text: // Copyright (c) 1994-2006 Sun Microsystems Inc.
  // All Rights Reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  // - Redistributions of source code must retain the above copyright notice,
  // this list of conditions and the following disclaimer.
  //
  // - Redistribution in binary form must reproduce the above copyright
  // notice, this list of conditions and the following disclaimer in the
  // documentation and/or other materials provided with the distribution.
  //
  // - Neither the name of Sun Microsystems or the names of contributors may
  // be used to endorse or promote products derived from this software without
  // specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  // IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  // THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  // PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  // The original source code covered by the above license above has been
  // modified significantly by Google Inc.
  // Copyright 2006-2009 the V8 project authors. All rights reserved.
  
  #ifndef V8_ASSEMBLER_H_
  #define V8_ASSEMBLER_H_
  
  #include "runtime.h"
  #include "top.h"
  #include "token.h"
  
  namespace v8 {
  namespace internal {
  
  
  // -----------------------------------------------------------------------------
  // Labels represent pc locations; they are typically jump or call targets.
  // After declaration, a label can be freely used to denote known or (yet)
  // unknown pc location. Assembler::bind() is used to bind a label to the
  // current pc. A label can be bound only once.
  
  class Label BASE_EMBEDDED {
   public:
    INLINE(Label())                 { Unuse(); }
    INLINE(~Label())                { ASSERT(!is_linked()); }
  
    INLINE(void Unuse())            { pos_ = 0; }
  
    INLINE(bool is_bound()  const)  { return pos_ <  0; }
    INLINE(bool is_unused() const)  { return pos_ == 0; }
    INLINE(bool is_linked() const)  { return pos_ >  0; }
  
    // Returns the position of bound or linked labels. Cannot be used
    // for unused labels.
    int pos() const;
  
   private:
    // pos_ encodes both the binding state (via its sign)
    // and the binding position (via its value) of a label.
    //
    // pos_ <  0  bound label, pos() returns the jump target position
    // pos_ == 0  unused label
    // pos_ >  0  linked label, pos() returns the last reference position
    int pos_;
  
    void bind_to(int pos)  {
      pos_ = -pos - 1;
      ASSERT(is_bound());
    }
    void link_to(int pos)  {
      pos_ =  pos + 1;
      ASSERT(is_linked());
    }
  
    friend class Assembler;
    friend class RegexpAssembler;
    friend class Displacement;
    friend class ShadowTarget;
    friend class RegExpMacroAssemblerIrregexp;
  };
  
  
  // -----------------------------------------------------------------------------
  // Relocation information
  
  
  // Relocation information consists of the address (pc) of the datum
  // to which the relocation information applies, the relocation mode
  // (rmode), and an optional data field. The relocation mode may be
  // "descriptive" and not indicate a need for relocation, but simply
  // describe a property of the datum. Such rmodes are useful for GC
  // and nice disassembly output.
  
  class RelocInfo BASE_EMBEDDED {
   public:
    // The constant kNoPosition is used with the collecting of source positions
    // in the relocation information. Two types of source positions are collected
    // "position" (RelocMode position) and "statement position" (RelocMode
    // statement_position). The "position" is collected at places in the source
    // code which are of interest when making stack traces to pin-point the source
    // location of a stack frame as close as possible. The "statement position" is
    // collected at the beginning at each statement, and is used to indicate
    // possible break locations. kNoPosition is used to indicate an
    // invalid/uninitialized position value.
    static const int kNoPosition = -1;
  
    enum Mode {
      // Please note the order is important (see IsCodeTarget, IsGCRelocMode).
      CONSTRUCT_CALL,  // code target that is a call to a JavaScript constructor.
      CODE_TARGET_CONTEXT,  // code target used for contextual loads.
      DEBUG_BREAK,
      CODE_TARGET,         // code target which is not any of the above.
      EMBEDDED_OBJECT,
      EMBEDDED_STRING,
  
      // Everything after runtime_entry (inclusive) is not GC'ed.
      RUNTIME_ENTRY,
      JS_RETURN,  // Marks start of the ExitJSFrame code.
      COMMENT,
      POSITION,  // See comment for kNoPosition above.
      STATEMENT_POSITION,  // See comment for kNoPosition above.
      EXTERNAL_REFERENCE,  // The address of an external C++ function.
      INTERNAL_REFERENCE,  // An address inside the same function.
  
      // add more as needed
      // Pseudo-types
      NUMBER_OF_MODES,  // must be no greater than 14 - see RelocInfoWriter
      NONE,  // never recorded
      LAST_CODE_ENUM = CODE_TARGET,
      LAST_GCED_ENUM = EMBEDDED_STRING
    };
  
  
    RelocInfo() {}
    RelocInfo(byte* pc, Mode rmode, intptr_t data)
        : pc_(pc), rmode_(rmode), data_(data) {
    }
  
    static inline bool IsConstructCall(Mode mode) {
      return mode == CONSTRUCT_CALL;
    }
    static inline bool IsCodeTarget(Mode mode) {
      return mode <= LAST_CODE_ENUM;
    }
    // Is the relocation mode affected by GC?
    static inline bool IsGCRelocMode(Mode mode) {
      return mode <= LAST_GCED_ENUM;
    }
    static inline bool IsJSReturn(Mode mode) {
      return mode == JS_RETURN;
    }
    static inline bool IsComment(Mode mode) {
      return mode == COMMENT;
    }
    static inline bool IsPosition(Mode mode) {
      return mode == POSITION || mode == STATEMENT_POSITION;
    }
    static inline bool IsStatementPosition(Mode mode) {
      return mode == STATEMENT_POSITION;
    }
    static inline bool IsExternalReference(Mode mode) {
      return mode == EXTERNAL_REFERENCE;
    }
    static inline bool IsInternalReference(Mode mode) {
      return mode == INTERNAL_REFERENCE;
    }
    static inline int ModeMask(Mode mode) { return 1 << mode; }
  
    // Accessors
    byte* pc() const  { return pc_; }
    void set_pc(byte* pc) { pc_ = pc; }
    Mode rmode() const {  return rmode_; }
    intptr_t data() const  { return data_; }
  
    // Apply a relocation by delta bytes
    INLINE(void apply(intptr_t delta));
  
    // Read/modify the code target in the branch/call instruction
    // this relocation applies to;
    // can only be called if IsCodeTarget(rmode_) || rmode_ == RUNTIME_ENTRY
    INLINE(Address target_address());
    INLINE(void set_target_address(Address target));
    INLINE(Object* target_object());
    INLINE(Handle<Object> target_object_handle(Assembler* origin));
    INLINE(Object** target_object_address());
    INLINE(void set_target_object(Object* target));
  
    // Read the address of the word containing the target_address. Can only
    // be called if IsCodeTarget(rmode_) || rmode_ == RUNTIME_ENTRY.
    INLINE(Address target_address_address());
  
    // Read/modify the reference in the instruction this relocation
    // applies to; can only be called if rmode_ is external_reference
    INLINE(Address* target_reference_address());
  
    // Read/modify the address of a call instruction. This is used to relocate
    // the break points where straight-line code is patched with a call
    // instruction.
    INLINE(Address call_address());
    INLINE(void set_call_address(Address target));
    INLINE(Object* call_object());
    INLINE(Object** call_object_address());
    INLINE(void set_call_object(Object* target));
  
    // Patch the code with some other code.
    void PatchCode(byte* instructions, int instruction_count);
  
    // Patch the code with a call.
    void PatchCodeWithCall(Address target, int guard_bytes);
  
    // Check whether this return sequence has been patched
    // with a call to the debugger.
    INLINE(bool IsPatchedReturnSequence());
  
  #ifdef ENABLE_DISASSEMBLER
    // Printing
    static const char* RelocModeName(Mode rmode);
    void Print();
  #endif  // ENABLE_DISASSEMBLER
  #ifdef DEBUG
    // Debugging
    void Verify();
  #endif
  
    static const int kCodeTargetMask = (1 << (LAST_CODE_ENUM + 1)) - 1;
    static const int kPositionMask = 1 << POSITION | 1 << STATEMENT_POSITION;
    static const int kDebugMask = kPositionMask | 1 << COMMENT;
    static const int kApplyMask;  // Modes affected by apply. Depends on arch.
  
   private:
    // On ARM, note that pc_ is the address of the constant pool entry
    // to be relocated and not the address of the instruction
    // referencing the constant pool entry (except when rmode_ ==
    // comment).
    byte* pc_;
    Mode rmode_;
    intptr_t data_;
    friend class RelocIterator;
  };
  
  
  // RelocInfoWriter serializes a stream of relocation info. It writes towards
  // lower addresses.
  class RelocInfoWriter BASE_EMBEDDED {
   public:
    RelocInfoWriter() : pos_(NULL), last_pc_(NULL), last_data_(0) {}
    RelocInfoWriter(byte* pos, byte* pc) : pos_(pos), last_pc_(pc),
                                           last_data_(0) {}
  
    byte* pos() const { return pos_; }
    byte* last_pc() const { return last_pc_; }
  
    void Write(const RelocInfo* rinfo);
  
    // Update the state of the stream after reloc info buffer
    // and/or code is moved while the stream is active.
    void Reposition(byte* pos, byte* pc) {
      pos_ = pos;
      last_pc_ = pc;
    }
  
    // Max size (bytes) of a written RelocInfo. Longest encoding is
    // ExtraTag, VariableLengthPCJump, ExtraTag, pc_delta, ExtraTag, data_delta.
    // On ia32 and arm this is 1 + 4 + 1 + 1 + 1 + 4 = 12.
    // On x64 this is 1 + 4 + 1 + 1 + 1 + 8 == 16;
    // Here we use the maximum of the two.
    static const int kMaxSize = 16;
  
   private:
    inline uint32_t WriteVariableLengthPCJump(uint32_t pc_delta);
    inline void WriteTaggedPC(uint32_t pc_delta, int tag);
    inline void WriteExtraTaggedPC(uint32_t pc_delta, int extra_tag);
    inline void WriteExtraTaggedData(intptr_t data_delta, int top_tag);
    inline void WriteTaggedData(intptr_t data_delta, int tag);
    inline void WriteExtraTag(int extra_tag, int top_tag);
  
    byte* pos_;
    byte* last_pc_;
    intptr_t last_data_;
    DISALLOW_COPY_AND_ASSIGN(RelocInfoWriter);
  };
  
  
  // A RelocIterator iterates over relocation information.
  // Typical use:
  //
  //   for (RelocIterator it(code); !it.done(); it.next()) {
  //     // do something with it.rinfo() here
  //   }
  //
  // A mask can be specified to skip unwanted modes.
  class RelocIterator: public Malloced {
   public:
    // Create a new iterator positioned at
    // the beginning of the reloc info.
    // Relocation information with mode k is included in the
    // iteration iff bit k of mode_mask is set.
    explicit RelocIterator(Code* code, int mode_mask = -1);
    explicit RelocIterator(const CodeDesc& desc, int mode_mask = -1);
  
    // Iteration
    bool done() const  { return done_; }
    void next();
  
    // Return pointer valid until next next().
    RelocInfo* rinfo() {
      ASSERT(!done());
      return &rinfo_;
    }
  
   private:
    // Advance* moves the position before/after reading.
    // *Read* reads from current byte(s) into rinfo_.
    // *Get* just reads and returns info on current byte.
    void Advance(int bytes = 1) { pos_ -= bytes; }
    int AdvanceGetTag();
    int GetExtraTag();
    int GetTopTag();
    void ReadTaggedPC();
    void AdvanceReadPC();
    void AdvanceReadData();
    void AdvanceReadVariableLengthPCJump();
    int GetPositionTypeTag();
    void ReadTaggedData();
  
    static RelocInfo::Mode DebugInfoModeFromTag(int tag);
  
    // If the given mode is wanted, set it in rinfo_ and return true.
    // Else return false. Used for efficiently skipping unwanted modes.
    bool SetMode(RelocInfo::Mode mode) {
      return (mode_mask_ & 1 << mode) ? (rinfo_.rmode_ = mode, true) : false;
    }
  
    byte* pos_;
    byte* end_;
    RelocInfo rinfo_;
    bool done_;
    int mode_mask_;
    DISALLOW_COPY_AND_ASSIGN(RelocIterator);
  };
  
  
  //------------------------------------------------------------------------------
  // External function
  
  //----------------------------------------------------------------------------
  class IC_Utility;
  class SCTableReference;
  #ifdef ENABLE_DEBUGGER_SUPPORT
  class Debug_Address;
  #endif
  
  
  typedef void* ExternalReferenceRedirector(void* original, bool fp_return);
  
  
  // An ExternalReference represents a C++ address used in the generated
  // code. All references to C++ functions and variables must be encapsulated in
  // an ExternalReference instance. This is done in order to track the origin of
  // all external references in the code so that they can be bound to the correct
  // addresses when deserializing a heap.
  class ExternalReference BASE_EMBEDDED {
   public:
    explicit ExternalReference(Builtins::CFunctionId id);
  
    explicit ExternalReference(ApiFunction* ptr);
  
    explicit ExternalReference(Builtins::Name name);
  
    explicit ExternalReference(Runtime::FunctionId id);
  
    explicit ExternalReference(Runtime::Function* f);
  
    explicit ExternalReference(const IC_Utility& ic_utility);
  
  #ifdef ENABLE_DEBUGGER_SUPPORT
    explicit ExternalReference(const Debug_Address& debug_address);
  #endif
  
    explicit ExternalReference(StatsCounter* counter);
  
    explicit ExternalReference(Top::AddressId id);
  
    explicit ExternalReference(const SCTableReference& table_ref);
  
    // One-of-a-kind references. These references are not part of a general
    // pattern. This means that they have to be added to the
    // ExternalReferenceTable in serialize.cc manually.
  
    static ExternalReference perform_gc_function();
    static ExternalReference random_positive_smi_function();
    static ExternalReference transcendental_cache_array_address();
  
    // Static data in the keyed lookup cache.
    static ExternalReference keyed_lookup_cache_keys();
    static ExternalReference keyed_lookup_cache_field_offsets();
  
    // Static variable Factory::the_hole_value.location()
    static ExternalReference the_hole_value_location();
  
    // Static variable Heap::roots_address()
    static ExternalReference roots_address();
  
    // Static variable StackGuard::address_of_jslimit()
    static ExternalReference address_of_stack_limit();
  
    // Static variable StackGuard::address_of_real_jslimit()
    static ExternalReference address_of_real_stack_limit();
  
    // Static variable RegExpStack::limit_address()
    static ExternalReference address_of_regexp_stack_limit();
  
    // Static variables for RegExp.
    static ExternalReference address_of_static_offsets_vector();
    static ExternalReference address_of_regexp_stack_memory_address();
    static ExternalReference address_of_regexp_stack_memory_size();
  
    // Static variable Heap::NewSpaceStart()
    static ExternalReference new_space_start();
    static ExternalReference new_space_mask();
    static ExternalReference heap_always_allocate_scope_depth();
  
    // Used for fast allocation in generated code.
    static ExternalReference new_space_allocation_top_address();
    static ExternalReference new_space_allocation_limit_address();
  
    static ExternalReference double_fp_operation(Token::Value operation);
    static ExternalReference compare_doubles();
  
    static ExternalReference handle_scope_extensions_address();
    static ExternalReference handle_scope_next_address();
    static ExternalReference handle_scope_limit_address();
  
    static ExternalReference scheduled_exception_address();
  
    Address address() const {return reinterpret_cast<Address>(address_);}
  
  #ifdef ENABLE_DEBUGGER_SUPPORT
    // Function Debug::Break()
    static ExternalReference debug_break();
  
    // Used to check if single stepping is enabled in generated code.
    static ExternalReference debug_step_in_fp_address();
  #endif
  
  #ifdef V8_NATIVE_REGEXP
    // C functions called from RegExp generated code.
  
    // Function NativeRegExpMacroAssembler::CaseInsensitiveCompareUC16()
    static ExternalReference re_case_insensitive_compare_uc16();
  
    // Function RegExpMacroAssembler*::CheckStackGuardState()
    static ExternalReference re_check_stack_guard_state();
  
    // Function NativeRegExpMacroAssembler::GrowStack()
    static ExternalReference re_grow_stack();
  
    // byte NativeRegExpMacroAssembler::word_character_bitmap
    static ExternalReference re_word_character_map();
  
  #endif
  
    // This lets you register a function that rewrites all external references.
    // Used by the ARM simulator to catch calls to external references.
    static void set_redirector(ExternalReferenceRedirector* redirector) {
      ASSERT(redirector_ == NULL);  // We can't stack them.
      redirector_ = redirector;
    }
  
   private:
    explicit ExternalReference(void* address)
        : address_(address) {}
  
    static ExternalReferenceRedirector* redirector_;
  
    static void* Redirect(void* address, bool fp_return = false) {
      if (redirector_ == NULL) return address;
      void* answer = (*redirector_)(address, fp_return);
      return answer;
    }
  
    static void* Redirect(Address address_arg, bool fp_return = false) {
      void* address = reinterpret_cast<void*>(address_arg);
      void* answer = (redirector_ == NULL) ?
                     address :
                     (*redirector_)(address, fp_return);
      return answer;
    }
  
    void* address_;
  };
  
  
  // -----------------------------------------------------------------------------
  // Utility functions
  
  static inline bool is_intn(int x, int n)  {
    return -(1 << (n-1)) <= x && x < (1 << (n-1));
  }
  
  static inline bool is_int8(int x)  { return is_intn(x, 8); }
  static inline bool is_int16(int x)  { return is_intn(x, 16); }
  static inline bool is_int18(int x)  { return is_intn(x, 18); }
  static inline bool is_int24(int x)  { return is_intn(x, 24); }
  
  static inline bool is_uintn(int x, int n) {
    return (x & -(1 << n)) == 0;
  }
  
  static inline bool is_uint2(int x)  { return is_uintn(x, 2); }
  static inline bool is_uint3(int x)  { return is_uintn(x, 3); }
  static inline bool is_uint4(int x)  { return is_uintn(x, 4); }
  static inline bool is_uint5(int x)  { return is_uintn(x, 5); }
  static inline bool is_uint6(int x)  { return is_uintn(x, 6); }
  static inline bool is_uint8(int x)  { return is_uintn(x, 8); }
  static inline bool is_uint10(int x)  { return is_uintn(x, 10); }
  static inline bool is_uint12(int x)  { return is_uintn(x, 12); }
  static inline bool is_uint16(int x)  { return is_uintn(x, 16); }
  static inline bool is_uint24(int x)  { return is_uintn(x, 24); }
  static inline bool is_uint26(int x)  { return is_uintn(x, 26); }
  static inline bool is_uint28(int x)  { return is_uintn(x, 28); }
  
  static inline int NumberOfBitsSet(uint32_t x) {
    unsigned int num_bits_set;
    for (num_bits_set = 0; x; x >>= 1) {
      num_bits_set += x & 1;
    }
    return num_bits_set;
  }
  
  } }  // namespace v8::internal
  
  #endif  // V8_ASSEMBLER_H_
  