREGS)
      return SIM_ARM_FPS_REGNUM + reg;
    reg -= NUM_SREGS;
  
    internal_error (__FILE__, __LINE__, _("Bad REGNUM %d"), regnum);
  }
  
  /* NOTE: cagney/2001-08-20: Both convert_from_extended() and
     convert_to_extended() use floatformat_arm_ext_littlebyte_bigword.
     It is thought that this is is the floating-point register format on
     little-endian systems.  */
  
  static void
  convert_from_extended (const struct floatformat *fmt, const void *ptr,
  		       void *dbl, int endianess)
  {
    DOUBLEST d;
  
    if (endianess == BFD_ENDIAN_BIG)
      floatformat_to_doublest (&floatformat_arm_ext_big, ptr, &d);
    else
      floatformat_to_doublest (&floatformat_arm_ext_littlebyte_bigword,
  			     ptr, &d);
    floatformat_from_doublest (fmt, &d, dbl);
  }
  
  static void
  convert_to_extended (const struct floatformat *fmt, void *dbl, const void *ptr,
  		     int endianess)
  {
    DOUBLEST d;
  
    floatformat_to_doublest (fmt, ptr, &d);
    if (endianess == BFD_ENDIAN_BIG)
      floatformat_from_doublest (&floatformat_arm_ext_big, &d, dbl);
    else
      floatformat_from_doublest (&floatformat_arm_ext_littlebyte_bigword,
  			       &d, dbl);
  }
  
  /* Like insert_single_step_breakpoint, but make sure we use a breakpoint
     of the appropriate mode (as encoded in the PC value), even if this
     differs from what would be expected according to the symbol tables.  */
  
  void
  arm_insert_single_step_breakpoint (struct gdbarch *gdbarch,
  				   struct address_space *aspace,
  				   CORE_ADDR pc)
  {
    struct cleanup *old_chain
      = make_cleanup_restore_integer (&arm_override_mode);
  
    arm_override_mode = IS_THUMB_ADDR (pc);
    pc = gdbarch_addr_bits_remove (gdbarch, pc);
  
    insert_single_step_breakpoint (gdbarch, aspace, pc);
  
    do_cleanups (old_chain);
  }
  
  /* Given BUF, which is OLD_LEN bytes ending at ENDADDR, expand
     the buffer to be NEW_LEN bytes ending at ENDADDR.  Return
     NULL if an error occurs.  BUF is freed.  */
  
  static gdb_byte *
  extend_buffer_earlier (gdb_byte *buf, CORE_ADDR endaddr,
  		       int old_len, int new_len)
  {
    gdb_byte *new_buf;
    int bytes_to_read = new_len - old_len;
  
    new_buf = (gdb_byte *) xmalloc (new_len);
    memcpy (new_buf + bytes_to_read, buf, old_len);
    xfree (buf);
    if (target_read_memory (endaddr - new_len, new_buf, bytes_to_read) != 0)
      {
        xfree (new_buf);
        return NULL;
      }
    return new_buf;
  }
  
  /* An IT block is at most the 2-byte IT instruction followed by
     four 4-byte instructions.  The furthest back we must search to
     find an IT block that affects the current instruction is thus
     2 + 3 * 4 == 14 bytes.  */
  #define MAX_IT_BLOCK_PREFIX 14
  
  /* Use a quick scan if there are more than this many bytes of
     code.  */
  #define IT_SCAN_THRESHOLD 32
  
  /* Adjust a breakpoint's address to move breakpoints out of IT blocks.
     A breakpoint in an IT block may not be hit, depending on the
     condition flags.  */
  static CORE_ADDR
  arm_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
  {
    gdb_byte *buf;
    char map_type;
    CORE_ADDR boundary, func_start;
    int buf_len;
    enum bfd_endian order = gdbarch_byte_order_for_code (gdbarch);
    int i, any, last_it, last_it_count;
  
    /* If we are using BKPT breakpoints, none of this is necessary.  */
    if (gdbarch_tdep (gdbarch)->thumb2_breakpoint == NULL)
      return bpaddr;
  
    /* ARM mode does not have this problem.  */
    if (!arm_pc_is_thumb (gdbarch, bpaddr))
      return bpaddr;
  
    /* We are setting a breakpoint in Thumb code that could potentially
       contain an IT block.  The first step is to find how much Thumb
       code there is; we do not need to read outside of known Thumb
       sequences.  */
    map_type = arm_find_mapping_symbol (bpaddr, &boundary);
    if (map_type == 0)
      /* Thumb-2 code must have mapping symbols to have a chance.  */
      return bpaddr;
  
    bpaddr = gdbarch_addr_bits_remove (gdbarch, bpaddr);
  
    if (find_pc_partial_function (bpaddr, NULL, &func_start, NULL)
        && func_start > boundary)
      boundary = func_start;
  
    /* Search for a candidate IT instruction.  We have to do some fancy
       footwork to distinguish a real IT instruction from the second
       half of a 32-bit instruction, but there is no need for that if
       there's no candidate.  */
    buf_len = min (bpaddr - boundary, MAX_IT_BLOCK_PREFIX);
    if (buf_len == 0)
      /* No room for an IT instruction.  */
      return bpaddr;
  
    buf = (gdb_byte *) xmalloc (buf_len);
    if (target_read_memory (bpaddr - buf_len, buf, buf_len) != 0)
      return bpaddr;
    any = 0;
    for (i = 0; i < buf_len; i += 2)
      {
        unsigned short inst1 = extract_unsigned_integer (&buf[i], 2, order);
        if ((inst1 & 0xff00) == 0xbf00 && (inst1 & 0x000f) != 0)
  	{
  	  any = 1;
  	  break;
  	}
      }
  
    if (any == 0)
      {
        xfree (buf);
        return bpaddr;
      }
  
    /* OK, the code bytes before this instruction contain at least one
       halfword which resembles an IT instruction.  We know that it's
       Thumb code, but there are still two possibilities.  Either the
       halfword really is an IT instruction, or it is the second half of
       a 32-bit Thumb instruction.  The only way we can tell is to
       scan forwards from a known instruction boundary.  */
    if (bpaddr - boundary > IT_SCAN_THRESHOLD)
      {
        int definite;
  
        /* There's a lot of code before this instruction.  Start with an
  	 optimistic search; it's easy to recognize halfwords that can
  	 not be the start of a 32-bit instruction, and use that to
  	 lock on to the instruction boundaries.  */
        buf = extend_buffer_earlier (buf, bpaddr, buf_len, IT_SCAN_THRESHOLD);
        if (buf == NULL)
  	return bpaddr;
        buf_len = IT_SCAN_THRESHOLD;
  
        definite = 0;
        for (i = 0; i < buf_len - sizeof (buf) && ! definite; i += 2)
  	{
  	  unsigned short inst1 = extract_unsigned_integer (&buf[i], 2, order);
  	  if (thumb_insn_size (inst1) == 2)
  	    {
  	      definite = 1;
  	      break;
  	    }
  	}
  
        /* At this point, if DEFINITE, BUF[I] is the first place we
  	 are sure that we know the instruction boundaries, and it is far
  	 enough from BPADDR that we could not miss an IT instruction
  	 affecting BPADDR.  If ! DEFINITE, give up - start from a
  	 known boundary.  */
        if (! definite)
  	{
  	  buf = extend_buffer_earlier (buf, bpaddr, buf_len,
  				       bpaddr - boundary);
  	  if (buf == NULL)
  	    return bpaddr;
  	  buf_len = bpaddr - boundary;
  	  i = 0;
  	}
      }
    else
      {
        buf = extend_buffer_earlier (buf, bpaddr, buf_len, bpaddr - boundary);
        if (buf == NULL)
  	return bpaddr;
        buf_len = bpaddr - boundary;
        i = 0;
      }
  
    /* Scan forwards.  Find the last IT instruction before BPADDR.  */
    last_it = -1;
    last_it_count = 0;
    while (i < buf_len)
      {
        unsigned short inst1 = extract_unsigned_integer (&buf[i], 2, order);
        last_it_count--;
        if ((inst1 & 0xff00) == 0xbf00 && (inst1 & 0x000f) != 0)
  	{
  	  last_it = i;
  	  if (inst1 & 0x0001)
  	    last_it_count = 4;
  	  else if (inst1 & 0x0002)
  	    last_it_count = 3;
  	  else if (inst1 & 0x0004)
  	    last_it_count = 2;
  	  else
  	    last_it_count = 1;
  	}
        i += thumb_insn_size (inst1);
      }
  
    xfree (buf);
  
    if (last_it == -1)
      /* There wasn't really an IT instruction after all.  */
      return bpaddr;
  
    if (last_it_count < 1)
      /* It was too far away.  */
      return bpaddr;
  
    /* This really is a trouble spot.  Move the breakpoint to the IT
       instruction.  */
    return bpaddr - buf_len + last_it;
  }
  
  /* ARM displaced stepping support.
  
     Generally ARM displaced stepping works as follows:
  
     1. When an instruction is to be single-stepped, it is first decoded by
        arm_process_displaced_insn.  Depending on the type of instruction, it is
        then copied to a scratch location, possibly in a modified form.  The
        copy_* set of functions performs such modification, as necessary.  A
        breakpoint is placed after the modified instruction in the scratch space
        to return control to GDB.  Note in particular that instructions which
        modify the PC will no longer do so after modification.
  
     2. The instruction is single-stepped, by setting the PC to the scratch
        location address, and resuming.  Control returns to GDB when the
        breakpoint is hit.
  
     3. A cleanup function (cleanup_*) is called corresponding to the copy_*
        function used for the current instruction.  This function's job is to
        put the CPU/memory state back to what it would have been if the
        instruction had been executed unmodified in its original location.  */
  
  /* NOP instruction (mov r0, r0).  */
  #define ARM_NOP				0xe1a00000
  #define THUMB_NOP 0x4600
  
  /* Helper for register reads for displaced stepping.  In particular, this
     returns the PC as it would be seen by the instruction at its original
     location.  */
  
  ULONGEST
  displaced_read_reg (struct regcache *regs, struct displaced_step_closure *dsc,
  		    int regno)
  {
    ULONGEST ret;
    CORE_ADDR from = dsc->insn_addr;
  
    if (regno == ARM_PC_REGNUM)
      {
        /* Compute pipeline offset:
  	 - When executing an ARM instruction, PC reads as the address of the
  	 current instruction plus 8.
  	 - When executing a Thumb instruction, PC reads as the address of the
  	 current instruction plus 4.  */
  
        if (!dsc->is_thumb)
  	from += 8;
        else
  	from += 4;
  
        if (debug_displaced)
  	fprintf_unfiltered (gdb_stdlog, "displaced: read pc value %.8lx\n",
  			    (unsigned long) from);
        return (ULONGEST) from;
      }
    else
      {
        regcache_cooked_read_unsigned (regs, regno, &ret);
        if (debug_displaced)
  	fprintf_unfiltered (gdb_stdlog, "displaced: read r%d value %.8lx\n",
  			    regno, (unsigned long) ret);
        return ret;
      }
  }
  
  static int
  displaced_in_arm_mode (struct regcache *regs)
  {
    ULONGEST ps;
    ULONGEST t_bit = arm_psr_thumb_bit (get_regcache_arch (regs));
  
    regcache_cooked_read_unsigned (regs, ARM_PS_REGNUM, &ps);
  
    return (ps & t_bit) == 0;
  }
  
  /* Write to the PC as from a branch instruction.  */
  
  static void
  branch_write_pc (struct regcache *regs, struct displaced_step_closure *dsc,
  		 ULONGEST val)
  {
    if (!dsc->is_thumb)
      /* Note: If bits 0/1 are set, this branch would be unpredictable for
         architecture versions < 6.  */
      regcache_cooked_write_unsigned (regs, ARM_PC_REGNUM,
  				    val & ~(ULONGEST) 0x3);
    else
      regcache_cooked_write_unsigned (regs, ARM_PC_REGNUM,
  				    val & ~(ULONGEST) 0x1);
  }
  
  /* Write to the PC as from a branch-exchange instruction.  */
  
  static void
  bx_write_pc (struct regcache *regs, ULONGEST val)
  {
    ULONGEST ps;
    ULONGEST t_bit = arm_psr_thumb_bit (get_regcache_arch (regs));
  
    regcache_cooked_read_unsigned (regs, ARM_PS_REGNUM, &ps);
  
    if ((val & 1) == 1)
      {
        regcache_cooked_write_unsigned (regs, ARM_PS_REGNUM, ps | t_bit);
        regcache_cooked_write_unsigned (regs, ARM_PC_REGNUM, val & 0xfffffffe);
      }
    else if ((val & 2) == 0)
      {
        regcache_cooked_write_unsigned (regs, ARM_PS_REGNUM, ps & ~t_bit);
        regcache_cooked_write_unsigned (regs, ARM_PC_REGNUM, val);
      }
    else
      {
        /* Unpredictable behaviour.  Try to do something sensible (switch to ARM
  	  mode, align dest to 4 bytes).  */
        warning (_("Single-stepping BX to non-word-aligned ARM instruction."));
        regcache_cooked_write_unsigned (regs, ARM_PS_REGNUM, ps & ~t_bit);
        regcache_cooked_write_unsigned (regs, ARM_PC_REGNUM, val & 0xfffffffc);
      }
  }
  
  /* Write to the PC as if from a load instruction.  */
  
  static void
  load_write_pc (struct regcache *regs, struct displaced_step_closure *dsc,
  	       ULONGEST val)
  {
    if (DISPLACED_STEPPING_ARCH_VERSION >= 5)
      bx_write_pc (regs, val);
    else
      branch_write_pc (regs, dsc, val);
  }
  
  /* Write to the PC as if from an ALU instruction.  */
  
  static void
  alu_write_pc (struct regcache *regs, struct displaced_step_closure *dsc,
  	      ULONGEST val)
  {
    if (DISPLACED_STEPPING_ARCH_VERSION >= 7 && !dsc->is_thumb)
      bx_write_pc (regs, val);
    else
      branch_write_pc (regs, dsc, val);
  }
  
  /* Helper for writing to registers for displaced stepping.  Writing to the PC
     has a varying effects depending on the instruction which does the write:
     this is controlled by the WRITE_PC argument.  */
  
  void
  displaced_write_reg (struct regcache *regs, struct displaced_step_closure *dsc,
  		     int regno, ULONGEST val, enum pc_write_style write_pc)
  {
    if (regno == ARM_PC_REGNUM)
      {
        if (debug_displaced)
  	fprintf_unfiltered (gdb_stdlog, "displaced: writing pc %.8lx\n",
  			    (unsigned long) val);
        switch (write_pc)
  	{
  	case BRANCH_WRITE_PC:
  	  branch_write_pc (regs, dsc, val);
  	  break;
  
  	case BX_WRITE_PC:
  	  bx_write_pc (regs, val);
    	  break;
  
  	case LOAD_WRITE_PC:
  	  load_write_pc (regs, dsc, val);
    	  break;
  
  	case ALU_WRITE_PC:
  	  alu_write_pc (regs, dsc, val);
    	  break;
  
  	case CANNOT_WRITE_PC:
  	  warning (_("Instruction wrote to PC in an unexpected way when "
  		     "single-stepping"));
  	  break;
  
  	default:
  	  internal_error (__FILE__, __LINE__,
  			  _("Invalid argument to displaced_write_reg"));
  	}
  
        dsc->wrote_to_pc = 1;
      }
    else
      {
        if (debug_displaced)
  	fprintf_unfiltered (gdb_stdlog, "displaced: writing r%d value %.8lx\n",
  			    regno, (unsigned long) val);
        regcache_cooked_write_unsigned (regs, regno, val);
      }
  }
  
  /* This function is used to concisely determine if an instruction INSN
     references PC.  Register fields of interest in INSN should have the
     corresponding fields of BITMASK set to 0b1111.  The function
     returns return 1 if any of these fields in INSN reference the PC
     (also 0b1111, r15), else it returns 0.  */
  
  static int
  insn_references_pc (uint32_t insn, uint32_t bitmask)
  {
    uint32_t lowbit = 1;
  
    while (bitmask != 0)
      {
        uint32_t mask;
  
        for (; lowbit && (bitmask & lowbit) == 0; lowbit <<= 1)
  	;
  
        if (!lowbit)
  	break;
  
        mask = lowbit * 0xf;
  
        if ((insn & mask) == mask)
  	return 1;
  
        bitmask &= ~mask;
      }
  
    return 0;
  }
  
  /* The simplest copy function.  Many instructions have the same effect no
     matter what address they are executed at: in those cases, use this.  */
  
  static int
  arm_copy_unmodified (struct gdbarch *gdbarch, uint32_t insn,
  		     const char *iname, struct displaced_step_closure *dsc)
  {
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying insn %.8lx, "
  			"opcode/class '%s' unmodified\n", (unsigned long) insn,
  			iname);
  
    dsc->modinsn[0] = insn;
  
    return 0;
  }
  
  static int
  thumb_copy_unmodified_32bit (struct gdbarch *gdbarch, uint16_t insn1,
  			     uint16_t insn2, const char *iname,
  			     struct displaced_step_closure *dsc)
  {
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying insn %.4x %.4x, "
  			"opcode/class '%s' unmodified\n", insn1, insn2,
  			iname);
  
    dsc->modinsn[0] = insn1;
    dsc->modinsn[1] = insn2;
    dsc->numinsns = 2;
  
    return 0;
  }
  
  /* Copy 16-bit Thumb(Thumb and 16-bit Thumb-2) instruction without any
     modification.  */
  static int
  thumb_copy_unmodified_16bit (struct gdbarch *gdbarch, uint16_t insn,
  			     const char *iname,
  			     struct displaced_step_closure *dsc)
  {
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying insn %.4x, "
  			"opcode/class '%s' unmodified\n", insn,
  			iname);
  
    dsc->modinsn[0] = insn;
  
    return 0;
  }
  
  /* Preload instructions with immediate offset.  */
  
  static void
  cleanup_preload (struct gdbarch *gdbarch,
  		 struct regcache *regs, struct displaced_step_closure *dsc)
  {
    displaced_write_reg (regs, dsc, 0, dsc->tmp[0], CANNOT_WRITE_PC);
    if (!dsc->u.preload.immed)
      displaced_write_reg (regs, dsc, 1, dsc->tmp[1], CANNOT_WRITE_PC);
  }
  
  static void
  install_preload (struct gdbarch *gdbarch, struct regcache *regs,
  		 struct displaced_step_closure *dsc, unsigned int rn)
  {
    ULONGEST rn_val;
    /* Preload instructions:
  
       {pli/pld} [rn, #+/-imm]
       ->
       {pli/pld} [r0, #+/-imm].  */
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    rn_val = displaced_read_reg (regs, dsc, rn);
    displaced_write_reg (regs, dsc, 0, rn_val, CANNOT_WRITE_PC);
    dsc->u.preload.immed = 1;
  
    dsc->cleanup = &cleanup_preload;
  }
  
  static int
  arm_copy_preload (struct gdbarch *gdbarch, uint32_t insn, struct regcache *regs,
  		  struct displaced_step_closure *dsc)
  {
    unsigned int rn = bits (insn, 16, 19);
  
    if (!insn_references_pc (insn, 0x000f0000ul))
      return arm_copy_unmodified (gdbarch, insn, "preload", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying preload insn %.8lx\n",
  			(unsigned long) insn);
  
    dsc->modinsn[0] = insn & 0xfff0ffff;
  
    install_preload (gdbarch, regs, dsc, rn);
  
    return 0;
  }
  
  static int
  thumb2_copy_preload (struct gdbarch *gdbarch, uint16_t insn1, uint16_t insn2,
  		     struct regcache *regs, struct displaced_step_closure *dsc)
  {
    unsigned int rn = bits (insn1, 0, 3);
    unsigned int u_bit = bit (insn1, 7);
    int imm12 = bits (insn2, 0, 11);
    ULONGEST pc_val;
  
    if (rn != ARM_PC_REGNUM)
      return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2, "preload", dsc);
  
    /* PC is only allowed to use in PLI (immediate,literal) Encoding T3, and
       PLD (literal) Encoding T1.  */
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying pld/pli pc (0x%x) %c imm12 %.4x\n",
  			(unsigned int) dsc->insn_addr, u_bit ? '+' : '-',
  			imm12);
  
    if (!u_bit)
      imm12 = -1 * imm12;
  
    /* Rewrite instruction {pli/pld} PC imm12 into:
       Prepare: tmp[0] <- r0, tmp[1] <- r1, r0 <- pc, r1 <- imm12
  
       {pli/pld} [r0, r1]
  
       Cleanup: r0 <- tmp[0], r1 <- tmp[1].  */
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[1] = displaced_read_reg (regs, dsc, 1);
  
    pc_val = displaced_read_reg (regs, dsc, ARM_PC_REGNUM);
  
    displaced_write_reg (regs, dsc, 0, pc_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 1, imm12, CANNOT_WRITE_PC);
    dsc->u.preload.immed = 0;
  
    /* {pli/pld} [r0, r1] */
    dsc->modinsn[0] = insn1 & 0xfff0;
    dsc->modinsn[1] = 0xf001;
    dsc->numinsns = 2;
  
    dsc->cleanup = &cleanup_preload;
    return 0;
  }
  
  /* Preload instructions with register offset.  */
  
  static void
  install_preload_reg(struct gdbarch *gdbarch, struct regcache *regs,
  		    struct displaced_step_closure *dsc, unsigned int rn,
  		    unsigned int rm)
  {
    ULONGEST rn_val, rm_val;
  
    /* Preload register-offset instructions:
  
       {pli/pld} [rn, rm {, shift}]
       ->
       {pli/pld} [r0, r1 {, shift}].  */
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[1] = displaced_read_reg (regs, dsc, 1);
    rn_val = displaced_read_reg (regs, dsc, rn);
    rm_val = displaced_read_reg (regs, dsc, rm);
    displaced_write_reg (regs, dsc, 0, rn_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 1, rm_val, CANNOT_WRITE_PC);
    dsc->u.preload.immed = 0;
  
    dsc->cleanup = &cleanup_preload;
  }
  
  static int
  arm_copy_preload_reg (struct gdbarch *gdbarch, uint32_t insn,
  		      struct regcache *regs,
  		      struct displaced_step_closure *dsc)
  {
    unsigned int rn = bits (insn, 16, 19);
    unsigned int rm = bits (insn, 0, 3);
  
  
    if (!insn_references_pc (insn, 0x000f000ful))
      return arm_copy_unmodified (gdbarch, insn, "preload reg", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying preload insn %.8lx\n",
  			(unsigned long) insn);
  
    dsc->modinsn[0] = (insn & 0xfff0fff0) | 0x1;
  
    install_preload_reg (gdbarch, regs, dsc, rn, rm);
    return 0;
  }
  
  /* Copy/cleanup coprocessor load and store instructions.  */
  
  static void
  cleanup_copro_load_store (struct gdbarch *gdbarch,
  			  struct regcache *regs,
  			  struct displaced_step_closure *dsc)
  {
    ULONGEST rn_val = displaced_read_reg (regs, dsc, 0);
  
    displaced_write_reg (regs, dsc, 0, dsc->tmp[0], CANNOT_WRITE_PC);
  
    if (dsc->u.ldst.writeback)
      displaced_write_reg (regs, dsc, dsc->u.ldst.rn, rn_val, LOAD_WRITE_PC);
  }
  
  static void
  install_copro_load_store (struct gdbarch *gdbarch, struct regcache *regs,
  			  struct displaced_step_closure *dsc,
  			  int writeback, unsigned int rn)
  {
    ULONGEST rn_val;
  
    /* Coprocessor load/store instructions:
  
       {stc/stc2} [<Rn>, #+/-imm]  (and other immediate addressing modes)
       ->
       {stc/stc2} [r0, #+/-imm].
  
       ldc/ldc2 are handled identically.  */
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    rn_val = displaced_read_reg (regs, dsc, rn);
    /* PC should be 4-byte aligned.  */
    rn_val = rn_val & 0xfffffffc;
    displaced_write_reg (regs, dsc, 0, rn_val, CANNOT_WRITE_PC);
  
    dsc->u.ldst.writeback = writeback;
    dsc->u.ldst.rn = rn;
  
    dsc->cleanup = &cleanup_copro_load_store;
  }
  
  static int
  arm_copy_copro_load_store (struct gdbarch *gdbarch, uint32_t insn,
  			   struct regcache *regs,
  			   struct displaced_step_closure *dsc)
  {
    unsigned int rn = bits (insn, 16, 19);
  
    if (!insn_references_pc (insn, 0x000f0000ul))
      return arm_copy_unmodified (gdbarch, insn, "copro load/store", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying coprocessor "
  			"load/store insn %.8lx\n", (unsigned long) insn);
  
    dsc->modinsn[0] = insn & 0xfff0ffff;
  
    install_copro_load_store (gdbarch, regs, dsc, bit (insn, 25), rn);
  
    return 0;
  }
  
  static int
  thumb2_copy_copro_load_store (struct gdbarch *gdbarch, uint16_t insn1,
  			      uint16_t insn2, struct regcache *regs,
  			      struct displaced_step_closure *dsc)
  {
    unsigned int rn = bits (insn1, 0, 3);
  
    if (rn != ARM_PC_REGNUM)
      return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					"copro load/store", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying coprocessor "
  			"load/store insn %.4x%.4x\n", insn1, insn2);
  
    dsc->modinsn[0] = insn1 & 0xfff0;
    dsc->modinsn[1] = insn2;
    dsc->numinsns = 2;
  
    /* This function is called for copying instruction LDC/LDC2/VLDR, which
       doesn't support writeback, so pass 0.  */
    install_copro_load_store (gdbarch, regs, dsc, 0, rn);
  
    return 0;
  }
  
  /* Clean up branch instructions (actually perform the branch, by setting
     PC).  */
  
  static void
  cleanup_branch (struct gdbarch *gdbarch, struct regcache *regs,
  		struct displaced_step_closure *dsc)
  {
    uint32_t status = displaced_read_reg (regs, dsc, ARM_PS_REGNUM);
    int branch_taken = condition_true (dsc->u.branch.cond, status);
    enum pc_write_style write_pc = dsc->u.branch.exchange
  				 ? BX_WRITE_PC : BRANCH_WRITE_PC;
  
    if (!branch_taken)
      return;
  
    if (dsc->u.branch.link)
      {
        /* The value of LR should be the next insn of current one.  In order
         not to confuse logic hanlding later insn `bx lr', if current insn mode
         is Thumb, the bit 0 of LR value should be set to 1.  */
        ULONGEST next_insn_addr = dsc->insn_addr + dsc->insn_size;
  
        if (dsc->is_thumb)
  	next_insn_addr |= 0x1;
  
        displaced_write_reg (regs, dsc, ARM_LR_REGNUM, next_insn_addr,
  			   CANNOT_WRITE_PC);
      }
  
    displaced_write_reg (regs, dsc, ARM_PC_REGNUM, dsc->u.branch.dest, write_pc);
  }
  
  /* Copy B/BL/BLX instructions with immediate destinations.  */
  
  static void
  install_b_bl_blx (struct gdbarch *gdbarch, struct regcache *regs,
  		  struct displaced_step_closure *dsc,
  		  unsigned int cond, int exchange, int link, long offset)
  {
    /* Implement "BL<cond> <label>" as:
  
       Preparation: cond <- instruction condition
       Insn: mov r0, r0  (nop)
       Cleanup: if (condition true) { r14 <- pc; pc <- label }.
  
       B<cond> similar, but don't set r14 in cleanup.  */
  
    dsc->u.branch.cond = cond;
    dsc->u.branch.link = link;
    dsc->u.branch.exchange = exchange;
  
    dsc->u.branch.dest = dsc->insn_addr;
    if (link && exchange)
      /* For BLX, offset is computed from the Align (PC, 4).  */
      dsc->u.branch.dest = dsc->u.branch.dest & 0xfffffffc;
  
    if (dsc->is_thumb)
      dsc->u.branch.dest += 4 + offset;
    else
      dsc->u.branch.dest += 8 + offset;
  
    dsc->cleanup = &cleanup_branch;
  }
  static int
  arm_copy_b_bl_blx (struct gdbarch *gdbarch, uint32_t insn,
  		   struct regcache *regs, struct displaced_step_closure *dsc)
  {
    unsigned int cond = bits (insn, 28, 31);
    int exchange = (cond == 0xf);
    int link = exchange || bit (insn, 24);
    long offset;
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying %s immediate insn "
  			"%.8lx\n", (exchange) ? "blx" : (link) ? "bl" : "b",
  			(unsigned long) insn);
    if (exchange)
      /* For BLX, set bit 0 of the destination.  The cleanup_branch function will
         then arrange the switch into Thumb mode.  */
      offset = (bits (insn, 0, 23) << 2) | (bit (insn, 24) << 1) | 1;
    else
      offset = bits (insn, 0, 23) << 2;
  
    if (bit (offset, 25))
      offset = offset | ~0x3ffffff;
  
    dsc->modinsn[0] = ARM_NOP;
  
    install_b_bl_blx (gdbarch, regs, dsc, cond, exchange, link, offset);
    return 0;
  }
  
  static int
  thumb2_copy_b_bl_blx (struct gdbarch *gdbarch, uint16_t insn1,
  		      uint16_t insn2, struct regcache *regs,
  		      struct displaced_step_closure *dsc)
  {
    int link = bit (insn2, 14);
    int exchange = link && !bit (insn2, 12);
    int cond = INST_AL;
    long offset = 0;
    int j1 = bit (insn2, 13);
    int j2 = bit (insn2, 11);
    int s = sbits (insn1, 10, 10);
    int i1 = !(j1 ^ bit (insn1, 10));
    int i2 = !(j2 ^ bit (insn1, 10));
  
    if (!link && !exchange) /* B */
      {
        offset = (bits (insn2, 0, 10) << 1);
        if (bit (insn2, 12)) /* Encoding T4 */
  	{
  	  offset |= (bits (insn1, 0, 9) << 12)
  	    | (i2 << 22)
  	    | (i1 << 23)
  	    | (s << 24);
  	  cond = INST_AL;
  	}
        else /* Encoding T3 */
  	{
  	  offset |= (bits (insn1, 0, 5) << 12)
  	    | (j1 << 18)
  	    | (j2 << 19)
  	    | (s << 20);
  	  cond = bits (insn1, 6, 9);
  	}
      }
    else
      {
        offset = (bits (insn1, 0, 9) << 12);
        offset |= ((i2 << 22) | (i1 << 23) | (s << 24));
        offset |= exchange ?
  	(bits (insn2, 1, 10) << 2) : (bits (insn2, 0, 10) << 1);
      }
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying %s insn "
  			"%.4x %.4x with offset %.8lx\n",
  			link ? (exchange) ? "blx" : "bl" : "b",
  			insn1, insn2, offset);
  
    dsc->modinsn[0] = THUMB_NOP;
  
    install_b_bl_blx (gdbarch, regs, dsc, cond, exchange, link, offset);
    return 0;
  }
  
  /* Copy B Thumb instructions.  */
  static int
  thumb_copy_b (struct gdbarch *gdbarch, uint16_t insn,
  	      struct displaced_step_closure *dsc)
  {
    unsigned int cond = 0;
    int offset = 0;
    unsigned short bit_12_15 = bits (insn, 12, 15);
    CORE_ADDR from = dsc->insn_addr;
  
    if (bit_12_15 == 0xd)
      {
        /* offset = SignExtend (imm8:0, 32) */
        offset = sbits ((insn << 1), 0, 8);
        cond = bits (insn, 8, 11);
      }
    else if (bit_12_15 == 0xe) /* Encoding T2 */
      {
        offset = sbits ((insn << 1), 0, 11);
        cond = INST_AL;
      }
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying b immediate insn %.4x "
  			"with offset %d\n", insn, offset);
  
    dsc->u.branch.cond = cond;
    dsc->u.branch.link = 0;
    dsc->u.branch.exchange = 0;
    dsc->u.branch.dest = from + 4 + offset;
  
    dsc->modinsn[0] = THUMB_NOP;
  
    dsc->cleanup = &cleanup_branch;
  
    return 0;
  }
  
  /* Copy BX/BLX with register-specified destinations.  */
  
  static void
  install_bx_blx_reg (struct gdbarch *gdbarch, struct regcache *regs,
  		    struct displaced_step_closure *dsc, int link,
  		    unsigned int cond, unsigned int rm)
  {
    /* Implement {BX,BLX}<cond> <reg>" as:
  
       Preparation: cond <- instruction condition
       Insn: mov r0, r0 (nop)
       Cleanup: if (condition true) { r14 <- pc; pc <- dest; }.
  
       Don't set r14 in cleanup for BX.  */
  
    dsc->u.branch.dest = displaced_read_reg (regs, dsc, rm);
  
    dsc->u.branch.cond = cond;
    dsc->u.branch.link = link;
  
    dsc->u.branch.exchange = 1;
  
    dsc->cleanup = &cleanup_branch;
  }
  
  static int
  arm_copy_bx_blx_reg (struct gdbarch *gdbarch, uint32_t insn,
  		     struct regcache *regs, struct displaced_step_closure *dsc)
  {
    unsigned int cond = bits (insn, 28, 31);
    /* BX:  x12xxx1x
       BLX: x12xxx3x.  */
    int link = bit (insn, 5);
    unsigned int rm = bits (insn, 0, 3);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying insn %.8lx",
  			(unsigned long) insn);
  
    dsc->modinsn[0] = ARM_NOP;
  
    install_bx_blx_reg (gdbarch, regs, dsc, link, cond, rm);
    return 0;
  }
  
  static int
  thumb_copy_bx_blx_reg (struct gdbarch *gdbarch, uint16_t insn,
  		       struct regcache *regs,
  		       struct displaced_step_closure *dsc)
  {
    int link = bit (insn, 7);
    unsigned int rm = bits (insn, 3, 6);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying insn %.4x",
  			(unsigned short) insn);
  
    dsc->modinsn[0] = THUMB_NOP;
  
    install_bx_blx_reg (gdbarch, regs, dsc, link, INST_AL, rm);
  
    return 0;
  }
  
  
  /* Copy/cleanup arithmetic/logic instruction with immediate RHS.  */
  
  static void
  cleanup_alu_imm (struct gdbarch *gdbarch,
  		 struct regcache *regs, struct displaced_step_closure *dsc)
  {
    ULONGEST rd_val = displaced_read_reg (regs, dsc, 0);
    displaced_write_reg (regs, dsc, 0, dsc->tmp[0], CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 1, dsc->tmp[1], CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, dsc->rd, rd_val, ALU_WRITE_PC);
  }
  
  static int
  arm_copy_alu_imm (struct gdbarch *gdbarch, uint32_t insn, struct regcache *regs,
  		  struct displaced_step_closure *dsc)
  {
    unsigned int rn = bits (insn, 16, 19);
    unsigned int rd = bits (insn, 12, 15);
    unsigned int op = bits (insn, 21, 24);
    int is_mov = (op == 0xd);
    ULONGEST rd_val, rn_val;
  
    if (!insn_references_pc (insn, 0x000ff000ul))
      return arm_copy_unmodified (gdbarch, insn, "ALU immediate", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying immediate %s insn "
  			"%.8lx\n", is_mov ? "move" : "ALU",
  			(unsigned long) insn);
  
    /* Instruction is of form:
  
       <op><cond> rd, [rn,] #imm
  
       Rewrite as:
  
       Preparation: tmp1, tmp2 <- r0, r1;
  		  r0, r1 <- rd, rn
       Insn: <op><cond> r0, r1, #imm
       Cleanup: rd <- r0; r0 <- tmp1; r1 <- tmp2
    */
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[1] = displaced_read_reg (regs, dsc, 1);
    rn_val = displaced_read_reg (regs, dsc, rn);
    rd_val = displaced_read_reg (regs, dsc, rd);
    displaced_write_reg (regs, dsc, 0, rd_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 1, rn_val, CANNOT_WRITE_PC);
    dsc->rd = rd;
  
    if (is_mov)
      dsc->modinsn[0] = insn & 0xfff00fff;
    else
      dsc->modinsn[0] = (insn & 0xfff00fff) | 0x10000;
  
    dsc->cleanup = &cleanup_alu_imm;
  
    return 0;
  }
  
  static int
  thumb2_copy_alu_imm (struct gdbarch *gdbarch, uint16_t insn1,
  		     uint16_t insn2, struct regcache *regs,
  		     struct displaced_step_closure *dsc)
  {
    unsigned int op = bits (insn1, 5, 8);
    unsigned int rn, rm, rd;
    ULONGEST rd_val, rn_val;
  
    rn = bits (insn1, 0, 3); /* Rn */
    rm = bits (insn2, 0, 3); /* Rm */
    rd = bits (insn2, 8, 11); /* Rd */
  
    /* This routine is only called for instruction MOV.  */
    gdb_assert (op == 0x2 && rn == 0xf);
  
    if (rm != ARM_PC_REGNUM && rd != ARM_PC_REGNUM)
      return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2, "ALU imm", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying reg %s insn %.4x%.4x\n",
  			"ALU", insn1, insn2);
  
    /* Instruction is of form:
  
       <op><cond> rd, [rn,] #imm
  
       Rewrite as:
  
       Preparation: tmp1, tmp2 <- r0, r1;
  		  r0, r1 <- rd, rn
       Insn: <op><cond> r0, r1, #imm
       Cleanup: rd <- r0; r0 <- tmp1; r1 <- tmp2
    */
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[1] = displaced_read_reg (regs, dsc, 1);
    rn_val = displaced_read_reg (regs, dsc, rn);
    rd_val = displaced_read_reg (regs, dsc, rd);
    displaced_write_reg (regs, dsc, 0, rd_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 1, rn_val, CANNOT_WRITE_PC);
    dsc->rd = rd;
  
    dsc->modinsn[0] = insn1;
    dsc->modinsn[1] = ((insn2 & 0xf0f0) | 0x1);
    dsc->numinsns = 2;
  
    dsc->cleanup = &cleanup_alu_imm;
  
    return 0;
  }
  
  /* Copy/cleanup arithmetic/logic insns with register RHS.  */
  
  static void
  cleanup_alu_reg (struct gdbarch *gdbarch,
  		 struct regcache *regs, struct displaced_step_closure *dsc)
  {
    ULONGEST rd_val;
    int i;
  
    rd_val = displaced_read_reg (regs, dsc, 0);
  
    for (i = 0; i < 3; i++)
      displaced_write_reg (regs, dsc, i, dsc->tmp[i], CANNOT_WRITE_PC);
  
    displaced_write_reg (regs, dsc, dsc->rd, rd_val, ALU_WRITE_PC);
  }
  
  static void
  install_alu_reg (struct gdbarch *gdbarch, struct regcache *regs,
  		 struct displaced_step_closure *dsc,
  		 unsigned int rd, unsigned int rn, unsigned int rm)
  {
    ULONGEST rd_val, rn_val, rm_val;
  
    /* Instruction is of form:
  
       <op><cond> rd, [rn,] rm [, <shift>]
  
       Rewrite as:
  
       Preparation: tmp1, tmp2, tmp3 <- r0, r1, r2;
  		  r0, r1, r2 <- rd, rn, rm
       Insn: <op><cond> r0, [r1,] r2 [, <shift>]
       Cleanup: rd <- r0; r0, r1, r2 <- tmp1, tmp2, tmp3
    */
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[1] = displaced_read_reg (regs, dsc, 1);
    dsc->tmp[2] = displaced_read_reg (regs, dsc, 2);
    rd_val = displaced_read_reg (regs, dsc, rd);
    rn_val = displaced_read_reg (regs, dsc, rn);
    rm_val = displaced_read_reg (regs, dsc, rm);
    displaced_write_reg (regs, dsc, 0, rd_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 1, rn_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 2, rm_val, CANNOT_WRITE_PC);
    dsc->rd = rd;
  
    dsc->cleanup = &cleanup_alu_reg;
  }
  
  static int
  arm_copy_alu_reg (struct gdbarch *gdbarch, uint32_t insn, struct regcache *regs,
  		  struct displaced_step_closure *dsc)
  {
    unsigned int op = bits (insn, 21, 24);
    int is_mov = (op == 0xd);
  
    if (!insn_references_pc (insn, 0x000ff00ful))
      return arm_copy_unmodified (gdbarch, insn, "ALU reg", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying reg %s insn %.8lx\n",
  			is_mov ? "move" : "ALU", (unsigned long) insn);
  
    if (is_mov)
      dsc->modinsn[0] = (insn & 0xfff00ff0) | 0x2;
    else
      dsc->modinsn[0] = (insn & 0xfff00ff0) | 0x10002;
  
    install_alu_reg (gdbarch, regs, dsc, bits (insn, 12, 15), bits (insn, 16, 19),
  		   bits (insn, 0, 3));
    return 0;
  }
  
  static int
  thumb_copy_alu_reg (struct gdbarch *gdbarch, uint16_t insn,
  		    struct regcache *regs,
  		    struct displaced_step_closure *dsc)
  {
    unsigned rm, rd;
  
    rm = bits (insn, 3, 6);
    rd = (bit (insn, 7) << 3) | bits (insn, 0, 2);
  
    if (rd != ARM_PC_REGNUM && rm != ARM_PC_REGNUM)
      return thumb_copy_unmodified_16bit (gdbarch, insn, "ALU reg", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying ALU reg insn %.4x\n",
  			(unsigned short) insn);
  
    dsc->modinsn[0] = ((insn & 0xff00) | 0x10);
  
    install_alu_reg (gdbarch, regs, dsc, rd, rd, rm);
  
    return 0;
  }
  
  /* Cleanup/copy arithmetic/logic insns with shifted register RHS.  */
  
  static void
  cleanup_alu_shifted_reg (struct gdbarch *gdbarch,
  			 struct regcache *regs,
  			 struct displaced_step_closure *dsc)
  {
    ULONGEST rd_val = displaced_read_reg (regs, dsc, 0);
    int i;
  
    for (i = 0; i < 4; i++)
      displaced_write_reg (regs, dsc, i, dsc->tmp[i], CANNOT_WRITE_PC);
  
    displaced_write_reg (regs, dsc, dsc->rd, rd_val, ALU_WRITE_PC);
  }
  
  static void
  install_alu_shifted_reg (struct gdbarch *gdbarch, struct regcache *regs,
  			 struct displaced_step_closure *dsc,
  			 unsigned int rd, unsigned int rn, unsigned int rm,
  			 unsigned rs)
  {
    int i;
    ULONGEST rd_val, rn_val, rm_val, rs_val;
  
    /* Instruction is of form:
  
       <op><cond> rd, [rn,] rm, <shift> rs
  
       Rewrite as:
  
       Preparation: tmp1, tmp2, tmp3, tmp4 <- r0, r1, r2, r3
  		  r0, r1, r2, r3 <- rd, rn, rm, rs
       Insn: <op><cond> r0, r1, r2, <shift> r3
       Cleanup: tmp5 <- r0
  	      r0, r1, r2, r3 <- tmp1, tmp2, tmp3, tmp4
  	      rd <- tmp5
    */
  
    for (i = 0; i < 4; i++)
      dsc->tmp[i] = displaced_read_reg (regs, dsc, i);
  
    rd_val = displaced_read_reg (regs, dsc, rd);
    rn_val = displaced_read_reg (regs, dsc, rn);
    rm_val = displaced_read_reg (regs, dsc, rm);
    rs_val = displaced_read_reg (regs, dsc, rs);
    displaced_write_reg (regs, dsc, 0, rd_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 1, rn_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 2, rm_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 3, rs_val, CANNOT_WRITE_PC);
    dsc->rd = rd;
    dsc->cleanup = &cleanup_alu_shifted_reg;
  }
  
  static int
  arm_copy_alu_shifted_reg (struct gdbarch *gdbarch, uint32_t insn,
  			  struct regcache *regs,
  			  struct displaced_step_closure *dsc)
  {
    unsigned int op = bits (insn, 21, 24);
    int is_mov = (op == 0xd);
    unsigned int rd, rn, rm, rs;
  
    if (!insn_references_pc (insn, 0x000fff0ful))
      return arm_copy_unmodified (gdbarch, insn, "ALU shifted reg", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying shifted reg %s insn "
  			"%.8lx\n", is_mov ? "move" : "ALU",
  			(unsigned long) insn);
  
    rn = bits (insn, 16, 19);
    rm = bits (insn, 0, 3);
    rs = bits (insn, 8, 11);
    rd = bits (insn, 12, 15);
  
    if (is_mov)
      dsc->modinsn[0] = (insn & 0xfff000f0) | 0x302;
    else
      dsc->modinsn[0] = (insn & 0xfff000f0) | 0x10302;
  
    install_alu_shifted_reg (gdbarch, regs, dsc, rd, rn, rm, rs);
  
    return 0;
  }
  
  /* Clean up load instructions.  */
  
  static void
  cleanup_load (struct gdbarch *gdbarch, struct regcache *regs,
  	      struct displaced_step_closure *dsc)
  {
    ULONGEST rt_val, rt_val2 = 0, rn_val;
  
    rt_val = displaced_read_reg (regs, dsc, 0);
    if (dsc->u.ldst.xfersize == 8)
      rt_val2 = displaced_read_reg (regs, dsc, 1);
    rn_val = displaced_read_reg (regs, dsc, 2);
  
    displaced_write_reg (regs, dsc, 0, dsc->tmp[0], CANNOT_WRITE_PC);
    if (dsc->u.ldst.xfersize > 4)
      displaced_write_reg (regs, dsc, 1, dsc->tmp[1], CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 2, dsc->tmp[2], CANNOT_WRITE_PC);
    if (!dsc->u.ldst.immed)
      displaced_write_reg (regs, dsc, 3, dsc->tmp[3], CANNOT_WRITE_PC);
  
    /* Handle register writeback.  */
    if (dsc->u.ldst.writeback)
      displaced_write_reg (regs, dsc, dsc->u.ldst.rn, rn_val, CANNOT_WRITE_PC);
    /* Put result in right place.  */
    displaced_write_reg (regs, dsc, dsc->rd, rt_val, LOAD_WRITE_PC);
    if (dsc->u.ldst.xfersize == 8)
      displaced_write_reg (regs, dsc, dsc->rd + 1, rt_val2, LOAD_WRITE_PC);
  }
  
  /* Clean up store instructions.  */
  
  static void
  cleanup_store (struct gdbarch *gdbarch, struct regcache *regs,
  	       struct displaced_step_closure *dsc)
  {
    ULONGEST rn_val = displaced_read_reg (regs, dsc, 2);
  
    displaced_write_reg (regs, dsc, 0, dsc->tmp[0], CANNOT_WRITE_PC);
    if (dsc->u.ldst.xfersize > 4)
      displaced_write_reg (regs, dsc, 1, dsc->tmp[1], CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 2, dsc->tmp[2], CANNOT_WRITE_PC);
    if (!dsc->u.ldst.immed)
      displaced_write_reg (regs, dsc, 3, dsc->tmp[3], CANNOT_WRITE_PC);
    if (!dsc->u.ldst.restore_r4)
      displaced_write_reg (regs, dsc, 4, dsc->tmp[4], CANNOT_WRITE_PC);
  
    /* Writeback.  */
    if (dsc->u.ldst.writeback)
      displaced_write_reg (regs, dsc, dsc->u.ldst.rn, rn_val, CANNOT_WRITE_PC);
  }
  
  /* Copy "extra" load/store instructions.  These are halfword/doubleword
     transfers, which have a different encoding to byte/word transfers.  */
  
  static int
  arm_copy_extra_ld_st (struct gdbarch *gdbarch, uint32_t insn, int unprivileged,
  		      struct regcache *regs, struct displaced_step_closure *dsc)
  {
    unsigned int op1 = bits (insn, 20, 24);
    unsigned int op2 = bits (insn, 5, 6);
    unsigned int rt = bits (insn, 12, 15);
    unsigned int rn = bits (insn, 16, 19);
    unsigned int rm = bits (insn, 0, 3);
    char load[12]     = {0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1};
    char bytesize[12] = {2, 2, 2, 2, 8, 1, 8, 1, 8, 2, 8, 2};
    int immed = (op1 & 0x4) != 0;
    int opcode;
    ULONGEST rt_val, rt_val2 = 0, rn_val, rm_val = 0;
  
    if (!insn_references_pc (insn, 0x000ff00ful))
      return arm_copy_unmodified (gdbarch, insn, "extra load/store", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying %sextra load/store "
  			"insn %.8lx\n", unprivileged ? "unprivileged " : "",
  			(unsigned long) insn);
  
    opcode = ((op2 << 2) | (op1 & 0x1) | ((op1 & 0x4) >> 1)) - 4;
  
    if (opcode < 0)
      internal_error (__FILE__, __LINE__,
  		    _("copy_extra_ld_st: instruction decode error"));
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[1] = displaced_read_reg (regs, dsc, 1);
    dsc->tmp[2] = displaced_read_reg (regs, dsc, 2);
    if (!immed)
      dsc->tmp[3] = displaced_read_reg (regs, dsc, 3);
  
    rt_val = displaced_read_reg (regs, dsc, rt);
    if (bytesize[opcode] == 8)
      rt_val2 = displaced_read_reg (regs, dsc, rt + 1);
    rn_val = displaced_read_reg (regs, dsc, rn);
    if (!immed)
      rm_val = displaced_read_reg (regs, dsc, rm);
  
    displaced_write_reg (regs, dsc, 0, rt_val, CANNOT_WRITE_PC);
    if (bytesize[opcode] == 8)
      displaced_write_reg (regs, dsc, 1, rt_val2, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 2, rn_val, CANNOT_WRITE_PC);
    if (!immed)
      displaced_write_reg (regs, dsc, 3, rm_val, CANNOT_WRITE_PC);
  
    dsc->rd = rt;
    dsc->u.ldst.xfersize = bytesize[opcode];
    dsc->u.ldst.rn = rn;
    dsc->u.ldst.immed = immed;
    dsc->u.ldst.writeback = bit (insn, 24) == 0 || bit (insn, 21) != 0;
    dsc->u.ldst.restore_r4 = 0;
  
    if (immed)
      /* {ldr,str}<width><cond> rt, [rt2,] [rn, #imm]
  	->
         {ldr,str}<width><cond> r0, [r1,] [r2, #imm].  */
      dsc->modinsn[0] = (insn & 0xfff00fff) | 0x20000;
    else
      /* {ldr,str}<width><cond> rt, [rt2,] [rn, +/-rm]
  	->
         {ldr,str}<width><cond> r0, [r1,] [r2, +/-r3].  */
      dsc->modinsn[0] = (insn & 0xfff00ff0) | 0x20003;
  
    dsc->cleanup = load[opcode] ? &cleanup_load : &cleanup_store;
  
    return 0;
  }
  
  /* Copy byte/half word/word loads and stores.  */
  
  static void
  install_load_store (struct gdbarch *gdbarch, struct regcache *regs,
  		    struct displaced_step_closure *dsc, int load,
  		    int immed, int writeback, int size, int usermode,
  		    int rt, int rm, int rn)
  {
    ULONGEST rt_val, rn_val, rm_val = 0;
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[2] = displaced_read_reg (regs, dsc, 2);
    if (!immed)
      dsc->tmp[3] = displaced_read_reg (regs, dsc, 3);
    if (!load)
      dsc->tmp[4] = displaced_read_reg (regs, dsc, 4);
  
    rt_val = displaced_read_reg (regs, dsc, rt);
    rn_val = displaced_read_reg (regs, dsc, rn);
    if (!immed)
      rm_val = displaced_read_reg (regs, dsc, rm);
  
    displaced_write_reg (regs, dsc, 0, rt_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 2, rn_val, CANNOT_WRITE_PC);
    if (!immed)
      displaced_write_reg (regs, dsc, 3, rm_val, CANNOT_WRITE_PC);
    dsc->rd = rt;
    dsc->u.ldst.xfersize = size;
    dsc->u.ldst.rn = rn;
    dsc->u.ldst.immed = immed;
    dsc->u.ldst.writeback = writeback;
  
    /* To write PC we can do:
  
       Before this sequence of instructions:
       r0 is the PC value got from displaced_read_reg, so r0 = from + 8;
       r2 is the Rn value got from dispalced_read_reg.
  
       Insn1: push {pc} Write address of STR instruction + offset on stack
       Insn2: pop  {r4} Read it back from stack, r4 = addr(Insn1) + offset
       Insn3: sub r4, r4, pc   r4 = addr(Insn1) + offset - pc
                                  = addr(Insn1) + offset - addr(Insn3) - 8
                                  = offset - 16
       Insn4: add r4, r4, #8   r4 = offset - 8
       Insn5: add r0, r0, r4   r0 = from + 8 + offset - 8
                                  = from + offset
       Insn6: str r0, [r2, #imm] (or str r0, [r2, r3])
  
       Otherwise we don't know what value to write for PC, since the offset is
       architecture-dependent (sometimes PC+8, sometimes PC+12).  More details
       of this can be found in Section "Saving from r15" in
       http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0204g/Cihbjifh.html */
  
    dsc->cleanup = load ? &cleanup_load : &cleanup_store;
  }
  
  
  static int
  thumb2_copy_load_literal (struct gdbarch *gdbarch, uint16_t insn1,
  			  uint16_t insn2, struct regcache *regs,
  			  struct displaced_step_closure *dsc, int size)
  {
    unsigned int u_bit = bit (insn1, 7);
    unsigned int rt = bits (insn2, 12, 15);
    int imm12 = bits (insn2, 0, 11);
    ULONGEST pc_val;
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying ldr pc (0x%x) R%d %c imm12 %.4x\n",
  			(unsigned int) dsc->insn_addr, rt, u_bit ? '+' : '-',
  			imm12);
  
    if (!u_bit)
      imm12 = -1 * imm12;
  
    /* Rewrite instruction LDR Rt imm12 into:
  
       Prepare: tmp[0] <- r0, tmp[1] <- r2, tmp[2] <- r3, r2 <- pc, r3 <- imm12
  
       LDR R0, R2, R3,
  
       Cleanup: rt <- r0, r0 <- tmp[0], r2 <- tmp[1], r3 <- tmp[2].  */
  
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[2] = displaced_read_reg (regs, dsc, 2);
    dsc->tmp[3] = displaced_read_reg (regs, dsc, 3);
  
    pc_val = displaced_read_reg (regs, dsc, ARM_PC_REGNUM);
  
    pc_val = pc_val & 0xfffffffc;
  
    displaced_write_reg (regs, dsc, 2, pc_val, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 3, imm12, CANNOT_WRITE_PC);
  
    dsc->rd = rt;
  
    dsc->u.ldst.xfersize = size;
    dsc->u.ldst.immed = 0;
    dsc->u.ldst.writeback = 0;
    dsc->u.ldst.restore_r4 = 0;
  
    /* LDR R0, R2, R3 */
    dsc->modinsn[0] = 0xf852;
    dsc->modinsn[1] = 0x3;
    dsc->numinsns = 2;
  
    dsc->cleanup = &cleanup_load;
  
    return 0;
  }
  
  static int
  thumb2_copy_load_reg_imm (struct gdbarch *gdbarch, uint16_t insn1,
  			  uint16_t insn2, struct regcache *regs,
  			  struct displaced_step_closure *dsc,
  			  int writeback, int immed)
  {
    unsigned int rt = bits (insn2, 12, 15);
    unsigned int rn = bits (insn1, 0, 3);
    unsigned int rm = bits (insn2, 0, 3);  /* Only valid if !immed.  */
    /* In LDR (register), there is also a register Rm, which is not allowed to
       be PC, so we don't have to check it.  */
  
    if (rt != ARM_PC_REGNUM && rn != ARM_PC_REGNUM)
      return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2, "load",
  					dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying ldr r%d [r%d] insn %.4x%.4x\n",
  			 rt, rn, insn1, insn2);
  
    install_load_store (gdbarch, regs, dsc, 1, immed, writeback, 4,
  		      0, rt, rm, rn);
  
    dsc->u.ldst.restore_r4 = 0;
  
    if (immed)
      /* ldr[b]<cond> rt, [rn, #imm], etc.
         ->
         ldr[b]<cond> r0, [r2, #imm].  */
      {
        dsc->modinsn[0] = (insn1 & 0xfff0) | 0x2;
        dsc->modinsn[1] = insn2 & 0x0fff;
      }
    else
      /* ldr[b]<cond> rt, [rn, rm], etc.
         ->
         ldr[b]<cond> r0, [r2, r3].  */
      {
        dsc->modinsn[0] = (insn1 & 0xfff0) | 0x2;
        dsc->modinsn[1] = (insn2 & 0x0ff0) | 0x3;
      }
  
    dsc->numinsns = 2;
  
    return 0;
  }
  
  
  static int
  arm_copy_ldr_str_ldrb_strb (struct gdbarch *gdbarch, uint32_t insn,
  			    struct regcache *regs,
  			    struct displaced_step_closure *dsc,
  			    int load, int size, int usermode)
  {
    int immed = !bit (insn, 25);
    int writeback = (bit (insn, 24) == 0 || bit (insn, 21) != 0);
    unsigned int rt = bits (insn, 12, 15);
    unsigned int rn = bits (insn, 16, 19);
    unsigned int rm = bits (insn, 0, 3);  /* Only valid if !immed.  */
  
    if (!insn_references_pc (insn, 0x000ff00ful))
      return arm_copy_unmodified (gdbarch, insn, "load/store", dsc);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying %s%s r%d [r%d] insn %.8lx\n",
  			load ? (size == 1 ? "ldrb" : "ldr")
  			     : (size == 1 ? "strb" : "str"), usermode ? "t" : "",
  			rt, rn,
  			(unsigned long) insn);
  
    install_load_store (gdbarch, regs, dsc, load, immed, writeback, size,
  		      usermode, rt, rm, rn);
  
    if (load || rt != ARM_PC_REGNUM)
      {
        dsc->u.ldst.restore_r4 = 0;
  
        if (immed)
  	/* {ldr,str}[b]<cond> rt, [rn, #imm], etc.
  	   ->
  	   {ldr,str}[b]<cond> r0, [r2, #imm].  */
  	dsc->modinsn[0] = (insn & 0xfff00fff) | 0x20000;
        else
  	/* {ldr,str}[b]<cond> rt, [rn, rm], etc.
  	   ->
  	   {ldr,str}[b]<cond> r0, [r2, r3].  */
  	dsc->modinsn[0] = (insn & 0xfff00ff0) | 0x20003;
      }
    else
      {
        /* We need to use r4 as scratch.  Make sure it's restored afterwards.  */
        dsc->u.ldst.restore_r4 = 1;
        dsc->modinsn[0] = 0xe92d8000;  /* push {pc} */
        dsc->modinsn[1] = 0xe8bd0010;  /* pop  {r4} */
        dsc->modinsn[2] = 0xe044400f;  /* sub r4, r4, pc.  */
        dsc->modinsn[3] = 0xe2844008;  /* add r4, r4, #8.  */
        dsc->modinsn[4] = 0xe0800004;  /* add r0, r0, r4.  */
  
        /* As above.  */
        if (immed)
  	dsc->modinsn[5] = (insn & 0xfff00fff) | 0x20000;
        else
  	dsc->modinsn[5] = (insn & 0xfff00ff0) | 0x20003;
  
        dsc->numinsns = 6;
      }
  
    dsc->cleanup = load ? &cleanup_load : &cleanup_store;
  
    return 0;
  }
  
  /* Cleanup LDM instructions with fully-populated register list.  This is an
     unfortunate corner case: it's impossible to implement correctly by modifying
     the instruction.  The issue is as follows: we have an instruction,
  
     ldm rN, {r0-r15}
  
     which we must rewrite to avoid loading PC.  A possible solution would be to
     do the load in two halves, something like (with suitable cleanup
     afterwards):
  
     mov r8, rN
     ldm[id][ab] r8!, {r0-r7}
     str r7, <temp>
     ldm[id][ab] r8, {r7-r14}
     <bkpt>
  
     but at present there's no suitable place for <temp>, since the scratch space
     is overwritten before the cleanup routine is called.  For now, we simply
     emulate the instruction.  */
  
  static void
  cleanup_block_load_all (struct gdbarch *gdbarch, struct regcache *regs,
  			struct displaced_step_closure *dsc)
  {
    int inc = dsc->u.block.increment;
    int bump_before = dsc->u.block.before ? (inc ? 4 : -4) : 0;
    int bump_after = dsc->u.block.before ? 0 : (inc ? 4 : -4);
    uint32_t regmask = dsc->u.block.regmask;
    int regno = inc ? 0 : 15;
    CORE_ADDR xfer_addr = dsc->u.block.xfer_addr;
    int exception_return = dsc->u.block.load && dsc->u.block.user
  			 && (regmask & 0x8000) != 0;
    uint32_t status = displaced_read_reg (regs, dsc, ARM_PS_REGNUM);
    int do_transfer = condition_true (dsc->u.block.cond, status);
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  
    if (!do_transfer)
      return;
  
    /* If the instruction is ldm rN, {...pc}^, I don't think there's anything
       sensible we can do here.  Complain loudly.  */
    if (exception_return)
      error (_("Cannot single-step exception return"));
  
    /* We don't handle any stores here for now.  */
    gdb_assert (dsc->u.block.load != 0);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: emulating block transfer: "
  			"%s %s %s\n", dsc->u.block.load ? "ldm" : "stm",
  			dsc->u.block.increment ? "inc" : "dec",
  			dsc->u.block.before ? "before" : "after");
  
    while (regmask)
      {
        uint32_t memword;
  
        if (inc)
  	while (regno <= ARM_PC_REGNUM && (regmask & (1 << regno)) == 0)
  	  regno++;
        else
  	while (regno >= 0 && (regmask & (1 << regno)) == 0)
  	  regno--;
  
        xfer_addr += bump_before;
  
        memword = read_memory_unsigned_integer (xfer_addr, 4, byte_order);
        displaced_write_reg (regs, dsc, regno, memword, LOAD_WRITE_PC);
  
        xfer_addr += bump_after;
  
        regmask &= ~(1 << regno);
      }
  
    if (dsc->u.block.writeback)
      displaced_write_reg (regs, dsc, dsc->u.block.rn, xfer_addr,
  			 CANNOT_WRITE_PC);
  }
  
  /* Clean up an STM which included the PC in the register list.  */
  
  static void
  cleanup_block_store_pc (struct gdbarch *gdbarch, struct regcache *regs,
  			struct displaced_step_closure *dsc)
  {
    uint32_t status = displaced_read_reg (regs, dsc, ARM_PS_REGNUM);
    int store_executed = condition_true (dsc->u.block.cond, status);
    CORE_ADDR pc_stored_at, transferred_regs = bitcount (dsc->u.block.regmask);
    CORE_ADDR stm_insn_addr;
    uint32_t pc_val;
    long offset;
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  
    /* If condition code fails, there's nothing else to do.  */
    if (!store_executed)
      return;
  
    if (dsc->u.block.increment)
      {
        pc_stored_at = dsc->u.block.xfer_addr + 4 * transferred_regs;
  
        if (dsc->u.block.before)
  	 pc_stored_at += 4;
      }
    else
      {
        pc_stored_at = dsc->u.block.xfer_addr;
  
        if (dsc->u.block.before)
  	 pc_stored_at -= 4;
      }
  
    pc_val = read_memory_unsigned_integer (pc_stored_at, 4, byte_order);
    stm_insn_addr = dsc->scratch_base;
    offset = pc_val - stm_insn_addr;
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: detected PC offset %.8lx for "
  			"STM instruction\n", offset);
  
    /* Rewrite the stored PC to the proper value for the non-displaced original
       instruction.  */
    write_memory_unsigned_integer (pc_stored_at, 4, byte_order,
  				 dsc->insn_addr + offset);
  }
  
  /* Clean up an LDM which includes the PC in the register list.  We clumped all
     the registers in the transferred list into a contiguous range r0...rX (to
     avoid loading PC directly and losing control of the debugged program), so we
     must undo that here.  */
  
  static void
  cleanup_block_load_pc (struct gdbarch *gdbarch,
  		       struct regcache *regs,
  		       struct displaced_step_closure *dsc)
  {
    uint32_t status = displaced_read_reg (regs, dsc, ARM_PS_REGNUM);
    int load_executed = condition_true (dsc->u.block.cond, status);
    unsigned int mask = dsc->u.block.regmask, write_reg = ARM_PC_REGNUM;
    unsigned int regs_loaded = bitcount (mask);
    unsigned int num_to_shuffle = regs_loaded, clobbered;
  
    /* The method employed here will fail if the register list is fully populated
       (we need to avoid loading PC directly).  */
    gdb_assert (num_to_shuffle < 16);
  
    if (!load_executed)
      return;
  
    clobbered = (1 << num_to_shuffle) - 1;
  
    while (num_to_shuffle > 0)
      {
        if ((mask & (1 << write_reg)) != 0)
  	{
  	  unsigned int read_reg = num_to_shuffle - 1;
  
  	  if (read_reg != write_reg)
  	    {
  	      ULONGEST rval = displaced_read_reg (regs, dsc, read_reg);
  	      displaced_write_reg (regs, dsc, write_reg, rval, LOAD_WRITE_PC);
  	      if (debug_displaced)
  		fprintf_unfiltered (gdb_stdlog, _("displaced: LDM: move "
  				    "loaded register r%d to r%d\n"), read_reg,
  				    write_reg);
  	    }
  	  else if (debug_displaced)
  	    fprintf_unfiltered (gdb_stdlog, _("displaced: LDM: register "
  				"r%d already in the right place\n"),
  				write_reg);
  
  	  clobbered &= ~(1 << write_reg);
  
  	  num_to_shuffle--;
  	}
  
        write_reg--;
      }
  
    /* Restore any registers we scribbled over.  */
    for (write_reg = 0; clobbered != 0; write_reg++)
      {
        if ((clobbered & (1 << write_reg)) != 0)
  	{
  	  displaced_write_reg (regs, dsc, write_reg, dsc->tmp[write_reg],
  			       CANNOT_WRITE_PC);
  	  if (debug_displaced)
  	    fprintf_unfiltered (gdb_stdlog, _("displaced: LDM: restored "
  				"clobbered register r%d\n"), write_reg);
  	  clobbered &= ~(1 << write_reg);
  	}
      }
  
    /* Perform register writeback manually.  */
    if (dsc->u.block.writeback)
      {
        ULONGEST new_rn_val = dsc->u.block.xfer_addr;
  
        if (dsc->u.block.increment)
  	new_rn_val += regs_loaded * 4;
        else
  	new_rn_val -= regs_loaded * 4;
  
        displaced_write_reg (regs, dsc, dsc->u.block.rn, new_rn_val,
  			   CANNOT_WRITE_PC);
      }
  }
  
  /* Handle ldm/stm, apart from some tricky cases which are unlikely to occur
     in user-level code (in particular exception return, ldm rn, {...pc}^).  */
  
  static int
  arm_copy_block_xfer (struct gdbarch *gdbarch, uint32_t insn,
  		     struct regcache *regs,
  		     struct displaced_step_closure *dsc)
  {
    int load = bit (insn, 20);
    int user = bit (insn, 22);
    int increment = bit (insn, 23);
    int before = bit (insn, 24);
    int writeback = bit (insn, 21);
    int rn = bits (insn, 16, 19);
  
    /* Block transfers which don't mention PC can be run directly
       out-of-line.  */
    if (rn != ARM_PC_REGNUM && (insn & 0x8000) == 0)
      return arm_copy_unmodified (gdbarch, insn, "ldm/stm", dsc);
  
    if (rn == ARM_PC_REGNUM)
      {
        warning (_("displaced: Unpredictable LDM or STM with "
  		 "base register r15"));
        return arm_copy_unmodified (gdbarch, insn, "unpredictable ldm/stm", dsc);
      }
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying block transfer insn "
  			"%.8lx\n", (unsigned long) insn);
  
    dsc->u.block.xfer_addr = displaced_read_reg (regs, dsc, rn);
    dsc->u.block.rn = rn;
  
    dsc->u.block.load = load;
    dsc->u.block.user = user;
    dsc->u.block.increment = increment;
    dsc->u.block.before = before;
    dsc->u.block.writeback = writeback;
    dsc->u.block.cond = bits (insn, 28, 31);
  
    dsc->u.block.regmask = insn & 0xffff;
  
    if (load)
      {
        if ((insn & 0xffff) == 0xffff)
  	{
  	  /* LDM with a fully-populated register list.  This case is
  	     particularly tricky.  Implement for now by fully emulating the
  	     instruction (which might not behave perfectly in all cases, but
  	     these instructions should be rare enough for that not to matter
  	     too much).  */
  	  dsc->modinsn[0] = ARM_NOP;
  
  	  dsc->cleanup = &cleanup_block_load_all;
  	}
        else
  	{
  	  /* LDM of a list of registers which includes PC.  Implement by
  	     rewriting the list of registers to be transferred into a
  	     contiguous chunk r0...rX before doing the transfer, then shuffling
  	     registers into the correct places in the cleanup routine.  */
  	  unsigned int regmask = insn & 0xffff;
  	  unsigned int num_in_list = bitcount (regmask), new_regmask;
  	  unsigned int i;
  
  	  for (i = 0; i < num_in_list; i++)
  	    dsc->tmp[i] = displaced_read_reg (regs, dsc, i);
  
  	  /* Writeback makes things complicated.  We need to avoid clobbering
  	     the base register with one of the registers in our modified
  	     register list, but just using a different register can't work in
  	     all cases, e.g.:
  
  	       ldm r14!, {r0-r13,pc}
  
  	     which would need to be rewritten as:
  
  	       ldm rN!, {r0-r14}
  
  	     but that can't work, because there's no free register for N.
  
  	     Solve this by turning off the writeback bit, and emulating
  	     writeback manually in the cleanup routine.  */
  
  	  if (writeback)
  	    insn &= ~(1 << 21);
  
  	  new_regmask = (1 << num_in_list) - 1;
  
  	  if (debug_displaced)
  	    fprintf_unfiltered (gdb_stdlog, _("displaced: LDM r%d%s, "
  				"{..., pc}: original reg list %.4x, modified "
  				"list %.4x\n"), rn, writeback ? "!" : "",
  				(int) insn & 0xffff, new_regmask);
  
  	  dsc->modinsn[0] = (insn & ~0xffff) | (new_regmask & 0xffff);
  
  	  dsc->cleanup = &cleanup_block_load_pc;
  	}
      }
    else
      {
        /* STM of a list of registers which includes PC.  Run the instruction
  	 as-is, but out of line: this will store the wrong value for the PC,
  	 so we must manually fix up the memory in the cleanup routine.
  	 Doing things this way has the advantage that we can auto-detect
  	 the offset of the PC write (which is architecture-dependent) in
  	 the cleanup routine.  */
        dsc->modinsn[0] = insn;
  
        dsc->cleanup = &cleanup_block_store_pc;
      }
  
    return 0;
  }
  
  static int
  thumb2_copy_block_xfer (struct gdbarch *gdbarch, uint16_t insn1, uint16_t insn2,
  			struct regcache *regs,
  			struct displaced_step_closure *dsc)
  {
    int rn = bits (insn1, 0, 3);
    int load = bit (insn1, 4);
    int writeback = bit (insn1, 5);
  
    /* Block transfers which don't mention PC can be run directly
       out-of-line.  */
    if (rn != ARM_PC_REGNUM && (insn2 & 0x8000) == 0)
      return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2, "ldm/stm", dsc);
  
    if (rn == ARM_PC_REGNUM)
      {
        warning (_("displaced: Unpredictable LDM or STM with "
  		 "base register r15"));
        return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					  "unpredictable ldm/stm", dsc);
      }
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying block transfer insn "
  			"%.4x%.4x\n", insn1, insn2);
  
    /* Clear bit 13, since it should be always zero.  */
    dsc->u.block.regmask = (insn2 & 0xdfff);
    dsc->u.block.rn = rn;
  
    dsc->u.block.load = load;
    dsc->u.block.user = 0;
    dsc->u.block.increment = bit (insn1, 7);
    dsc->u.block.before = bit (insn1, 8);
    dsc->u.block.writeback = writeback;
    dsc->u.block.cond = INST_AL;
    dsc->u.block.xfer_addr = displaced_read_reg (regs, dsc, rn);
  
    if (load)
      {
        if (dsc->u.block.regmask == 0xffff)
  	{
  	  /* This branch is impossible to happen.  */
  	  gdb_assert (0);
  	}
        else
  	{
  	  unsigned int regmask = dsc->u.block.regmask;
  	  unsigned int num_in_list = bitcount (regmask), new_regmask;
  	  unsigned int i;
  
  	  for (i = 0; i < num_in_list; i++)
  	    dsc->tmp[i] = displaced_read_reg (regs, dsc, i);
  
  	  if (writeback)
  	    insn1 &= ~(1 << 5);
  
  	  new_regmask = (1 << num_in_list) - 1;
  
  	  if (debug_displaced)
  	    fprintf_unfiltered (gdb_stdlog, _("displaced: LDM r%d%s, "
  				"{..., pc}: original reg list %.4x, modified "
  				"list %.4x\n"), rn, writeback ? "!" : "",
  				(int) dsc->u.block.regmask, new_regmask);
  
  	  dsc->modinsn[0] = insn1;
  	  dsc->modinsn[1] = (new_regmask & 0xffff);
  	  dsc->numinsns = 2;
  
  	  dsc->cleanup = &cleanup_block_load_pc;
  	}
      }
    else
      {
        dsc->modinsn[0] = insn1;
        dsc->modinsn[1] = insn2;
        dsc->numinsns = 2;
        dsc->cleanup = &cleanup_block_store_pc;
      }
    return 0;
  }
  
  /* Wrapper over read_memory_unsigned_integer for use in arm_get_next_pcs.
   This is used to avoid a dependency on BFD's bfd_endian enum.  */
  
  ULONGEST
  arm_get_next_pcs_read_memory_unsigned_integer (CORE_ADDR memaddr, int len,
  					       int byte_order)
  {
    return read_memory_unsigned_integer (memaddr, len,
  				       (enum bfd_endian) byte_order);
  }
  
  /* Wrapper over gdbarch_addr_bits_remove for use in arm_get_next_pcs.  */
  
  CORE_ADDR
  arm_get_next_pcs_addr_bits_remove (struct arm_get_next_pcs *self,
  				   CORE_ADDR val)
  {
    return gdbarch_addr_bits_remove (get_regcache_arch (self->regcache), val);
  }
  
  /* Wrapper over syscall_next_pc for use in get_next_pcs.  */
  
  static CORE_ADDR
  arm_get_next_pcs_syscall_next_pc (struct arm_get_next_pcs *self)
  {
    return 0;
  }
  
  /* Wrapper over arm_is_thumb for use in arm_get_next_pcs.  */
  
  int
  arm_get_next_pcs_is_thumb (struct arm_get_next_pcs *self)
  {
    return arm_is_thumb (self->regcache);
  }
  
  /* single_step() is called just before we want to resume the inferior,
     if we want to single-step it but there is no hardware or kernel
     single-step support.  We find the target of the coming instructions
     and breakpoint them.  */
  
  int
  arm_software_single_step (struct frame_info *frame)
  {
    struct regcache *regcache = get_current_regcache ();
    struct gdbarch *gdbarch = get_regcache_arch (regcache);
    struct address_space *aspace = get_regcache_aspace (regcache);
    struct arm_get_next_pcs next_pcs_ctx;
    CORE_ADDR pc;
    int i;
    VEC (CORE_ADDR) *next_pcs = NULL;
    struct cleanup *old_chain = make_cleanup (VEC_cleanup (CORE_ADDR), &next_pcs);
  
    arm_get_next_pcs_ctor (&next_pcs_ctx,
  			 &arm_get_next_pcs_ops,
  			 gdbarch_byte_order (gdbarch),
  			 gdbarch_byte_order_for_code (gdbarch),
  			 0,
  			 regcache);
  
    next_pcs = arm_get_next_pcs (&next_pcs_ctx);
  
    for (i = 0; VEC_iterate (CORE_ADDR, next_pcs, i, pc); i++)
      arm_insert_single_step_breakpoint (gdbarch, aspace, pc);
  
    do_cleanups (old_chain);
  
    return 1;
  }
  
  /* Cleanup/copy SVC (SWI) instructions.  These two functions are overridden
     for Linux, where some SVC instructions must be treated specially.  */
  
  static void
  cleanup_svc (struct gdbarch *gdbarch, struct regcache *regs,
  	     struct displaced_step_closure *dsc)
  {
    CORE_ADDR resume_addr = dsc->insn_addr + dsc->insn_size;
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: cleanup for svc, resume at "
  			"%.8lx\n", (unsigned long) resume_addr);
  
    displaced_write_reg (regs, dsc, ARM_PC_REGNUM, resume_addr, BRANCH_WRITE_PC);
  }
  
  
  /* Common copy routine for svc instruciton.  */
  
  static int
  install_svc (struct gdbarch *gdbarch, struct regcache *regs,
  	     struct displaced_step_closure *dsc)
  {
    /* Preparation: none.
       Insn: unmodified svc.
       Cleanup: pc <- insn_addr + insn_size.  */
  
    /* Pretend we wrote to the PC, so cleanup doesn't set PC to the next
       instruction.  */
    dsc->wrote_to_pc = 1;
  
    /* Allow OS-specific code to override SVC handling.  */
    if (dsc->u.svc.copy_svc_os)
      return dsc->u.svc.copy_svc_os (gdbarch, regs, dsc);
    else
      {
        dsc->cleanup = &cleanup_svc;
        return 0;
      }
  }
  
  static int
  arm_copy_svc (struct gdbarch *gdbarch, uint32_t insn,
  	      struct regcache *regs, struct displaced_step_closure *dsc)
  {
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying svc insn %.8lx\n",
  			(unsigned long) insn);
  
    dsc->modinsn[0] = insn;
  
    return install_svc (gdbarch, regs, dsc);
  }
  
  static int
  thumb_copy_svc (struct gdbarch *gdbarch, uint16_t insn,
  		struct regcache *regs, struct displaced_step_closure *dsc)
  {
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying svc insn %.4x\n",
  			insn);
  
    dsc->modinsn[0] = insn;
  
    return install_svc (gdbarch, regs, dsc);
  }
  
  /* Copy undefined instructions.  */
  
  static int
  arm_copy_undef (struct gdbarch *gdbarch, uint32_t insn,
  		struct displaced_step_closure *dsc)
  {
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying undefined insn %.8lx\n",
  			(unsigned long) insn);
  
    dsc->modinsn[0] = insn;
  
    return 0;
  }
  
  static int
  thumb_32bit_copy_undef (struct gdbarch *gdbarch, uint16_t insn1, uint16_t insn2,
                         struct displaced_step_closure *dsc)
  {
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying undefined insn "
                         "%.4x %.4x\n", (unsigned short) insn1,
                         (unsigned short) insn2);
  
    dsc->modinsn[0] = insn1;
    dsc->modinsn[1] = insn2;
    dsc->numinsns = 2;
  
    return 0;
  }
  
  /* Copy unpredictable instructions.  */
  
  static int
  arm_copy_unpred (struct gdbarch *gdbarch, uint32_t insn,
  		 struct displaced_step_closure *dsc)
  {
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying unpredictable insn "
  			"%.8lx\n", (unsigned long) insn);
  
    dsc->modinsn[0] = insn;
  
    return 0;
  }
  
  /* The decode_* functions are instruction decoding helpers.  They mostly follow
     the presentation in the ARM ARM.  */
  
  static int
  arm_decode_misc_memhint_neon (struct gdbarch *gdbarch, uint32_t insn,
  			      struct regcache *regs,
  			      struct displaced_step_closure *dsc)
  {
    unsigned int op1 = bits (insn, 20, 26), op2 = bits (insn, 4, 7);
    unsigned int rn = bits (insn, 16, 19);
  
    if (op1 == 0x10 && (op2 & 0x2) == 0x0 && (rn & 0xe) == 0x0)
      return arm_copy_unmodified (gdbarch, insn, "cps", dsc);
    else if (op1 == 0x10 && op2 == 0x0 && (rn & 0xe) == 0x1)
      return arm_copy_unmodified (gdbarch, insn, "setend", dsc);
    else if ((op1 & 0x60) == 0x20)
      return arm_copy_unmodified (gdbarch, insn, "neon dataproc", dsc);
    else if ((op1 & 0x71) == 0x40)
      return arm_copy_unmodified (gdbarch, insn, "neon elt/struct load/store",
  				dsc);
    else if ((op1 & 0x77) == 0x41)
      return arm_copy_unmodified (gdbarch, insn, "unallocated mem hint", dsc);
    else if ((op1 & 0x77) == 0x45)
      return arm_copy_preload (gdbarch, insn, regs, dsc);  /* pli.  */
    else if ((op1 & 0x77) == 0x51)
      {
        if (rn != 0xf)
  	return arm_copy_preload (gdbarch, insn, regs, dsc);  /* pld/pldw.  */
        else
  	return arm_copy_unpred (gdbarch, insn, dsc);
      }
    else if ((op1 & 0x77) == 0x55)
      return arm_copy_preload (gdbarch, insn, regs, dsc);  /* pld/pldw.  */
    else if (op1 == 0x57)
      switch (op2)
        {
        case 0x1: return arm_copy_unmodified (gdbarch, insn, "clrex", dsc);
        case 0x4: return arm_copy_unmodified (gdbarch, insn, "dsb", dsc);
        case 0x5: return arm_copy_unmodified (gdbarch, insn, "dmb", dsc);
        case 0x6: return arm_copy_unmodified (gdbarch, insn, "isb", dsc);
        default: return arm_copy_unpred (gdbarch, insn, dsc);
        }
    else if ((op1 & 0x63) == 0x43)
      return arm_copy_unpred (gdbarch, insn, dsc);
    else if ((op2 & 0x1) == 0x0)
      switch (op1 & ~0x80)
        {
        case 0x61:
  	return arm_copy_unmodified (gdbarch, insn, "unallocated mem hint", dsc);
        case 0x65:
  	return arm_copy_preload_reg (gdbarch, insn, regs, dsc);  /* pli reg.  */
        case 0x71: case 0x75:
          /* pld/pldw reg.  */
  	return arm_copy_preload_reg (gdbarch, insn, regs, dsc);
        case 0x63: case 0x67: case 0x73: case 0x77:
  	return arm_copy_unpred (gdbarch, insn, dsc);
        default:
  	return arm_copy_undef (gdbarch, insn, dsc);
        }
    else
      return arm_copy_undef (gdbarch, insn, dsc);  /* Probably unreachable.  */
  }
  
  static int
  arm_decode_unconditional (struct gdbarch *gdbarch, uint32_t insn,
  			  struct regcache *regs,
  			  struct displaced_step_closure *dsc)
  {
    if (bit (insn, 27) == 0)
      return arm_decode_misc_memhint_neon (gdbarch, insn, regs, dsc);
    /* Switch on bits: 0bxxxxx321xxx0xxxxxxxxxxxxxxxxxxxx.  */
    else switch (((insn & 0x7000000) >> 23) | ((insn & 0x100000) >> 20))
      {
      case 0x0: case 0x2:
        return arm_copy_unmodified (gdbarch, insn, "srs", dsc);
  
      case 0x1: case 0x3:
        return arm_copy_unmodified (gdbarch, insn, "rfe", dsc);
  
      case 0x4: case 0x5: case 0x6: case 0x7:
        return arm_copy_b_bl_blx (gdbarch, insn, regs, dsc);
  
      case 0x8:
        switch ((insn & 0xe00000) >> 21)
  	{
  	case 0x1: case 0x3: case 0x4: case 0x5: case 0x6: case 0x7:
  	  /* stc/stc2.  */
  	  return arm_copy_copro_load_store (gdbarch, insn, regs, dsc);
  
  	case 0x2:
  	  return arm_copy_unmodified (gdbarch, insn, "mcrr/mcrr2", dsc);
  
  	default:
  	  return arm_copy_undef (gdbarch, insn, dsc);
  	}
  
      case 0x9:
        {
  	 int rn_f = (bits (insn, 16, 19) == 0xf);
  	switch ((insn & 0xe00000) >> 21)
  	  {
  	  case 0x1: case 0x3:
  	    /* ldc/ldc2 imm (undefined for rn == pc).  */
  	    return rn_f ? arm_copy_undef (gdbarch, insn, dsc)
  			: arm_copy_copro_load_store (gdbarch, insn, regs, dsc);
  
  	  case 0x2:
  	    return arm_copy_unmodified (gdbarch, insn, "mrrc/mrrc2", dsc);
  
  	  case 0x4: case 0x5: case 0x6: case 0x7:
  	    /* ldc/ldc2 lit (undefined for rn != pc).  */
  	    return rn_f ? arm_copy_copro_load_store (gdbarch, insn, regs, dsc)
  			: arm_copy_undef (gdbarch, insn, dsc);
  
  	  default:
  	    return arm_copy_undef (gdbarch, insn, dsc);
  	  }
        }
  
      case 0xa:
        return arm_copy_unmodified (gdbarch, insn, "stc/stc2", dsc);
  
      case 0xb:
        if (bits (insn, 16, 19) == 0xf)
          /* ldc/ldc2 lit.  */
  	return arm_copy_copro_load_store (gdbarch, insn, regs, dsc);
        else
  	return arm_copy_undef (gdbarch, insn, dsc);
  
      case 0xc:
        if (bit (insn, 4))
  	return arm_copy_unmodified (gdbarch, insn, "mcr/mcr2", dsc);
        else
  	return arm_copy_unmodified (gdbarch, insn, "cdp/cdp2", dsc);
  
      case 0xd:
        if (bit (insn, 4))
  	return arm_copy_unmodified (gdbarch, insn, "mrc/mrc2", dsc);
        else
  	return arm_copy_unmodified (gdbarch, insn, "cdp/cdp2", dsc);
  
      default:
        return arm_copy_undef (gdbarch, insn, dsc);
      }
  }
  
  /* Decode miscellaneous instructions in dp/misc encoding space.  */
  
  static int
  arm_decode_miscellaneous (struct gdbarch *gdbarch, uint32_t insn,
  			  struct regcache *regs,
  			  struct displaced_step_closure *dsc)
  {
    unsigned int op2 = bits (insn, 4, 6);
    unsigned int op = bits (insn, 21, 22);
  
    switch (op2)
      {
      case 0x0:
        return arm_copy_unmodified (gdbarch, insn, "mrs/msr", dsc);
  
      case 0x1:
        if (op == 0x1)  /* bx.  */
  	return arm_copy_bx_blx_reg (gdbarch, insn, regs, dsc);
        else if (op == 0x3)
  	return arm_copy_unmodified (gdbarch, insn, "clz", dsc);
        else
  	return arm_copy_undef (gdbarch, insn, dsc);
  
      case 0x2:
        if (op == 0x1)
          /* Not really supported.  */
  	return arm_copy_unmodified (gdbarch, insn, "bxj", dsc);
        else
  	return arm_copy_undef (gdbarch, insn, dsc);
  
      case 0x3:
        if (op == 0x1)
  	return arm_copy_bx_blx_reg (gdbarch, insn,
  				regs, dsc);  /* blx register.  */
        else
  	return arm_copy_undef (gdbarch, insn, dsc);
  
      case 0x5:
        return arm_copy_unmodified (gdbarch, insn, "saturating add/sub", dsc);
  
      case 0x7:
        if (op == 0x1)
  	return arm_copy_unmodified (gdbarch, insn, "bkpt", dsc);
        else if (op == 0x3)
          /* Not really supported.  */
  	return arm_copy_unmodified (gdbarch, insn, "smc", dsc);
  
      default:
        return arm_copy_undef (gdbarch, insn, dsc);
      }
  }
  
  static int
  arm_decode_dp_misc (struct gdbarch *gdbarch, uint32_t insn,
  		    struct regcache *regs,
  		    struct displaced_step_closure *dsc)
  {
    if (bit (insn, 25))
      switch (bits (insn, 20, 24))
        {
        case 0x10:
  	return arm_copy_unmodified (gdbarch, insn, "movw", dsc);
  
        case 0x14:
  	return arm_copy_unmodified (gdbarch, insn, "movt", dsc);
  
        case 0x12: case 0x16:
  	return arm_copy_unmodified (gdbarch, insn, "msr imm", dsc);
  
        default:
  	return arm_copy_alu_imm (gdbarch, insn, regs, dsc);
        }
    else
      {
        uint32_t op1 = bits (insn, 20, 24), op2 = bits (insn, 4, 7);
  
        if ((op1 & 0x19) != 0x10 && (op2 & 0x1) == 0x0)
  	return arm_copy_alu_reg (gdbarch, insn, regs, dsc);
        else if ((op1 & 0x19) != 0x10 && (op2 & 0x9) == 0x1)
  	return arm_copy_alu_shifted_reg (gdbarch, insn, regs, dsc);
        else if ((op1 & 0x19) == 0x10 && (op2 & 0x8) == 0x0)
  	return arm_decode_miscellaneous (gdbarch, insn, regs, dsc);
        else if ((op1 & 0x19) == 0x10 && (op2 & 0x9) == 0x8)
  	return arm_copy_unmodified (gdbarch, insn, "halfword mul/mla", dsc);
        else if ((op1 & 0x10) == 0x00 && op2 == 0x9)
  	return arm_copy_unmodified (gdbarch, insn, "mul/mla", dsc);
        else if ((op1 & 0x10) == 0x10 && op2 == 0x9)
  	return arm_copy_unmodified (gdbarch, insn, "synch", dsc);
        else if (op2 == 0xb || (op2 & 0xd) == 0xd)
  	/* 2nd arg means "unprivileged".  */
  	return arm_copy_extra_ld_st (gdbarch, insn, (op1 & 0x12) == 0x02, regs,
  				     dsc);
      }
  
    /* Should be unreachable.  */
    return 1;
  }
  
  static int
  arm_decode_ld_st_word_ubyte (struct gdbarch *gdbarch, uint32_t insn,
  			     struct regcache *regs,
  			     struct displaced_step_closure *dsc)
  {
    int a = bit (insn, 25), b = bit (insn, 4);
    uint32_t op1 = bits (insn, 20, 24);
  
    if ((!a && (op1 & 0x05) == 0x00 && (op1 & 0x17) != 0x02)
        || (a && (op1 & 0x05) == 0x00 && (op1 & 0x17) != 0x02 && !b))
      return arm_copy_ldr_str_ldrb_strb (gdbarch, insn, regs, dsc, 0, 4, 0);
    else if ((!a && (op1 & 0x17) == 0x02)
  	    || (a && (op1 & 0x17) == 0x02 && !b))
      return arm_copy_ldr_str_ldrb_strb (gdbarch, insn, regs, dsc, 0, 4, 1);
    else if ((!a && (op1 & 0x05) == 0x01 && (op1 & 0x17) != 0x03)
  	    || (a && (op1 & 0x05) == 0x01 && (op1 & 0x17) != 0x03 && !b))
      return arm_copy_ldr_str_ldrb_strb (gdbarch, insn, regs, dsc, 1, 4, 0);
    else if ((!a && (op1 & 0x17) == 0x03)
  	   || (a && (op1 & 0x17) == 0x03 && !b))
      return arm_copy_ldr_str_ldrb_strb (gdbarch, insn, regs, dsc, 1, 4, 1);
    else if ((!a && (op1 & 0x05) == 0x04 && (op1 & 0x17) != 0x06)
  	    || (a && (op1 & 0x05) == 0x04 && (op1 & 0x17) != 0x06 && !b))
      return arm_copy_ldr_str_ldrb_strb (gdbarch, insn, regs, dsc, 0, 1, 0);
    else if ((!a && (op1 & 0x17) == 0x06)
  	   || (a && (op1 & 0x17) == 0x06 && !b))
      return arm_copy_ldr_str_ldrb_strb (gdbarch, insn, regs, dsc, 0, 1, 1);
    else if ((!a && (op1 & 0x05) == 0x05 && (op1 & 0x17) != 0x07)
  	   || (a && (op1 & 0x05) == 0x05 && (op1 & 0x17) != 0x07 && !b))
      return arm_copy_ldr_str_ldrb_strb (gdbarch, insn, regs, dsc, 1, 1, 0);
    else if ((!a && (op1 & 0x17) == 0x07)
  	   || (a && (op1 & 0x17) == 0x07 && !b))
      return arm_copy_ldr_str_ldrb_strb (gdbarch, insn, regs, dsc, 1, 1, 1);
  
    /* Should be unreachable.  */
    return 1;
  }
  
  static int
  arm_decode_media (struct gdbarch *gdbarch, uint32_t insn,
  		  struct displaced_step_closure *dsc)
  {
    switch (bits (insn, 20, 24))
      {
      case 0x00: case 0x01: case 0x02: case 0x03:
        return arm_copy_unmodified (gdbarch, insn, "parallel add/sub signed", dsc);
  
      case 0x04: case 0x05: case 0x06: case 0x07:
        return arm_copy_unmodified (gdbarch, insn, "parallel add/sub unsigned", dsc);
  
      case 0x08: case 0x09: case 0x0a: case 0x0b:
      case 0x0c: case 0x0d: case 0x0e: case 0x0f:
        return arm_copy_unmodified (gdbarch, insn,
  			      "decode/pack/unpack/saturate/reverse", dsc);
  
      case 0x18:
        if (bits (insn, 5, 7) == 0)  /* op2.  */
  	 {
  	  if (bits (insn, 12, 15) == 0xf)
  	    return arm_copy_unmodified (gdbarch, insn, "usad8", dsc);
  	  else
  	    return arm_copy_unmodified (gdbarch, insn, "usada8", dsc);
  	}
        else
  	 return arm_copy_undef (gdbarch, insn, dsc);
  
      case 0x1a: case 0x1b:
        if (bits (insn, 5, 6) == 0x2)  /* op2[1:0].  */
  	return arm_copy_unmodified (gdbarch, insn, "sbfx", dsc);
        else
  	return arm_copy_undef (gdbarch, insn, dsc);
  
      case 0x1c: case 0x1d:
        if (bits (insn, 5, 6) == 0x0)  /* op2[1:0].  */
  	 {
  	  if (bits (insn, 0, 3) == 0xf)
  	    return arm_copy_unmodified (gdbarch, insn, "bfc", dsc);
  	  else
  	    return arm_copy_unmodified (gdbarch, insn, "bfi", dsc);
  	}
        else
  	return arm_copy_undef (gdbarch, insn, dsc);
  
      case 0x1e: case 0x1f:
        if (bits (insn, 5, 6) == 0x2)  /* op2[1:0].  */
  	return arm_copy_unmodified (gdbarch, insn, "ubfx", dsc);
        else
  	return arm_copy_undef (gdbarch, insn, dsc);
      }
  
    /* Should be unreachable.  */
    return 1;
  }
  
  static int
  arm_decode_b_bl_ldmstm (struct gdbarch *gdbarch, uint32_t insn,
  			struct regcache *regs,
  			struct displaced_step_closure *dsc)
  {
    if (bit (insn, 25))
      return arm_copy_b_bl_blx (gdbarch, insn, regs, dsc);
    else
      return arm_copy_block_xfer (gdbarch, insn, regs, dsc);
  }
  
  static int
  arm_decode_ext_reg_ld_st (struct gdbarch *gdbarch, uint32_t insn,
  			  struct regcache *regs,
  			  struct displaced_step_closure *dsc)
  {
    unsigned int opcode = bits (insn, 20, 24);
  
    switch (opcode)
      {
      case 0x04: case 0x05:  /* VFP/Neon mrrc/mcrr.  */
        return arm_copy_unmodified (gdbarch, insn, "vfp/neon mrrc/mcrr", dsc);
  
      case 0x08: case 0x0a: case 0x0c: case 0x0e:
      case 0x12: case 0x16:
        return arm_copy_unmodified (gdbarch, insn, "vfp/neon vstm/vpush", dsc);
  
      case 0x09: case 0x0b: case 0x0d: case 0x0f:
      case 0x13: case 0x17:
        return arm_copy_unmodified (gdbarch, insn, "vfp/neon vldm/vpop", dsc);
  
      case 0x10: case 0x14: case 0x18: case 0x1c:  /* vstr.  */
      case 0x11: case 0x15: case 0x19: case 0x1d:  /* vldr.  */
        /* Note: no writeback for these instructions.  Bit 25 will always be
  	 zero though (via caller), so the following works OK.  */
        return arm_copy_copro_load_store (gdbarch, insn, regs, dsc);
      }
  
    /* Should be unreachable.  */
    return 1;
  }
  
  /* Decode shifted register instructions.  */
  
  static int
  thumb2_decode_dp_shift_reg (struct gdbarch *gdbarch, uint16_t insn1,
  			    uint16_t insn2,  struct regcache *regs,
  			    struct displaced_step_closure *dsc)
  {
    /* PC is only allowed to be used in instruction MOV.  */
  
    unsigned int op = bits (insn1, 5, 8);
    unsigned int rn = bits (insn1, 0, 3);
  
    if (op == 0x2 && rn == 0xf) /* MOV */
      return thumb2_copy_alu_imm (gdbarch, insn1, insn2, regs, dsc);
    else
      return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					"dp (shift reg)", dsc);
  }
  
  
  /* Decode extension register load/store.  Exactly the same as
     arm_decode_ext_reg_ld_st.  */
  
  static int
  thumb2_decode_ext_reg_ld_st (struct gdbarch *gdbarch, uint16_t insn1,
  			     uint16_t insn2,  struct regcache *regs,
  			     struct displaced_step_closure *dsc)
  {
    unsigned int opcode = bits (insn1, 4, 8);
  
    switch (opcode)
      {
      case 0x04: case 0x05:
        return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					  "vfp/neon vmov", dsc);
  
      case 0x08: case 0x0c: /* 01x00 */
      case 0x0a: case 0x0e: /* 01x10 */
      case 0x12: case 0x16: /* 10x10 */
        return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					  "vfp/neon vstm/vpush", dsc);
  
      case 0x09: case 0x0d: /* 01x01 */
      case 0x0b: case 0x0f: /* 01x11 */
      case 0x13: case 0x17: /* 10x11 */
        return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					  "vfp/neon vldm/vpop", dsc);
  
      case 0x10: case 0x14: case 0x18: case 0x1c:  /* vstr.  */
        return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					  "vstr", dsc);
      case 0x11: case 0x15: case 0x19: case 0x1d:  /* vldr.  */
        return thumb2_copy_copro_load_store (gdbarch, insn1, insn2, regs, dsc);
      }
  
    /* Should be unreachable.  */
    return 1;
  }
  
  static int
  arm_decode_svc_copro (struct gdbarch *gdbarch, uint32_t insn,
  		      struct regcache *regs, struct displaced_step_closure *dsc)
  {
    unsigned int op1 = bits (insn, 20, 25);
    int op = bit (insn, 4);
    unsigned int coproc = bits (insn, 8, 11);
  
    if ((op1 & 0x20) == 0x00 && (op1 & 0x3a) != 0x00 && (coproc & 0xe) == 0xa)
      return arm_decode_ext_reg_ld_st (gdbarch, insn, regs, dsc);
    else if ((op1 & 0x21) == 0x00 && (op1 & 0x3a) != 0x00
  	   && (coproc & 0xe) != 0xa)
      /* stc/stc2.  */
      return arm_copy_copro_load_store (gdbarch, insn, regs, dsc);
    else if ((op1 & 0x21) == 0x01 && (op1 & 0x3a) != 0x00
  	   && (coproc & 0xe) != 0xa)
      /* ldc/ldc2 imm/lit.  */
      return arm_copy_copro_load_store (gdbarch, insn, regs, dsc);
    else if ((op1 & 0x3e) == 0x00)
      return arm_copy_undef (gdbarch, insn, dsc);
    else if ((op1 & 0x3e) == 0x04 && (coproc & 0xe) == 0xa)
      return arm_copy_unmodified (gdbarch, insn, "neon 64bit xfer", dsc);
    else if (op1 == 0x04 && (coproc & 0xe) != 0xa)
      return arm_copy_unmodified (gdbarch, insn, "mcrr/mcrr2", dsc);
    else if (op1 == 0x05 && (coproc & 0xe) != 0xa)
      return arm_copy_unmodified (gdbarch, insn, "mrrc/mrrc2", dsc);
    else if ((op1 & 0x30) == 0x20 && !op)
      {
        if ((coproc & 0xe) == 0xa)
  	return arm_copy_unmodified (gdbarch, insn, "vfp dataproc", dsc);
        else
  	return arm_copy_unmodified (gdbarch, insn, "cdp/cdp2", dsc);
      }
    else if ((op1 & 0x30) == 0x20 && op)
      return arm_copy_unmodified (gdbarch, insn, "neon 8/16/32 bit xfer", dsc);
    else if ((op1 & 0x31) == 0x20 && op && (coproc & 0xe) != 0xa)
      return arm_copy_unmodified (gdbarch, insn, "mcr/mcr2", dsc);
    else if ((op1 & 0x31) == 0x21 && op && (coproc & 0xe) != 0xa)
      return arm_copy_unmodified (gdbarch, insn, "mrc/mrc2", dsc);
    else if ((op1 & 0x30) == 0x30)
      return arm_copy_svc (gdbarch, insn, regs, dsc);
    else
      return arm_copy_undef (gdbarch, insn, dsc);  /* Possibly unreachable.  */
  }
  
  static int
  thumb2_decode_svc_copro (struct gdbarch *gdbarch, uint16_t insn1,
  			 uint16_t insn2, struct regcache *regs,
  			 struct displaced_step_closure *dsc)
  {
    unsigned int coproc = bits (insn2, 8, 11);
    unsigned int bit_5_8 = bits (insn1, 5, 8);
    unsigned int bit_9 = bit (insn1, 9);
    unsigned int bit_4 = bit (insn1, 4);
  
    if (bit_9 == 0)
      {
        if (bit_5_8 == 2)
  	return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					    "neon 64bit xfer/mrrc/mrrc2/mcrr/mcrr2",
  					    dsc);
        else if (bit_5_8 == 0) /* UNDEFINED.  */
  	return thumb_32bit_copy_undef (gdbarch, insn1, insn2, dsc);
        else
  	{
  	   /*coproc is 101x.  SIMD/VFP, ext registers load/store.  */
  	  if ((coproc & 0xe) == 0xa)
  	    return thumb2_decode_ext_reg_ld_st (gdbarch, insn1, insn2, regs,
  						dsc);
  	  else /* coproc is not 101x.  */
  	    {
  	      if (bit_4 == 0) /* STC/STC2.  */
  		return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						    "stc/stc2", dsc);
  	      else /* LDC/LDC2 {literal, immeidate}.  */
  		return thumb2_copy_copro_load_store (gdbarch, insn1, insn2,
  						     regs, dsc);
  	    }
  	}
      }
    else
      return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2, "coproc", dsc);
  
    return 0;
  }
  
  static void
  install_pc_relative (struct gdbarch *gdbarch, struct regcache *regs,
  		     struct displaced_step_closure *dsc, int rd)
  {
    /* ADR Rd, #imm
  
       Rewrite as:
  
       Preparation: Rd <- PC
       Insn: ADD Rd, #imm
       Cleanup: Null.
    */
  
    /* Rd <- PC */
    int val = displaced_read_reg (regs, dsc, ARM_PC_REGNUM);
    displaced_write_reg (regs, dsc, rd, val, CANNOT_WRITE_PC);
  }
  
  static int
  thumb_copy_pc_relative_16bit (struct gdbarch *gdbarch, struct regcache *regs,
  			      struct displaced_step_closure *dsc,
  			      int rd, unsigned int imm)
  {
  
    /* Encoding T2: ADDS Rd, #imm */
    dsc->modinsn[0] = (0x3000 | (rd << 8) | imm);
  
    install_pc_relative (gdbarch, regs, dsc, rd);
  
    return 0;
  }
  
  static int
  thumb_decode_pc_relative_16bit (struct gdbarch *gdbarch, uint16_t insn,
  				struct regcache *regs,
  				struct displaced_step_closure *dsc)
  {
    unsigned int rd = bits (insn, 8, 10);
    unsigned int imm8 = bits (insn, 0, 7);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying thumb adr r%d, #%d insn %.4x\n",
  			rd, imm8, insn);
  
    return thumb_copy_pc_relative_16bit (gdbarch, regs, dsc, rd, imm8);
  }
  
  static int
  thumb_copy_pc_relative_32bit (struct gdbarch *gdbarch, uint16_t insn1,
  			      uint16_t insn2, struct regcache *regs,
  			      struct displaced_step_closure *dsc)
  {
    unsigned int rd = bits (insn2, 8, 11);
    /* Since immediate has the same encoding in ADR ADD and SUB, so we simply
       extract raw immediate encoding rather than computing immediate.  When
       generating ADD or SUB instruction, we can simply perform OR operation to
       set immediate into ADD.  */
    unsigned int imm_3_8 = insn2 & 0x70ff;
    unsigned int imm_i = insn1 & 0x0400; /* Clear all bits except bit 10.  */
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying thumb adr r%d, #%d:%d insn %.4x%.4x\n",
  			rd, imm_i, imm_3_8, insn1, insn2);
  
    if (bit (insn1, 7)) /* Encoding T2 */
      {
        /* Encoding T3: SUB Rd, Rd, #imm */
        dsc->modinsn[0] = (0xf1a0 | rd | imm_i);
        dsc->modinsn[1] = ((rd << 8) | imm_3_8);
      }
    else /* Encoding T3 */
      {
        /* Encoding T3: ADD Rd, Rd, #imm */
        dsc->modinsn[0] = (0xf100 | rd | imm_i);
        dsc->modinsn[1] = ((rd << 8) | imm_3_8);
      }
    dsc->numinsns = 2;
  
    install_pc_relative (gdbarch, regs, dsc, rd);
  
    return 0;
  }
  
  static int
  thumb_copy_16bit_ldr_literal (struct gdbarch *gdbarch, uint16_t insn1,
  			      struct regcache *regs,
  			      struct displaced_step_closure *dsc)
  {
    unsigned int rt = bits (insn1, 8, 10);
    unsigned int pc;
    int imm8 = (bits (insn1, 0, 7) << 2);
  
    /* LDR Rd, #imm8
  
       Rwrite as:
  
       Preparation: tmp0 <- R0, tmp2 <- R2, tmp3 <- R3, R2 <- PC, R3 <- #imm8;
  
       Insn: LDR R0, [R2, R3];
       Cleanup: R2 <- tmp2, R3 <- tmp3, Rd <- R0, R0 <- tmp0 */
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying thumb ldr r%d [pc #%d]\n"
  			, rt, imm8);
  
    dsc->tmp[0] = displaced_read_reg (regs, dsc, 0);
    dsc->tmp[2] = displaced_read_reg (regs, dsc, 2);
    dsc->tmp[3] = displaced_read_reg (regs, dsc, 3);
    pc = displaced_read_reg (regs, dsc, ARM_PC_REGNUM);
    /* The assembler calculates the required value of the offset from the
       Align(PC,4) value of this instruction to the label.  */
    pc = pc & 0xfffffffc;
  
    displaced_write_reg (regs, dsc, 2, pc, CANNOT_WRITE_PC);
    displaced_write_reg (regs, dsc, 3, imm8, CANNOT_WRITE_PC);
  
    dsc->rd = rt;
    dsc->u.ldst.xfersize = 4;
    dsc->u.ldst.rn = 0;
    dsc->u.ldst.immed = 0;
    dsc->u.ldst.writeback = 0;
    dsc->u.ldst.restore_r4 = 0;
  
    dsc->modinsn[0] = 0x58d0; /* ldr r0, [r2, r3]*/
  
    dsc->cleanup = &cleanup_load;
  
    return 0;
  }
  
  /* Copy Thumb cbnz/cbz insruction.  */
  
  static int
  thumb_copy_cbnz_cbz (struct gdbarch *gdbarch, uint16_t insn1,
  		     struct regcache *regs,
  		     struct displaced_step_closure *dsc)
  {
    int non_zero = bit (insn1, 11);
    unsigned int imm5 = (bit (insn1, 9) << 6) | (bits (insn1, 3, 7) << 1);
    CORE_ADDR from = dsc->insn_addr;
    int rn = bits (insn1, 0, 2);
    int rn_val = displaced_read_reg (regs, dsc, rn);
  
    dsc->u.branch.cond = (rn_val && non_zero) || (!rn_val && !non_zero);
    /* CBNZ and CBZ do not affect the condition flags.  If condition is true,
       set it INST_AL, so cleanup_branch will know branch is taken, otherwise,
       condition is false, let it be, cleanup_branch will do nothing.  */
    if (dsc->u.branch.cond)
      {
        dsc->u.branch.cond = INST_AL;
        dsc->u.branch.dest = from + 4 + imm5;
      }
    else
        dsc->u.branch.dest = from + 2;
  
    dsc->u.branch.link = 0;
    dsc->u.branch.exchange = 0;
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copying %s [r%d = 0x%x]"
  			" insn %.4x to %.8lx\n", non_zero ? "cbnz" : "cbz",
  			rn, rn_val, insn1, dsc->u.branch.dest);
  
    dsc->modinsn[0] = THUMB_NOP;
  
    dsc->cleanup = &cleanup_branch;
    return 0;
  }
  
  /* Copy Table Branch Byte/Halfword */
  static int
  thumb2_copy_table_branch (struct gdbarch *gdbarch, uint16_t insn1,
  			  uint16_t insn2, struct regcache *regs,
  			  struct displaced_step_closure *dsc)
  {
    ULONGEST rn_val, rm_val;
    int is_tbh = bit (insn2, 4);
    CORE_ADDR halfwords = 0;
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  
    rn_val = displaced_read_reg (regs, dsc, bits (insn1, 0, 3));
    rm_val = displaced_read_reg (regs, dsc, bits (insn2, 0, 3));
  
    if (is_tbh)
      {
        gdb_byte buf[2];
  
        target_read_memory (rn_val + 2 * rm_val, buf, 2);
        halfwords = extract_unsigned_integer (buf, 2, byte_order);
      }
    else
      {
        gdb_byte buf[1];
  
        target_read_memory (rn_val + rm_val, buf, 1);
        halfwords = extract_unsigned_integer (buf, 1, byte_order);
      }
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: %s base 0x%x offset 0x%x"
  			" offset 0x%x\n", is_tbh ? "tbh" : "tbb",
  			(unsigned int) rn_val, (unsigned int) rm_val,
  			(unsigned int) halfwords);
  
    dsc->u.branch.cond = INST_AL;
    dsc->u.branch.link = 0;
    dsc->u.branch.exchange = 0;
    dsc->u.branch.dest = dsc->insn_addr + 4 + 2 * halfwords;
  
    dsc->cleanup = &cleanup_branch;
  
    return 0;
  }
  
  static void
  cleanup_pop_pc_16bit_all (struct gdbarch *gdbarch, struct regcache *regs,
  			  struct displaced_step_closure *dsc)
  {
    /* PC <- r7 */
    int val = displaced_read_reg (regs, dsc, 7);
    displaced_write_reg (regs, dsc, ARM_PC_REGNUM, val, BX_WRITE_PC);
  
    /* r7 <- r8 */
    val = displaced_read_reg (regs, dsc, 8);
    displaced_write_reg (regs, dsc, 7, val, CANNOT_WRITE_PC);
  
    /* r8 <- tmp[0] */
    displaced_write_reg (regs, dsc, 8, dsc->tmp[0], CANNOT_WRITE_PC);
  
  }
  
  static int
  thumb_copy_pop_pc_16bit (struct gdbarch *gdbarch, uint16_t insn1,
  			 struct regcache *regs,
  			 struct displaced_step_closure *dsc)
  {
    dsc->u.block.regmask = insn1 & 0x00ff;
  
    /* Rewrite instruction: POP {rX, rY, ...,rZ, PC}
       to :
  
       (1) register list is full, that is, r0-r7 are used.
       Prepare: tmp[0] <- r8
  
       POP {r0, r1, ...., r6, r7}; remove PC from reglist
       MOV r8, r7; Move value of r7 to r8;
       POP {r7}; Store PC value into r7.
  
       Cleanup: PC <- r7, r7 <- r8, r8 <-tmp[0]
  
       (2) register list is not full, supposing there are N registers in
       register list (except PC, 0 <= N <= 7).
       Prepare: for each i, 0 - N, tmp[i] <- ri.
  
       POP {r0, r1, ...., rN};
  
       Cleanup: Set registers in original reglist from r0 - rN.  Restore r0 - rN
       from tmp[] properly.
    */
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog,
  			"displaced: copying thumb pop {%.8x, pc} insn %.4x\n",
  			dsc->u.block.regmask, insn1);
  
    if (dsc->u.block.regmask == 0xff)
      {
        dsc->tmp[0] = displaced_read_reg (regs, dsc, 8);
  
        dsc->modinsn[0] = (insn1 & 0xfeff); /* POP {r0,r1,...,r6, r7} */
        dsc->modinsn[1] = 0x46b8; /* MOV r8, r7 */
        dsc->modinsn[2] = 0xbc80; /* POP {r7} */
  
        dsc->numinsns = 3;
        dsc->cleanup = &cleanup_pop_pc_16bit_all;
      }
    else
      {
        unsigned int num_in_list = bitcount (dsc->u.block.regmask);
        unsigned int i;
        unsigned int new_regmask;
  
        for (i = 0; i < num_in_list + 1; i++)
  	dsc->tmp[i] = displaced_read_reg (regs, dsc, i);
  
        new_regmask = (1 << (num_in_list + 1)) - 1;
  
        if (debug_displaced)
  	fprintf_unfiltered (gdb_stdlog, _("displaced: POP "
  					  "{..., pc}: original reg list %.4x,"
  					  " modified list %.4x\n"),
  			    (int) dsc->u.block.regmask, new_regmask);
  
        dsc->u.block.regmask |= 0x8000;
        dsc->u.block.writeback = 0;
        dsc->u.block.cond = INST_AL;
  
        dsc->modinsn[0] = (insn1 & ~0x1ff) | (new_regmask & 0xff);
  
        dsc->cleanup = &cleanup_block_load_pc;
      }
  
    return 0;
  }
  
  static void
  thumb_process_displaced_16bit_insn (struct gdbarch *gdbarch, uint16_t insn1,
  				    struct regcache *regs,
  				    struct displaced_step_closure *dsc)
  {
    unsigned short op_bit_12_15 = bits (insn1, 12, 15);
    unsigned short op_bit_10_11 = bits (insn1, 10, 11);
    int err = 0;
  
    /* 16-bit thumb instructions.  */
    switch (op_bit_12_15)
      {
        /* Shift (imme), add, subtract, move and compare.  */
      case 0: case 1: case 2: case 3:
        err = thumb_copy_unmodified_16bit (gdbarch, insn1,
  					 "shift/add/sub/mov/cmp",
  					 dsc);
        break;
      case 4:
        switch (op_bit_10_11)
  	{
  	case 0: /* Data-processing */
  	  err = thumb_copy_unmodified_16bit (gdbarch, insn1,
  					     "data-processing",
  					     dsc);
  	  break;
  	case 1: /* Special data instructions and branch and exchange.  */
  	  {
  	    unsigned short op = bits (insn1, 7, 9);
  	    if (op == 6 || op == 7) /* BX or BLX */
  	      err = thumb_copy_bx_blx_reg (gdbarch, insn1, regs, dsc);
  	    else if (bits (insn1, 6, 7) != 0) /* ADD/MOV/CMP high registers.  */
  	      err = thumb_copy_alu_reg (gdbarch, insn1, regs, dsc);
  	    else
  	      err = thumb_copy_unmodified_16bit (gdbarch, insn1, "special data",
  						 dsc);
  	  }
  	  break;
  	default: /* LDR (literal) */
  	  err = thumb_copy_16bit_ldr_literal (gdbarch, insn1, regs, dsc);
  	}
        break;
      case 5: case 6: case 7: case 8: case 9: /* Load/Store single data item */
        err = thumb_copy_unmodified_16bit (gdbarch, insn1, "ldr/str", dsc);
        break;
      case 10:
        if (op_bit_10_11 < 2) /* Generate PC-relative address */
  	err = thumb_decode_pc_relative_16bit (gdbarch, insn1, regs, dsc);
        else /* Generate SP-relative address */
  	err = thumb_copy_unmodified_16bit (gdbarch, insn1, "sp-relative", dsc);
        break;
      case 11: /* Misc 16-bit instructions */
        {
  	switch (bits (insn1, 8, 11))
  	  {
  	  case 1: case 3:  case 9: case 11: /* CBNZ, CBZ */
  	    err = thumb_copy_cbnz_cbz (gdbarch, insn1, regs, dsc);
  	    break;
  	  case 12: case 13: /* POP */
  	    if (bit (insn1, 8)) /* PC is in register list.  */
  	      err = thumb_copy_pop_pc_16bit (gdbarch, insn1, regs, dsc);
  	    else
  	      err = thumb_copy_unmodified_16bit (gdbarch, insn1, "pop", dsc);
  	    break;
  	  case 15: /* If-Then, and hints */
  	    if (bits (insn1, 0, 3))
  	      /* If-Then makes up to four following instructions conditional.
  		 IT instruction itself is not conditional, so handle it as a
  		 common unmodified instruction.  */
  	      err = thumb_copy_unmodified_16bit (gdbarch, insn1, "If-Then",
  						 dsc);
  	    else
  	      err = thumb_copy_unmodified_16bit (gdbarch, insn1, "hints", dsc);
  	    break;
  	  default:
  	    err = thumb_copy_unmodified_16bit (gdbarch, insn1, "misc", dsc);
  	  }
        }
        break;
      case 12:
        if (op_bit_10_11 < 2) /* Store multiple registers */
  	err = thumb_copy_unmodified_16bit (gdbarch, insn1, "stm", dsc);
        else /* Load multiple registers */
  	err = thumb_copy_unmodified_16bit (gdbarch, insn1, "ldm", dsc);
        break;
      case 13: /* Conditional branch and supervisor call */
        if (bits (insn1, 9, 11) != 7) /* conditional branch */
  	err = thumb_copy_b (gdbarch, insn1, dsc);
        else
  	err = thumb_copy_svc (gdbarch, insn1, regs, dsc);
        break;
      case 14: /* Unconditional branch */
        err = thumb_copy_b (gdbarch, insn1, dsc);
        break;
      default:
        err = 1;
      }
  
    if (err)
      internal_error (__FILE__, __LINE__,
  		    _("thumb_process_displaced_16bit_insn: Instruction decode error"));
  }
  
  static int
  decode_thumb_32bit_ld_mem_hints (struct gdbarch *gdbarch,
  				 uint16_t insn1, uint16_t insn2,
  				 struct regcache *regs,
  				 struct displaced_step_closure *dsc)
  {
    int rt = bits (insn2, 12, 15);
    int rn = bits (insn1, 0, 3);
    int op1 = bits (insn1, 7, 8);
  
    switch (bits (insn1, 5, 6))
      {
      case 0: /* Load byte and memory hints */
        if (rt == 0xf) /* PLD/PLI */
  	{
  	  if (rn == 0xf)
  	    /* PLD literal or Encoding T3 of PLI(immediate, literal).  */
  	    return thumb2_copy_preload (gdbarch, insn1, insn2, regs, dsc);
  	  else
  	    return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						"pli/pld", dsc);
  	}
        else
  	{
  	  if (rn == 0xf) /* LDRB/LDRSB (literal) */
  	    return thumb2_copy_load_literal (gdbarch, insn1, insn2, regs, dsc,
  					     1);
  	  else
  	    return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						"ldrb{reg, immediate}/ldrbt",
  						dsc);
  	}
  
        break;
      case 1: /* Load halfword and memory hints.  */
        if (rt == 0xf) /* PLD{W} and Unalloc memory hint.  */
  	return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					    "pld/unalloc memhint", dsc);
        else
  	{
  	  if (rn == 0xf)
  	    return thumb2_copy_load_literal (gdbarch, insn1, insn2, regs, dsc,
  					     2);
  	  else
  	    return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						"ldrh/ldrht", dsc);
  	}
        break;
      case 2: /* Load word */
        {
  	int insn2_bit_8_11 = bits (insn2, 8, 11);
  
  	if (rn == 0xf)
  	  return thumb2_copy_load_literal (gdbarch, insn1, insn2, regs, dsc, 4);
  	else if (op1 == 0x1) /* Encoding T3 */
  	  return thumb2_copy_load_reg_imm (gdbarch, insn1, insn2, regs, dsc,
  					   0, 1);
  	else /* op1 == 0x0 */
  	  {
  	    if (insn2_bit_8_11 == 0xc || (insn2_bit_8_11 & 0x9) == 0x9)
  	      /* LDR (immediate) */
  	      return thumb2_copy_load_reg_imm (gdbarch, insn1, insn2, regs,
  					       dsc, bit (insn2, 8), 1);
  	    else if (insn2_bit_8_11 == 0xe) /* LDRT */
  	      return thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						  "ldrt", dsc);
  	    else
  	      /* LDR (register) */
  	      return thumb2_copy_load_reg_imm (gdbarch, insn1, insn2, regs,
  					       dsc, 0, 0);
  	  }
  	break;
        }
      default:
        return thumb_32bit_copy_undef (gdbarch, insn1, insn2, dsc);
        break;
      }
    return 0;
  }
  
  static void
  thumb_process_displaced_32bit_insn (struct gdbarch *gdbarch, uint16_t insn1,
  				    uint16_t insn2, struct regcache *regs,
  				    struct displaced_step_closure *dsc)
  {
    int err = 0;
    unsigned short op = bit (insn2, 15);
    unsigned int op1 = bits (insn1, 11, 12);
  
    switch (op1)
      {
      case 1:
        {
  	switch (bits (insn1, 9, 10))
  	  {
  	  case 0:
  	    if (bit (insn1, 6))
  	      {
  		/* Load/store {dual, execlusive}, table branch.  */
  		if (bits (insn1, 7, 8) == 1 && bits (insn1, 4, 5) == 1
  		    && bits (insn2, 5, 7) == 0)
  		  err = thumb2_copy_table_branch (gdbarch, insn1, insn2, regs,
  						  dsc);
  		else
  		  /* PC is not allowed to use in load/store {dual, exclusive}
  		     instructions.  */
  		  err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						     "load/store dual/ex", dsc);
  	      }
  	    else /* load/store multiple */
  	      {
  		switch (bits (insn1, 7, 8))
  		  {
  		  case 0: case 3: /* SRS, RFE */
  		    err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						       "srs/rfe", dsc);
  		    break;
  		  case 1: case 2: /* LDM/STM/PUSH/POP */
  		    err = thumb2_copy_block_xfer (gdbarch, insn1, insn2, regs, dsc);
  		    break;
  		  }
  	      }
  	    break;
  
  	  case 1:
  	    /* Data-processing (shift register).  */
  	    err = thumb2_decode_dp_shift_reg (gdbarch, insn1, insn2, regs,
  					      dsc);
  	    break;
  	  default: /* Coprocessor instructions.  */
  	    err = thumb2_decode_svc_copro (gdbarch, insn1, insn2, regs, dsc);
  	    break;
  	  }
        break;
        }
      case 2: /* op1 = 2 */
        if (op) /* Branch and misc control.  */
  	{
  	  if (bit (insn2, 14)  /* BLX/BL */
  	      || bit (insn2, 12) /* Unconditional branch */
  	      || (bits (insn1, 7, 9) != 0x7)) /* Conditional branch */
  	    err = thumb2_copy_b_bl_blx (gdbarch, insn1, insn2, regs, dsc);
  	  else
  	    err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					       "misc ctrl", dsc);
  	}
        else
  	{
  	  if (bit (insn1, 9)) /* Data processing (plain binary imm).  */
  	    {
  	      int op = bits (insn1, 4, 8);
  	      int rn = bits (insn1, 0, 3);
  	      if ((op == 0 || op == 0xa) && rn == 0xf)
  		err = thumb_copy_pc_relative_32bit (gdbarch, insn1, insn2,
  						    regs, dsc);
  	      else
  		err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						   "dp/pb", dsc);
  	    }
  	  else /* Data processing (modified immeidate) */
  	    err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					       "dp/mi", dsc);
  	}
        break;
      case 3: /* op1 = 3 */
        switch (bits (insn1, 9, 10))
  	{
  	case 0:
  	  if (bit (insn1, 4))
  	    err = decode_thumb_32bit_ld_mem_hints (gdbarch, insn1, insn2,
  						   regs, dsc);
  	  else /* NEON Load/Store and Store single data item */
  	    err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  					       "neon elt/struct load/store",
  					       dsc);
  	  break;
  	case 1: /* op1 = 3, bits (9, 10) == 1 */
  	  switch (bits (insn1, 7, 8))
  	    {
  	    case 0: case 1: /* Data processing (register) */
  	      err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						 "dp(reg)", dsc);
  	      break;
  	    case 2: /* Multiply and absolute difference */
  	      err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						 "mul/mua/diff", dsc);
  	      break;
  	    case 3: /* Long multiply and divide */
  	      err = thumb_copy_unmodified_32bit (gdbarch, insn1, insn2,
  						 "lmul/lmua", dsc);
  	      break;
  	    }
  	  break;
  	default: /* Coprocessor instructions */
  	  err = thumb2_decode_svc_copro (gdbarch, insn1, insn2, regs, dsc);
  	  break;
  	}
        break;
      default:
        err = 1;
      }
  
    if (err)
      internal_error (__FILE__, __LINE__,
  		    _("thumb_process_displaced_32bit_insn: Instruction decode error"));
  
  }
  
  static void
  thumb_process_displaced_insn (struct gdbarch *gdbarch, CORE_ADDR from,
  			      struct regcache *regs,
  			      struct displaced_step_closure *dsc)
  {
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    uint16_t insn1
      = read_memory_unsigned_integer (from, 2, byte_order_for_code);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: process thumb insn %.4x "
  			"at %.8lx\n", insn1, (unsigned long) from);
  
    dsc->is_thumb = 1;
    dsc->insn_size = thumb_insn_size (insn1);
    if (thumb_insn_size (insn1) == 4)
      {
        uint16_t insn2
  	= read_memory_unsigned_integer (from + 2, 2, byte_order_for_code);
        thumb_process_displaced_32bit_insn (gdbarch, insn1, insn2, regs, dsc);
      }
    else
      thumb_process_displaced_16bit_insn (gdbarch, insn1, regs, dsc);
  }
  
  void
  arm_process_displaced_insn (struct gdbarch *gdbarch, CORE_ADDR from,
  			    CORE_ADDR to, struct regcache *regs,
  			    struct displaced_step_closure *dsc)
  {
    int err = 0;
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    uint32_t insn;
  
    /* Most displaced instructions use a 1-instruction scratch space, so set this
       here and override below if/when necessary.  */
    dsc->numinsns = 1;
    dsc->insn_addr = from;
    dsc->scratch_base = to;
    dsc->cleanup = NULL;
    dsc->wrote_to_pc = 0;
  
    if (!displaced_in_arm_mode (regs))
      return thumb_process_displaced_insn (gdbarch, from, regs, dsc);
  
    dsc->is_thumb = 0;
    dsc->insn_size = 4;
    insn = read_memory_unsigned_integer (from, 4, byte_order_for_code);
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: stepping insn %.8lx "
  			"at %.8lx\n", (unsigned long) insn,
  			(unsigned long) from);
  
    if ((insn & 0xf0000000) == 0xf0000000)
      err = arm_decode_unconditional (gdbarch, insn, regs, dsc);
    else switch (((insn & 0x10) >> 4) | ((insn & 0xe000000) >> 24))
      {
      case 0x0: case 0x1: case 0x2: case 0x3:
        err = arm_decode_dp_misc (gdbarch, insn, regs, dsc);
        break;
  
      case 0x4: case 0x5: case 0x6:
        err = arm_decode_ld_st_word_ubyte (gdbarch, insn, regs, dsc);
        break;
  
      case 0x7:
        err = arm_decode_media (gdbarch, insn, dsc);
        break;
  
      case 0x8: case 0x9: case 0xa: case 0xb:
        err = arm_decode_b_bl_ldmstm (gdbarch, insn, regs, dsc);
        break;
  
      case 0xc: case 0xd: case 0xe: case 0xf:
        err = arm_decode_svc_copro (gdbarch, insn, regs, dsc);
        break;
      }
  
    if (err)
      internal_error (__FILE__, __LINE__,
  		    _("arm_process_displaced_insn: Instruction decode error"));
  }
  
  /* Actually set up the scratch space for a displaced instruction.  */
  
  void
  arm_displaced_init_closure (struct gdbarch *gdbarch, CORE_ADDR from,
  			    CORE_ADDR to, struct displaced_step_closure *dsc)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
    unsigned int i, len, offset;
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
    int size = dsc->is_thumb? 2 : 4;
    const gdb_byte *bkp_insn;
  
    offset = 0;
    /* Poke modified instruction(s).  */
    for (i = 0; i < dsc->numinsns; i++)
      {
        if (debug_displaced)
  	{
  	  fprintf_unfiltered (gdb_stdlog, "displaced: writing insn ");
  	  if (size == 4)
  	    fprintf_unfiltered (gdb_stdlog, "%.8lx",
  				dsc->modinsn[i]);
  	  else if (size == 2)
  	    fprintf_unfiltered (gdb_stdlog, "%.4x",
  				(unsigned short)dsc->modinsn[i]);
  
  	  fprintf_unfiltered (gdb_stdlog, " at %.8lx\n",
  			      (unsigned long) to + offset);
  
  	}
        write_memory_unsigned_integer (to + offset, size,
  				     byte_order_for_code,
  				     dsc->modinsn[i]);
        offset += size;
      }
  
    /* Choose the correct breakpoint instruction.  */
    if (dsc->is_thumb)
      {
        bkp_insn = tdep->thumb_breakpoint;
        len = tdep->thumb_breakpoint_size;
      }
    else
      {
        bkp_insn = tdep->arm_breakpoint;
        len = tdep->arm_breakpoint_size;
      }
  
    /* Put breakpoint afterwards.  */
    write_memory (to + offset, bkp_insn, len);
  
    if (debug_displaced)
      fprintf_unfiltered (gdb_stdlog, "displaced: copy %s->%s: ",
  			paddress (gdbarch, from), paddress (gdbarch, to));
  }
  
  /* Entry point for cleaning things up after a displaced instruction has been
     single-stepped.  */
  
  void
  arm_displaced_step_fixup (struct gdbarch *gdbarch,
  			  struct displaced_step_closure *dsc,
  			  CORE_ADDR from, CORE_ADDR to,
  			  struct regcache *regs)
  {
    if (dsc->cleanup)
      dsc->cleanup (gdbarch, regs, dsc);
  
    if (!dsc->wrote_to_pc)
      regcache_cooked_write_unsigned (regs, ARM_PC_REGNUM,
  				    dsc->insn_addr + dsc->insn_size);
  
  }
  
  #include "bfd-in2.h"
  #include "libcoff.h"
  
  static int
  gdb_print_insn_arm (bfd_vma memaddr, disassemble_info *info)
  {
    struct gdbarch *gdbarch = (struct gdbarch *) info->application_data;
  
    if (arm_pc_is_thumb (gdbarch, memaddr))
      {
        static asymbol *asym;
        static combined_entry_type ce;
        static struct coff_symbol_struct csym;
        static struct bfd fake_bfd;
        static bfd_target fake_target;
  
        if (csym.native == NULL)
  	{
  	  /* Create a fake symbol vector containing a Thumb symbol.
  	     This is solely so that the code in print_insn_little_arm() 
  	     and print_insn_big_arm() in opcodes/arm-dis.c will detect
  	     the presence of a Thumb symbol and switch to decoding
  	     Thumb instructions.  */
  
  	  fake_target.flavour = bfd_target_coff_flavour;
  	  fake_bfd.xvec = &fake_target;
  	  ce.u.syment.n_sclass = C_THUMBEXTFUNC;
  	  csym.native = &ce;
  	  csym.symbol.the_bfd = &fake_bfd;
  	  csym.symbol.name = "fake";
  	  asym = (asymbol *) & csym;
  	}
  
        memaddr = UNMAKE_THUMB_ADDR (memaddr);
        info->symbols = &asym;
      }
    else
      info->symbols = NULL;
  
    if (info->endian == BFD_ENDIAN_BIG)
      return print_insn_big_arm (memaddr, info);
    else
      return print_insn_little_arm (memaddr, info);
  }
  
  /* The following define instruction sequences that will cause ARM
     cpu's to take an undefined instruction trap.  These are used to
     signal a breakpoint to GDB.
     
     The newer ARMv4T cpu's are capable of operating in ARM or Thumb
     modes.  A different instruction is required for each mode.  The ARM
     cpu's can also be big or little endian.  Thus four different
     instructions are needed to support all cases.
     
     Note: ARMv4 defines several new instructions that will take the
     undefined instruction trap.  ARM7TDMI is nominally ARMv4T, but does
     not in fact add the new instructions.  The new undefined
     instructions in ARMv4 are all instructions that had no defined
     behaviour in earlier chips.  There is no guarantee that they will
     raise an exception, but may be treated as NOP's.  In practice, it
     may only safe to rely on instructions matching:
     
     3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 
     1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
     C C C C 0 1 1 x x x x x x x x x x x x x x x x x x x x 1 x x x x
     
     Even this may only true if the condition predicate is true.  The
     following use a condition predicate of ALWAYS so it is always TRUE.
     
     There are other ways of forcing a breakpoint.  GNU/Linux, RISC iX,
     and NetBSD all use a software interrupt rather than an undefined
     instruction to force a trap.  This can be handled by by the
     abi-specific code during establishment of the gdbarch vector.  */
  
  #define ARM_LE_BREAKPOINT {0xFE,0xDE,0xFF,0xE7}
  #define ARM_BE_BREAKPOINT {0xE7,0xFF,0xDE,0xFE}
  #define THUMB_LE_BREAKPOINT {0xbe,0xbe}
  #define THUMB_BE_BREAKPOINT {0xbe,0xbe}
  
  static const gdb_byte arm_default_arm_le_breakpoint[] = ARM_LE_BREAKPOINT;
  static const gdb_byte arm_default_arm_be_breakpoint[] = ARM_BE_BREAKPOINT;
  static const gdb_byte arm_default_thumb_le_breakpoint[] = THUMB_LE_BREAKPOINT;
  static const gdb_byte arm_default_thumb_be_breakpoint[] = THUMB_BE_BREAKPOINT;
  
  /* Determine the type and size of breakpoint to insert at PCPTR.  Uses
     the program counter value to determine whether a 16-bit or 32-bit
     breakpoint should be used.  It returns a pointer to a string of
     bytes that encode a breakpoint instruction, stores the length of
     the string to *lenptr, and adjusts the program counter (if
     necessary) to point to the actual memory location where the
     breakpoint should be inserted.  */
  
  static const unsigned char *
  arm_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr, int *lenptr)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
    enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
  
    if (arm_pc_is_thumb (gdbarch, *pcptr))
      {
        *pcptr = UNMAKE_THUMB_ADDR (*pcptr);
  
        /* If we have a separate 32-bit breakpoint instruction for Thumb-2,
  	 check whether we are replacing a 32-bit instruction.  */
        if (tdep->thumb2_breakpoint != NULL)
  	{
  	  gdb_byte buf[2];
  	  if (target_read_memory (*pcptr, buf, 2) == 0)
  	    {
  	      unsigned short inst1;
  	      inst1 = extract_unsigned_integer (buf, 2, byte_order_for_code);
  	      if (thumb_insn_size (inst1) == 4)
  		{
  		  *lenptr = tdep->thumb2_breakpoint_size;
  		  return tdep->thumb2_breakpoint;
  		}
  	    }
  	}
  
        *lenptr = tdep->thumb_breakpoint_size;
        return tdep->thumb_breakpoint;
      }
    else
      {
        *lenptr = tdep->arm_breakpoint_size;
        return tdep->arm_breakpoint;
      }
  }
  
  static void
  arm_remote_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr,
  			       int *kindptr)
  {
    arm_breakpoint_from_pc (gdbarch, pcptr, kindptr);
  
    if (arm_pc_is_thumb (gdbarch, *pcptr) && *kindptr == 4)
      /* The documented magic value for a 32-bit Thumb-2 breakpoint, so
         that this is not confused with a 32-bit ARM breakpoint.  */
      *kindptr = 3;
  }
  
  /* Extract from an array REGBUF containing the (raw) register state a
     function return value of type TYPE, and copy that, in virtual
     format, into VALBUF.  */
  
  static void
  arm_extract_return_value (struct type *type, struct regcache *regs,
  			  gdb_byte *valbuf)
  {
    struct gdbarch *gdbarch = get_regcache_arch (regs);
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  
    if (TYPE_CODE_FLT == TYPE_CODE (type))
      {
        switch (gdbarch_tdep (gdbarch)->fp_model)
  	{
  	case ARM_FLOAT_FPA:
  	  {
  	    /* The value is in register F0 in internal format.  We need to
  	       extract the raw value and then convert it to the desired
  	       internal type.  */
  	    bfd_byte tmpbuf[FP_REGISTER_SIZE];
  
  	    regcache_cooked_read (regs, ARM_F0_REGNUM, tmpbuf);
  	    convert_from_extended (floatformat_from_type (type), tmpbuf,
  				   valbuf, gdbarch_byte_order (gdbarch));
  	  }
  	  break;
  
  	case ARM_FLOAT_SOFT_FPA:
  	case ARM_FLOAT_SOFT_VFP:
  	  /* ARM_FLOAT_VFP can arise if this is a variadic function so
  	     not using the VFP ABI code.  */
  	case ARM_FLOAT_VFP:
  	  regcache_cooked_read (regs, ARM_A1_REGNUM, valbuf);
  	  if (TYPE_LENGTH (type) > 4)
  	    regcache_cooked_read (regs, ARM_A1_REGNUM + 1,
  				  valbuf + INT_REGISTER_SIZE);
  	  break;
  
  	default:
  	  internal_error (__FILE__, __LINE__,
  			  _("arm_extract_return_value: "
  			    "Floating point model not supported"));
  	  break;
  	}
      }
    else if (TYPE_CODE (type) == TYPE_CODE_INT
  	   || TYPE_CODE (type) == TYPE_CODE_CHAR
  	   || TYPE_CODE (type) == TYPE_CODE_BOOL
  	   || TYPE_CODE (type) == TYPE_CODE_PTR
  	   || TYPE_CODE (type) == TYPE_CODE_REF
  	   || TYPE_CODE (type) == TYPE_CODE_ENUM)
      {
        /* If the type is a plain integer, then the access is
  	 straight-forward.  Otherwise we have to play around a bit
  	 more.  */
        int len = TYPE_LENGTH (type);
        int regno = ARM_A1_REGNUM;
        ULONGEST tmp;
  
        while (len > 0)
  	{
  	  /* By using store_unsigned_integer we avoid having to do
  	     anything special for small big-endian values.  */
  	  regcache_cooked_read_unsigned (regs, regno++, &tmp);
  	  store_unsigned_integer (valbuf, 
  				  (len > INT_REGISTER_SIZE
  				   ? INT_REGISTER_SIZE : len),
  				  byte_order, tmp);
  	  len -= INT_REGISTER_SIZE;
  	  valbuf += INT_REGISTER_SIZE;
  	}
      }
    else
      {
        /* For a structure or union the behaviour is as if the value had
           been stored to word-aligned memory and then loaded into 
           registers with 32-bit load instruction(s).  */
        int len = TYPE_LENGTH (type);
        int regno = ARM_A1_REGNUM;
        bfd_byte tmpbuf[INT_REGISTER_SIZE];
  
        while (len > 0)
  	{
  	  regcache_cooked_read (regs, regno++, tmpbuf);
  	  memcpy (valbuf, tmpbuf,
  		  len > INT_REGISTER_SIZE ? INT_REGISTER_SIZE : len);
  	  len -= INT_REGISTER_SIZE;
  	  valbuf += INT_REGISTER_SIZE;
  	}
      }
  }
  
  
  /* Will a function return an aggregate type in memory or in a
     register?  Return 0 if an aggregate type can be returned in a
     register, 1 if it must be returned in memory.  */
  
  static int
  arm_return_in_memory (struct gdbarch *gdbarch, struct type *type)
  {
    enum type_code code;
  
    type = check_typedef (type);
  
    /* Simple, non-aggregate types (ie not including vectors and
       complex) are always returned in a register (or registers).  */
    code = TYPE_CODE (type);
    if (TYPE_CODE_STRUCT != code && TYPE_CODE_UNION != code
        && TYPE_CODE_ARRAY != code && TYPE_CODE_COMPLEX != code)
      return 0;
  
    if (TYPE_CODE_ARRAY == code && TYPE_VECTOR (type))
      {
        /* Vector values should be returned using ARM registers if they
  	 are not over 16 bytes.  */
        return (TYPE_LENGTH (type) > 16);
      }
  
    if (gdbarch_tdep (gdbarch)->arm_abi != ARM_ABI_APCS)
      {
        /* The AAPCS says all aggregates not larger than a word are returned
  	 in a register.  */
        if (TYPE_LENGTH (type) <= INT_REGISTER_SIZE)
  	return 0;
  
        return 1;
      }
    else
      {
        int nRc;
  
        /* All aggregate types that won't fit in a register must be returned
  	 in memory.  */
        if (TYPE_LENGTH (type) > INT_REGISTER_SIZE)
  	return 1;
  
        /* In the ARM ABI, "integer" like aggregate types are returned in
  	 registers.  For an aggregate type to be integer like, its size
  	 must be less than or equal to INT_REGISTER_SIZE and the
  	 offset of each addressable subfield must be zero.  Note that bit
  	 fields are not addressable, and all addressable subfields of
  	 unions always start at offset zero.
  
  	 This function is based on the behaviour of GCC 2.95.1.
  	 See: gcc/arm.c: arm_return_in_memory() for details.
  
  	 Note: All versions of GCC before GCC 2.95.2 do not set up the
  	 parameters correctly for a function returning the following
  	 structure: struct { float f;}; This should be returned in memory,
  	 not a register.  Richard Earnshaw sent me a patch, but I do not
  	 know of any way to detect if a function like the above has been
  	 compiled with the correct calling convention.  */
  
        /* Assume all other aggregate types can be returned in a register.
  	 Run a check for structures, unions and arrays.  */
        nRc = 0;
  
        if ((TYPE_CODE_STRUCT == code) || (TYPE_CODE_UNION == code))
  	{
  	  int i;
  	  /* Need to check if this struct/union is "integer" like.  For
  	     this to be true, its size must be less than or equal to
  	     INT_REGISTER_SIZE and the offset of each addressable
  	     subfield must be zero.  Note that bit fields are not
  	     addressable, and unions always start at offset zero.  If any
  	     of the subfields is a floating point type, the struct/union
  	     cannot be an integer type.  */
  
  	  /* For each field in the object, check:
  	     1) Is it FP? --> yes, nRc = 1;
  	     2) Is it addressable (bitpos != 0) and
  	     not packed (bitsize == 0)?
  	     --> yes, nRc = 1
  	  */
  
  	  for (i = 0; i < TYPE_NFIELDS (type); i++)
  	    {
  	      enum type_code field_type_code;
  
  	      field_type_code
  		= TYPE_CODE (check_typedef (TYPE_FIELD_TYPE (type,
  							     i)));
  
  	      /* Is it a floating point type field?  */
  	      if (field_type_code == TYPE_CODE_FLT)
  		{
  		  nRc = 1;
  		  break;
  		}
  
  	      /* If bitpos != 0, then we have to care about it.  */
  	      if (TYPE_FIELD_BITPOS (type, i) != 0)
  		{
  		  /* Bitfields are not addressable.  If the field bitsize is 
  		     zero, then the field is not packed.  Hence it cannot be
  		     a bitfield or any other packed type.  */
  		  if (TYPE_FIELD_BITSIZE (type, i) == 0)
  		    {
  		      nRc = 1;
  		      break;
  		    }
  		}
  	    }
  	}
  
        return nRc;
      }
  }
  
  /* Write into appropriate registers a function return value of type
     TYPE, given in virtual format.  */
  
  static void
  arm_store_return_value (struct type *type, struct regcache *regs,
  			const gdb_byte *valbuf)
  {
    struct gdbarch *gdbarch = get_regcache_arch (regs);
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  
    if (TYPE_CODE (type) == TYPE_CODE_FLT)
      {
        gdb_byte buf[MAX_REGISTER_SIZE];
  
        switch (gdbarch_tdep (gdbarch)->fp_model)
  	{
  	case ARM_FLOAT_FPA:
  
  	  convert_to_extended (floatformat_from_type (type), buf, valbuf,
  			       gdbarch_byte_order (gdbarch));
  	  regcache_cooked_write (regs, ARM_F0_REGNUM, buf);
  	  break;
  
  	case ARM_FLOAT_SOFT_FPA:
  	case ARM_FLOAT_SOFT_VFP:
  	  /* ARM_FLOAT_VFP can arise if this is a variadic function so
  	     not using the VFP ABI code.  */
  	case ARM_FLOAT_VFP:
  	  regcache_cooked_write (regs, ARM_A1_REGNUM, valbuf);
  	  if (TYPE_LENGTH (type) > 4)
  	    regcache_cooked_write (regs, ARM_A1_REGNUM + 1, 
  				   valbuf + INT_REGISTER_SIZE);
  	  break;
  
  	default:
  	  internal_error (__FILE__, __LINE__,
  			  _("arm_store_return_value: Floating "
  			    "point model not supported"));
  	  break;
  	}
      }
    else if (TYPE_CODE (type) == TYPE_CODE_INT
  	   || TYPE_CODE (type) == TYPE_CODE_CHAR
  	   || TYPE_CODE (type) == TYPE_CODE_BOOL
  	   || TYPE_CODE (type) == TYPE_CODE_PTR
  	   || TYPE_CODE (type) == TYPE_CODE_REF
  	   || TYPE_CODE (type) == TYPE_CODE_ENUM)
      {
        if (TYPE_LENGTH (type) <= 4)
  	{
  	  /* Values of one word or less are zero/sign-extended and
  	     returned in r0.  */
  	  bfd_byte tmpbuf[INT_REGISTER_SIZE];
  	  LONGEST val = unpack_long (type, valbuf);
  
  	  store_signed_integer (tmpbuf, INT_REGISTER_SIZE, byte_order, val);
  	  regcache_cooked_write (regs, ARM_A1_REGNUM, tmpbuf);
  	}
        else
  	{
  	  /* Integral values greater than one word are stored in consecutive
  	     registers starting with r0.  This will always be a multiple of
  	     the regiser size.  */
  	  int len = TYPE_LENGTH (type);
  	  int regno = ARM_A1_REGNUM;
  
  	  while (len > 0)
  	    {
  	      regcache_cooked_write (regs, regno++, valbuf);
  	      len -= INT_REGISTER_SIZE;
  	      valbuf += INT_REGISTER_SIZE;
  	    }
  	}
      }
    else
      {
        /* For a structure or union the behaviour is as if the value had
           been stored to word-aligned memory and then loaded into 
           registers with 32-bit load instruction(s).  */
        int len = TYPE_LENGTH (type);
        int regno = ARM_A1_REGNUM;
        bfd_byte tmpbuf[INT_REGISTER_SIZE];
  
        while (len > 0)
  	{
  	  memcpy (tmpbuf, valbuf,
  		  len > INT_REGISTER_SIZE ? INT_REGISTER_SIZE : len);
  	  regcache_cooked_write (regs, regno++, tmpbuf);
  	  len -= INT_REGISTER_SIZE;
  	  valbuf += INT_REGISTER_SIZE;
  	}
      }
  }
  
  
  /* Handle function return values.  */
  
  static enum return_value_convention
  arm_return_value (struct gdbarch *gdbarch, struct value *function,
  		  struct type *valtype, struct regcache *regcache,
  		  gdb_byte *readbuf, const gdb_byte *writebuf)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
    struct type *func_type = function ? value_type (function) : NULL;
    enum arm_vfp_cprc_base_type vfp_base_type;
    int vfp_base_count;
  
    if (arm_vfp_abi_for_function (gdbarch, func_type)
        && arm_vfp_call_candidate (valtype, &vfp_base_type, &vfp_base_count))
      {
        int reg_char = arm_vfp_cprc_reg_char (vfp_base_type);
        int unit_length = arm_vfp_cprc_unit_length (vfp_base_type);
        int i;
        for (i = 0; i < vfp_base_count; i++)
  	{
  	  if (reg_char == 'q')
  	    {
  	      if (writebuf)
  		arm_neon_quad_write (gdbarch, regcache, i,
  				     writebuf + i * unit_length);
  
  	      if (readbuf)
  		arm_neon_quad_read (gdbarch, regcache, i,
  				    readbuf + i * unit_length);
  	    }
  	  else
  	    {
  	      char name_buf[4];
  	      int regnum;
  
  	      xsnprintf (name_buf, sizeof (name_buf), "%c%d", reg_char, i);
  	      regnum = user_reg_map_name_to_regnum (gdbarch, name_buf,
  						    strlen (name_buf));
  	      if (writebuf)
  		regcache_cooked_write (regcache, regnum,
  				       writebuf + i * unit_length);
  	      if (readbuf)
  		regcache_cooked_read (regcache, regnum,
  				      readbuf + i * unit_length);
  	    }
  	}
        return RETURN_VALUE_REGISTER_CONVENTION;
      }
  
    if (TYPE_CODE (valtype) == TYPE_CODE_STRUCT
        || TYPE_CODE (valtype) == TYPE_CODE_UNION
        || TYPE_CODE (valtype) == TYPE_CODE_ARRAY)
      {
        if (tdep->struct_return == pcc_struct_return
  	  || arm_return_in_memory (gdbarch, valtype))
  	return RETURN_VALUE_STRUCT_CONVENTION;
      }
    else if (TYPE_CODE (valtype) == TYPE_CODE_COMPLEX)
      {
        if (arm_return_in_memory (gdbarch, valtype))
  	return RETURN_VALUE_STRUCT_CONVENTION;
      }
  
    if (writebuf)
      arm_store_return_value (valtype, regcache, writebuf);
  
    if (readbuf)
      arm_extract_return_value (valtype, regcache, readbuf);
  
    return RETURN_VALUE_REGISTER_CONVENTION;
  }
  
  
  static int
  arm_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
  {
    struct gdbarch *gdbarch = get_frame_arch (frame);
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
    enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
    CORE_ADDR jb_addr;
    gdb_byte buf[INT_REGISTER_SIZE];
    
    jb_addr = get_frame_register_unsigned (frame, ARM_A1_REGNUM);
  
    if (target_read_memory (jb_addr + tdep->jb_pc * tdep->jb_elt_size, buf,
  			  INT_REGISTER_SIZE))
      return 0;
  
    *pc = extract_unsigned_integer (buf, INT_REGISTER_SIZE, byte_order);
    return 1;
  }
  
  /* Recognize GCC and GNU ld's trampolines.  If we are in a trampoline,
     return the target PC.  Otherwise return 0.  */
  
  CORE_ADDR
  arm_skip_stub (struct frame_info *frame, CORE_ADDR pc)
  {
    const char *name;
    int namelen;
    CORE_ADDR start_addr;
  
    /* Find the starting address and name of the function containing the PC.  */
    if (find_pc_partial_function (pc, &name, &start_addr, NULL) == 0)
      {
        /* Trampoline 'bx reg' doesn't belong to any functions.  Do the
  	 check here.  */
        start_addr = arm_skip_bx_reg (frame, pc);
        if (start_addr != 0)
  	return start_addr;
  
        return 0;
      }
  
    /* If PC is in a Thumb call or return stub, return the address of the
       target PC, which is in a register.  The thunk functions are called
       _call_via_xx, where x is the register name.  The possible names
       are r0-r9, sl, fp, ip, sp, and lr.  ARM RealView has similar
       functions, named __ARM_call_via_r[0-7].  */
    if (startswith (name, "_call_via_")
        || startswith (name, "__ARM_call_via_"))
      {
        /* Use the name suffix to determine which register contains the
           target PC.  */
        static char *table[15] =
        {"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
         "r8", "r9", "sl", "fp", "ip", "sp", "lr"
        };
        int regno;
        int offset = strlen (name) - 2;
  
        for (regno = 0; regno <= 14; regno++)
  	if (strcmp (&name[offset], table[regno]) == 0)
  	  return get_frame_register_unsigned (frame, regno);
      }
  
    /* GNU ld generates __foo_from_arm or __foo_from_thumb for
       non-interworking calls to foo.  We could decode the stubs
       to find the target but it's easier to use the symbol table.  */
    namelen = strlen (name);
    if (name[0] == '_' && name[1] == '_'
        && ((namelen > 2 + strlen ("_from_thumb")
  	   && startswith (name + namelen - strlen ("_from_thumb"), "_from_thumb"))
  	  || (namelen > 2 + strlen ("_from_arm")
  	      && startswith (name + namelen - strlen ("_from_arm"), "_from_arm"))))
      {
        char *target_name;
        int target_len = namelen - 2;
        struct bound_minimal_symbol minsym;
        struct objfile *objfile;
        struct obj_section *sec;
  
        if (name[namelen - 1] == 'b')
  	target_len -= strlen ("_from_thumb");
        else
  	target_len -= strlen ("_from_arm");
  
        target_name = (char *) alloca (target_len + 1);
        memcpy (target_name, name + 2, target_len);
        target_name[target_len] = '\0';
  
        sec = find_pc_section (pc);
        objfile = (sec == NULL) ? NULL : sec->objfile;
        minsym = lookup_minimal_symbol (target_name, NULL, objfile);
        if (minsym.minsym != NULL)
  	return BMSYMBOL_VALUE_ADDRESS (minsym);
        else
  	return 0;
      }
  
    return 0;			/* not a stub */
  }
  
  static void
  set_arm_command (char *args, int from_tty)
  {
    printf_unfiltered (_("\
  \"set arm\" must be followed by an apporpriate subcommand.\n"));
    help_list (setarmcmdlist, "set arm ", all_commands, gdb_stdout);
  }
  
  static void
  show_arm_command (char *args, int from_tty)
  {
    cmd_show_list (showarmcmdlist, from_tty, "");
  }
  
  static void
  arm_update_current_architecture (void)
  {
    struct gdbarch_info info;
  
    /* If the current architecture is not ARM, we have nothing to do.  */
    if (gdbarch_bfd_arch_info (target_gdbarch ())->arch != bfd_arch_arm)
      return;
  
    /* Update the architecture.  */
    gdbarch_info_init (&info);
  
    if (!gdbarch_update_p (info))
      internal_error (__FILE__, __LINE__, _("could not update architecture"));
  }
  
  static void
  set_fp_model_sfunc (char *args, int from_tty,
  		    struct cmd_list_element *c)
  {
    int fp_model;
  
    for (fp_model = ARM_FLOAT_AUTO; fp_model != ARM_FLOAT_LAST; fp_model++)
      if (strcmp (current_fp_model, fp_model_strings[fp_model]) == 0)
        {
  	arm_fp_model = (enum arm_float_model) fp_model;
  	break;
        }
  
    if (fp_model == ARM_FLOAT_LAST)
      internal_error (__FILE__, __LINE__, _("Invalid fp model accepted: %s."),
  		    current_fp_model);
  
    arm_update_current_architecture ();
  }
  
  static void
  show_fp_model (struct ui_file *file, int from_tty,
  	       struct cmd_list_element *c, const char *value)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (target_gdbarch ());
  
    if (arm_fp_model == ARM_FLOAT_AUTO
        && gdbarch_bfd_arch_info (target_gdbarch ())->arch == bfd_arch_arm)
      fprintf_filtered (file, _("\
  The current ARM floating point model is \"auto\" (currently \"%s\").\n"),
  		      fp_model_strings[tdep->fp_model]);
    else
      fprintf_filtered (file, _("\
  The current ARM floating point model is \"%s\".\n"),
  		      fp_model_strings[arm_fp_model]);
  }
  
  static void
  arm_set_abi (char *args, int from_tty,
  	     struct cmd_list_element *c)
  {
    int arm_abi;
  
    for (arm_abi = ARM_ABI_AUTO; arm_abi != ARM_ABI_LAST; arm_abi++)
      if (strcmp (arm_abi_string, arm_abi_strings[arm_abi]) == 0)
        {
  	arm_abi_global = (enum arm_abi_kind) arm_abi;
  	break;
        }
  
    if (arm_abi == ARM_ABI_LAST)
      internal_error (__FILE__, __LINE__, _("Invalid ABI accepted: %s."),
  		    arm_abi_string);
  
    arm_update_current_architecture ();
  }
  
  static void
  arm_show_abi (struct ui_file *file, int from_tty,
  	     struct cmd_list_element *c, const char *value)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (target_gdbarch ());
  
    if (arm_abi_global == ARM_ABI_AUTO
        && gdbarch_bfd_arch_info (target_gdbarch ())->arch == bfd_arch_arm)
      fprintf_filtered (file, _("\
  The current ARM ABI is \"auto\" (currently \"%s\").\n"),
  		      arm_abi_strings[tdep->arm_abi]);
    else
      fprintf_filtered (file, _("The current ARM ABI is \"%s\".\n"),
  		      arm_abi_string);
  }
  
  static void
  arm_show_fallback_mode (struct ui_file *file, int from_tty,
  			struct cmd_list_element *c, const char *value)
  {
    fprintf_filtered (file,
  		    _("The current execution mode assumed "
  		      "(when symbols are unavailable) is \"%s\".\n"),
  		    arm_fallback_mode_string);
  }
  
  static void
  arm_show_force_mode (struct ui_file *file, int from_tty,
  		     struct cmd_list_element *c, const char *value)
  {
    fprintf_filtered (file,
  		    _("The current execution mode assumed "
  		      "(even when symbols are available) is \"%s\".\n"),
  		    arm_force_mode_string);
  }
  
  /* If the user changes the register disassembly style used for info
     register and other commands, we have to also switch the style used
     in opcodes for disassembly output.  This function is run in the "set
     arm disassembly" command, and does that.  */
  
  static void
  set_disassembly_style_sfunc (char *args, int from_tty,
  			      struct cmd_list_element *c)
  {
    set_disassembly_style ();
  }
  
  /* Return the ARM register name corresponding to register I.  */
  static const char *
  arm_register_name (struct gdbarch *gdbarch, int i)
  {
    const int num_regs = gdbarch_num_regs (gdbarch);
  
    if (gdbarch_tdep (gdbarch)->have_vfp_pseudos
        && i >= num_regs && i < num_regs + 32)
      {
        static const char *const vfp_pseudo_names[] = {
  	"s0", "s1", "s2", "s3", "s4", "s5", "s6", "s7",
  	"s8", "s9", "s10", "s11", "s12", "s13", "s14", "s15",
  	"s16", "s17", "s18", "s19", "s20", "s21", "s22", "s23",
  	"s24", "s25", "s26", "s27", "s28", "s29", "s30", "s31",
        };
  
        return vfp_pseudo_names[i - num_regs];
      }
  
    if (gdbarch_tdep (gdbarch)->have_neon_pseudos
        && i >= num_regs + 32 && i < num_regs + 32 + 16)
      {
        static const char *const neon_pseudo_names[] = {
  	"q0", "q1", "q2", "q3", "q4", "q5", "q6", "q7",
  	"q8", "q9", "q10", "q11", "q12", "q13", "q14", "q15",
        };
  
        return neon_pseudo_names[i - num_regs - 32];
      }
  
    if (i >= ARRAY_SIZE (arm_register_names))
      /* These registers are only supported on targets which supply
         an XML description.  */
      return "";
  
    return arm_register_names[i];
  }
  
  static void
  set_disassembly_style (void)
  {
    int current;
  
    /* Find the style that the user wants.  */
    for (current = 0; current < num_disassembly_options; current++)
      if (disassembly_style == valid_disassembly_styles[current])
        break;
    gdb_assert (current < num_disassembly_options);
  
    /* Synchronize the disassembler.  */
    set_arm_regname_option (current);
  }
  
  /* Test whether the coff symbol specific value corresponds to a Thumb
     function.  */
  
  static int
  coff_sym_is_thumb (int val)
  {
    return (val == C_THUMBEXT
  	  || val == C_THUMBSTAT
  	  || val == C_THUMBEXTFUNC
  	  || val == C_THUMBSTATFUNC
  	  || val == C_THUMBLABEL);
  }
  
  /* arm_coff_make_msymbol_special()
     arm_elf_make_msymbol_special()
     
     These functions test whether the COFF or ELF symbol corresponds to
     an address in thumb code, and set a "special" bit in a minimal
     symbol to indicate that it does.  */
     
  static void
  arm_elf_make_msymbol_special(asymbol *sym, struct minimal_symbol *msym)
  {
    elf_symbol_type *elfsym = (elf_symbol_type *) sym;
  
    if (ARM_GET_SYM_BRANCH_TYPE (elfsym->internal_elf_sym.st_target_internal)
        == ST_BRANCH_TO_THUMB)
      MSYMBOL_SET_SPECIAL (msym);
  }
  
  static void
  arm_coff_make_msymbol_special(int val, struct minimal_symbol *msym)
  {
    if (coff_sym_is_thumb (val))
      MSYMBOL_SET_SPECIAL (msym);
  }
  
  static void
  arm_objfile_data_free (struct objfile *objfile, void *arg)
  {
    struct arm_per_objfile *data = (struct arm_per_objfile *) arg;
    unsigned int i;
  
    for (i = 0; i < objfile->obfd->section_count; i++)
      VEC_free (arm_mapping_symbol_s, data->section_maps[i]);
  }
  
  static void
  arm_record_special_symbol (struct gdbarch *gdbarch, struct objfile *objfile,
  			   asymbol *sym)
  {
    const char *name = bfd_asymbol_name (sym);
    struct arm_per_objfile *data;
    VEC(arm_mapping_symbol_s) **map_p;
    struct arm_mapping_symbol new_map_sym;
  
    gdb_assert (name[0] == '$');
    if (name[1] != 'a' && name[1] != 't' && name[1] != 'd')
      return;
  
    data = (struct arm_per_objfile *) objfile_data (objfile,
  						  arm_objfile_data_key);
    if (data == NULL)
      {
        data = OBSTACK_ZALLOC (&objfile->objfile_obstack,
  			     struct arm_per_objfile);
        set_objfile_data (objfile, arm_objfile_data_key, data);
        data->section_maps = OBSTACK_CALLOC (&objfile->objfile_obstack,
  					   objfile->obfd->section_count,
  					   VEC(arm_mapping_symbol_s) *);
      }
    map_p = &data->section_maps[bfd_get_section (sym)->index];
  
    new_map_sym.value = sym->value;
    new_map_sym.type = name[1];
  
    /* Assume that most mapping symbols appear in order of increasing
       value.  If they were randomly distributed, it would be faster to
       always push here and then sort at first use.  */
    if (!VEC_empty (arm_mapping_symbol_s, *map_p))
      {
        struct arm_mapping_symbol *prev_map_sym;
  
        prev_map_sym = VEC_last (arm_mapping_symbol_s, *map_p);
        if (prev_map_sym->value >= sym->value)
  	{
  	  unsigned int idx;
  	  idx = VEC_lower_bound (arm_mapping_symbol_s, *map_p, &new_map_sym,
  				 arm_compare_mapping_symbols);
  	  VEC_safe_insert (arm_mapping_symbol_s, *map_p, idx, &new_map_sym);
  	  return;
  	}
      }
  
    VEC_safe_push (arm_mapping_symbol_s, *map_p, &new_map_sym);
  }
  
  static void
  arm_write_pc (struct regcache *regcache, CORE_ADDR pc)
  {
    struct gdbarch *gdbarch = get_regcache_arch (regcache);
    regcache_cooked_write_unsigned (regcache, ARM_PC_REGNUM, pc);
  
    /* If necessary, set the T bit.  */
    if (arm_apcs_32)
      {
        ULONGEST val, t_bit;
        regcache_cooked_read_unsigned (regcache, ARM_PS_REGNUM, &val);
        t_bit = arm_psr_thumb_bit (gdbarch);
        if (arm_pc_is_thumb (gdbarch, pc))
  	regcache_cooked_write_unsigned (regcache, ARM_PS_REGNUM,
  					val | t_bit);
        else
  	regcache_cooked_write_unsigned (regcache, ARM_PS_REGNUM,
  					val & ~t_bit);
      }
  }
  
  /* Read the contents of a NEON quad register, by reading from two
     double registers.  This is used to implement the quad pseudo
     registers, and for argument passing in case the quad registers are
     missing; vectors are passed in quad registers when using the VFP
     ABI, even if a NEON unit is not present.  REGNUM is the index of
     the quad register, in [0, 15].  */
  
  static enum register_status
  arm_neon_quad_read (struct gdbarch *gdbarch, struct regcache *regcache,
  		    int regnum, gdb_byte *buf)
  {
    char name_buf[4];
    gdb_byte reg_buf[8];
    int offset, double_regnum;
    enum register_status status;
  
    xsnprintf (name_buf, sizeof (name_buf), "d%d", regnum << 1);
    double_regnum = user_reg_map_name_to_regnum (gdbarch, name_buf,
  					       strlen (name_buf));
  
    /* d0 is always the least significant half of q0.  */
    if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
      offset = 8;
    else
      offset = 0;
  
    status = regcache_raw_read (regcache, double_regnum, reg_buf);
    if (status != REG_VALID)
      return status;
    memcpy (buf + offset, reg_buf, 8);
  
    offset = 8 - offset;
    status = regcache_raw_read (regcache, double_regnum + 1, reg_buf);
    if (status != REG_VALID)
      return status;
    memcpy (buf + offset, reg_buf, 8);
  
    return REG_VALID;
  }
  
  static enum register_status
  arm_pseudo_read (struct gdbarch *gdbarch, struct regcache *regcache,
  		 int regnum, gdb_byte *buf)
  {
    const int num_regs = gdbarch_num_regs (gdbarch);
    char name_buf[4];
    gdb_byte reg_buf[8];
    int offset, double_regnum;
  
    gdb_assert (regnum >= num_regs);
    regnum -= num_regs;
  
    if (gdbarch_tdep (gdbarch)->have_neon_pseudos && regnum >= 32 && regnum < 48)
      /* Quad-precision register.  */
      return arm_neon_quad_read (gdbarch, regcache, regnum - 32, buf);
    else
      {
        enum register_status status;
  
        /* Single-precision register.  */
        gdb_assert (regnum < 32);
  
        /* s0 is always the least significant half of d0.  */
        if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
  	offset = (regnum & 1) ? 0 : 4;
        else
  	offset = (regnum & 1) ? 4 : 0;
  
        xsnprintf (name_buf, sizeof (name_buf), "d%d", regnum >> 1);
        double_regnum = user_reg_map_name_to_regnum (gdbarch, name_buf,
  						   strlen (name_buf));
  
        status = regcache_raw_read (regcache, double_regnum, reg_buf);
        if (status == REG_VALID)
  	memcpy (buf, reg_buf + offset, 4);
        return status;
      }
  }
  
  /* Store the contents of BUF to a NEON quad register, by writing to
     two double registers.  This is used to implement the quad pseudo
     registers, and for argument passing in case the quad registers are
     missing; vectors are passed in quad registers when using the VFP
     ABI, even if a NEON unit is not present.  REGNUM is the index
     of the quad register, in [0, 15].  */
  
  static void
  arm_neon_quad_write (struct gdbarch *gdbarch, struct regcache *regcache,
  		     int regnum, const gdb_byte *buf)
  {
    char name_buf[4];
    int offset, double_regnum;
  
    xsnprintf (name_buf, sizeof (name_buf), "d%d", regnum << 1);
    double_regnum = user_reg_map_name_to_regnum (gdbarch, name_buf,
  					       strlen (name_buf));
  
    /* d0 is always the least significant half of q0.  */
    if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
      offset = 8;
    else
      offset = 0;
  
    regcache_raw_write (regcache, double_regnum, buf + offset);
    offset = 8 - offset;
    regcache_raw_write (regcache, double_regnum + 1, buf + offset);
  }
  
  static void
  arm_pseudo_write (struct gdbarch *gdbarch, struct regcache *regcache,
  		  int regnum, const gdb_byte *buf)
  {
    const int num_regs = gdbarch_num_regs (gdbarch);
    char name_buf[4];
    gdb_byte reg_buf[8];
    int offset, double_regnum;
  
    gdb_assert (regnum >= num_regs);
    regnum -= num_regs;
  
    if (gdbarch_tdep (gdbarch)->have_neon_pseudos && regnum >= 32 && regnum < 48)
      /* Quad-precision register.  */
      arm_neon_quad_write (gdbarch, regcache, regnum - 32, buf);
    else
      {
        /* Single-precision register.  */
        gdb_assert (regnum < 32);
  
        /* s0 is always the least significant half of d0.  */
        if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
  	offset = (regnum & 1) ? 0 : 4;
        else
  	offset = (regnum & 1) ? 4 : 0;
  
        xsnprintf (name_buf, sizeof (name_buf), "d%d", regnum >> 1);
        double_regnum = user_reg_map_name_to_regnum (gdbarch, name_buf,
  						   strlen (name_buf));
  
        regcache_raw_read (regcache, double_regnum, reg_buf);
        memcpy (reg_buf + offset, buf, 4);
        regcache_raw_write (regcache, double_regnum, reg_buf);
      }
  }
  
  static struct value *
  value_of_arm_user_reg (struct frame_info *frame, const void *baton)
  {
    const int *reg_p = (const int *) baton;
    return value_of_register (*reg_p, frame);
  }
  
  static enum gdb_osabi
  arm_elf_osabi_sniffer (bfd *abfd)
  {
    unsigned int elfosabi;
    enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
  
    elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
  
    if (elfosabi == ELFOSABI_ARM)
      /* GNU tools use this value.  Check note sections in this case,
         as well.  */
      bfd_map_over_sections (abfd,
  			   generic_elf_osabi_sniff_abi_tag_sections, 
  			   &osabi);
  
    /* Anything else will be handled by the generic ELF sniffer.  */
    return osabi;
  }
  
  static int
  arm_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
  			  struct reggroup *group)
  {
    /* FPS register's type is INT, but belongs to float_reggroup.  Beside
       this, FPS register belongs to save_regroup, restore_reggroup, and
       all_reggroup, of course.  */
    if (regnum == ARM_FPS_REGNUM)
      return (group == float_reggroup
  	    || group == save_reggroup
  	    || group == restore_reggroup
  	    || group == all_reggroup);
    else
      return default_register_reggroup_p (gdbarch, regnum, group);
  }
  
  
  /* For backward-compatibility we allow two 'g' packet lengths with
     the remote protocol depending on whether FPA registers are
     supplied.  M-profile targets do not have FPA registers, but some
     stubs already exist in the wild which use a 'g' packet which
     supplies them albeit with dummy values.  The packet format which
     includes FPA registers should be considered deprecated for
     M-profile targets.  */
  
  static void
  arm_register_g_packet_guesses (struct gdbarch *gdbarch)
  {
    if (gdbarch_tdep (gdbarch)->is_m)
      {
        /* If we know from the executable this is an M-profile target,
  	 cater for remote targets whose register set layout is the
  	 same as the FPA layout.  */
        register_remote_g_packet_guess (gdbarch,
  				      /* r0-r12,sp,lr,pc; f0-f7; fps,xpsr */
  				      (16 * INT_REGISTER_SIZE)
  				      + (8 * FP_REGISTER_SIZE)
  				      + (2 * INT_REGISTER_SIZE),
  				      tdesc_arm_with_m_fpa_layout);
  
        /* The regular M-profile layout.  */
        register_remote_g_packet_guess (gdbarch,
  				      /* r0-r12,sp,lr,pc; xpsr */
  				      (16 * INT_REGISTER_SIZE)
  				      + INT_REGISTER_SIZE,
  				      tdesc_arm_with_m);
  
        /* M-profile plus M4F VFP.  */
        register_remote_g_packet_guess (gdbarch,
  				      /* r0-r12,sp,lr,pc; d0-d15; fpscr,xpsr */
  				      (16 * INT_REGISTER_SIZE)
  				      + (16 * VFP_REGISTER_SIZE)
  				      + (2 * INT_REGISTER_SIZE),
  				      tdesc_arm_with_m_vfp_d16);
      }
  
    /* Otherwise we don't have a useful guess.  */
  }
  
  /* Implement the code_of_frame_writable gdbarch method.  */
  
  static int
  arm_code_of_frame_writable (struct gdbarch *gdbarch, struct frame_info *frame)
  {
    if (gdbarch_tdep (gdbarch)->is_m
        && get_frame_type (frame) == SIGTRAMP_FRAME)
      {
        /* M-profile exception frames return to some magic PCs, where
  	 isn't writable at all.  */
        return 0;
      }
    else
      return 1;
  }
  
  
  /* Initialize the current architecture based on INFO.  If possible,
     re-use an architecture from ARCHES, which is a list of
     architectures already created during this debugging session.
  
     Called e.g. at program startup, when reading a core file, and when
     reading a binary file.  */
  
  static struct gdbarch *
  arm_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
  {
    struct gdbarch_tdep *tdep;
    struct gdbarch *gdbarch;
    struct gdbarch_list *best_arch;
    enum arm_abi_kind arm_abi = arm_abi_global;
    enum arm_float_model fp_model = arm_fp_model;
    struct tdesc_arch_data *tdesc_data = NULL;
    int i, is_m = 0;
    int vfp_register_count = 0, have_vfp_pseudos = 0, have_neon_pseudos = 0;
    int have_wmmx_registers = 0;
    int have_neon = 0;
    int have_fpa_registers = 1;
    const struct target_desc *tdesc = info.target_desc;
  
    /* If we have an object to base this architecture on, try to determine
       its ABI.  */
  
    if (arm_abi == ARM_ABI_AUTO && info.abfd != NULL)
      {
        int ei_osabi, e_flags;
  
        switch (bfd_get_flavour (info.abfd))
  	{
  	case bfd_target_aout_flavour:
  	  /* Assume it's an old APCS-style ABI.  */
  	  arm_abi = ARM_ABI_APCS;
  	  break;
  
  	case bfd_target_coff_flavour:
  	  /* Assume it's an old APCS-style ABI.  */
  	  /* XXX WinCE?  */
  	  arm_abi = ARM_ABI_APCS;
  	  break;
  
  	case bfd_target_elf_flavour:
  	  ei_osabi = elf_elfheader (info.abfd)->e_ident[EI_OSABI];
  	  e_flags = elf_elfheader (info.abfd)->e_flags;
  
  	  if (ei_osabi == ELFOSABI_ARM)
  	    {
  	      /* GNU tools used to use this value, but do not for EABI
  		 objects.  There's nowhere to tag an EABI version
  		 anyway, so assume APCS.  */
  	      arm_abi = ARM_ABI_APCS;
  	    }
  	  else if (ei_osabi == ELFOSABI_NONE || ei_osabi == ELFOSABI_GNU)
  	    {
  	      int eabi_ver = EF_ARM_EABI_VERSION (e_flags);
  	      int attr_arch, attr_profile;
  
  	      switch (eabi_ver)
  		{
  		case EF_ARM_EABI_UNKNOWN:
  		  /* Assume GNU tools.  */
  		  arm_abi = ARM_ABI_APCS;
  		  break;
  
  		case EF_ARM_EABI_VER4:
  		case EF_ARM_EABI_VER5:
  		  arm_abi = ARM_ABI_AAPCS;
  		  /* EABI binaries default to VFP float ordering.
  		     They may also contain build attributes that can
  		     be used to identify if the VFP argument-passing
  		     ABI is in use.  */
  		  if (fp_model == ARM_FLOAT_AUTO)
  		    {
  #ifdef HAVE_ELF
  		      switch (bfd_elf_get_obj_attr_int (info.abfd,
  							OBJ_ATTR_PROC,
  							Tag_ABI_VFP_args))
  			{
  			case AEABI_VFP_args_base:
  			  /* "The user intended FP parameter/result
  			     passing to conform to AAPCS, base
  			     variant".  */
  			  fp_model = ARM_FLOAT_SOFT_VFP;
  			  break;
  			case AEABI_VFP_args_vfp:
  			  /* "The user intended FP parameter/result
  			     passing to conform to AAPCS, VFP
  			     variant".  */
  			  fp_model = ARM_FLOAT_VFP;
  			  break;
  			case AEABI_VFP_args_toolchain:
  			  /* "The user intended FP parameter/result
  			     passing to conform to tool chain-specific
  			     conventions" - we don't know any such
  			     conventions, so leave it as "auto".  */
  			  break;
  			case AEABI_VFP_args_compatible:
  			  /* "Code is compatible with both the base
  			     and VFP variants; the user did not permit
  			     non-variadic functions to pass FP
  			     parameters/results" - leave it as
  			     "auto".  */
  			  break;
  			default:
  			  /* Attribute value not mentioned in the
  			     November 2012 ABI, so leave it as
  			     "auto".  */
  			  break;
  			}
  #else
  		      fp_model = ARM_FLOAT_SOFT_VFP;
  #endif
  		    }
  		  break;
  
  		default:
  		  /* Leave it as "auto".  */
  		  warning (_("unknown ARM EABI version 0x%x"), eabi_ver);
  		  break;
  		}
  
  #ifdef HAVE_ELF
  	      /* Detect M-profile programs.  This only works if the
  		 executable file includes build attributes; GCC does
  		 copy them to the executable, but e.g. RealView does
  		 not.  */
  	      attr_arch = bfd_elf_get_obj_attr_int (info.abfd, OBJ_ATTR_PROC,
  						    Tag_CPU_arch);
  	      attr_profile = bfd_elf_get_obj_attr_int (info.abfd,
  						       OBJ_ATTR_PROC,
  						       Tag_CPU_arch_profile);
  	      /* GCC specifies the profile for v6-M; RealView only
  		 specifies the profile for architectures starting with
  		 V7 (as opposed to architectures with a tag
  		 numerically greater than TAG_CPU_ARCH_V7).  */
  	      if (!tdesc_has_registers (tdesc)
  		  && (attr_arch == TAG_CPU_ARCH_V6_M
  		      || attr_arch == TAG_CPU_ARCH_V6S_M
  		      || attr_profile == 'M'))
  		is_m = 1;
  #endif
  	    }
  
  	  if (fp_model == ARM_FLOAT_AUTO)
  	    {
  	      int e_flags = elf_elfheader (info.abfd)->e_flags;
  
  	      switch (e_flags & (EF_ARM_SOFT_FLOAT | EF_ARM_VFP_FLOAT))
  		{
  		case 0:
  		  /* Leave it as "auto".  Strictly speaking this case
  		     means FPA, but almost nobody uses that now, and
  		     many toolchains fail to set the appropriate bits
  		     for the floating-point model they use.  */
  		  break;
  		case EF_ARM_SOFT_FLOAT:
  		  fp_model = ARM_FLOAT_SOFT_FPA;
  		  break;
  		case EF_ARM_VFP_FLOAT:
  		  fp_model = ARM_FLOAT_VFP;
  		  break;
  		case EF_ARM_SOFT_FLOAT | EF_ARM_VFP_FLOAT:
  		  fp_model = ARM_FLOAT_SOFT_VFP;
  		  break;
  		}
  	    }
  
  	  if (e_flags & EF_ARM_BE8)
  	    info.byte_order_for_code = BFD_ENDIAN_LITTLE;
  
  	  break;
  
  	default:
  	  /* Leave it as "auto".  */
  	  break;
  	}
      }
  
    /* Check any target description for validity.  */
    if (tdesc_has_registers (tdesc))
      {
        /* For most registers we require GDB's default names; but also allow
  	 the numeric names for sp / lr / pc, as a convenience.  */
        static const char *const arm_sp_names[] = { "r13", "sp", NULL };
        static const char *const arm_lr_names[] = { "r14", "lr", NULL };
        static const char *const arm_pc_names[] = { "r15", "pc", NULL };
  
        const struct tdesc_feature *feature;
        int valid_p;
  
        feature = tdesc_find_feature (tdesc,
  				    "org.gnu.gdb.arm.core");
        if (feature == NULL)
  	{
  	  feature = tdesc_find_feature (tdesc,
  					"org.gnu.gdb.arm.m-profile");
  	  if (feature == NULL)
  	    return NULL;
  	  else
  	    is_m = 1;
  	}
  
        tdesc_data = tdesc_data_alloc ();
  
        valid_p = 1;
        for (i = 0; i < ARM_SP_REGNUM; i++)
  	valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
  					    arm_register_names[i]);
        valid_p &= tdesc_numbered_register_choices (feature, tdesc_data,
  						  ARM_SP_REGNUM,
  						  arm_sp_names);
        valid_p &= tdesc_numbered_register_choices (feature, tdesc_data,
  						  ARM_LR_REGNUM,
  						  arm_lr_names);
        valid_p &= tdesc_numbered_register_choices (feature, tdesc_data,
  						  ARM_PC_REGNUM,
  						  arm_pc_names);
        if (is_m)
  	valid_p &= tdesc_numbered_register (feature, tdesc_data,
  					    ARM_PS_REGNUM, "xpsr");
        else
  	valid_p &= tdesc_numbered_register (feature, tdesc_data,
  					    ARM_PS_REGNUM, "cpsr");
  
        if (!valid_p)
  	{
  	  tdesc_data_cleanup (tdesc_data);
  	  return NULL;
  	}
  
        feature = tdesc_find_feature (tdesc,
  				    "org.gnu.gdb.arm.fpa");
        if (feature != NULL)
  	{
  	  valid_p = 1;
  	  for (i = ARM_F0_REGNUM; i <= ARM_FPS_REGNUM; i++)
  	    valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
  						arm_register_names[i]);
  	  if (!valid_p)
  	    {
  	      tdesc_data_cleanup (tdesc_data);
  	      return NULL;
  	    }
  	}
        else
  	have_fpa_registers = 0;
  
        feature = tdesc_find_feature (tdesc,
  				    "org.gnu.gdb.xscale.iwmmxt");
        if (feature != NULL)
  	{
  	  static const char *const iwmmxt_names[] = {
  	    "wR0", "wR1", "wR2", "wR3", "wR4", "wR5", "wR6", "wR7",
  	    "wR8", "wR9", "wR10", "wR11", "wR12", "wR13", "wR14", "wR15",
  	    "wCID", "wCon", "wCSSF", "wCASF", "", "", "", "",
  	    "wCGR0", "wCGR1", "wCGR2", "wCGR3", "", "", "", "",
  	  };
  
  	  valid_p = 1;
  	  for (i = ARM_WR0_REGNUM; i <= ARM_WR15_REGNUM; i++)
  	    valid_p
  	      &= tdesc_numbered_register (feature, tdesc_data, i,
  					  iwmmxt_names[i - ARM_WR0_REGNUM]);
  
  	  /* Check for the control registers, but do not fail if they
  	     are missing.  */
  	  for (i = ARM_WC0_REGNUM; i <= ARM_WCASF_REGNUM; i++)
  	    tdesc_numbered_register (feature, tdesc_data, i,
  				     iwmmxt_names[i - ARM_WR0_REGNUM]);
  
  	  for (i = ARM_WCGR0_REGNUM; i <= ARM_WCGR3_REGNUM; i++)
  	    valid_p
  	      &= tdesc_numbered_register (feature, tdesc_data, i,
  					  iwmmxt_names[i - ARM_WR0_REGNUM]);
  
  	  if (!valid_p)
  	    {
  	      tdesc_data_cleanup (tdesc_data);
  	      return NULL;
  	    }
  
  	  have_wmmx_registers = 1;
  	}
  
        /* If we have a VFP unit, check whether the single precision registers
  	 are present.  If not, then we will synthesize them as pseudo
  	 registers.  */
        feature = tdesc_find_feature (tdesc,
  				    "org.gnu.gdb.arm.vfp");
        if (feature != NULL)
  	{
  	  static const char *const vfp_double_names[] = {
  	    "d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7",
  	    "d8", "d9", "d10", "d11", "d12", "d13", "d14", "d15",
  	    "d16", "d17", "d18", "d19", "d20", "d21", "d22", "d23",
  	    "d24", "d25", "d26", "d27", "d28", "d29", "d30", "d31",
  	  };
  
  	  /* Require the double precision registers.  There must be either
  	     16 or 32.  */
  	  valid_p = 1;
  	  for (i = 0; i < 32; i++)
  	    {
  	      valid_p &= tdesc_numbered_register (feature, tdesc_data,
  						  ARM_D0_REGNUM + i,
  						  vfp_double_names[i]);
  	      if (!valid_p)
  		break;
  	    }
  	  if (!valid_p && i == 16)
  	    valid_p = 1;
  
  	  /* Also require FPSCR.  */
  	  valid_p &= tdesc_numbered_register (feature, tdesc_data,
  					      ARM_FPSCR_REGNUM, "fpscr");
  	  if (!valid_p)
  	    {
  	      tdesc_data_cleanup (tdesc_data);
  	      return NULL;
  	    }
  
  	  if (tdesc_unnumbered_register (feature, "s0") == 0)
  	    have_vfp_pseudos = 1;
  
  	  vfp_register_count = i;
  
  	  /* If we have VFP, also check for NEON.  The architecture allows
  	     NEON without VFP (integer vector operations only), but GDB
  	     does not support that.  */
  	  feature = tdesc_find_feature (tdesc,
  					"org.gnu.gdb.arm.neon");
  	  if (feature != NULL)
  	    {
  	      /* NEON requires 32 double-precision registers.  */
  	      if (i != 32)
  		{
  		  tdesc_data_cleanup (tdesc_data);
  		  return NULL;
  		}
  
  	      /* If there are quad registers defined by the stub, use
  		 their type; otherwise (normally) provide them with
  		 the default type.  */
  	      if (tdesc_unnumbered_register (feature, "q0") == 0)
  		have_neon_pseudos = 1;
  
  	      have_neon = 1;
  	    }
  	}
      }
  
    /* If there is already a candidate, use it.  */
    for (best_arch = gdbarch_list_lookup_by_info (arches, &info);
         best_arch != NULL;
         best_arch = gdbarch_list_lookup_by_info (best_arch->next, &info))
      {
        if (arm_abi != ARM_ABI_AUTO
  	  && arm_abi != gdbarch_tdep (best_arch->gdbarch)->arm_abi)
  	continue;
  
        if (fp_model != ARM_FLOAT_AUTO
  	  && fp_model != gdbarch_tdep (best_arch->gdbarch)->fp_model)
  	continue;
  
        /* There are various other properties in tdep that we do not
  	 need to check here: those derived from a target description,
  	 since gdbarches with a different target description are
  	 automatically disqualified.  */
  
        /* Do check is_m, though, since it might come from the binary.  */
        if (is_m != gdbarch_tdep (best_arch->gdbarch)->is_m)
  	continue;
  
        /* Found a match.  */
        break;
      }
  
    if (best_arch != NULL)
      {
        if (tdesc_data != NULL)
  	tdesc_data_cleanup (tdesc_data);
        return best_arch->gdbarch;
      }
  
    tdep = XCNEW (struct gdbarch_tdep);
    gdbarch = gdbarch_alloc (&info, tdep);
  
    /* Record additional information about the architecture we are defining.
       These are gdbarch discriminators, like the OSABI.  */
    tdep->arm_abi = arm_abi;
    tdep->fp_model = fp_model;
    tdep->is_m = is_m;
    tdep->have_fpa_registers = have_fpa_registers;
    tdep->have_wmmx_registers = have_wmmx_registers;
    gdb_assert (vfp_register_count == 0
  	      || vfp_register_count == 16
  	      || vfp_register_count == 32);
    tdep->vfp_register_count = vfp_register_count;
    tdep->have_vfp_pseudos = have_vfp_pseudos;
    tdep->have_neon_pseudos = have_neon_pseudos;
    tdep->have_neon = have_neon;
  
    arm_register_g_packet_guesses (gdbarch);
  
    /* Breakpoints.  */
    switch (info.byte_order_for_code)
      {
      case BFD_ENDIAN_BIG:
        tdep->arm_breakpoint = arm_default_arm_be_breakpoint;
        tdep->arm_breakpoint_size = sizeof (arm_default_arm_be_breakpoint);
        tdep->thumb_breakpoint = arm_default_thumb_be_breakpoint;
        tdep->thumb_breakpoint_size = sizeof (arm_default_thumb_be_breakpoint);
  
        break;
  
      case BFD_ENDIAN_LITTLE:
        tdep->arm_breakpoint = arm_default_arm_le_breakpoint;
        tdep->arm_breakpoint_size = sizeof (arm_default_arm_le_breakpoint);
        tdep->thumb_breakpoint = arm_default_thumb_le_breakpoint;
        tdep->thumb_breakpoint_size = sizeof (arm_default_thumb_le_breakpoint);
  
        break;
  
      default:
        internal_error (__FILE__, __LINE__,
  		      _("arm_gdbarch_init: bad byte order for float format"));
      }
  
    /* On ARM targets char defaults to unsigned.  */
    set_gdbarch_char_signed (gdbarch, 0);
  
    /* Note: for displaced stepping, this includes the breakpoint, and one word
       of additional scratch space.  This setting isn't used for anything beside
       displaced stepping at present.  */
    set_gdbarch_max_insn_length (gdbarch, 4 * DISPLACED_MODIFIED_INSNS);
  
    /* This should be low enough for everything.  */
    tdep->lowest_pc = 0x20;
    tdep->jb_pc = -1;	/* Longjump support not enabled by default.  */
  
    /* The default, for both APCS and AAPCS, is to return small
       structures in registers.  */
    tdep->struct_return = reg_struct_return;
  
    set_gdbarch_push_dummy_call (gdbarch, arm_push_dummy_call);
    set_gdbarch_frame_align (gdbarch, arm_frame_align);
  
    if (is_m)
      set_gdbarch_code_of_frame_writable (gdbarch, arm_code_of_frame_writable);
  
    set_gdbarch_write_pc (gdbarch, arm_write_pc);
  
    /* Frame handling.  */
    set_gdbarch_dummy_id (gdbarch, arm_dummy_id);
    set_gdbarch_unwind_pc (gdbarch, arm_unwind_pc);
    set_gdbarch_unwind_sp (gdbarch, arm_unwind_sp);
  
    frame_base_set_default (gdbarch, &arm_normal_base);
  
    /* Address manipulation.  */
    set_gdbarch_addr_bits_remove (gdbarch, arm_addr_bits_remove);
  
    /* Advance PC across function entry code.  */
    set_gdbarch_skip_prologue (gdbarch, arm_skip_prologue);
  
    /* Detect whether PC is at a point where the stack has been destroyed.  */
    set_gdbarch_stack_frame_destroyed_p (gdbarch, arm_stack_frame_destroyed_p);
  
    /* Skip trampolines.  */
    set_gdbarch_skip_trampoline_code (gdbarch, arm_skip_stub);
  
    /* The stack grows downward.  */
    set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
  
    /* Breakpoint manipulation.  */
    set_gdbarch_breakpoint_from_pc (gdbarch, arm_breakpoint_from_pc);
    set_gdbarch_remote_breakpoint_from_pc (gdbarch,
  					 arm_remote_breakpoint_from_pc);
  
    /* Information about registers, etc.  */
    set_gdbarch_sp_regnum (gdbarch, ARM_SP_REGNUM);
    set_gdbarch_pc_regnum (gdbarch, ARM_PC_REGNUM);
    set_gdbarch_num_regs (gdbarch, ARM_NUM_REGS);
    set_gdbarch_register_type (gdbarch, arm_register_type);
    set_gdbarch_register_reggroup_p (gdbarch, arm_register_reggroup_p);
  
    /* This "info float" is FPA-specific.  Use the generic version if we
       do not have FPA.  */
    if (gdbarch_tdep (gdbarch)->have_fpa_registers)
      set_gdbarch_print_float_info (gdbarch, arm_print_float_info);
  
    /* Internal <-> external register number maps.  */
    set_gdbarch_dwarf2_reg_to_regnum (gdbarch, arm_dwarf_reg_to_regnum);
    set_gdbarch_register_sim_regno (gdbarch, arm_register_sim_regno);
  
    set_gdbarch_register_name (gdbarch, arm_register_name);
  
    /* Returning results.  */
    set_gdbarch_return_value (gdbarch, arm_return_value);
  
    /* Disassembly.  */
    set_gdbarch_print_insn (gdbarch, gdb_print_insn_arm);
  
    /* Minsymbol frobbing.  */
    set_gdbarch_elf_make_msymbol_special (gdbarch, arm_elf_make_msymbol_special);
    set_gdbarch_coff_make_msymbol_special (gdbarch,
  					 arm_coff_make_msymbol_special);
    set_gdbarch_record_special_symbol (gdbarch, arm_record_special_symbol);
  
    /* Thumb-2 IT block support.  */
    set_gdbarch_adjust_breakpoint_address (gdbarch,
  					 arm_adjust_breakpoint_address);
  
    /* Virtual tables.  */
    set_gdbarch_vbit_in_delta (gdbarch, 1);
  
    /* Hook in the ABI-specific overrides, if they have been registered.  */
    gdbarch_init_osabi (info, gdbarch);
  
    dwarf2_frame_set_init_reg (gdbarch, arm_dwarf2_frame_init_reg);
  
    /* Add some default predicates.  */
    if (is_m)
      frame_unwind_append_unwinder (gdbarch, &arm_m_exception_unwind);
    frame_unwind_append_unwinder (gdbarch, &arm_stub_unwind);
    dwarf2_append_unwinders (gdbarch);
    frame_unwind_append_unwinder (gdbarch, &arm_exidx_unwind);
    frame_unwind_append_unwinder (gdbarch, &arm_epilogue_frame_unwind);
    frame_unwind_append_unwinder (gdbarch, &arm_prologue_unwind);
  
    /* Now we have tuned the configuration, set a few final things,
       based on what the OS ABI has told us.  */
  
    /* If the ABI is not otherwise marked, assume the old GNU APCS.  EABI
       binaries are always marked.  */
    if (tdep->arm_abi == ARM_ABI_AUTO)
      tdep->arm_abi = ARM_ABI_APCS;
  
    /* Watchpoints are not steppable.  */
    set_gdbarch_have_nonsteppable_watchpoint (gdbarch, 1);
  
    /* We used to default to FPA for generic ARM, but almost nobody
       uses that now, and we now provide a way for the user to force
       the model.  So default to the most useful variant.  */
    if (tdep->fp_model == ARM_FLOAT_AUTO)
      tdep->fp_model = ARM_FLOAT_SOFT_FPA;
  
    if (tdep->jb_pc >= 0)
      set_gdbarch_get_longjmp_target (gdbarch, arm_get_longjmp_target);
  
    /* Floating point sizes and format.  */
    set_gdbarch_float_format (gdbarch, floatformats_ieee_single);
    if (tdep->fp_model == ARM_FLOAT_SOFT_FPA || tdep->fp_model == ARM_FLOAT_FPA)
      {
        set_gdbarch_double_format
  	(gdbarch, floatformats_ieee_double_littlebyte_bigword);
        set_gdbarch_long_double_format
  	(gdbarch, floatformats_ieee_double_littlebyte_bigword);
      }
    else
      {
        set_gdbarch_double_format (gdbarch, floatformats_ieee_double);
        set_gdbarch_long_double_format (gdbarch, floatformats_ieee_double);
      }
  
    if (have_vfp_pseudos)
      {
        /* NOTE: These are the only pseudo registers used by
  	 the ARM target at the moment.  If more are added, a
  	 little more care in numbering will be needed.  */
  
        int num_pseudos = 32;
        if (have_neon_pseudos)
  	num_pseudos += 16;
        set_gdbarch_num_pseudo_regs (gdbarch, num_pseudos);
        set_gdbarch_pseudo_register_read (gdbarch, arm_pseudo_read);
        set_gdbarch_pseudo_register_write (gdbarch, arm_pseudo_write);
      }
  
    if (tdesc_data)
      {
        set_tdesc_pseudo_register_name (gdbarch, arm_register_name);
  
        tdesc_use_registers (gdbarch, tdesc, tdesc_data);
  
        /* Override tdesc_register_type to adjust the types of VFP
  	 registers for NEON.  */
        set_gdbarch_register_type (gdbarch, arm_register_type);
      }
  
    /* Add standard register aliases.  We add aliases even for those
       nanes which are used by the current architecture - it's simpler,
       and does no harm, since nothing ever lists user registers.  */
    for (i = 0; i < ARRAY_SIZE (arm_register_aliases); i++)
      user_reg_add (gdbarch, arm_register_aliases[i].name,
  		  value_of_arm_user_reg, &arm_register_aliases[i].regnum);
  
    return gdbarch;
  }
  
  static void
  arm_dump_tdep (struct gdbarch *gdbarch, struct ui_file *file)
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  
    if (tdep == NULL)
      return;
  
    fprintf_unfiltered (file, _("arm_dump_tdep: Lowest pc = 0x%lx"),
  		      (unsigned long) tdep->lowest_pc);
  }
  
  extern initialize_file_ftype _initialize_arm_tdep; /* -Wmissing-prototypes */
  
  void
  _initialize_arm_tdep (void)
  {
    struct ui_file *stb;
    long length;
    const char *setname;
    const char *setdesc;
    const char *const *regnames;
    int i;
    static char *helptext;
    char regdesc[1024], *rdptr = regdesc;
    size_t rest = sizeof (regdesc);
  
    gdbarch_register (bfd_arch_arm, arm_gdbarch_init, arm_dump_tdep);
  
    arm_objfile_data_key
      = register_objfile_data_with_cleanup (NULL, arm_objfile_data_free);
  
    /* Add ourselves to objfile event chain.  */
    observer_attach_new_objfile (arm_exidx_new_objfile);
    arm_exidx_data_key
      = register_objfile_data_with_cleanup (NULL, arm_exidx_data_free);
  
    /* Register an ELF OS ABI sniffer for ARM binaries.  */
    gdbarch_register_osabi_sniffer (bfd_arch_arm,
  				  bfd_target_elf_flavour,
  				  arm_elf_osabi_sniffer);
  
    /* Initialize the standard target descriptions.  */
    initialize_tdesc_arm_with_m ();
    initialize_tdesc_arm_with_m_fpa_layout ();
    initialize_tdesc_arm_with_m_vfp_d16 ();
    initialize_tdesc_arm_with_iwmmxt ();
    initialize_tdesc_arm_with_vfpv2 ();
    initialize_tdesc_arm_with_vfpv3 ();
    initialize_tdesc_arm_with_neon ();
  
    /* Get the number of possible sets of register names defined in opcodes.  */
    num_disassembly_options = get_arm_regname_num_options ();
  
    /* Add root prefix command for all "set arm"/"show arm" commands.  */
    add_prefix_cmd ("arm", no_class, set_arm_command,
  		  _("Various ARM-specific commands."),
  		  &setarmcmdlist, "set arm ", 0, &setlist);
  
    add_prefix_cmd ("arm", no_class, show_arm_command,
  		  _("Various ARM-specific commands."),
  		  &showarmcmdlist, "show arm ", 0, &showlist);
  
    /* Sync the opcode insn printer with our register viewer.  */
    parse_arm_disassembler_option ("reg-names-std");
  
    /* Initialize the array that will be passed to
       add_setshow_enum_cmd().  */
    valid_disassembly_styles = XNEWVEC (const char *,
  				      num_disassembly_options + 1);
    for (i = 0; i < num_disassembly_options; i++)
      {
        get_arm_regnames (i, &setname, &setdesc, &regnames);
        valid_disassembly_styles[i] = setname;
        length = snprintf (rdptr, rest, "%s - %s\n", setname, setdesc);
        rdptr += length;
        rest -= length;
        /* When we find the default names, tell the disassembler to use
  	 them.  */
        if (!strcmp (setname, "std"))
  	{
            disassembly_style = setname;
            set_arm_regname_option (i);
  	}
      }
    /* Mark the end of valid options.  */
    valid_disassembly_styles[num_disassembly_options] = NULL;
  
    /* Create the help text.  */
    stb = mem_fileopen ();
    fprintf_unfiltered (stb, "%s%s%s",
  		      _("The valid values are:\n"),
  		      regdesc,
  		      _("The default is \"std\"."));
    helptext = ui_file_xstrdup (stb, NULL);
    ui_file_delete (stb);
  
    add_setshow_enum_cmd("disassembler", no_class,
  		       valid_disassembly_styles, &disassembly_style,
  		       _("Set the disassembly style."),
  		       _("Show the disassembly style."),
  		       helptext,
  		       set_disassembly_style_sfunc,
  		       NULL, /* FIXME: i18n: The disassembly style is
  				\"%s\".  */
  		       &setarmcmdlist, &showarmcmdlist);
  
    add_setshow_boolean_cmd ("apcs32", no_class, &arm_apcs_32,
  			   _("Set usage of ARM 32-bit mode."),
  			   _("Show usage of ARM 32-bit mode."),
  			   _("When off, a 26-bit PC will be used."),
  			   NULL,
  			   NULL, /* FIXME: i18n: Usage of ARM 32-bit
  				    mode is %s.  */
  			   &setarmcmdlist, &showarmcmdlist);
  
    /* Add a command to allow the user to force the FPU model.  */
    add_setshow_enum_cmd ("fpu", no_class, fp_model_strings, &current_fp_model,
  			_("Set the floating point type."),
  			_("Show the floating point type."),
  			_("auto - Determine the FP typefrom the OS-ABI.\n\
  softfpa - Software FP, mixed-endian doubles on little-endian ARMs.\n\
  fpa - FPA co-processor (GCC compiled).\n\
  softvfp - Software FP with pure-endian doubles.\n\
  vfp - VFP co-processor."),
  			set_fp_model_sfunc, show_fp_model,
  			&setarmcmdlist, &showarmcmdlist);
  
    /* Add a command to allow the user to force the ABI.  */
    add_setshow_enum_cmd ("abi", class_support, arm_abi_strings, &arm_abi_string,
  			_("Set the ABI."),
  			_("Show the ABI."),
  			NULL, arm_set_abi, arm_show_abi,
  			&setarmcmdlist, &showarmcmdlist);
  
    /* Add two commands to allow the user to force the assumed
       execution mode.  */
    add_setshow_enum_cmd ("fallback-mode", class_support,
  			arm_mode_strings, &arm_fallback_mode_string,
  			_("Set the mode assumed when symbols are unavailable."),
  			_("Show the mode assumed when symbols are unavailable."),
  			NULL, NULL, arm_show_fallback_mode,
  			&setarmcmdlist, &showarmcmdlist);
    add_setshow_enum_cmd ("force-mode", class_support,
  			arm_mode_strings, &arm_force_mode_string,
  			_("Set the mode assumed even when symbols are available."),
  			_("Show the mode assumed even when symbols are available."),
  			NULL, NULL, arm_show_force_mode,
  			&setarmcmdlist, &showarmcmdlist);
  
    /* Debugging flag.  */
    add_setshow_boolean_cmd ("arm", class_maintenance, &arm_debug,
  			   _("Set ARM debugging."),
  			   _("Show ARM debugging."),
  			   _("When on, arm-specific debugging is enabled."),
  			   NULL,
  			   NULL, /* FIXME: i18n: "ARM debugging is %s.  */
  			   &setdebuglist, &showdebuglist);
  }
  
  /* ARM-reversible process record data structures.  */
  
  #define ARM_INSN_SIZE_BYTES 4    
  #define THUMB_INSN_SIZE_BYTES 2
  #define THUMB2_INSN_SIZE_BYTES 4
  
  
  /* Position of the bit within a 32-bit ARM instruction
     that defines whether the instruction is a load or store.  */
  #define INSN_S_L_BIT_NUM 20
  
  #define REG_ALLOC(REGS, LENGTH, RECORD_BUF) \
          do  \
            { \
              unsigned int reg_len = LENGTH; \
              if (reg_len) \
                { \
                  REGS = XNEWVEC (uint32_t, reg_len); \
                  memcpy(&REGS[0], &RECORD_BUF[0], sizeof(uint32_t)*LENGTH); \
                } \
            } \
          while (0)
  
  #define MEM_ALLOC(MEMS, LENGTH, RECORD_BUF) \
          do  \
            { \
              unsigned int mem_len = LENGTH; \
              if (mem_len) \
              { \
                MEMS =  XNEWVEC (struct arm_mem_r, mem_len);  \
                memcpy(&MEMS->len, &RECORD_BUF[0], \
                       sizeof(struct arm_mem_r) * LENGTH); \
              } \
            } \
            while (0)
  
  /* Checks whether insn is already recorded or yet to be decoded. (boolean expression).  */
  #define INSN_RECORDED(ARM_RECORD) \
          (0 != (ARM_RECORD)->reg_rec_count || 0 != (ARM_RECORD)->mem_rec_count)
  
  /* ARM memory record structure.  */
  struct arm_mem_r
  {
    uint32_t len;    /* Record length.  */
    uint32_t addr;   /* Memory address.  */
  };
  
  /* ARM instruction record contains opcode of current insn
     and execution state (before entry to decode_insn()),
     contains list of to-be-modified registers and
     memory blocks (on return from decode_insn()).  */
  
  typedef struct insn_decode_record_t
  {
    struct gdbarch *gdbarch;
    struct regcache *regcache;
    CORE_ADDR this_addr;          /* Address of the insn being decoded.  */
    uint32_t arm_insn;            /* Should accommodate thumb.  */
    uint32_t cond;                /* Condition code.  */
    uint32_t opcode;              /* Insn opcode.  */
    uint32_t decode;              /* Insn decode bits.  */
    uint32_t mem_rec_count;       /* No of mem records.  */
    uint32_t reg_rec_count;       /* No of reg records.  */
    uint32_t *arm_regs;           /* Registers to be saved for this record.  */
    struct arm_mem_r *arm_mems;   /* Memory to be saved for this record.  */
  } insn_decode_record;
  
  
  /* Checks ARM SBZ and SBO mandatory fields.  */
  
  static int
  sbo_sbz (uint32_t insn, uint32_t bit_num, uint32_t len, uint32_t sbo)
  {
    uint32_t ones = bits (insn, bit_num - 1, (bit_num -1) + (len - 1));
  
    if (!len)
      return 1;
  
    if (!sbo)
      ones = ~ones;
  
    while (ones)
      {
        if (!(ones & sbo))
          {
            return 0;
          }
        ones = ones >> 1;
      }
    return 1;
  }
  
  enum arm_record_result
  {
    ARM_RECORD_SUCCESS = 0,
    ARM_RECORD_FAILURE = 1
  };
  
  typedef enum
  {
    ARM_RECORD_STRH=1,
    ARM_RECORD_STRD
  } arm_record_strx_t;
  
  typedef enum
  {
    ARM_RECORD=1,
    THUMB_RECORD,
    THUMB2_RECORD
  } record_type_t;
  
  
  static int
  arm_record_strx (insn_decode_record *arm_insn_r, uint32_t *record_buf, 
                   uint32_t *record_buf_mem, arm_record_strx_t str_type)
  {
  
    struct regcache *reg_cache = arm_insn_r->regcache;
    ULONGEST u_regval[2]= {0};
  
    uint32_t reg_src1 = 0, reg_src2 = 0;
    uint32_t immed_high = 0, immed_low = 0,offset_8 = 0, tgt_mem_addr = 0;
  
    arm_insn_r->opcode = bits (arm_insn_r->arm_insn, 21, 24);
    arm_insn_r->decode = bits (arm_insn_r->arm_insn, 4, 7);
  
    if (14 == arm_insn_r->opcode || 10 == arm_insn_r->opcode)
      {
        /* 1) Handle misc store, immediate offset.  */
        immed_low = bits (arm_insn_r->arm_insn, 0, 3);
        immed_high = bits (arm_insn_r->arm_insn, 8, 11);
        reg_src1 = bits (arm_insn_r->arm_insn, 16, 19);
        regcache_raw_read_unsigned (reg_cache, reg_src1,
                                    &u_regval[0]);
        if (ARM_PC_REGNUM == reg_src1)
          {
            /* If R15 was used as Rn, hence current PC+8.  */
            u_regval[0] = u_regval[0] + 8;
          }
        offset_8 = (immed_high << 4) | immed_low;
        /* Calculate target store address.  */
        if (14 == arm_insn_r->opcode)
          {
            tgt_mem_addr = u_regval[0] + offset_8;
          }
        else
          {
            tgt_mem_addr = u_regval[0] - offset_8;
          }
        if (ARM_RECORD_STRH == str_type)
          {
            record_buf_mem[0] = 2;
            record_buf_mem[1] = tgt_mem_addr;
            arm_insn_r->mem_rec_count = 1;
          }
        else if (ARM_RECORD_STRD == str_type)
          {
            record_buf_mem[0] = 4;
            record_buf_mem[1] = tgt_mem_addr;
            record_buf_mem[2] = 4;
            record_buf_mem[3] = tgt_mem_addr + 4;
            arm_insn_r->mem_rec_count = 2;
          }
      }
    else if (12 == arm_insn_r->opcode || 8 == arm_insn_r->opcode)
      {
        /* 2) Store, register offset.  */
        /* Get Rm.  */
        reg_src1 = bits (arm_insn_r->arm_insn, 0, 3);
        /* Get Rn.  */
        reg_src2 = bits (arm_insn_r->arm_insn, 16, 19);
        regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval[0]);
        regcache_raw_read_unsigned (reg_cache, reg_src2, &u_regval[1]);
        if (15 == reg_src2)
          {
            /* If R15 was used as Rn, hence current PC+8.  */
            u_regval[0] = u_regval[0] + 8;
          }
        /* Calculate target store address, Rn +/- Rm, register offset.  */
        if (12 == arm_insn_r->opcode)
          {
            tgt_mem_addr = u_regval[0] + u_regval[1];
          }
        else
          {
            tgt_mem_addr = u_regval[1] - u_regval[0];
          }
        if (ARM_RECORD_STRH == str_type)
          {
            record_buf_mem[0] = 2;
            record_buf_mem[1] = tgt_mem_addr;
            arm_insn_r->mem_rec_count = 1;
          }
        else if (ARM_RECORD_STRD == str_type)
          {
            record_buf_mem[0] = 4;
            record_buf_mem[1] = tgt_mem_addr;
            record_buf_mem[2] = 4;
            record_buf_mem[3] = tgt_mem_addr + 4;
            arm_insn_r->mem_rec_count = 2;
          }
      }
    else if (11 == arm_insn_r->opcode || 15 == arm_insn_r->opcode
             || 2 == arm_insn_r->opcode  || 6 == arm_insn_r->opcode)
      {
        /* 3) Store, immediate pre-indexed.  */
        /* 5) Store, immediate post-indexed.  */
        immed_low = bits (arm_insn_r->arm_insn, 0, 3);
        immed_high = bits (arm_insn_r->arm_insn, 8, 11);
        offset_8 = (immed_high << 4) | immed_low;
        reg_src1 = bits (arm_insn_r->arm_insn, 16, 19);
        regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval[0]);
        /* Calculate target store address, Rn +/- Rm, register offset.  */
        if (15 == arm_insn_r->opcode || 6 == arm_insn_r->opcode)
          {
            tgt_mem_addr = u_regval[0] + offset_8;
          }
        else
          {
            tgt_mem_addr = u_regval[0] - offset_8;
          }
        if (ARM_RECORD_STRH == str_type)
          {
            record_buf_mem[0] = 2;
            record_buf_mem[1] = tgt_mem_addr;
            arm_insn_r->mem_rec_count = 1;
          }
        else if (ARM_RECORD_STRD == str_type)
          {
            record_buf_mem[0] = 4;
            record_buf_mem[1] = tgt_mem_addr;
            record_buf_mem[2] = 4;
            record_buf_mem[3] = tgt_mem_addr + 4;
            arm_insn_r->mem_rec_count = 2;
          }
        /* Record Rn also as it changes.  */
        *(record_buf) = bits (arm_insn_r->arm_insn, 16, 19);
        arm_insn_r->reg_rec_count = 1;
      }
    else if (9 == arm_insn_r->opcode || 13 == arm_insn_r->opcode
             || 0 == arm_insn_r->opcode || 4 == arm_insn_r->opcode)
      {
        /* 4) Store, register pre-indexed.  */
        /* 6) Store, register post -indexed.  */
        reg_src1 = bits (arm_insn_r->arm_insn, 0, 3);
        reg_src2 = bits (arm_insn_r->arm_insn, 16, 19);
        regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval[0]);
        regcache_raw_read_unsigned (reg_cache, reg_src2, &u_regval[1]);
        /* Calculate target store address, Rn +/- Rm, register offset.  */
        if (13 == arm_insn_r->opcode || 4 == arm_insn_r->opcode)
          {
            tgt_mem_addr = u_regval[0] + u_regval[1];
          }
        else
          {
            tgt_mem_addr = u_regval[1] - u_regval[0];
          }
        if (ARM_RECORD_STRH == str_type)
          {
            record_buf_mem[0] = 2;
            record_buf_mem[1] = tgt_mem_addr;
            arm_insn_r->mem_rec_count = 1;
          }
        else if (ARM_RECORD_STRD == str_type)
          {
            record_buf_mem[0] = 4;
            record_buf_mem[1] = tgt_mem_addr;
            record_buf_mem[2] = 4;
            record_buf_mem[3] = tgt_mem_addr + 4;
            arm_insn_r->mem_rec_count = 2;
          }
        /* Record Rn also as it changes.  */
        *(record_buf) = bits (arm_insn_r->arm_insn, 16, 19);
        arm_insn_r->reg_rec_count = 1;
      }
    return 0;
  }
  
  /* Handling ARM extension space insns.  */
  
  static int
  arm_record_extension_space (insn_decode_record *arm_insn_r)
  {
    uint32_t ret = 0;  /* Return value: -1:record failure ;  0:success  */
    uint32_t opcode1 = 0, opcode2 = 0, insn_op1 = 0;
    uint32_t record_buf[8], record_buf_mem[8];
    uint32_t reg_src1 = 0;
    struct regcache *reg_cache = arm_insn_r->regcache;
    ULONGEST u_regval = 0;
  
    gdb_assert (!INSN_RECORDED(arm_insn_r));
    /* Handle unconditional insn extension space.  */
  
    opcode1 = bits (arm_insn_r->arm_insn, 20, 27);
    opcode2 = bits (arm_insn_r->arm_insn, 4, 7);
    if (arm_insn_r->cond)
      {
        /* PLD has no affect on architectural state, it just affects
           the caches.  */
        if (5 == ((opcode1 & 0xE0) >> 5))
          {
            /* BLX(1) */
            record_buf[0] = ARM_PS_REGNUM;
            record_buf[1] = ARM_LR_REGNUM;
            arm_insn_r->reg_rec_count = 2;
          }
        /* STC2, LDC2, MCR2, MRC2, CDP2: <TBD>, co-processor insn.  */
      }
  
  
    opcode1 = bits (arm_insn_r->arm_insn, 25, 27);
    if (3 == opcode1 && bit (arm_insn_r->arm_insn, 4))
      {
        ret = -1;
        /* Undefined instruction on ARM V5; need to handle if later 
           versions define it.  */
      }
  
    opcode1 = bits (arm_insn_r->arm_insn, 24, 27);
    opcode2 = bits (arm_insn_r->arm_insn, 4, 7);
    insn_op1 = bits (arm_insn_r->arm_insn, 20, 23);
  
    /* Handle arithmetic insn extension space.  */
    if (!opcode1 && 9 == opcode2 && 1 != arm_insn_r->cond
        && !INSN_RECORDED(arm_insn_r))
      {
        /* Handle MLA(S) and MUL(S).  */
        if (0 <= insn_op1 && 3 >= insn_op1)
        {
          record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
          record_buf[1] = ARM_PS_REGNUM;
          arm_insn_r->reg_rec_count = 2;
        }
        else if (4 <= insn_op1 && 15 >= insn_op1)
        {
          /* Handle SMLAL(S), SMULL(S), UMLAL(S), UMULL(S).  */
          record_buf[0] = bits (arm_insn_r->arm_insn, 16, 19);
          record_buf[1] = bits (arm_insn_r->arm_insn, 12, 15);
          record_buf[2] = ARM_PS_REGNUM;
          arm_insn_r->reg_rec_count = 3;
        }
      }
  
    opcode1 = bits (arm_insn_r->arm_insn, 26, 27);
    opcode2 = bits (arm_insn_r->arm_insn, 23, 24);
    insn_op1 = bits (arm_insn_r->arm_insn, 21, 22);
  
    /* Handle control insn extension space.  */
  
    if (!opcode1 && 2 == opcode2 && !bit (arm_insn_r->arm_insn, 20)
        && 1 != arm_insn_r->cond && !INSN_RECORDED(arm_insn_r))
      {
        if (!bit (arm_insn_r->arm_insn,25))
          {
            if (!bits (arm_insn_r->arm_insn, 4, 7))
              {
                if ((0 == insn_op1) || (2 == insn_op1))
                  {
                    /* MRS.  */
                    record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
                    arm_insn_r->reg_rec_count = 1;
                  }
                else if (1 == insn_op1)
                  {
                    /* CSPR is going to be changed.  */
                    record_buf[0] = ARM_PS_REGNUM;
                    arm_insn_r->reg_rec_count = 1;
                  }
                else if (3 == insn_op1)
                  {
                    /* SPSR is going to be changed.  */
                    /* We need to get SPSR value, which is yet to be done.  */
                    return -1;
                  }
              }
            else if (1 == bits (arm_insn_r->arm_insn, 4, 7))
              {
                if (1 == insn_op1)
                  {
                    /* BX.  */
                    record_buf[0] = ARM_PS_REGNUM;
                    arm_insn_r->reg_rec_count = 1;
                  }
                else if (3 == insn_op1)
                  {
                    /* CLZ.  */
                    record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
                    arm_insn_r->reg_rec_count = 1;
                  }
              }
            else if (3 == bits (arm_insn_r->arm_insn, 4, 7))
              {
                /* BLX.  */
                record_buf[0] = ARM_PS_REGNUM;
                record_buf[1] = ARM_LR_REGNUM;
                arm_insn_r->reg_rec_count = 2;
              }
            else if (5 == bits (arm_insn_r->arm_insn, 4, 7))
              {
                /* QADD, QSUB, QDADD, QDSUB */
                record_buf[0] = ARM_PS_REGNUM;
                record_buf[1] = bits (arm_insn_r->arm_insn, 12, 15);
                arm_insn_r->reg_rec_count = 2;
              }
            else if (7 == bits (arm_insn_r->arm_insn, 4, 7))
              {
                /* BKPT.  */
                record_buf[0] = ARM_PS_REGNUM;
                record_buf[1] = ARM_LR_REGNUM;
                arm_insn_r->reg_rec_count = 2;
  
                /* Save SPSR also;how?  */
                return -1;
              }
            else if(8 == bits (arm_insn_r->arm_insn, 4, 7) 
                    || 10 == bits (arm_insn_r->arm_insn, 4, 7)
                    || 12 == bits (arm_insn_r->arm_insn, 4, 7)
                    || 14 == bits (arm_insn_r->arm_insn, 4, 7)
                   )
              {
                if (0 == insn_op1 || 1 == insn_op1)
                  {
                    /* SMLA<x><y>, SMLAW<y>, SMULW<y>.  */
                    /* We dont do optimization for SMULW<y> where we
                       need only Rd.  */
                    record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
                    record_buf[1] = ARM_PS_REGNUM;
                    arm_insn_r->reg_rec_count = 2;
                  }
                else if (2 == insn_op1)
                  {
                    /* SMLAL<x><y>.  */
                    record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
                    record_buf[1] = bits (arm_insn_r->arm_insn, 16, 19);
                    arm_insn_r->reg_rec_count = 2;
                  }
                else if (3 == insn_op1)
                  {
                    /* SMUL<x><y>.  */
                    record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
                    arm_insn_r->reg_rec_count = 1;
                  }
              }
          }
        else
          {
            /* MSR : immediate form.  */
            if (1 == insn_op1)
              {
                /* CSPR is going to be changed.  */
                record_buf[0] = ARM_PS_REGNUM;
                arm_insn_r->reg_rec_count = 1;
              }
            else if (3 == insn_op1)
              {
                /* SPSR is going to be changed.  */
                /* we need to get SPSR value, which is yet to be done  */
                return -1;
              }
          }
      }
  
    opcode1 = bits (arm_insn_r->arm_insn, 25, 27);
    opcode2 = bits (arm_insn_r->arm_insn, 20, 24);
    insn_op1 = bits (arm_insn_r->arm_insn, 5, 6);
  
    /* Handle load/store insn extension space.  */
  
    if (!opcode1 && bit (arm_insn_r->arm_insn, 7) 
        && bit (arm_insn_r->arm_insn, 4) && 1 != arm_insn_r->cond
        && !INSN_RECORDED(arm_insn_r))
      {
        /* SWP/SWPB.  */
        if (0 == insn_op1)
          {
            /* These insn, changes register and memory as well.  */
            /* SWP or SWPB insn.  */
            /* Get memory address given by Rn.  */
            reg_src1 = bits (arm_insn_r->arm_insn, 16, 19);
            regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval);
            /* SWP insn ?, swaps word.  */
            if (8 == arm_insn_r->opcode)
              {
                record_buf_mem[0] = 4;
              }
            else
              {
                /* SWPB insn, swaps only byte.  */
                record_buf_mem[0] = 1;
              }
            record_buf_mem[1] = u_regval;
            arm_insn_r->mem_rec_count = 1;
            record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
            arm_insn_r->reg_rec_count = 1;
          }
        else if (1 == insn_op1 && !bit (arm_insn_r->arm_insn, 20))
          {
            /* STRH.  */
            arm_record_strx(arm_insn_r, &record_buf[0], &record_buf_mem[0],
                            ARM_RECORD_STRH);
          }
        else if (2 == insn_op1 && !bit (arm_insn_r->arm_insn, 20))
          {
            /* LDRD.  */
            record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
            record_buf[1] = record_buf[0] + 1;
            arm_insn_r->reg_rec_count = 2;
          }
        else if (3 == insn_op1 && !bit (arm_insn_r->arm_insn, 20))
          {
            /* STRD.  */
            arm_record_strx(arm_insn_r, &record_buf[0], &record_buf_mem[0],
                          ARM_RECORD_STRD);
          }
        else if (bit (arm_insn_r->arm_insn, 20) && insn_op1 <= 3)
          {
            /* LDRH, LDRSB, LDRSH.  */
            record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
            arm_insn_r->reg_rec_count = 1;
          }
  
      }
  
    opcode1 = bits (arm_insn_r->arm_insn, 23, 27);
    if (24 == opcode1 && bit (arm_insn_r->arm_insn, 21)
        && !INSN_RECORDED(arm_insn_r))
      {
        ret = -1;
        /* Handle coprocessor insn extension space.  */
      }
  
    /* To be done for ARMv5 and later; as of now we return -1.  */
    if (-1 == ret)
      return ret;
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (arm_insn_r->arm_mems, arm_insn_r->mem_rec_count, record_buf_mem);
  
    return ret;
  }
  
  /* Handling opcode 000 insns.  */
  
  static int
  arm_record_data_proc_misc_ld_str (insn_decode_record *arm_insn_r)
  {
    struct regcache *reg_cache = arm_insn_r->regcache;
    uint32_t record_buf[8], record_buf_mem[8];
    ULONGEST u_regval[2] = {0};
  
    uint32_t reg_src1 = 0, reg_dest = 0;
    uint32_t opcode1 = 0;
  
    arm_insn_r->opcode = bits (arm_insn_r->arm_insn, 21, 24);
    arm_insn_r->decode = bits (arm_insn_r->arm_insn, 4, 7);
    opcode1 = bits (arm_insn_r->arm_insn, 20, 24);
  
    /* Data processing insn /multiply insn.  */
    if (9 == arm_insn_r->decode
        && ((4 <= arm_insn_r->opcode && 7 >= arm_insn_r->opcode)
        ||  (0 == arm_insn_r->opcode || 1 == arm_insn_r->opcode)))
      {
        /* Handle multiply instructions.  */
        /* MLA, MUL, SMLAL, SMULL, UMLAL, UMULL.  */
          if (0 == arm_insn_r->opcode || 1 == arm_insn_r->opcode)
            {
              /* Handle MLA and MUL.  */
              record_buf[0] = bits (arm_insn_r->arm_insn, 16, 19);
              record_buf[1] = ARM_PS_REGNUM;
              arm_insn_r->reg_rec_count = 2;
            }
          else if (4 <= arm_insn_r->opcode && 7 >= arm_insn_r->opcode)
            {
              /* Handle SMLAL, SMULL, UMLAL, UMULL.  */
              record_buf[0] = bits (arm_insn_r->arm_insn, 16, 19);
              record_buf[1] = bits (arm_insn_r->arm_insn, 12, 15);
              record_buf[2] = ARM_PS_REGNUM;
              arm_insn_r->reg_rec_count = 3;
            }
      }
    else if (bit (arm_insn_r->arm_insn, INSN_S_L_BIT_NUM)
             && (11 == arm_insn_r->decode || 13 == arm_insn_r->decode))
      {
        /* Handle misc load insns, as 20th bit  (L = 1).  */
        /* LDR insn has a capability to do branching, if
           MOV LR, PC is precceded by LDR insn having Rn as R15
           in that case, it emulates branch and link insn, and hence we 
           need to save CSPR and PC as well. I am not sure this is right
           place; as opcode = 010 LDR insn make this happen, if R15 was
           used.  */
        reg_dest = bits (arm_insn_r->arm_insn, 12, 15);
        if (15 != reg_dest)
          {
            record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
            arm_insn_r->reg_rec_count = 1;
          }
        else
          {
            record_buf[0] = reg_dest;
            record_buf[1] = ARM_PS_REGNUM;
            arm_insn_r->reg_rec_count = 2;
          }
      }
    else if ((9 == arm_insn_r->opcode || 11 == arm_insn_r->opcode)
             && sbo_sbz (arm_insn_r->arm_insn, 5, 12, 0)
             && sbo_sbz (arm_insn_r->arm_insn, 13, 4, 1)
             && 2 == bits (arm_insn_r->arm_insn, 20, 21))
      {
        /* Handle MSR insn.  */
        if (9 == arm_insn_r->opcode)
          {
            /* CSPR is going to be changed.  */
            record_buf[0] = ARM_PS_REGNUM;
            arm_insn_r->reg_rec_count = 1;
          }
        else
          {
            /* SPSR is going to be changed.  */
            /* How to read SPSR value?  */
            return -1;
          }
      }
    else if (9 == arm_insn_r->decode
             && (8 == arm_insn_r->opcode || 10 == arm_insn_r->opcode)
             && !bit (arm_insn_r->arm_insn, INSN_S_L_BIT_NUM))
      {
        /* Handling SWP, SWPB.  */
        /* These insn, changes register and memory as well.  */
        /* SWP or SWPB insn.  */
  
        reg_src1 = bits (arm_insn_r->arm_insn, 16, 19);
        regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval[0]);
        /* SWP insn ?, swaps word.  */
        if (8 == arm_insn_r->opcode)
          {
            record_buf_mem[0] = 4;
          }
          else
          {
            /* SWPB insn, swaps only byte.  */
            record_buf_mem[0] = 1;
          }
        record_buf_mem[1] = u_regval[0];
        arm_insn_r->mem_rec_count = 1;
        record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
        arm_insn_r->reg_rec_count = 1;
      }
    else if (3 == arm_insn_r->decode && 0x12 == opcode1
             && sbo_sbz (arm_insn_r->arm_insn, 9, 12, 1))
      {
        /* Handle BLX, branch and link/exchange.  */
        if (9 == arm_insn_r->opcode)
        {
          /* Branch is chosen by setting T bit of CSPR, bitp[0] of Rm,
             and R14 stores the return address.  */
          record_buf[0] = ARM_PS_REGNUM;
          record_buf[1] = ARM_LR_REGNUM;
          arm_insn_r->reg_rec_count = 2;
        }
      }
    else if (7 == arm_insn_r->decode && 0x12 == opcode1)
      {
        /* Handle enhanced software breakpoint insn, BKPT.  */
        /* CPSR is changed to be executed in ARM state,  disabling normal
           interrupts, entering abort mode.  */
        /* According to high vector configuration PC is set.  */
        /* user hit breakpoint and type reverse, in
           that case, we need to go back with previous CPSR and
           Program Counter.  */
        record_buf[0] = ARM_PS_REGNUM;
        record_buf[1] = ARM_LR_REGNUM;
        arm_insn_r->reg_rec_count = 2;
  
        /* Save SPSR also; how?  */
        return -1;
      }
    else if (11 == arm_insn_r->decode
             && !bit (arm_insn_r->arm_insn, INSN_S_L_BIT_NUM))
    {
      /* Handle enhanced store insns and DSP insns (e.g. LDRD).  */
  
      /* Handle str(x) insn */
      arm_record_strx(arm_insn_r, &record_buf[0], &record_buf_mem[0],
                      ARM_RECORD_STRH);
    }
    else if (1 == arm_insn_r->decode && 0x12 == opcode1
             && sbo_sbz (arm_insn_r->arm_insn, 9, 12, 1))
      {
        /* Handle BX, branch and link/exchange.  */
        /* Branch is chosen by setting T bit of CSPR, bitp[0] of Rm.  */
        record_buf[0] = ARM_PS_REGNUM;
        arm_insn_r->reg_rec_count = 1;
      }
    else if (1 == arm_insn_r->decode && 0x16 == opcode1
             && sbo_sbz (arm_insn_r->arm_insn, 9, 4, 1)
             && sbo_sbz (arm_insn_r->arm_insn, 17, 4, 1))
      {
        /* Count leading zeros: CLZ.  */
        record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
        arm_insn_r->reg_rec_count = 1;
      }
    else if (!bit (arm_insn_r->arm_insn, INSN_S_L_BIT_NUM)
             && (8 == arm_insn_r->opcode || 10 == arm_insn_r->opcode)
             && sbo_sbz (arm_insn_r->arm_insn, 17, 4, 1)
             && sbo_sbz (arm_insn_r->arm_insn, 1, 12, 0)
            )
      {
        /* Handle MRS insn.  */
        record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
        arm_insn_r->reg_rec_count = 1;
      }
    else if (arm_insn_r->opcode <= 15)
      {
        /* Normal data processing insns.  */
        /* Out of 11 shifter operands mode, all the insn modifies destination
           register, which is specified by 13-16 decode.  */
        record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
        record_buf[1] = ARM_PS_REGNUM;
        arm_insn_r->reg_rec_count = 2;
      }
    else
      {
        return -1;
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (arm_insn_r->arm_mems, arm_insn_r->mem_rec_count, record_buf_mem);
    return 0;
  }
  
  /* Handling opcode 001 insns.  */
  
  static int
  arm_record_data_proc_imm (insn_decode_record *arm_insn_r)
  {
    uint32_t record_buf[8], record_buf_mem[8];
  
    arm_insn_r->opcode = bits (arm_insn_r->arm_insn, 21, 24);
    arm_insn_r->decode = bits (arm_insn_r->arm_insn, 4, 7);
  
    if ((9 == arm_insn_r->opcode || 11 == arm_insn_r->opcode)
        && 2 == bits (arm_insn_r->arm_insn, 20, 21)
        && sbo_sbz (arm_insn_r->arm_insn, 13, 4, 1)
       )
      {
        /* Handle MSR insn.  */
        if (9 == arm_insn_r->opcode)
          {
            /* CSPR is going to be changed.  */
            record_buf[0] = ARM_PS_REGNUM;
            arm_insn_r->reg_rec_count = 1;
          }
        else
          {
            /* SPSR is going to be changed.  */
          }
      }
    else if (arm_insn_r->opcode <= 15)
      {
        /* Normal data processing insns.  */
        /* Out of 11 shifter operands mode, all the insn modifies destination
           register, which is specified by 13-16 decode.  */
        record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
        record_buf[1] = ARM_PS_REGNUM;
        arm_insn_r->reg_rec_count = 2;
      }
    else
      {
        return -1;
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (arm_insn_r->arm_mems, arm_insn_r->mem_rec_count, record_buf_mem);
    return 0;
  }
  
  static int
  arm_record_media (insn_decode_record *arm_insn_r)
  {
    uint32_t record_buf[8];
  
    switch (bits (arm_insn_r->arm_insn, 22, 24))
      {
      case 0:
        /* Parallel addition and subtraction, signed */
      case 1:
        /* Parallel addition and subtraction, unsigned */
      case 2:
      case 3:
        /* Packing, unpacking, saturation and reversal */
        {
  	int rd = bits (arm_insn_r->arm_insn, 12, 15);
  
  	record_buf[arm_insn_r->reg_rec_count++] = rd;
        }
        break;
  
      case 4:
      case 5:
        /* Signed multiplies */
        {
  	int rd = bits (arm_insn_r->arm_insn, 16, 19);
  	unsigned int op1 = bits (arm_insn_r->arm_insn, 20, 22);
  
  	record_buf[arm_insn_r->reg_rec_count++] = rd;
  	if (op1 == 0x0)
  	  record_buf[arm_insn_r->reg_rec_count++] = ARM_PS_REGNUM;
  	else if (op1 == 0x4)
  	  record_buf[arm_insn_r->reg_rec_count++]
  	    = bits (arm_insn_r->arm_insn, 12, 15);
        }
        break;
  
      case 6:
        {
  	if (bit (arm_insn_r->arm_insn, 21)
  	    && bits (arm_insn_r->arm_insn, 5, 6) == 0x2)
  	  {
  	    /* SBFX */
  	    record_buf[arm_insn_r->reg_rec_count++]
  	      = bits (arm_insn_r->arm_insn, 12, 15);
  	  }
  	else if (bits (arm_insn_r->arm_insn, 20, 21) == 0x0
  		 && bits (arm_insn_r->arm_insn, 5, 7) == 0x0)
  	  {
  	    /* USAD8 and USADA8 */
  	    record_buf[arm_insn_r->reg_rec_count++]
  	      = bits (arm_insn_r->arm_insn, 16, 19);
  	  }
        }
        break;
  
      case 7:
        {
  	if (bits (arm_insn_r->arm_insn, 20, 21) == 0x3
  	    && bits (arm_insn_r->arm_insn, 5, 7) == 0x7)
  	  {
  	    /* Permanently UNDEFINED */
  	    return -1;
  	  }
  	else
  	  {
  	    /* BFC, BFI and UBFX */
  	    record_buf[arm_insn_r->reg_rec_count++]
  	      = bits (arm_insn_r->arm_insn, 12, 15);
  	  }
        }
        break;
  
      default:
        return -1;
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
  
    return 0;
  }
  
  /* Handle ARM mode instructions with opcode 010.  */
  
  static int
  arm_record_ld_st_imm_offset (insn_decode_record *arm_insn_r)
  {
    struct regcache *reg_cache = arm_insn_r->regcache;
  
    uint32_t reg_base , reg_dest;
    uint32_t offset_12, tgt_mem_addr;
    uint32_t record_buf[8], record_buf_mem[8];
    unsigned char wback;
    ULONGEST u_regval;
  
    /* Calculate wback.  */
    wback = (bit (arm_insn_r->arm_insn, 24) == 0)
  	  || (bit (arm_insn_r->arm_insn, 21) == 1);
  
    arm_insn_r->reg_rec_count = 0;
    reg_base = bits (arm_insn_r->arm_insn, 16, 19);
  
    if (bit (arm_insn_r->arm_insn, INSN_S_L_BIT_NUM))
      {
        /* LDR (immediate), LDR (literal), LDRB (immediate), LDRB (literal), LDRBT
  	 and LDRT.  */
  
        reg_dest = bits (arm_insn_r->arm_insn, 12, 15);
        record_buf[arm_insn_r->reg_rec_count++] = reg_dest;
  
        /* The LDR instruction is capable of doing branching.  If MOV LR, PC
  	 preceeds a LDR instruction having R15 as reg_base, it
  	 emulates a branch and link instruction, and hence we need to save
  	 CPSR and PC as well.  */
        if (ARM_PC_REGNUM == reg_dest)
  	record_buf[arm_insn_r->reg_rec_count++] = ARM_PS_REGNUM;
  
        /* If wback is true, also save the base register, which is going to be
  	 written to.  */
        if (wback)
  	record_buf[arm_insn_r->reg_rec_count++] = reg_base;
      }
    else
      {
        /* STR (immediate), STRB (immediate), STRBT and STRT.  */
  
        offset_12 = bits (arm_insn_r->arm_insn, 0, 11);
        regcache_raw_read_unsigned (reg_cache, reg_base, &u_regval);
  
        /* Handle bit U.  */
        if (bit (arm_insn_r->arm_insn, 23))
  	{
  	  /* U == 1: Add the offset. */
  	  tgt_mem_addr = (uint32_t) u_regval + offset_12;
  	}
        else
  	{
  	  /* U == 0: subtract the offset. */
  	  tgt_mem_addr = (uint32_t) u_regval - offset_12;
  	}
  
        /* Bit 22 tells us whether the store instruction writes 1 byte or 4
  	 bytes.  */
        if (bit (arm_insn_r->arm_insn, 22))
  	{
  	  /* STRB and STRBT: 1 byte.  */
  	  record_buf_mem[0] = 1;
  	}
        else
  	{
  	  /* STR and STRT: 4 bytes.  */
  	  record_buf_mem[0] = 4;
  	}
  
        /* Handle bit P.  */
        if (bit (arm_insn_r->arm_insn, 24))
  	record_buf_mem[1] = tgt_mem_addr;
        else
  	record_buf_mem[1] = (uint32_t) u_regval;
  
        arm_insn_r->mem_rec_count = 1;
  
        /* If wback is true, also save the base register, which is going to be
  	 written to.  */
        if (wback)
  	record_buf[arm_insn_r->reg_rec_count++] = reg_base;
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (arm_insn_r->arm_mems, arm_insn_r->mem_rec_count, record_buf_mem);
    return 0;
  }
  
  /* Handling opcode 011 insns.  */
  
  static int
  arm_record_ld_st_reg_offset (insn_decode_record *arm_insn_r)
  {
    struct regcache *reg_cache = arm_insn_r->regcache;
  
    uint32_t shift_imm = 0;
    uint32_t reg_src1 = 0, reg_src2 = 0, reg_dest = 0;
    uint32_t offset_12 = 0, tgt_mem_addr = 0;
    uint32_t record_buf[8], record_buf_mem[8];
  
    LONGEST s_word;
    ULONGEST u_regval[2];
  
    if (bit (arm_insn_r->arm_insn, 4))
      return arm_record_media (arm_insn_r);
  
    arm_insn_r->opcode = bits (arm_insn_r->arm_insn, 21, 24);
    arm_insn_r->decode = bits (arm_insn_r->arm_insn, 4, 7);
  
    /* Handle enhanced store insns and LDRD DSP insn,
       order begins according to addressing modes for store insns
       STRH insn.  */
  
    /* LDR or STR?  */
    if (bit (arm_insn_r->arm_insn, INSN_S_L_BIT_NUM))
      {
        reg_dest = bits (arm_insn_r->arm_insn, 12, 15);
        /* LDR insn has a capability to do branching, if
           MOV LR, PC is precedded by LDR insn having Rn as R15
           in that case, it emulates branch and link insn, and hence we
           need to save CSPR and PC as well.  */
        if (15 != reg_dest)
          {
            record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
            arm_insn_r->reg_rec_count = 1;
          }
        else
          {
            record_buf[0] = reg_dest;
            record_buf[1] = ARM_PS_REGNUM;
            arm_insn_r->reg_rec_count = 2;
          }
      }
    else
      {
        if (! bits (arm_insn_r->arm_insn, 4, 11))
          {
            /* Store insn, register offset and register pre-indexed,
               register post-indexed.  */
            /* Get Rm.  */
            reg_src1 = bits (arm_insn_r->arm_insn, 0, 3);
            /* Get Rn.  */
            reg_src2 = bits (arm_insn_r->arm_insn, 16, 19);
            regcache_raw_read_unsigned (reg_cache, reg_src1
                                        , &u_regval[0]);
            regcache_raw_read_unsigned (reg_cache, reg_src2
                                        , &u_regval[1]);
            if (15 == reg_src2)
              {
                /* If R15 was used as Rn, hence current PC+8.  */
                /* Pre-indexed mode doesnt reach here ; illegal insn.  */
                  u_regval[0] = u_regval[0] + 8;
              }
            /* Calculate target store address, Rn +/- Rm, register offset.  */
            /* U == 1.  */
            if (bit (arm_insn_r->arm_insn, 23))
              {
                tgt_mem_addr = u_regval[0] + u_regval[1];
              }
            else
              {
                tgt_mem_addr = u_regval[1] - u_regval[0];
              }
  
            switch (arm_insn_r->opcode)
              {
                /* STR.  */
                case 8:
                case 12:
                /* STR.  */    
                case 9:
                case 13:
                /* STRT.  */
                case 1:
                case 5:
                /* STR.  */
                case 0:
                case 4:
                  record_buf_mem[0] = 4;
                break;
  
                /* STRB.  */
                case 10:
                case 14:
                /* STRB.  */
                case 11:
                case 15:
                /* STRBT.  */    
                case 3:
                case 7:
                /* STRB.  */
                case 2:
                case 6:
                  record_buf_mem[0] = 1;
                break;
  
                default:
                  gdb_assert_not_reached ("no decoding pattern found");
                break;
              }
            record_buf_mem[1] = tgt_mem_addr;
            arm_insn_r->mem_rec_count = 1;
  
            if (9 == arm_insn_r->opcode || 11 == arm_insn_r->opcode
                || 13 == arm_insn_r->opcode || 15 == arm_insn_r->opcode
                || 0 == arm_insn_r->opcode || 2 == arm_insn_r->opcode
                || 4 == arm_insn_r->opcode || 6 == arm_insn_r->opcode
                || 1 == arm_insn_r->opcode || 3 == arm_insn_r->opcode
                || 5 == arm_insn_r->opcode || 7 == arm_insn_r->opcode
               )
              {
                /* Rn is going to be changed in pre-indexed mode and
                   post-indexed mode as well.  */
                record_buf[0] = reg_src2;
                arm_insn_r->reg_rec_count = 1;
              }
          }
        else
          {
            /* Store insn, scaled register offset; scaled pre-indexed.  */
            offset_12 = bits (arm_insn_r->arm_insn, 5, 6);
            /* Get Rm.  */
            reg_src1 = bits (arm_insn_r->arm_insn, 0, 3);
            /* Get Rn.  */
            reg_src2 = bits (arm_insn_r->arm_insn, 16, 19);
            /* Get shift_imm.  */
            shift_imm = bits (arm_insn_r->arm_insn, 7, 11);
            regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval[0]);
            regcache_raw_read_signed (reg_cache, reg_src1, &s_word);
            regcache_raw_read_unsigned (reg_cache, reg_src2, &u_regval[1]);
            /* Offset_12 used as shift.  */
            switch (offset_12)
              {
                case 0:
                  /* Offset_12 used as index.  */
                  offset_12 = u_regval[0] << shift_imm;
                break;
  
                case 1:
                  offset_12 = (!shift_imm)?0:u_regval[0] >> shift_imm;
                break;
  
                case 2:
                  if (!shift_imm)
                    {
                      if (bit (u_regval[0], 31))
                        {
                          offset_12 = 0xFFFFFFFF;
                        }
                      else
                        {
                          offset_12 = 0;
                        }
                    }
                  else
                    {
                      /* This is arithmetic shift.  */
                      offset_12 = s_word >> shift_imm;
                    }
                  break;
  
                case 3:
                  if (!shift_imm)
                    {
                      regcache_raw_read_unsigned (reg_cache, ARM_PS_REGNUM,
                                                  &u_regval[1]);
                      /* Get C flag value and shift it by 31.  */
                      offset_12 = (((bit (u_regval[1], 29)) << 31) \
                                    | (u_regval[0]) >> 1);
                    }
                  else
                    {
                      offset_12 = (u_regval[0] >> shift_imm) \
                                  | (u_regval[0] <<
                                  (sizeof(uint32_t) - shift_imm));
                    }
                break;
  
                default:
                  gdb_assert_not_reached ("no decoding pattern found");
                break;
              }
  
            regcache_raw_read_unsigned (reg_cache, reg_src2, &u_regval[1]);
            /* bit U set.  */
            if (bit (arm_insn_r->arm_insn, 23))
              {
                tgt_mem_addr = u_regval[1] + offset_12;
              }
            else
              {
                tgt_mem_addr = u_regval[1] - offset_12;
              }
  
            switch (arm_insn_r->opcode)
              {
                /* STR.  */
                case 8:
                case 12:
                /* STR.  */    
                case 9:
                case 13:
                /* STRT.  */
                case 1:
                case 5:
                /* STR.  */
                case 0:
                case 4:
                  record_buf_mem[0] = 4;
                break;
  
                /* STRB.  */
                case 10:
                case 14:
                /* STRB.  */
                case 11:
                case 15:
                /* STRBT.  */    
                case 3:
                case 7:
                /* STRB.  */
                case 2:
                case 6:
                  record_buf_mem[0] = 1;
                break;
  
                default:
                  gdb_assert_not_reached ("no decoding pattern found");
                break;
              }
            record_buf_mem[1] = tgt_mem_addr;
            arm_insn_r->mem_rec_count = 1;
  
            if (9 == arm_insn_r->opcode || 11 == arm_insn_r->opcode
                || 13 == arm_insn_r->opcode || 15 == arm_insn_r->opcode
                || 0 == arm_insn_r->opcode || 2 == arm_insn_r->opcode
                || 4 == arm_insn_r->opcode || 6 == arm_insn_r->opcode
                || 1 == arm_insn_r->opcode || 3 == arm_insn_r->opcode
                || 5 == arm_insn_r->opcode || 7 == arm_insn_r->opcode
               )
              {
                /* Rn is going to be changed in register scaled pre-indexed
                   mode,and scaled post indexed mode.  */
                record_buf[0] = reg_src2;
                arm_insn_r->reg_rec_count = 1;
              }
          }
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (arm_insn_r->arm_mems, arm_insn_r->mem_rec_count, record_buf_mem);
    return 0;
  }
  
  /* Handle ARM mode instructions with opcode 100.  */
  
  static int
  arm_record_ld_st_multiple (insn_decode_record *arm_insn_r)
  {
    struct regcache *reg_cache = arm_insn_r->regcache;
    uint32_t register_count = 0, register_bits;
    uint32_t reg_base, addr_mode;
    uint32_t record_buf[24], record_buf_mem[48];
    uint32_t wback;
    ULONGEST u_regval;
  
    /* Fetch the list of registers.  */
    register_bits = bits (arm_insn_r->arm_insn, 0, 15);
    arm_insn_r->reg_rec_count = 0;
  
    /* Fetch the base register that contains the address we are loading data
       to.  */
    reg_base = bits (arm_insn_r->arm_insn, 16, 19);
  
    /* Calculate wback.  */
    wback = (bit (arm_insn_r->arm_insn, 21) == 1);
  
    if (bit (arm_insn_r->arm_insn, INSN_S_L_BIT_NUM))
      {
        /* LDM/LDMIA/LDMFD, LDMDA/LDMFA, LDMDB and LDMIB.  */
  
        /* Find out which registers are going to be loaded from memory.  */
        while (register_bits)
  	{
  	  if (register_bits & 0x00000001)
  	    record_buf[arm_insn_r->reg_rec_count++] = register_count;
  	  register_bits = register_bits >> 1;
  	  register_count++;
  	}
  
    
        /* If wback is true, also save the base register, which is going to be
  	 written to.  */
        if (wback)
  	record_buf[arm_insn_r->reg_rec_count++] = reg_base;
  
        /* Save the CPSR register.  */
        record_buf[arm_insn_r->reg_rec_count++] = ARM_PS_REGNUM;
      }
    else
      {
        /* STM (STMIA, STMEA), STMDA (STMED), STMDB (STMFD) and STMIB (STMFA).  */
  
        addr_mode = bits (arm_insn_r->arm_insn, 23, 24); 
  
        regcache_raw_read_unsigned (reg_cache, reg_base, &u_regval);
  
        /* Find out how many registers are going to be stored to memory.  */
        while (register_bits)
  	{
  	  if (register_bits & 0x00000001)
  	    register_count++;
  	  register_bits = register_bits >> 1;
  	}
  
        switch (addr_mode)
  	{
  	  /* STMDA (STMED): Decrement after.  */
  	  case 0:
  	  record_buf_mem[1] = (uint32_t) u_regval
  			      - register_count * INT_REGISTER_SIZE + 4;
  	  break;
  	  /* STM (STMIA, STMEA): Increment after.  */
  	  case 1:
  	  record_buf_mem[1] = (uint32_t) u_regval;
  	  break;
  	  /* STMDB (STMFD): Decrement before.  */
  	  case 2:
  	  record_buf_mem[1] = (uint32_t) u_regval
  			      - register_count * INT_REGISTER_SIZE;
  	  break;
  	  /* STMIB (STMFA): Increment before.  */
  	  case 3:
  	  record_buf_mem[1] = (uint32_t) u_regval + INT_REGISTER_SIZE;
  	  break;
  	  default:
  	    gdb_assert_not_reached ("no decoding pattern found");
  	  break;
  	}
  
        record_buf_mem[0] = register_count * INT_REGISTER_SIZE;
        arm_insn_r->mem_rec_count = 1;
  
        /* If wback is true, also save the base register, which is going to be
  	 written to.  */
        if (wback)
  	record_buf[arm_insn_r->reg_rec_count++] = reg_base;
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (arm_insn_r->arm_mems, arm_insn_r->mem_rec_count, record_buf_mem);
    return 0;
  }
  
  /* Handling opcode 101 insns.  */
  
  static int
  arm_record_b_bl (insn_decode_record *arm_insn_r)
  {
    uint32_t record_buf[8];
  
    /* Handle B, BL, BLX(1) insns.  */
    /* B simply branches so we do nothing here.  */
    /* Note: BLX(1) doesnt fall here but instead it falls into
       extension space.  */
    if (bit (arm_insn_r->arm_insn, 24))
    {
      record_buf[0] = ARM_LR_REGNUM;
      arm_insn_r->reg_rec_count = 1;
    }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
  
    return 0;
  }
  
  static int
  arm_record_unsupported_insn (insn_decode_record *arm_insn_r)
  {
    printf_unfiltered (_("Process record does not support instruction "
  		       "0x%0x at address %s.\n"),arm_insn_r->arm_insn,
  		     paddress (arm_insn_r->gdbarch, arm_insn_r->this_addr));
  
    return -1;
  }
  
  /* Record handler for vector data transfer instructions.  */
  
  static int
  arm_record_vdata_transfer_insn (insn_decode_record *arm_insn_r)
  {
    uint32_t bits_a, bit_c, bit_l, reg_t, reg_v;
    uint32_t record_buf[4];
  
    reg_t = bits (arm_insn_r->arm_insn, 12, 15);
    reg_v = bits (arm_insn_r->arm_insn, 21, 23);
    bits_a = bits (arm_insn_r->arm_insn, 21, 23);
    bit_l = bit (arm_insn_r->arm_insn, 20);
    bit_c = bit (arm_insn_r->arm_insn, 8);
  
    /* Handle VMOV instruction.  */
    if (bit_l && bit_c)
      {
        record_buf[0] = reg_t;
        arm_insn_r->reg_rec_count = 1;
      }
    else if (bit_l && !bit_c)
      {
        /* Handle VMOV instruction.  */
        if (bits_a == 0x00)
          {
  	  record_buf[0] = reg_t;
            arm_insn_r->reg_rec_count = 1;
          }
        /* Handle VMRS instruction.  */
        else if (bits_a == 0x07)
          {
            if (reg_t == 15)
              reg_t = ARM_PS_REGNUM;
  
            record_buf[0] = reg_t;
            arm_insn_r->reg_rec_count = 1;
          }
      }
    else if (!bit_l && !bit_c)
      {
        /* Handle VMOV instruction.  */
        if (bits_a == 0x00)
          {
  	  record_buf[0] = ARM_D0_REGNUM + reg_v;
  
            arm_insn_r->reg_rec_count = 1;
          }
        /* Handle VMSR instruction.  */
        else if (bits_a == 0x07)
          {
            record_buf[0] = ARM_FPSCR_REGNUM;
            arm_insn_r->reg_rec_count = 1;
          }
      }
    else if (!bit_l && bit_c)
      {
        /* Handle VMOV instruction.  */
        if (!(bits_a & 0x04))
          {
            record_buf[0] = (reg_v | (bit (arm_insn_r->arm_insn, 7) << 4))
                            + ARM_D0_REGNUM;
            arm_insn_r->reg_rec_count = 1;
          }
        /* Handle VDUP instruction.  */
        else
          {
            if (bit (arm_insn_r->arm_insn, 21))
              {
                reg_v = reg_v | (bit (arm_insn_r->arm_insn, 7) << 4);
                record_buf[0] = reg_v + ARM_D0_REGNUM;
                record_buf[1] = reg_v + ARM_D0_REGNUM + 1;
                arm_insn_r->reg_rec_count = 2;
              }
            else
              {
                reg_v = reg_v | (bit (arm_insn_r->arm_insn, 7) << 4);
                record_buf[0] = reg_v + ARM_D0_REGNUM;
                arm_insn_r->reg_rec_count = 1;
              }
          }
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    return 0;
  }
  
  /* Record handler for extension register load/store instructions.  */
  
  static int
  arm_record_exreg_ld_st_insn (insn_decode_record *arm_insn_r)
  {
    uint32_t opcode, single_reg;
    uint8_t op_vldm_vstm;
    uint32_t record_buf[8], record_buf_mem[128];
    ULONGEST u_regval = 0;
  
    struct regcache *reg_cache = arm_insn_r->regcache;
  
    opcode = bits (arm_insn_r->arm_insn, 20, 24);
    single_reg = !bit (arm_insn_r->arm_insn, 8);
    op_vldm_vstm = opcode & 0x1b;
  
    /* Handle VMOV instructions.  */
    if ((opcode & 0x1e) == 0x04)
      {
        if (bit (arm_insn_r->arm_insn, 20)) /* to_arm_registers bit 20? */
  	{
  	  record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
  	  record_buf[1] = bits (arm_insn_r->arm_insn, 16, 19);
  	  arm_insn_r->reg_rec_count = 2;
  	}
        else
  	{
  	  uint8_t reg_m = bits (arm_insn_r->arm_insn, 0, 3);
  	  uint8_t bit_m = bit (arm_insn_r->arm_insn, 5);
  
  	  if (single_reg)
  	    {
  	      /* The first S register number m is REG_M:M (M is bit 5),
  		 the corresponding D register number is REG_M:M / 2, which
  		 is REG_M.  */
  	      record_buf[arm_insn_r->reg_rec_count++] = ARM_D0_REGNUM + reg_m;
  	      /* The second S register number is REG_M:M + 1, the
  		 corresponding D register number is (REG_M:M + 1) / 2.
  		 IOW, if bit M is 1, the first and second S registers
  		 are mapped to different D registers, otherwise, they are
  		 in the same D register.  */
  	      if (bit_m)
  		{
  		  record_buf[arm_insn_r->reg_rec_count++]
  		    = ARM_D0_REGNUM + reg_m + 1;
  		}
  	    }
  	  else
  	    {
  	      record_buf[0] = ((bit_m << 4) + reg_m + ARM_D0_REGNUM);
  	      arm_insn_r->reg_rec_count = 1;
  	    }
  	}
      }
    /* Handle VSTM and VPUSH instructions.  */
    else if (op_vldm_vstm == 0x08 || op_vldm_vstm == 0x0a
  	   || op_vldm_vstm == 0x12)
      {
        uint32_t start_address, reg_rn, imm_off32, imm_off8, memory_count;
        uint32_t memory_index = 0;
  
        reg_rn = bits (arm_insn_r->arm_insn, 16, 19);
        regcache_raw_read_unsigned (reg_cache, reg_rn, &u_regval);
        imm_off8 = bits (arm_insn_r->arm_insn, 0, 7);
        imm_off32 = imm_off8 << 2;
        memory_count = imm_off8;
  
        if (bit (arm_insn_r->arm_insn, 23))
  	start_address = u_regval;
        else
  	start_address = u_regval - imm_off32;
  
        if (bit (arm_insn_r->arm_insn, 21))
  	{
  	  record_buf[0] = reg_rn;
  	  arm_insn_r->reg_rec_count = 1;
  	}
  
        while (memory_count > 0)
  	{
  	  if (single_reg)
  	    {
  	      record_buf_mem[memory_index] = 4;
  	      record_buf_mem[memory_index + 1] = start_address;
  	      start_address = start_address + 4;
  	      memory_index = memory_index + 2;
  	    }
  	  else
  	    {
  	      record_buf_mem[memory_index] = 4;
  	      record_buf_mem[memory_index + 1] = start_address;
  	      record_buf_mem[memory_index + 2] = 4;
  	      record_buf_mem[memory_index + 3] = start_address + 4;
  	      start_address = start_address + 8;
  	      memory_index = memory_index + 4;
  	    }
  	  memory_count--;
  	}
        arm_insn_r->mem_rec_count = (memory_index >> 1);
      }
    /* Handle VLDM instructions.  */
    else if (op_vldm_vstm == 0x09 || op_vldm_vstm == 0x0b
  	   || op_vldm_vstm == 0x13)
      {
        uint32_t reg_count, reg_vd;
        uint32_t reg_index = 0;
        uint32_t bit_d = bit (arm_insn_r->arm_insn, 22);
  
        reg_vd = bits (arm_insn_r->arm_insn, 12, 15);
        reg_count = bits (arm_insn_r->arm_insn, 0, 7);
  
        /* REG_VD is the first D register number.  If the instruction
  	 loads memory to S registers (SINGLE_REG is TRUE), the register
  	 number is (REG_VD << 1 | bit D), so the corresponding D
  	 register number is (REG_VD << 1 | bit D) / 2 = REG_VD.  */
        if (!single_reg)
  	reg_vd = reg_vd | (bit_d << 4);
  
        if (bit (arm_insn_r->arm_insn, 21) /* write back */)
  	record_buf[reg_index++] = bits (arm_insn_r->arm_insn, 16, 19);
  
        /* If the instruction loads memory to D register, REG_COUNT should
  	 be divided by 2, according to the ARM Architecture Reference
  	 Manual.  If the instruction loads memory to S register, divide by
  	 2 as well because two S registers are mapped to D register.  */
        reg_count  = reg_count / 2;
        if (single_reg && bit_d)
  	{
  	  /* Increase the register count if S register list starts from
  	     an odd number (bit d is one).  */
  	  reg_count++;
  	}
  
        while (reg_count > 0)
  	{
  	  record_buf[reg_index++] = ARM_D0_REGNUM + reg_vd + reg_count - 1;
  	  reg_count--;
  	}
        arm_insn_r->reg_rec_count = reg_index;
      }
    /* VSTR Vector store register.  */
    else if ((opcode & 0x13) == 0x10)
      {
        uint32_t start_address, reg_rn, imm_off32, imm_off8;
        uint32_t memory_index = 0;
  
        reg_rn = bits (arm_insn_r->arm_insn, 16, 19);
        regcache_raw_read_unsigned (reg_cache, reg_rn, &u_regval);
        imm_off8 = bits (arm_insn_r->arm_insn, 0, 7);
        imm_off32 = imm_off8 << 2;
  
        if (bit (arm_insn_r->arm_insn, 23))
  	start_address = u_regval + imm_off32;
        else
  	start_address = u_regval - imm_off32;
  
        if (single_reg)
  	{
  	  record_buf_mem[memory_index] = 4;
  	  record_buf_mem[memory_index + 1] = start_address;
  	  arm_insn_r->mem_rec_count = 1;
  	}
        else
  	{
  	  record_buf_mem[memory_index] = 4;
  	  record_buf_mem[memory_index + 1] = start_address;
  	  record_buf_mem[memory_index + 2] = 4;
  	  record_buf_mem[memory_index + 3] = start_address + 4;
  	  arm_insn_r->mem_rec_count = 2;
  	}
      }
    /* VLDR Vector load register.  */
    else if ((opcode & 0x13) == 0x11)
      {
        uint32_t reg_vd = bits (arm_insn_r->arm_insn, 12, 15);
  
        if (!single_reg)
  	{
  	  reg_vd = reg_vd | (bit (arm_insn_r->arm_insn, 22) << 4);
  	  record_buf[0] = ARM_D0_REGNUM + reg_vd;
  	}
        else
  	{
  	  reg_vd = (reg_vd << 1) | bit (arm_insn_r->arm_insn, 22);
  	  /* Record register D rather than pseudo register S.  */
  	  record_buf[0] = ARM_D0_REGNUM + reg_vd / 2;
  	}
        arm_insn_r->reg_rec_count = 1;
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (arm_insn_r->arm_mems, arm_insn_r->mem_rec_count, record_buf_mem);
    return 0;
  }
  
  /* Record handler for arm/thumb mode VFP data processing instructions.  */
  
  static int
  arm_record_vfp_data_proc_insn (insn_decode_record *arm_insn_r)
  {
    uint32_t opc1, opc2, opc3, dp_op_sz, bit_d, reg_vd;
    uint32_t record_buf[4];
    enum insn_types {INSN_T0, INSN_T1, INSN_T2, INSN_T3, INSN_INV};
    enum insn_types curr_insn_type = INSN_INV;
  
    reg_vd = bits (arm_insn_r->arm_insn, 12, 15);
    opc1 = bits (arm_insn_r->arm_insn, 20, 23);
    opc2 = bits (arm_insn_r->arm_insn, 16, 19);
    opc3 = bits (arm_insn_r->arm_insn, 6, 7);
    dp_op_sz = bit (arm_insn_r->arm_insn, 8);
    bit_d = bit (arm_insn_r->arm_insn, 22);
    opc1 = opc1 & 0x04;
  
    /* Handle VMLA, VMLS.  */
    if (opc1 == 0x00)
      {
        if (bit (arm_insn_r->arm_insn, 10))
          {
            if (bit (arm_insn_r->arm_insn, 6))
              curr_insn_type = INSN_T0;
            else
              curr_insn_type = INSN_T1;
          }
        else
          {
            if (dp_op_sz)
              curr_insn_type = INSN_T1;
            else
              curr_insn_type = INSN_T2;
          }
      }
    /* Handle VNMLA, VNMLS, VNMUL.  */
    else if (opc1 == 0x01)
      {
        if (dp_op_sz)
          curr_insn_type = INSN_T1;
        else
          curr_insn_type = INSN_T2;
      }
    /* Handle VMUL.  */
    else if (opc1 == 0x02 && !(opc3 & 0x01))
      {
        if (bit (arm_insn_r->arm_insn, 10))
          {
            if (bit (arm_insn_r->arm_insn, 6))
              curr_insn_type = INSN_T0;
            else
              curr_insn_type = INSN_T1;
          }
        else
          {
            if (dp_op_sz)
              curr_insn_type = INSN_T1;
            else
              curr_insn_type = INSN_T2;
          }
      }
    /* Handle VADD, VSUB.  */
    else if (opc1 == 0x03)
      {
        if (!bit (arm_insn_r->arm_insn, 9))
          {
            if (bit (arm_insn_r->arm_insn, 6))
              curr_insn_type = INSN_T0;
            else
              curr_insn_type = INSN_T1;
          }
        else
          {
            if (dp_op_sz)
              curr_insn_type = INSN_T1;
            else
              curr_insn_type = INSN_T2;
          }
      }
    /* Handle VDIV.  */
    else if (opc1 == 0x0b)
      {
        if (dp_op_sz)
          curr_insn_type = INSN_T1;
        else
          curr_insn_type = INSN_T2;
      }
    /* Handle all other vfp data processing instructions.  */
    else if (opc1 == 0x0b)
      {
        /* Handle VMOV.  */
        if (!(opc3 & 0x01) || (opc2 == 0x00 && opc3 == 0x01))
          {
            if (bit (arm_insn_r->arm_insn, 4))
              {
                if (bit (arm_insn_r->arm_insn, 6))
                  curr_insn_type = INSN_T0;
                else
                  curr_insn_type = INSN_T1;
              }
            else
              {
                if (dp_op_sz)
                  curr_insn_type = INSN_T1;
                else
                  curr_insn_type = INSN_T2;
              }
          }
        /* Handle VNEG and VABS.  */
        else if ((opc2 == 0x01 && opc3 == 0x01)
                || (opc2 == 0x00 && opc3 == 0x03))
          {
            if (!bit (arm_insn_r->arm_insn, 11))
              {
                if (bit (arm_insn_r->arm_insn, 6))
                  curr_insn_type = INSN_T0;
                else
                  curr_insn_type = INSN_T1;
              }
            else
              {
                if (dp_op_sz)
                  curr_insn_type = INSN_T1;
                else
                  curr_insn_type = INSN_T2;
              }
          }
        /* Handle VSQRT.  */
        else if (opc2 == 0x01 && opc3 == 0x03)
          {
            if (dp_op_sz)
              curr_insn_type = INSN_T1;
            else
              curr_insn_type = INSN_T2;
          }
        /* Handle VCVT.  */
        else if (opc2 == 0x07 && opc3 == 0x03)
          {
            if (!dp_op_sz)
              curr_insn_type = INSN_T1;
            else
              curr_insn_type = INSN_T2;
          }
        else if (opc3 & 0x01)
          {
            /* Handle VCVT.  */
            if ((opc2 == 0x08) || (opc2 & 0x0e) == 0x0c)
              {
                if (!bit (arm_insn_r->arm_insn, 18))
                  curr_insn_type = INSN_T2;
                else
                  {
                    if (dp_op_sz)
                      curr_insn_type = INSN_T1;
                    else
                      curr_insn_type = INSN_T2;
                  }
              }
            /* Handle VCVT.  */
            else if ((opc2 & 0x0e) == 0x0a || (opc2 & 0x0e) == 0x0e)
              {
                if (dp_op_sz)
                  curr_insn_type = INSN_T1;
                else
                  curr_insn_type = INSN_T2;
              }
            /* Handle VCVTB, VCVTT.  */
            else if ((opc2 & 0x0e) == 0x02)
              curr_insn_type = INSN_T2;
            /* Handle VCMP, VCMPE.  */
            else if ((opc2 & 0x0e) == 0x04)
              curr_insn_type = INSN_T3;
          }
      }
  
    switch (curr_insn_type)
      {
        case INSN_T0:
          reg_vd = reg_vd | (bit_d << 4);
          record_buf[0] = reg_vd + ARM_D0_REGNUM;
          record_buf[1] = reg_vd + ARM_D0_REGNUM + 1;
          arm_insn_r->reg_rec_count = 2;
          break;
  
        case INSN_T1:
          reg_vd = reg_vd | (bit_d << 4);
          record_buf[0] = reg_vd + ARM_D0_REGNUM;
          arm_insn_r->reg_rec_count = 1;
          break;
  
        case INSN_T2:
          reg_vd = (reg_vd << 1) | bit_d;
          record_buf[0] = reg_vd + ARM_D0_REGNUM;
          arm_insn_r->reg_rec_count = 1;
          break;
  
        case INSN_T3:
          record_buf[0] = ARM_FPSCR_REGNUM;
          arm_insn_r->reg_rec_count = 1;
          break;
  
        default:
          gdb_assert_not_reached ("no decoding pattern found");
          break;
      }
  
    REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, record_buf);
    return 0;
  }
  
  /* Handling opcode 110 insns.  */
  
  static int
  arm_record_asimd_vfp_coproc (insn_decode_record *arm_insn_r)
  {
    uint32_t op1, op1_ebit, coproc;
  
    coproc = bits (arm_insn_r->arm_insn, 8, 11);
    op1 = bits (arm_insn_r->arm_insn, 20, 25);
    op1_ebit = bit (arm_insn_r->arm_insn, 20);
  
    if ((coproc & 0x0e) == 0x0a)
      {
        /* Handle extension register ld/st instructions.  */
        if (!(op1 & 0x20))
          return arm_record_exreg_ld_st_insn (arm_insn_r);
  
        /* 64-bit transfers between arm core and extension registers.  */
        if ((op1 & 0x3e) == 0x04)
          return arm_record_exreg_ld_st_insn (arm_insn_r);
      }
    else
      {
        /* Handle coprocessor ld/st instructions.  */
        if (!(op1 & 0x3a))
          {
            /* Store.  */
            if (!op1_ebit)
              return arm_record_unsupported_insn (arm_insn_r);
            else
              /* Load.  */
              return arm_record_unsupported_insn (arm_insn_r);
          }
  
        /* Move to coprocessor from two arm core registers.  */
        if (op1 == 0x4)
          return arm_record_unsupported_insn (arm_insn_r);
  
        /* Move to two arm core registers from coprocessor.  */
        if (op1 == 0x5)
          {
            uint32_t reg_t[2];
  
            reg_t[0] = bits (arm_insn_r->arm_insn, 12, 15);
            reg_t[1] = bits (arm_insn_r->arm_insn, 16, 19);
            arm_insn_r->reg_rec_count = 2;
  
            REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count, reg_t);
            return 0;
         }
      }
    return arm_record_unsupported_insn (arm_insn_r);
  }
  
  /* Handling opcode 111 insns.  */
  
  static int
  arm_record_coproc_data_proc (insn_decode_record *arm_insn_r)
  {
    uint32_t op, op1_sbit, op1_ebit, coproc;
    struct gdbarch_tdep *tdep = gdbarch_tdep (arm_insn_r->gdbarch);
    struct regcache *reg_cache = arm_insn_r->regcache;
  
    arm_insn_r->opcode = bits (arm_insn_r->arm_insn, 24, 27);
    coproc = bits (arm_insn_r->arm_insn, 8, 11);
    op1_sbit = bit (arm_insn_r->arm_insn, 24);
    op1_ebit = bit (arm_insn_r->arm_insn, 20);
    op = bit (arm_insn_r->arm_insn, 4);
  
    /* Handle arm SWI/SVC system call instructions.  */
    if (op1_sbit)
      {
        if (tdep->arm_syscall_record != NULL)
          {
            ULONGEST svc_operand, svc_number;
  
            svc_operand = (0x00ffffff & arm_insn_r->arm_insn);
  
            if (svc_operand)  /* OABI.  */
              svc_number = svc_operand - 0x900000;
            else /* EABI.  */
              regcache_raw_read_unsigned (reg_cache, 7, &svc_number);
  
            return tdep->arm_syscall_record (reg_cache, svc_number);
          }
        else
          {
            printf_unfiltered (_("no syscall record support\n"));
            return -1;
          }
      }
  
    if ((coproc & 0x0e) == 0x0a)
      {
        /* VFP data-processing instructions.  */
        if (!op1_sbit && !op)
          return arm_record_vfp_data_proc_insn (arm_insn_r);
  
        /* Advanced SIMD, VFP instructions.  */
        if (!op1_sbit && op)
          return arm_record_vdata_transfer_insn (arm_insn_r);
      }
    else
      {
        /* Coprocessor data operations.  */
        if (!op1_sbit && !op)
          return arm_record_unsupported_insn (arm_insn_r);
  
        /* Move to Coprocessor from ARM core register.  */
        if (!op1_sbit && !op1_ebit && op)
          return arm_record_unsupported_insn (arm_insn_r);
  
        /* Move to arm core register from coprocessor.  */
        if (!op1_sbit && op1_ebit && op)
          {
            uint32_t record_buf[1];
  
            record_buf[0] = bits (arm_insn_r->arm_insn, 12, 15);
            if (record_buf[0] == 15)
              record_buf[0] = ARM_PS_REGNUM;
  
            arm_insn_r->reg_rec_count = 1;
            REG_ALLOC (arm_insn_r->arm_regs, arm_insn_r->reg_rec_count,
                       record_buf);
            return 0;
          }
      }
  
    return arm_record_unsupported_insn (arm_insn_r);
  }
  
  /* Handling opcode 000 insns.  */
  
  static int
  thumb_record_shift_add_sub (insn_decode_record *thumb_insn_r)
  {
    uint32_t record_buf[8];
    uint32_t reg_src1 = 0;
  
    reg_src1 = bits (thumb_insn_r->arm_insn, 0, 2);
  
    record_buf[0] = ARM_PS_REGNUM;
    record_buf[1] = reg_src1;
    thumb_insn_r->reg_rec_count = 2;
  
    REG_ALLOC (thumb_insn_r->arm_regs, thumb_insn_r->reg_rec_count, record_buf);
  
    return 0;
  }
  
  
  /* Handling opcode 001 insns.  */
  
  static int
  thumb_record_add_sub_cmp_mov (insn_decode_record *thumb_insn_r)
  {
    uint32_t record_buf[8];
    uint32_t reg_src1 = 0;
  
    reg_src1 = bits (thumb_insn_r->arm_insn, 8, 10);
  
    record_buf[0] = ARM_PS_REGNUM;
    record_buf[1] = reg_src1;
    thumb_insn_r->reg_rec_count = 2;
  
    REG_ALLOC (thumb_insn_r->arm_regs, thumb_insn_r->reg_rec_count, record_buf);
  
    return 0;
  }
  
  /* Handling opcode 010 insns.  */
  
  static int
  thumb_record_ld_st_reg_offset (insn_decode_record *thumb_insn_r)
  {
    struct regcache *reg_cache =  thumb_insn_r->regcache;
    uint32_t record_buf[8], record_buf_mem[8];
  
    uint32_t reg_src1 = 0, reg_src2 = 0;
    uint32_t opcode1 = 0, opcode2 = 0, opcode3 = 0;
  
    ULONGEST u_regval[2] = {0};
  
    opcode1 = bits (thumb_insn_r->arm_insn, 10, 12);
  
    if (bit (thumb_insn_r->arm_insn, 12))
      {
        /* Handle load/store register offset.  */
        opcode2 = bits (thumb_insn_r->arm_insn, 9, 10);
        if (opcode2 >= 12 && opcode2 <= 15)
          {
            /* LDR(2), LDRB(2) , LDRH(2), LDRSB, LDRSH.  */
            reg_src1 = bits (thumb_insn_r->arm_insn,0, 2);
            record_buf[0] = reg_src1;
            thumb_insn_r->reg_rec_count = 1;
          }
        else if (opcode2 >= 8 && opcode2 <= 10)
          {
            /* STR(2), STRB(2), STRH(2) .  */
            reg_src1 = bits (thumb_insn_r->arm_insn, 3, 5);
            reg_src2 = bits (thumb_insn_r->arm_insn, 6, 8);
            regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval[0]);
            regcache_raw_read_unsigned (reg_cache, reg_src2, &u_regval[1]);
            if (8 == opcode2)
              record_buf_mem[0] = 4;    /* STR (2).  */
            else if (10 == opcode2)
              record_buf_mem[0] = 1;    /*  STRB (2).  */
            else if (9 == opcode2)
              record_buf_mem[0] = 2;    /* STRH (2).  */
            record_buf_mem[1] = u_regval[0] + u_regval[1];
            thumb_insn_r->mem_rec_count = 1;
          }
      }
    else if (bit (thumb_insn_r->arm_insn, 11))
      {
        /* Handle load from literal pool.  */
        /* LDR(3).  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 8, 10);
        record_buf[0] = reg_src1;
        thumb_insn_r->reg_rec_count = 1;
      }
    else if (opcode1)
      {
        opcode2 = bits (thumb_insn_r->arm_insn, 8, 9);
        opcode3 = bits (thumb_insn_r->arm_insn, 0, 2);
        if ((3 == opcode2) && (!opcode3))
          {
            /* Branch with exchange.  */
            record_buf[0] = ARM_PS_REGNUM;
            thumb_insn_r->reg_rec_count = 1;
          }
        else
          {
  	  /* Format 8; special data processing insns.  */
  	  record_buf[0] = ARM_PS_REGNUM;
  	  record_buf[1] = (bit (thumb_insn_r->arm_insn, 7) << 3
  			   | bits (thumb_insn_r->arm_insn, 0, 2));
            thumb_insn_r->reg_rec_count = 2;
          }
      }
    else
      {
        /* Format 5; data processing insns.  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 0, 2);
        if (bit (thumb_insn_r->arm_insn, 7))
          {
            reg_src1 = reg_src1 + 8;
          }
        record_buf[0] = ARM_PS_REGNUM;
        record_buf[1] = reg_src1;
        thumb_insn_r->reg_rec_count = 2;
      }
  
    REG_ALLOC (thumb_insn_r->arm_regs, thumb_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (thumb_insn_r->arm_mems, thumb_insn_r->mem_rec_count,
               record_buf_mem);
  
    return 0;
  }
  
  /* Handling opcode 001 insns.  */
  
  static int
  thumb_record_ld_st_imm_offset (insn_decode_record *thumb_insn_r)
  {
    struct regcache *reg_cache = thumb_insn_r->regcache;
    uint32_t record_buf[8], record_buf_mem[8];
  
    uint32_t reg_src1 = 0;
    uint32_t opcode = 0, immed_5 = 0;
  
    ULONGEST u_regval = 0;
  
    opcode = bits (thumb_insn_r->arm_insn, 11, 12);
  
    if (opcode)
      {
        /* LDR(1).  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 0, 2);
        record_buf[0] = reg_src1;
        thumb_insn_r->reg_rec_count = 1;
      }
    else
      {
        /* STR(1).  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 3, 5);
        immed_5 = bits (thumb_insn_r->arm_insn, 6, 10);
        regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval);
        record_buf_mem[0] = 4;
        record_buf_mem[1] = u_regval + (immed_5 * 4);
        thumb_insn_r->mem_rec_count = 1;
      }
  
    REG_ALLOC (thumb_insn_r->arm_regs, thumb_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (thumb_insn_r->arm_mems, thumb_insn_r->mem_rec_count, 
               record_buf_mem);
  
    return 0;
  }
  
  /* Handling opcode 100 insns.  */
  
  static int
  thumb_record_ld_st_stack (insn_decode_record *thumb_insn_r)
  {
    struct regcache *reg_cache = thumb_insn_r->regcache;
    uint32_t record_buf[8], record_buf_mem[8];
  
    uint32_t reg_src1 = 0;
    uint32_t opcode = 0, immed_8 = 0, immed_5 = 0;
  
    ULONGEST u_regval = 0;
  
    opcode = bits (thumb_insn_r->arm_insn, 11, 12);
  
    if (3 == opcode)
      {
        /* LDR(4).  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 8, 10);
        record_buf[0] = reg_src1;
        thumb_insn_r->reg_rec_count = 1;
      }
    else if (1 == opcode)
      {
        /* LDRH(1).  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 0, 2);
        record_buf[0] = reg_src1;
        thumb_insn_r->reg_rec_count = 1;
      }
    else if (2 == opcode)
      {
        /* STR(3).  */
        immed_8 = bits (thumb_insn_r->arm_insn, 0, 7);
        regcache_raw_read_unsigned (reg_cache, ARM_SP_REGNUM, &u_regval);
        record_buf_mem[0] = 4;
        record_buf_mem[1] = u_regval + (immed_8 * 4);
        thumb_insn_r->mem_rec_count = 1;
      }
    else if (0 == opcode)
      {
        /* STRH(1).  */
        immed_5 = bits (thumb_insn_r->arm_insn, 6, 10);
        reg_src1 = bits (thumb_insn_r->arm_insn, 3, 5);
        regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval);
        record_buf_mem[0] = 2;
        record_buf_mem[1] = u_regval + (immed_5 * 2);
        thumb_insn_r->mem_rec_count = 1;
      }
  
    REG_ALLOC (thumb_insn_r->arm_regs, thumb_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (thumb_insn_r->arm_mems, thumb_insn_r->mem_rec_count,
               record_buf_mem);
  
    return 0;
  }
  
  /* Handling opcode 101 insns.  */
  
  static int
  thumb_record_misc (insn_decode_record *thumb_insn_r)
  {
    struct regcache *reg_cache = thumb_insn_r->regcache;
  
    uint32_t opcode = 0, opcode1 = 0, opcode2 = 0;
    uint32_t register_bits = 0, register_count = 0;
    uint32_t index = 0, start_address = 0;
    uint32_t record_buf[24], record_buf_mem[48];
    uint32_t reg_src1;
  
    ULONGEST u_regval = 0;
  
    opcode = bits (thumb_insn_r->arm_insn, 11, 12);
    opcode1 = bits (thumb_insn_r->arm_insn, 8, 12);
    opcode2 = bits (thumb_insn_r->arm_insn, 9, 12);
  
    if (14 == opcode2)
      {
        /* POP.  */
        register_bits = bits (thumb_insn_r->arm_insn, 0, 7);
        while (register_bits)
        {
          if (register_bits & 0x00000001)
            record_buf[index++] = register_count;
          register_bits = register_bits >> 1;
          register_count++;
        }
        record_buf[index++] = ARM_PS_REGNUM;
        record_buf[index++] = ARM_SP_REGNUM;
        thumb_insn_r->reg_rec_count = index;
      }
    else if (10 == opcode2)
      {
        /* PUSH.  */
        register_bits = bits (thumb_insn_r->arm_insn, 0, 7);
        regcache_raw_read_unsigned (reg_cache, ARM_SP_REGNUM, &u_regval);
        while (register_bits)
          {
            if (register_bits & 0x00000001)
              register_count++;
            register_bits = register_bits >> 1;
          }
        start_address = u_regval -  \
                    (4 * (bit (thumb_insn_r->arm_insn, 8) + register_count));
        thumb_insn_r->mem_rec_count = register_count;
        while (register_count)
          {
            record_buf_mem[(register_count * 2) - 1] = start_address;
            record_buf_mem[(register_count * 2) - 2] = 4;
            start_address = start_address + 4;
            register_count--;
          }
        record_buf[0] = ARM_SP_REGNUM;
        thumb_insn_r->reg_rec_count = 1;
      }
    else if (0x1E == opcode1)
      {
        /* BKPT insn.  */
        /* Handle enhanced software breakpoint insn, BKPT.  */
        /* CPSR is changed to be executed in ARM state,  disabling normal
           interrupts, entering abort mode.  */
        /* According to high vector configuration PC is set.  */
        /* User hits breakpoint and type reverse, in that case, we need to go back with 
        previous CPSR and Program Counter.  */
        record_buf[0] = ARM_PS_REGNUM;
        record_buf[1] = ARM_LR_REGNUM;
        thumb_insn_r->reg_rec_count = 2;
        /* We need to save SPSR value, which is not yet done.  */
        printf_unfiltered (_("Process record does not support instruction "
                             "0x%0x at address %s.\n"),
                             thumb_insn_r->arm_insn,
                             paddress (thumb_insn_r->gdbarch,
                             thumb_insn_r->this_addr));
        return -1;
      }
    else if ((0 == opcode) || (1 == opcode))
      {
        /* ADD(5), ADD(6).  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 8, 10);
        record_buf[0] = reg_src1;
        thumb_insn_r->reg_rec_count = 1;
      }
    else if (2 == opcode)
      {
        /* ADD(7), SUB(4).  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 8, 10);
        record_buf[0] = ARM_SP_REGNUM;
        thumb_insn_r->reg_rec_count = 1;
      }
  
    REG_ALLOC (thumb_insn_r->arm_regs, thumb_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (thumb_insn_r->arm_mems, thumb_insn_r->mem_rec_count,
               record_buf_mem);
  
    return 0;
  }
  
  /* Handling opcode 110 insns.  */
  
  static int
  thumb_record_ldm_stm_swi (insn_decode_record *thumb_insn_r)                
  {
    struct gdbarch_tdep *tdep = gdbarch_tdep (thumb_insn_r->gdbarch);
    struct regcache *reg_cache = thumb_insn_r->regcache;
  
    uint32_t ret = 0; /* function return value: -1:record failure ;  0:success  */
    uint32_t reg_src1 = 0;
    uint32_t opcode1 = 0, opcode2 = 0, register_bits = 0, register_count = 0;
    uint32_t index = 0, start_address = 0;
    uint32_t record_buf[24], record_buf_mem[48];
  
    ULONGEST u_regval = 0;
  
    opcode1 = bits (thumb_insn_r->arm_insn, 8, 12);
    opcode2 = bits (thumb_insn_r->arm_insn, 11, 12);
  
    if (1 == opcode2)
      {
  
        /* LDMIA.  */
        register_bits = bits (thumb_insn_r->arm_insn, 0, 7);
        /* Get Rn.  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 8, 10);
        while (register_bits)
          {
            if (register_bits & 0x00000001)
              record_buf[index++] = register_count;
            register_bits = register_bits >> 1;
            register_count++;
          }
        record_buf[index++] = reg_src1;
        thumb_insn_r->reg_rec_count = index;
      }
    else if (0 == opcode2)
      {
        /* It handles both STMIA.  */
        register_bits = bits (thumb_insn_r->arm_insn, 0, 7);
        /* Get Rn.  */
        reg_src1 = bits (thumb_insn_r->arm_insn, 8, 10);
        regcache_raw_read_unsigned (reg_cache, reg_src1, &u_regval);
        while (register_bits)
          {
            if (register_bits & 0x00000001)
              register_count++;
            register_bits = register_bits >> 1;
          }
        start_address = u_regval;
        thumb_insn_r->mem_rec_count = register_count;
        while (register_count)
          {
            record_buf_mem[(register_count * 2) - 1] = start_address;
            record_buf_mem[(register_count * 2) - 2] = 4;
            start_address = start_address + 4;
            register_count--;
          }
      }
    else if (0x1F == opcode1)
      {
          /* Handle arm syscall insn.  */
          if (tdep->arm_syscall_record != NULL)
            {
              regcache_raw_read_unsigned (reg_cache, 7, &u_regval);
              ret = tdep->arm_syscall_record (reg_cache, u_regval);
            }
          else
            {
              printf_unfiltered (_("no syscall record support\n"));
              return -1;
            }
      }
  
    /* B (1), conditional branch is automatically taken care in process_record,
      as PC is saved there.  */
  
    REG_ALLOC (thumb_insn_r->arm_regs, thumb_insn_r->reg_rec_count, record_buf);
    MEM_ALLOC (thumb_insn_r->arm_mems, thumb_insn_r->mem_rec_count,
               record_buf_mem);
  
    return ret;
  }
  
  /* Handling opcode 111 insns.  */
  
  static int
  thumb_record_branch (insn_decode_record *thumb_insn_r)
  {
    uint32_t record_buf[8];
    uint32_t bits_h = 0;
  
    bits_h = bits (thumb_insn_r->arm_insn, 11, 12);
  
    if (2 == bits_h || 3 == bits_h)
      {
        /* BL */
        record_buf[0] = ARM_LR_REGNUM;
        thumb_insn_r->reg_rec_count = 1;
      }
    else if (1 == bits_h)
      {
        /* BLX(1). */
        record_buf[0] = ARM_PS_REGNUM;
        record_buf[1] = ARM_LR_REGNUM;
        thumb_insn_r->reg_rec_count = 2;
      }
  
    /* B(2) is automatically taken care in process_record, as PC is 
       saved there.  */
  
    REG_ALLOC (thumb_insn_r->arm_regs, thumb_insn_r->reg_rec_count, record_buf);
  
    return 0;     
  }
  
  /* Handler for thumb2 load/store multiple instructions.  */
  
  static int
  thumb2_record_ld_st_multiple (insn_decode_record *thumb2_insn_r)
  {
    struct regcache *reg_cache = thumb2_insn_r->regcache;
  
    uint32_t reg_rn, op;
    uint32_t register_bits = 0, register_count = 0;
    uint32_t index = 0, start_address = 0;
    uint32_t record_buf[24], record_buf_mem[48];
  
    ULONGEST u_regval = 0;
  
    reg_rn = bits (thumb2_insn_r->arm_insn, 16, 19);
    op = bits (thumb2_insn_r->arm_insn, 23, 24);
  
    if (0 == op || 3 == op)
      {
        if (bit (thumb2_insn_r->arm_insn, INSN_S_L_BIT_NUM))
          {
            /* Handle RFE instruction.  */
            record_buf[0] = ARM_PS_REGNUM;
            thumb2_insn_r->reg_rec_count = 1;
          }
        else
          {
            /* Handle SRS instruction after reading banked SP.  */
            return arm_record_unsupported_insn (thumb2_insn_r);
          }
      }
    else if (1 == op || 2 == op)
      {
        if (bit (thumb2_insn_r->arm_insn, INSN_S_L_BIT_NUM))
          {
            /* Handle LDM/LDMIA/LDMFD and LDMDB/LDMEA instructions.  */
            register_bits = bits (thumb2_insn_r->arm_insn, 0, 15);
            while (register_bits)
              {
                if (register_bits & 0x00000001)
                  record_buf[index++] = register_count;
  
                register_count++;
                register_bits = register_bits >> 1;
              }
            record_buf[index++] = reg_rn;
            record_buf[index++] = ARM_PS_REGNUM;
            thumb2_insn_r->reg_rec_count = index;
          }
        else
          {
            /* Handle STM/STMIA/STMEA and STMDB/STMFD.  */
            register_bits = bits (thumb2_insn_r->arm_insn, 0, 15);
            regcache_raw_read_unsigned (reg_cache, reg_rn, &u_regval);
            while (register_bits)
              {
                if (register_bits & 0x00000001)
                  register_count++;
  
                register_bits = register_bits >> 1;
              }
  
            if (1 == op)
              {
                /* Start address calculation for LDMDB/LDMEA.  */
                start_address = u_regval;
              }
            else if (2 == op)
              {
                /* Start address calculation for LDMDB/LDMEA.  */
                start_address = u_regval - register_count * 4;
              }
  
            thumb2_insn_r->mem_rec_count = register_count;
            while (register_count)
              {
                record_buf_mem[register_count * 2 - 1] = start_address;
                record_buf_mem[register_count * 2 - 2] = 4;
                start_address = start_address + 4;
                register_count--;
              }
            record_buf[0] = reg_rn;
            record_buf[1] = ARM_PS_REGNUM;
            thumb2_insn_r->reg_rec_count = 2;
          }
      }
  
    MEM_ALLOC (thumb2_insn_r->arm_mems, thumb2_insn_r->mem_rec_count,
              record_buf_mem);
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    return ARM_RECORD_SUCCESS;
  }
  
  /* Handler for thumb2 load/store (dual/exclusive) and table branch
     instructions.  */
  
  static int
  thumb2_record_ld_st_dual_ex_tbb (insn_decode_record *thumb2_insn_r)
  {
    struct regcache *reg_cache = thumb2_insn_r->regcache;
  
    uint32_t reg_rd, reg_rn, offset_imm;
    uint32_t reg_dest1, reg_dest2;
    uint32_t address, offset_addr;
    uint32_t record_buf[8], record_buf_mem[8];
    uint32_t op1, op2, op3;
  
    ULONGEST u_regval[2];
  
    op1 = bits (thumb2_insn_r->arm_insn, 23, 24);
    op2 = bits (thumb2_insn_r->arm_insn, 20, 21);
    op3 = bits (thumb2_insn_r->arm_insn, 4, 7);
  
    if (bit (thumb2_insn_r->arm_insn, INSN_S_L_BIT_NUM))
      {
        if(!(1 == op1 && 1 == op2 && (0 == op3 || 1 == op3)))
          {
            reg_dest1 = bits (thumb2_insn_r->arm_insn, 12, 15);
            record_buf[0] = reg_dest1;
            record_buf[1] = ARM_PS_REGNUM;
            thumb2_insn_r->reg_rec_count = 2;
          }
  
        if (3 == op2 || (op1 & 2) || (1 == op1 && 1 == op2 && 7 == op3))
          {
            reg_dest2 = bits (thumb2_insn_r->arm_insn, 8, 11);
            record_buf[2] = reg_dest2;
            thumb2_insn_r->reg_rec_count = 3;
          }
      }
    else
      {
        reg_rn = bits (thumb2_insn_r->arm_insn, 16, 19);
        regcache_raw_read_unsigned (reg_cache, reg_rn, &u_regval[0]);
  
        if (0 == op1 && 0 == op2)
          {
            /* Handle STREX.  */
            offset_imm = bits (thumb2_insn_r->arm_insn, 0, 7);
            address = u_regval[0] + (offset_imm * 4);
            record_buf_mem[0] = 4;
            record_buf_mem[1] = address;
            thumb2_insn_r->mem_rec_count = 1;
            reg_rd = bits (thumb2_insn_r->arm_insn, 0, 3);
            record_buf[0] = reg_rd;
            thumb2_insn_r->reg_rec_count = 1;
          }
        else if (1 == op1 && 0 == op2)
          {
            reg_rd = bits (thumb2_insn_r->arm_insn, 0, 3);
            record_buf[0] = reg_rd;
            thumb2_insn_r->reg_rec_count = 1;
            address = u_regval[0];
            record_buf_mem[1] = address;
  
            if (4 == op3)
              {
                /* Handle STREXB.  */
                record_buf_mem[0] = 1;
                thumb2_insn_r->mem_rec_count = 1;
              }
            else if (5 == op3)
              {
                /* Handle STREXH.  */
                record_buf_mem[0] = 2 ;
                thumb2_insn_r->mem_rec_count = 1;
              }
            else if (7 == op3)
              {
                /* Handle STREXD.  */
                address = u_regval[0];
                record_buf_mem[0] = 4;
                record_buf_mem[2] = 4;
                record_buf_mem[3] = address + 4;
                thumb2_insn_r->mem_rec_count = 2;
              }
          }
        else
          {
            offset_imm = bits (thumb2_insn_r->arm_insn, 0, 7);
  
            if (bit (thumb2_insn_r->arm_insn, 24))
              {
                if (bit (thumb2_insn_r->arm_insn, 23))
                  offset_addr = u_regval[0] + (offset_imm * 4);
                else
                  offset_addr = u_regval[0] - (offset_imm * 4);
  
                address = offset_addr;
              }
            else
              address = u_regval[0];
  
            record_buf_mem[0] = 4;
            record_buf_mem[1] = address;
            record_buf_mem[2] = 4;
            record_buf_mem[3] = address + 4;
            thumb2_insn_r->mem_rec_count = 2;
            record_buf[0] = reg_rn;
            thumb2_insn_r->reg_rec_count = 1;
          }
      }
  
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    MEM_ALLOC (thumb2_insn_r->arm_mems, thumb2_insn_r->mem_rec_count,
              record_buf_mem);
    return ARM_RECORD_SUCCESS;
  }
  
  /* Handler for thumb2 data processing (shift register and modified immediate)
     instructions.  */
  
  static int
  thumb2_record_data_proc_sreg_mimm (insn_decode_record *thumb2_insn_r)
  {
    uint32_t reg_rd, op;
    uint32_t record_buf[8];
  
    op = bits (thumb2_insn_r->arm_insn, 21, 24);
    reg_rd = bits (thumb2_insn_r->arm_insn, 8, 11);
  
    if ((0 == op || 4 == op || 8 == op || 13 == op) && 15 == reg_rd)
      {
        record_buf[0] = ARM_PS_REGNUM;
        thumb2_insn_r->reg_rec_count = 1;
      }
    else
      {
        record_buf[0] = reg_rd;
        record_buf[1] = ARM_PS_REGNUM;
        thumb2_insn_r->reg_rec_count = 2;
      }
  
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    return ARM_RECORD_SUCCESS;
  }
  
  /* Generic handler for thumb2 instructions which effect destination and PS
     registers.  */
  
  static int
  thumb2_record_ps_dest_generic (insn_decode_record *thumb2_insn_r)
  {
    uint32_t reg_rd;
    uint32_t record_buf[8];
  
    reg_rd = bits (thumb2_insn_r->arm_insn, 8, 11);
  
    record_buf[0] = reg_rd;
    record_buf[1] = ARM_PS_REGNUM;
    thumb2_insn_r->reg_rec_count = 2;
  
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    return ARM_RECORD_SUCCESS;
  }
  
  /* Handler for thumb2 branch and miscellaneous control instructions.  */
  
  static int
  thumb2_record_branch_misc_cntrl (insn_decode_record *thumb2_insn_r)
  {
    uint32_t op, op1, op2;
    uint32_t record_buf[8];
  
    op = bits (thumb2_insn_r->arm_insn, 20, 26);
    op1 = bits (thumb2_insn_r->arm_insn, 12, 14);
    op2 = bits (thumb2_insn_r->arm_insn, 8, 11);
  
    /* Handle MSR insn.  */
    if (!(op1 & 0x2) && 0x38 == op)
      {
        if (!(op2 & 0x3))
          {
            /* CPSR is going to be changed.  */
            record_buf[0] = ARM_PS_REGNUM;
            thumb2_insn_r->reg_rec_count = 1;
          }
        else
          {
            arm_record_unsupported_insn(thumb2_insn_r);
            return -1;
          }
      }
    else if (4 == (op1 & 0x5) || 5 == (op1 & 0x5))
      {
        /* BLX.  */
        record_buf[0] = ARM_PS_REGNUM;
        record_buf[1] = ARM_LR_REGNUM;
        thumb2_insn_r->reg_rec_count = 2;
      }
  
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    return ARM_RECORD_SUCCESS;
  }
  
  /* Handler for thumb2 store single data item instructions.  */
  
  static int
  thumb2_record_str_single_data (insn_decode_record *thumb2_insn_r)
  {
    struct regcache *reg_cache = thumb2_insn_r->regcache;
  
    uint32_t reg_rn, reg_rm, offset_imm, shift_imm;
    uint32_t address, offset_addr;
    uint32_t record_buf[8], record_buf_mem[8];
    uint32_t op1, op2;
  
    ULONGEST u_regval[2];
  
    op1 = bits (thumb2_insn_r->arm_insn, 21, 23);
    op2 = bits (thumb2_insn_r->arm_insn, 6, 11);
    reg_rn = bits (thumb2_insn_r->arm_insn, 16, 19);
    regcache_raw_read_unsigned (reg_cache, reg_rn, &u_regval[0]);
  
    if (bit (thumb2_insn_r->arm_insn, 23))
      {
        /* T2 encoding.  */
        offset_imm = bits (thumb2_insn_r->arm_insn, 0, 11);
        offset_addr = u_regval[0] + offset_imm;
        address = offset_addr;
      }
    else
      {
        /* T3 encoding.  */
        if ((0 == op1 || 1 == op1 || 2 == op1) && !(op2 & 0x20))
          {
            /* Handle STRB (register).  */
            reg_rm = bits (thumb2_insn_r->arm_insn, 0, 3);
            regcache_raw_read_unsigned (reg_cache, reg_rm, &u_regval[1]);
            shift_imm = bits (thumb2_insn_r->arm_insn, 4, 5);
            offset_addr = u_regval[1] << shift_imm;
            address = u_regval[0] + offset_addr;
          }
        else
          {
            offset_imm = bits (thumb2_insn_r->arm_insn, 0, 7);
            if (bit (thumb2_insn_r->arm_insn, 10))
              {
                if (bit (thumb2_insn_r->arm_insn, 9))
                  offset_addr = u_regval[0] + offset_imm;
                else
                  offset_addr = u_regval[0] - offset_imm;
  
                address = offset_addr;
              }
            else
              address = u_regval[0];
          }
      }
  
    switch (op1)
      {
        /* Store byte instructions.  */
        case 4:
        case 0:
          record_buf_mem[0] = 1;
          break;
        /* Store half word instructions.  */
        case 1:
        case 5:
          record_buf_mem[0] = 2;
          break;
        /* Store word instructions.  */
        case 2:
        case 6:
          record_buf_mem[0] = 4;
          break;
  
        default:
          gdb_assert_not_reached ("no decoding pattern found");
          break;
      }
  
    record_buf_mem[1] = address;
    thumb2_insn_r->mem_rec_count = 1;
    record_buf[0] = reg_rn;
    thumb2_insn_r->reg_rec_count = 1;
  
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    MEM_ALLOC (thumb2_insn_r->arm_mems, thumb2_insn_r->mem_rec_count,
              record_buf_mem);
    return ARM_RECORD_SUCCESS;
  }
  
  /* Handler for thumb2 load memory hints instructions.  */
  
  static int
  thumb2_record_ld_mem_hints (insn_decode_record *thumb2_insn_r)
  {
    uint32_t record_buf[8];
    uint32_t reg_rt, reg_rn;
  
    reg_rt = bits (thumb2_insn_r->arm_insn, 12, 15);
    reg_rn = bits (thumb2_insn_r->arm_insn, 16, 19);
  
    if (ARM_PC_REGNUM != reg_rt)
      {
        record_buf[0] = reg_rt;
        record_buf[1] = reg_rn;
        record_buf[2] = ARM_PS_REGNUM;
        thumb2_insn_r->reg_rec_count = 3;
  
        REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
                  record_buf);
        return ARM_RECORD_SUCCESS;
      }
  
    return ARM_RECORD_FAILURE;
  }
  
  /* Handler for thumb2 load word instructions.  */
  
  static int
  thumb2_record_ld_word (insn_decode_record *thumb2_insn_r)
  {
    uint32_t record_buf[8];
  
    record_buf[0] = bits (thumb2_insn_r->arm_insn, 12, 15);
    record_buf[1] = ARM_PS_REGNUM;
    thumb2_insn_r->reg_rec_count = 2;
  
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    return ARM_RECORD_SUCCESS;
  }
  
  /* Handler for thumb2 long multiply, long multiply accumulate, and
     divide instructions.  */
  
  static int
  thumb2_record_lmul_lmla_div (insn_decode_record *thumb2_insn_r)
  {
    uint32_t opcode1 = 0, opcode2 = 0;
    uint32_t record_buf[8];
  
    opcode1 = bits (thumb2_insn_r->arm_insn, 20, 22);
    opcode2 = bits (thumb2_insn_r->arm_insn, 4, 7);
  
    if (0 == opcode1 || 2 == opcode1 || (opcode1 >= 4 && opcode1 <= 6))
      {
        /* Handle SMULL, UMULL, SMULAL.  */
        /* Handle SMLAL(S), SMULL(S), UMLAL(S), UMULL(S).  */
        record_buf[0] = bits (thumb2_insn_r->arm_insn, 16, 19);
        record_buf[1] = bits (thumb2_insn_r->arm_insn, 12, 15);
        record_buf[2] = ARM_PS_REGNUM;
        thumb2_insn_r->reg_rec_count = 3;
      }
    else if (1 == opcode1 || 3 == opcode2)
      {
        /* Handle SDIV and UDIV.  */
        record_buf[0] = bits (thumb2_insn_r->arm_insn, 16, 19);
        record_buf[1] = bits (thumb2_insn_r->arm_insn, 12, 15);
        record_buf[2] = ARM_PS_REGNUM;
        thumb2_insn_r->reg_rec_count = 3;
      }
    else
      return ARM_RECORD_FAILURE;
  
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    return ARM_RECORD_SUCCESS;
  }
  
  /* Record handler for thumb32 coprocessor instructions.  */
  
  static int
  thumb2_record_coproc_insn (insn_decode_record *thumb2_insn_r)
  {
    if (bit (thumb2_insn_r->arm_insn, 25))
      return arm_record_coproc_data_proc (thumb2_insn_r);
    else
      return arm_record_asimd_vfp_coproc (thumb2_insn_r);
  }
  
  /* Record handler for advance SIMD structure load/store instructions.  */
  
  static int
  thumb2_record_asimd_struct_ld_st (insn_decode_record *thumb2_insn_r)
  {
    struct regcache *reg_cache = thumb2_insn_r->regcache;
    uint32_t l_bit, a_bit, b_bits;
    uint32_t record_buf[128], record_buf_mem[128];
    uint32_t reg_rn, reg_vd, address, f_elem;
    uint32_t index_r = 0, index_e = 0, bf_regs = 0, index_m = 0, loop_t = 0;
    uint8_t f_ebytes;
  
    l_bit = bit (thumb2_insn_r->arm_insn, 21);
    a_bit = bit (thumb2_insn_r->arm_insn, 23);
    b_bits = bits (thumb2_insn_r->arm_insn, 8, 11);
    reg_rn = bits (thumb2_insn_r->arm_insn, 16, 19);
    reg_vd = bits (thumb2_insn_r->arm_insn, 12, 15);
    reg_vd = (bit (thumb2_insn_r->arm_insn, 22) << 4) | reg_vd;
    f_ebytes = (1 << bits (thumb2_insn_r->arm_insn, 6, 7));
    f_elem = 8 / f_ebytes;
  
    if (!l_bit)
      {
        ULONGEST u_regval = 0;
        regcache_raw_read_unsigned (reg_cache, reg_rn, &u_regval);
        address = u_regval;
  
        if (!a_bit)
          {
            /* Handle VST1.  */
            if (b_bits == 0x02 || b_bits == 0x0a || (b_bits & 0x0e) == 0x06)
              {
                if (b_bits == 0x07)
                  bf_regs = 1;
                else if (b_bits == 0x0a)
                  bf_regs = 2;
                else if (b_bits == 0x06)
                  bf_regs = 3;
                else if (b_bits == 0x02)
                  bf_regs = 4;
                else
                  bf_regs = 0;
  
                for (index_r = 0; index_r < bf_regs; index_r++)
                  {
                    for (index_e = 0; index_e < f_elem; index_e++)
                      {
                        record_buf_mem[index_m++] = f_ebytes;
                        record_buf_mem[index_m++] = address;
                        address = address + f_ebytes;
                        thumb2_insn_r->mem_rec_count += 1;
                      }
                  }
              }
            /* Handle VST2.  */
            else if (b_bits == 0x03 || (b_bits & 0x0e) == 0x08)
              {
                if (b_bits == 0x09 || b_bits == 0x08)
                  bf_regs = 1;
                else if (b_bits == 0x03)
                  bf_regs = 2;
                else
                  bf_regs = 0;
  
                for (index_r = 0; index_r < bf_regs; index_r++)
                  for (index_e = 0; index_e < f_elem; index_e++)
                    {
                      for (loop_t = 0; loop_t < 2; loop_t++)
                        {
                          record_buf_mem[index_m++] = f_ebytes;
                          record_buf_mem[index_m++] = address + (loop_t * f_ebytes);
                          thumb2_insn_r->mem_rec_count += 1;
                        }
                      address = address + (2 * f_ebytes);
                    }
              }
            /* Handle VST3.  */
            else if ((b_bits & 0x0e) == 0x04)
              {
                for (index_e = 0; index_e < f_elem; index_e++)
                  {
                    for (loop_t = 0; loop_t < 3; loop_t++)
                      {
                        record_buf_mem[index_m++] = f_ebytes;
                        record_buf_mem[index_m++] = address + (loop_t * f_ebytes);
                        thumb2_insn_r->mem_rec_count += 1;
                      }
                    address = address + (3 * f_ebytes);
                  }
              }
            /* Handle VST4.  */
            else if (!(b_bits & 0x0e))
              {
                for (index_e = 0; index_e < f_elem; index_e++)
                  {
                    for (loop_t = 0; loop_t < 4; loop_t++)
                      {
                        record_buf_mem[index_m++] = f_ebytes;
                        record_buf_mem[index_m++] = address + (loop_t * f_ebytes);
                        thumb2_insn_r->mem_rec_count += 1;
                      }
                    address = address + (4 * f_ebytes);
                  }
              }
          }
        else
          {
            uint8_t bft_size = bits (thumb2_insn_r->arm_insn, 10, 11);
  
            if (bft_size == 0x00)
              f_ebytes = 1;
            else if (bft_size == 0x01)
              f_ebytes = 2;
            else if (bft_size == 0x02)
              f_ebytes = 4;
            else
              f_ebytes = 0;
  
            /* Handle VST1.  */
            if (!(b_bits & 0x0b) || b_bits == 0x08)
              thumb2_insn_r->mem_rec_count = 1;
            /* Handle VST2.  */
            else if ((b_bits & 0x0b) == 0x01 || b_bits == 0x09)
              thumb2_insn_r->mem_rec_count = 2;
            /* Handle VST3.  */
            else if ((b_bits & 0x0b) == 0x02 || b_bits == 0x0a)
              thumb2_insn_r->mem_rec_count = 3;
            /* Handle VST4.  */
            else if ((b_bits & 0x0b) == 0x03 || b_bits == 0x0b)
              thumb2_insn_r->mem_rec_count = 4;
  
            for (index_m = 0; index_m < thumb2_insn_r->mem_rec_count; index_m++)
              {
                record_buf_mem[index_m] = f_ebytes;
                record_buf_mem[index_m] = address + (index_m * f_ebytes);
              }
          }
      }
    else
      {
        if (!a_bit)
          {
            /* Handle VLD1.  */
            if (b_bits == 0x02 || b_bits == 0x0a || (b_bits & 0x0e) == 0x06)
              thumb2_insn_r->reg_rec_count = 1;
            /* Handle VLD2.  */
            else if (b_bits == 0x03 || (b_bits & 0x0e) == 0x08)
              thumb2_insn_r->reg_rec_count = 2;
            /* Handle VLD3.  */
            else if ((b_bits & 0x0e) == 0x04)
              thumb2_insn_r->reg_rec_count = 3;
            /* Handle VLD4.  */
            else if (!(b_bits & 0x0e))
              thumb2_insn_r->reg_rec_count = 4;
          }
        else
          {
            /* Handle VLD1.  */
            if (!(b_bits & 0x0b) || b_bits == 0x08 || b_bits == 0x0c)
              thumb2_insn_r->reg_rec_count = 1;
            /* Handle VLD2.  */
            else if ((b_bits & 0x0b) == 0x01 || b_bits == 0x09 || b_bits == 0x0d)
              thumb2_insn_r->reg_rec_count = 2;
            /* Handle VLD3.  */
            else if ((b_bits & 0x0b) == 0x02 || b_bits == 0x0a || b_bits == 0x0e)
              thumb2_insn_r->reg_rec_count = 3;
            /* Handle VLD4.  */
            else if ((b_bits & 0x0b) == 0x03 || b_bits == 0x0b || b_bits == 0x0f)
              thumb2_insn_r->reg_rec_count = 4;
  
            for (index_r = 0; index_r < thumb2_insn_r->reg_rec_count; index_r++)
              record_buf[index_r] = reg_vd + ARM_D0_REGNUM + index_r;
          }
      }
  
    if (bits (thumb2_insn_r->arm_insn, 0, 3) != 15)
      {
        record_buf[index_r] = reg_rn;
        thumb2_insn_r->reg_rec_count += 1;
      }
  
    REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count,
              record_buf);
    MEM_ALLOC (thumb2_insn_r->arm_mems, thumb2_insn_r->mem_rec_count,
              record_buf_mem);
    return 0;
  }
  
  /* Decodes thumb2 instruction type and invokes its record handler.  */
  
  static unsigned int
  thumb2_record_decode_insn_handler (insn_decode_record *thumb2_insn_r)
  {
    uint32_t op, op1, op2;
  
    op = bit (thumb2_insn_r->arm_insn, 15);
    op1 = bits (thumb2_insn_r->arm_insn, 27, 28);
    op2 = bits (thumb2_insn_r->arm_insn, 20, 26);
  
    if (op1 == 0x01)
      {
        if (!(op2 & 0x64 ))
          {
            /* Load/store multiple instruction.  */
            return thumb2_record_ld_st_multiple (thumb2_insn_r);
          }
        else if (!((op2 & 0x64) ^ 0x04))
          {
            /* Load/store (dual/exclusive) and table branch instruction.  */
            return thumb2_record_ld_st_dual_ex_tbb (thumb2_insn_r);
          }
        else if (!((op2 & 0x20) ^ 0x20))
          {
            /* Data-processing (shifted register).  */
            return thumb2_record_data_proc_sreg_mimm (thumb2_insn_r);
          }
        else if (op2 & 0x40)
          {
            /* Co-processor instructions.  */
            return thumb2_record_coproc_insn (thumb2_insn_r);
          }
      }
    else if (op1 == 0x02)
      {
        if (op)
          {
            /* Branches and miscellaneous control instructions.  */
            return thumb2_record_branch_misc_cntrl (thumb2_insn_r);
          }
        else if (op2 & 0x20)
          {
            /* Data-processing (plain binary immediate) instruction.  */
            return thumb2_record_ps_dest_generic (thumb2_insn_r);
          }
        else
          {
            /* Data-processing (modified immediate).  */
            return thumb2_record_data_proc_sreg_mimm (thumb2_insn_r);
          }
      }
    else if (op1 == 0x03)
      {
        if (!(op2 & 0x71 ))
          {
            /* Store single data item.  */
            return thumb2_record_str_single_data (thumb2_insn_r);
          }
        else if (!((op2 & 0x71) ^ 0x10))
          {
            /* Advanced SIMD or structure load/store instructions.  */
            return thumb2_record_asimd_struct_ld_st (thumb2_insn_r);
          }
        else if (!((op2 & 0x67) ^ 0x01))
          {
            /* Load byte, memory hints instruction.  */
            return thumb2_record_ld_mem_hints (thumb2_insn_r);
          }
        else if (!((op2 & 0x67) ^ 0x03))
          {
            /* Load halfword, memory hints instruction.  */
            return thumb2_record_ld_mem_hints (thumb2_insn_r);
          }
        else if (!((op2 & 0x67) ^ 0x05))
          {
            /* Load word instruction.  */
            return thumb2_record_ld_word (thumb2_insn_r);
          }
        else if (!((op2 & 0x70) ^ 0x20))
          {
            /* Data-processing (register) instruction.  */
            return thumb2_record_ps_dest_generic (thumb2_insn_r);
          }
        else if (!((op2 & 0x78) ^ 0x30))
          {
            /* Multiply, multiply accumulate, abs diff instruction.  */
            return thumb2_record_ps_dest_generic (thumb2_insn_r);
          }
        else if (!((op2 & 0x78) ^ 0x38))
          {
            /* Long multiply, long multiply accumulate, and divide.  */
            return thumb2_record_lmul_lmla_div (thumb2_insn_r);
          }
        else if (op2 & 0x40)
          {
            /* Co-processor instructions.  */
            return thumb2_record_coproc_insn (thumb2_insn_r);
          }
     }
  
    return -1;
  }
  
  /* Extracts arm/thumb/thumb2 insn depending on the size, and returns 0 on success 
  and positive val on fauilure.  */
  
  static int
  extract_arm_insn (insn_decode_record *insn_record, uint32_t insn_size)
  {
    gdb_byte buf[insn_size];
  
    memset (&buf[0], 0, insn_size);
    
    if (target_read_memory (insn_record->this_addr, &buf[0], insn_size))
      return 1;
    insn_record->arm_insn = (uint32_t) extract_unsigned_integer (&buf[0],
                             insn_size, 
  			   gdbarch_byte_order_for_code (insn_record->gdbarch));
    return 0;
  }
  
  typedef int (*sti_arm_hdl_fp_t) (insn_decode_record*);
  
  /* Decode arm/thumb insn depending on condition cods and opcodes; and
     dispatch it.  */
  
  static int
  decode_insn (insn_decode_record *arm_record, record_type_t record_type,
  	     uint32_t insn_size)
  {
  
    /* (Starting from numerical 0); bits 25, 26, 27 decodes type of arm
       instruction.  */
    static const sti_arm_hdl_fp_t arm_handle_insn[8] =
    {
      arm_record_data_proc_misc_ld_str,   /* 000.  */
      arm_record_data_proc_imm,           /* 001.  */
      arm_record_ld_st_imm_offset,        /* 010.  */
      arm_record_ld_st_reg_offset,        /* 011.  */
      arm_record_ld_st_multiple,          /* 100.  */
      arm_record_b_bl,                    /* 101.  */
      arm_record_asimd_vfp_coproc,        /* 110.  */
      arm_record_coproc_data_proc         /* 111.  */
    };
  
    /* (Starting from numerical 0); bits 13,14,15 decodes type of thumb
       instruction.  */
    static const sti_arm_hdl_fp_t thumb_handle_insn[8] =
    { \
      thumb_record_shift_add_sub,        /* 000.  */
      thumb_record_add_sub_cmp_mov,      /* 001.  */
      thumb_record_ld_st_reg_offset,     /* 010.  */
      thumb_record_ld_st_imm_offset,     /* 011.  */
      thumb_record_ld_st_stack,          /* 100.  */
      thumb_record_misc,                 /* 101.  */
      thumb_record_ldm_stm_swi,          /* 110.  */
      thumb_record_branch                /* 111.  */
    };
  
    uint32_t ret = 0;    /* return value: negative:failure   0:success.  */
    uint32_t insn_id = 0;
  
    if (extract_arm_insn (arm_record, insn_size))
      {
        if (record_debug)
  	{
  	  printf_unfiltered (_("Process record: error reading memory at "
  			       "addr %s len = %d.\n"),
  			     paddress (arm_record->gdbarch,
  				       arm_record->this_addr), insn_size);
  	}
        return -1;
      }
    else if (ARM_RECORD == record_type)
      {
        arm_record->cond = bits (arm_record->arm_insn, 28, 31);
        insn_id = bits (arm_record->arm_insn, 25, 27);
  
        if (arm_record->cond == 0xf)
  	ret = arm_record_extension_space (arm_record);
        else
  	{
  	  /* If this insn has fallen into extension space
  	     then we need not decode it anymore.  */
  	  ret = arm_handle_insn[insn_id] (arm_record);
  	}
        if (ret != ARM_RECORD_SUCCESS)
  	{
  	  arm_record_unsupported_insn (arm_record);
  	  ret = -1;
  	}
      }
    else if (THUMB_RECORD == record_type)
      {
        /* As thumb does not have condition codes, we set negative.  */
        arm_record->cond = -1;
        insn_id = bits (arm_record->arm_insn, 13, 15);
        ret = thumb_handle_insn[insn_id] (arm_record);
        if (ret != ARM_RECORD_SUCCESS)
  	{
  	  arm_record_unsupported_insn (arm_record);
  	  ret = -1;
  	}
      }
    else if (THUMB2_RECORD == record_type)
      {
        /* As thumb does not have condition codes, we set negative.  */
        arm_record->cond = -1;
  
        /* Swap first half of 32bit thumb instruction with second half.  */
        arm_record->arm_insn
  	= (arm_record->arm_insn >> 16) | (arm_record->arm_insn << 16);
  
        ret = thumb2_record_decode_insn_handler (arm_record);
  
        if (ret != ARM_RECORD_SUCCESS)
  	{
  	  arm_record_unsupported_insn (arm_record);
  	  ret = -1;
  	}
      }
    else
      {
        /* Throw assertion.  */
        gdb_assert_not_reached ("not a valid instruction, could not decode");
      }
  
    return ret;
  }
  
  
  /* Cleans up local record registers and memory allocations.  */
  
  static void 
  deallocate_reg_mem (insn_decode_record *record)
  {
    xfree (record->arm_regs);
    xfree (record->arm_mems);    
  }
  
  
  /* Parse the current instruction and record the values of the registers and
     memory that will be changed in current instruction to record_arch_list".
     Return -1 if something is wrong.  */
  
  int
  arm_process_record (struct gdbarch *gdbarch, struct regcache *regcache,
  		    CORE_ADDR insn_addr)
  {
  
    uint32_t no_of_rec = 0;
    uint32_t ret = 0;  /* return value: -1:record failure ;  0:success  */
    ULONGEST t_bit = 0, insn_id = 0;
  
    ULONGEST u_regval = 0;
  
    insn_decode_record arm_record;
  
    memset (&arm_record, 0, sizeof (insn_decode_record));
    arm_record.regcache = regcache;
    arm_record.this_addr = insn_addr;
    arm_record.gdbarch = gdbarch;
  
  
    if (record_debug > 1)
      {
        fprintf_unfiltered (gdb_stdlog, "Process record: arm_process_record "
  			  "addr = %s\n",
        paddress (gdbarch, arm_record.this_addr));
      }
  
    if (extract_arm_insn (&arm_record, 2))
      {
        if (record_debug)
  	{
  	  printf_unfiltered (_("Process record: error reading memory at "
  			       "addr %s len = %d.\n"),
  			     paddress (arm_record.gdbarch,
  				       arm_record.this_addr), 2);
  	}
        return -1;
      }
  
    /* Check the insn, whether it is thumb or arm one.  */
  
    t_bit = arm_psr_thumb_bit (arm_record.gdbarch);
    regcache_raw_read_unsigned (arm_record.regcache, ARM_PS_REGNUM, &u_regval);
  
  
    if (!(u_regval & t_bit))
      {
        /* We are decoding arm insn.  */
        ret = decode_insn (&arm_record, ARM_RECORD, ARM_INSN_SIZE_BYTES);
      }
    else
      {
        insn_id = bits (arm_record.arm_insn, 11, 15);
        /* is it thumb2 insn?  */
        if ((0x1D == insn_id) || (0x1E == insn_id) || (0x1F == insn_id))
  	{
  	  ret = decode_insn (&arm_record, THUMB2_RECORD,
  			     THUMB2_INSN_SIZE_BYTES);
  	}
        else
  	{
  	  /* We are decoding thumb insn.  */
  	  ret = decode_insn (&arm_record, THUMB_RECORD, THUMB_INSN_SIZE_BYTES);
  	}
      }
  
    if (0 == ret)
      {
        /* Record registers.  */
        record_full_arch_list_add_reg (arm_record.regcache, ARM_PC_REGNUM);
        if (arm_record.arm_regs)
  	{
  	  for (no_of_rec = 0; no_of_rec < arm_record.reg_rec_count; no_of_rec++)
  	    {
  	      if (record_full_arch_list_add_reg
  		  (arm_record.regcache , arm_record.arm_regs[no_of_rec]))
  		ret = -1;
  	    }
  	}
        /* Record memories.  */
        if (arm_record.arm_mems)
  	{
  	  for (no_of_rec = 0; no_of_rec < arm_record.mem_rec_count; no_of_rec++)
  	    {
  	      if (record_full_arch_list_add_mem
  		  ((CORE_ADDR)arm_record.arm_mems[no_of_rec].addr,
  		   arm_record.arm_mems[no_of_rec].len))
  		ret = -1;
  	    }
  	}
  
        if (record_full_arch_list_add_end ())
  	ret = -1;
      }
  
  
    deallocate_reg_mem (&arm_record);
  
    return ret;
  }
  