text: /*
   * This file is part of the MicroPython project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2013, 2014 Damien P. George
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  // Essentially normal Python has 1 type: Python objects
  // Viper has more than 1 type, and is just a more complicated (a superset of) Python.
  // If you declare everything in Viper as a Python object (ie omit type decls) then
  // it should in principle be exactly the same as Python native.
  // Having types means having more opcodes, like binary_op_nat_nat, binary_op_nat_obj etc.
  // In practice we won't have a VM but rather do this in asm which is actually very minimal.
  
  // Because it breaks strict Python equivalence it should be a completely separate
  // decorator.  It breaks equivalence because overflow on integers wraps around.
  // It shouldn't break equivalence if you don't use the new types, but since the
  // type decls might be used in normal Python for other reasons, it's probably safest,
  // cleanest and clearest to make it a separate decorator.
  
  // Actually, it does break equivalence because integers default to native integers,
  // not Python objects.
  
  // for x in l[0:8]: can be compiled into a native loop if l has pointer type
  
  #include <stdio.h>
  #include <string.h>
  #include <assert.h>
  
  #include "py/emit.h"
  #include "py/nativeglue.h"
  #include "py/objfun.h"
  #include "py/objstr.h"
  
  #if MICROPY_DEBUG_VERBOSE // print debugging info
  #define DEBUG_PRINT (1)
  #define DEBUG_printf DEBUG_printf
  #else // don't print debugging info
  #define DEBUG_printf(...) (void)0
  #endif
  
  // wrapper around everything in this file
  #if N_X64 || N_X86 || N_THUMB || N_ARM || N_XTENSA || N_XTENSAWIN
  
  // C stack layout for native functions:
  //  0:                          nlr_buf_t [optional]
  //                              return_value [optional word]
  //                              exc_handler_unwind [optional word]
  //  emit->code_state_start:     mp_code_state_native_t
  //  emit->stack_start:          Python object stack             | emit->n_state
  //                              locals (reversed, L0 at end)    |
  //
  // C stack layout for native generator functions:
  //  0=emit->stack_start:        nlr_buf_t
  //                              return_value
  //                              exc_handler_unwind [optional word]
  //
  //  Then REG_GENERATOR_STATE points to:
  //  0=emit->code_state_start:   mp_code_state_native_t
  //  emit->stack_start:          Python object stack             | emit->n_state
  //                              locals (reversed, L0 at end)    |
  //
  // C stack layout for viper functions:
  //  0:                          nlr_buf_t [optional]
  //                              return_value [optional word]
  //                              exc_handler_unwind [optional word]
  //  emit->code_state_start:     fun_obj, old_globals [optional]
  //  emit->stack_start:          Python object stack             | emit->n_state
  //                              locals (reversed, L0 at end)    |
  //                              (L0-L2 may be in regs instead)
  
  // Native emitter needs to know the following sizes and offsets of C structs (on the target):
  #if MICROPY_DYNAMIC_COMPILER
  #define SIZEOF_NLR_BUF (2 + mp_dynamic_compiler.nlr_buf_num_regs + 1) // the +1 is conservative in case MICROPY_ENABLE_PYSTACK enabled
  #else
  #define SIZEOF_NLR_BUF (sizeof(nlr_buf_t) / sizeof(uintptr_t))
  #endif
  #define SIZEOF_CODE_STATE (sizeof(mp_code_state_native_t) / sizeof(uintptr_t))
  #define OFFSETOF_CODE_STATE_STATE (offsetof(mp_code_state_native_t, state) / sizeof(uintptr_t))
  #define OFFSETOF_CODE_STATE_FUN_BC (offsetof(mp_code_state_native_t, fun_bc) / sizeof(uintptr_t))
  #define OFFSETOF_CODE_STATE_IP (offsetof(mp_code_state_native_t, ip) / sizeof(uintptr_t))
  #define OFFSETOF_CODE_STATE_SP (offsetof(mp_code_state_native_t, sp) / sizeof(uintptr_t))
  #define OFFSETOF_CODE_STATE_N_STATE (offsetof(mp_code_state_native_t, n_state) / sizeof(uintptr_t))
  #define OFFSETOF_OBJ_FUN_BC_CONTEXT (offsetof(mp_obj_fun_bc_t, context) / sizeof(uintptr_t))
  #define OFFSETOF_OBJ_FUN_BC_CHILD_TABLE (offsetof(mp_obj_fun_bc_t, child_table) / sizeof(uintptr_t))
  #define OFFSETOF_OBJ_FUN_BC_BYTECODE (offsetof(mp_obj_fun_bc_t, bytecode) / sizeof(uintptr_t))
  #define OFFSETOF_MODULE_CONTEXT_QSTR_TABLE (offsetof(mp_module_context_t, constants.qstr_table) / sizeof(uintptr_t))
  #define OFFSETOF_MODULE_CONTEXT_OBJ_TABLE (offsetof(mp_module_context_t, constants.obj_table) / sizeof(uintptr_t))
  #define OFFSETOF_MODULE_CONTEXT_GLOBALS (offsetof(mp_module_context_t, module.globals) / sizeof(uintptr_t))
  
  // If not already defined, set parent args to same as child call registers
  #ifndef REG_PARENT_RET
  #define REG_PARENT_RET REG_RET
  #define REG_PARENT_ARG_1 REG_ARG_1
  #define REG_PARENT_ARG_2 REG_ARG_2
  #define REG_PARENT_ARG_3 REG_ARG_3
  #define REG_PARENT_ARG_4 REG_ARG_4
  #endif
  
  // Word index of nlr_buf_t.ret_val
  #define NLR_BUF_IDX_RET_VAL (1)
  
  // Whether the viper function needs access to fun_obj
  #define NEED_FUN_OBJ(emit) ((emit)->scope->exc_stack_size > 0 \
      || ((emit)->scope->scope_flags & (MP_SCOPE_FLAG_REFGLOBALS | MP_SCOPE_FLAG_HASCONSTS)))
  
  // Whether the native/viper function needs to be wrapped in an exception handler
  #define NEED_GLOBAL_EXC_HANDLER(emit) ((emit)->scope->exc_stack_size > 0 \
      || ((emit)->scope->scope_flags & (MP_SCOPE_FLAG_GENERATOR | MP_SCOPE_FLAG_REFGLOBALS)))
  
  // Whether a slot is needed to store LOCAL_IDX_EXC_HANDLER_UNWIND
  #define NEED_EXC_HANDLER_UNWIND(emit) ((emit)->scope->exc_stack_size > 0)
  
  // Whether registers can be used to store locals (only true if there are no
  // exception handlers, because otherwise an nlr_jump will restore registers to
  // their state at the start of the function and updates to locals will be lost)
  #define CAN_USE_REGS_FOR_LOCALS(emit) ((emit)->scope->exc_stack_size == 0 && !(emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR))
  
  // Indices within the local C stack for various variables
  #define LOCAL_IDX_EXC_VAL(emit) (NLR_BUF_IDX_RET_VAL)
  #define LOCAL_IDX_EXC_HANDLER_PC(emit) (NLR_BUF_IDX_LOCAL_1)
  #define LOCAL_IDX_EXC_HANDLER_UNWIND(emit) (SIZEOF_NLR_BUF + 1) // this needs a dedicated variable outside nlr_buf_t
  #define LOCAL_IDX_RET_VAL(emit) (SIZEOF_NLR_BUF) // needed when NEED_GLOBAL_EXC_HANDLER is true
  #define LOCAL_IDX_FUN_OBJ(emit) ((emit)->code_state_start + OFFSETOF_CODE_STATE_FUN_BC)
  #define LOCAL_IDX_OLD_GLOBALS(emit) ((emit)->code_state_start + OFFSETOF_CODE_STATE_IP)
  #define LOCAL_IDX_GEN_PC(emit) ((emit)->code_state_start + OFFSETOF_CODE_STATE_IP)
  #define LOCAL_IDX_LOCAL_VAR(emit, local_num) ((emit)->stack_start + (emit)->n_state - 1 - (local_num))
  
  #if MICROPY_PERSISTENT_CODE_SAVE
  
  // When building with the ability to save native code to .mpy files:
  //  - Qstrs are indirect via qstr_table, and REG_LOCAL_3 always points to qstr_table.
  //  - In a generator no registers are used to store locals, and REG_LOCAL_2 points to the generator state.
  //  - At most 2 registers hold local variables (see CAN_USE_REGS_FOR_LOCALS for when this is possible).
  
  #define REG_GENERATOR_STATE (REG_LOCAL_2)
  #define REG_QSTR_TABLE (REG_LOCAL_3)
  #define MAX_REGS_FOR_LOCAL_VARS (2)
  
  STATIC const uint8_t reg_local_table[MAX_REGS_FOR_LOCAL_VARS] = {REG_LOCAL_1, REG_LOCAL_2};
  
  #else
  
  // When building without the ability to save native code to .mpy files:
  //  - Qstrs values are written directly into the machine code.
  //  - In a generator no registers are used to store locals, and REG_LOCAL_3 points to the generator state.
  //  - At most 3 registers hold local variables (see CAN_USE_REGS_FOR_LOCALS for when this is possible).
  
  #define REG_GENERATOR_STATE (REG_LOCAL_3)
  #define MAX_REGS_FOR_LOCAL_VARS (3)
  
  STATIC const uint8_t reg_local_table[MAX_REGS_FOR_LOCAL_VARS] = {REG_LOCAL_1, REG_LOCAL_2, REG_LOCAL_3};
  
  #endif
  
  #define REG_LOCAL_LAST (reg_local_table[MAX_REGS_FOR_LOCAL_VARS - 1])
  
  #define EMIT_NATIVE_VIPER_TYPE_ERROR(emit, ...) do { \
          *emit->error_slot = mp_obj_new_exception_msg_varg(&mp_type_ViperTypeError, __VA_ARGS__); \
  } while (0)
  
  typedef enum {
      STACK_VALUE,
      STACK_REG,
      STACK_IMM,
  } stack_info_kind_t;
  
  // these enums must be distinct and the bottom 4 bits
  // must correspond to the correct MP_NATIVE_TYPE_xxx value
  typedef enum {
      VTYPE_PYOBJ = 0x00 | MP_NATIVE_TYPE_OBJ,
      VTYPE_BOOL = 0x00 | MP_NATIVE_TYPE_BOOL,
      VTYPE_INT = 0x00 | MP_NATIVE_TYPE_INT,
      VTYPE_UINT = 0x00 | MP_NATIVE_TYPE_UINT,
      VTYPE_PTR = 0x00 | MP_NATIVE_TYPE_PTR,
      VTYPE_PTR8 = 0x00 | MP_NATIVE_TYPE_PTR8,
      VTYPE_PTR16 = 0x00 | MP_NATIVE_TYPE_PTR16,
      VTYPE_PTR32 = 0x00 | MP_NATIVE_TYPE_PTR32,
  
      VTYPE_PTR_NONE = 0x50 | MP_NATIVE_TYPE_PTR,
  
      VTYPE_UNBOUND = 0x60 | MP_NATIVE_TYPE_OBJ,
      VTYPE_BUILTIN_CAST = 0x70 | MP_NATIVE_TYPE_OBJ,
  } vtype_kind_t;
  
  STATIC qstr vtype_to_qstr(vtype_kind_t vtype) {
      switch (vtype) {
          case VTYPE_PYOBJ:
              return MP_QSTR_object;
          case VTYPE_BOOL:
              return MP_QSTR_bool;
          case VTYPE_INT:
              return MP_QSTR_int;
          case VTYPE_UINT:
              return MP_QSTR_uint;
          case VTYPE_PTR:
              return MP_QSTR_ptr;
          case VTYPE_PTR8:
              return MP_QSTR_ptr8;
          case VTYPE_PTR16:
              return MP_QSTR_ptr16;
          case VTYPE_PTR32:
              return MP_QSTR_ptr32;
          case VTYPE_PTR_NONE:
          default:
              return MP_QSTR_None;
      }
  }
  
  typedef struct _stack_info_t {
      vtype_kind_t vtype;
      stack_info_kind_t kind;
      union {
          int u_reg;
          mp_int_t u_imm;
      } data;
  } stack_info_t;
  
  #define UNWIND_LABEL_UNUSED (0x7fff)
  #define UNWIND_LABEL_DO_FINAL_UNWIND (0x7ffe)
  
  typedef struct _exc_stack_entry_t {
      uint16_t label : 15;
      uint16_t is_finally : 1;
      uint16_t unwind_label : 15;
      uint16_t is_active : 1;
  } exc_stack_entry_t;
  
  struct _emit_t {
      mp_emit_common_t *emit_common;
      mp_obj_t *error_slot;
      uint *label_slot;
      uint exit_label;
      int pass;
  
      bool do_viper_types;
      bool prelude_offset_uses_u16_encoding;
  
      mp_uint_t local_vtype_alloc;
      vtype_kind_t *local_vtype;
  
      mp_uint_t stack_info_alloc;
      stack_info_t *stack_info;
      vtype_kind_t saved_stack_vtype;
  
      size_t exc_stack_alloc;
      size_t exc_stack_size;
      exc_stack_entry_t *exc_stack;
  
      int prelude_offset;
      int prelude_ptr_index;
      int start_offset;
      int n_state;
      uint16_t code_state_start;
      uint16_t stack_start;
      int stack_size;
      uint16_t n_info;
      uint16_t n_cell;
  
      bool last_emit_was_return_value;
  
      scope_t *scope;
  
      ASM_T *as;
  };
  
  STATIC void emit_load_reg_with_object(emit_t *emit, int reg, mp_obj_t obj);
  STATIC void emit_native_global_exc_entry(emit_t *emit);
  STATIC void emit_native_global_exc_exit(emit_t *emit);
  STATIC void emit_native_load_const_obj(emit_t *emit, mp_obj_t obj);
  
  emit_t *EXPORT_FUN(new)(mp_emit_common_t * emit_common, mp_obj_t *error_slot, uint *label_slot, mp_uint_t max_num_labels) {
      emit_t *emit = m_new0(emit_t, 1);
      emit->emit_common = emit_common;
      emit->error_slot = error_slot;
      emit->label_slot = label_slot;
      emit->stack_info_alloc = 8;
      emit->stack_info = m_new(stack_info_t, emit->stack_info_alloc);
      emit->exc_stack_alloc = 8;
      emit->exc_stack = m_new(exc_stack_entry_t, emit->exc_stack_alloc);
      emit->as = m_new0(ASM_T, 1);
      mp_asm_base_init(&emit->as->base, max_num_labels);
      return emit;
  }
  
  void EXPORT_FUN(free)(emit_t * emit) {
      mp_asm_base_deinit(&emit->as->base, false);
      m_del_obj(ASM_T, emit->as);
      m_del(exc_stack_entry_t, emit->exc_stack, emit->exc_stack_alloc);
      m_del(vtype_kind_t, emit->local_vtype, emit->local_vtype_alloc);
      m_del(stack_info_t, emit->stack_info, emit->stack_info_alloc);
      m_del_obj(emit_t, emit);
  }
  
  STATIC void emit_call_with_imm_arg(emit_t *emit, mp_fun_kind_t fun_kind, mp_int_t arg_val, int arg_reg);
  
  STATIC void emit_native_mov_reg_const(emit_t *emit, int reg_dest, int const_val) {
      ASM_LOAD_REG_REG_OFFSET(emit->as, reg_dest, REG_FUN_TABLE, const_val);
  }
  
  STATIC void emit_native_mov_state_reg(emit_t *emit, int local_num, int reg_src) {
      if (emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR) {
          ASM_STORE_REG_REG_OFFSET(emit->as, reg_src, REG_GENERATOR_STATE, local_num);
      } else {
          ASM_MOV_LOCAL_REG(emit->as, local_num, reg_src);
      }
  }
  
  STATIC void emit_native_mov_reg_state(emit_t *emit, int reg_dest, int local_num) {
      if (emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR) {
          ASM_LOAD_REG_REG_OFFSET(emit->as, reg_dest, REG_GENERATOR_STATE, local_num);
      } else {
          ASM_MOV_REG_LOCAL(emit->as, reg_dest, local_num);
      }
  }
  
  STATIC void emit_native_mov_reg_state_addr(emit_t *emit, int reg_dest, int local_num) {
      if (emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR) {
          ASM_MOV_REG_IMM(emit->as, reg_dest, local_num * ASM_WORD_SIZE);
          ASM_ADD_REG_REG(emit->as, reg_dest, REG_GENERATOR_STATE);
      } else {
          ASM_MOV_REG_LOCAL_ADDR(emit->as, reg_dest, local_num);
      }
  }
  
  STATIC void emit_native_mov_reg_qstr(emit_t *emit, int arg_reg, qstr qst) {
      #if MICROPY_PERSISTENT_CODE_SAVE
      ASM_LOAD16_REG_REG_OFFSET(emit->as, arg_reg, REG_QSTR_TABLE, mp_emit_common_use_qstr(emit->emit_common, qst));
      #else
      ASM_MOV_REG_IMM(emit->as, arg_reg, qst);
      #endif
  }
  
  STATIC void emit_native_mov_reg_qstr_obj(emit_t *emit, int reg_dest, qstr qst) {
      #if MICROPY_PERSISTENT_CODE_SAVE
      emit_load_reg_with_object(emit, reg_dest, MP_OBJ_NEW_QSTR(qst));
      #else
      ASM_MOV_REG_IMM(emit->as, reg_dest, (mp_uint_t)MP_OBJ_NEW_QSTR(qst));
      #endif
  }
  
  #define emit_native_mov_state_imm_via(emit, local_num, imm, reg_temp) \
      do { \
          ASM_MOV_REG_IMM((emit)->as, (reg_temp), (imm)); \
          emit_native_mov_state_reg((emit), (local_num), (reg_temp)); \
      } while (false)
  
  STATIC void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scope) {
      DEBUG_printf("start_pass(pass=%u, scope=%p)\n", pass, scope);
  
      emit->pass = pass;
      emit->do_viper_types = scope->emit_options == MP_EMIT_OPT_VIPER;
      emit->stack_size = 0;
      emit->last_emit_was_return_value = false;
      emit->scope = scope;
  
      // allocate memory for keeping track of the types of locals
      if (emit->local_vtype_alloc < scope->num_locals) {
          emit->local_vtype = m_renew(vtype_kind_t, emit->local_vtype, emit->local_vtype_alloc, scope->num_locals);
          emit->local_vtype_alloc = scope->num_locals;
      }
  
      // set default type for arguments
      mp_uint_t num_args = emit->scope->num_pos_args + emit->scope->num_kwonly_args;
      if (scope->scope_flags & MP_SCOPE_FLAG_VARARGS) {
          num_args += 1;
      }
      if (scope->scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) {
          num_args += 1;
      }
      for (mp_uint_t i = 0; i < num_args; i++) {
          emit->local_vtype[i] = VTYPE_PYOBJ;
      }
  
      // Set viper type for arguments
      if (emit->do_viper_types) {
          for (int i = 0; i < emit->scope->id_info_len; ++i) {
              id_info_t *id = &emit->scope->id_info[i];
              if (id->flags & ID_FLAG_IS_PARAM) {
                  assert(id->local_num < emit->local_vtype_alloc);
                  emit->local_vtype[id->local_num] = id->flags >> ID_FLAG_VIPER_TYPE_POS;
              }
          }
      }
  
      // local variables begin unbound, and have unknown type
      for (mp_uint_t i = num_args; i < emit->local_vtype_alloc; i++) {
          emit->local_vtype[i] = VTYPE_UNBOUND;
      }
  
      // values on stack begin unbound
      for (mp_uint_t i = 0; i < emit->stack_info_alloc; i++) {
          emit->stack_info[i].kind = STACK_VALUE;
          emit->stack_info[i].vtype = VTYPE_UNBOUND;
      }
  
      mp_asm_base_start_pass(&emit->as->base, pass == MP_PASS_EMIT ? MP_ASM_PASS_EMIT : MP_ASM_PASS_COMPUTE);
  
      // generate code for entry to function
  
      // Work out start of code state (mp_code_state_native_t or reduced version for viper)
      emit->code_state_start = 0;
      if (NEED_GLOBAL_EXC_HANDLER(emit)) {
          emit->code_state_start = SIZEOF_NLR_BUF; // for nlr_buf_t
          emit->code_state_start += 1;  // for return_value
          if (NEED_EXC_HANDLER_UNWIND(emit)) {
              emit->code_state_start += 1;
          }
      }
  
      size_t fun_table_off = mp_emit_common_use_const_obj(emit->emit_common, MP_OBJ_FROM_PTR(&mp_fun_table));
  
      if (emit->do_viper_types) {
          // Work out size of state (locals plus stack)
          // n_state counts all stack and locals, even those in registers
          emit->n_state = scope->num_locals + scope->stack_size;
          int num_locals_in_regs = 0;
          if (CAN_USE_REGS_FOR_LOCALS(emit)) {
              num_locals_in_regs = scope->num_locals;
              if (num_locals_in_regs > MAX_REGS_FOR_LOCAL_VARS) {
                  num_locals_in_regs = MAX_REGS_FOR_LOCAL_VARS;
              }
              // Need a spot for REG_LOCAL_LAST (see below)
              if (scope->num_pos_args >= MAX_REGS_FOR_LOCAL_VARS + 1) {
                  --num_locals_in_regs;
              }
          }
  
          // Work out where the locals and Python stack start within the C stack
          if (NEED_GLOBAL_EXC_HANDLER(emit)) {
              // Reserve 2 words for function object and old globals
              emit->stack_start = emit->code_state_start + 2;
          } else if (scope->scope_flags & MP_SCOPE_FLAG_HASCONSTS) {
              // Reserve 1 word for function object, to access const table
              emit->stack_start = emit->code_state_start + 1;
          } else {
              emit->stack_start = emit->code_state_start + 0;
          }
  
          // Entry to function
          ASM_ENTRY(emit->as, emit->stack_start + emit->n_state - num_locals_in_regs);
  
          #if N_X86
          asm_x86_mov_arg_to_r32(emit->as, 0, REG_PARENT_ARG_1);
          #endif
  
          // Load REG_FUN_TABLE with a pointer to mp_fun_table, found in the const_table
          ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_PARENT_ARG_1, OFFSETOF_OBJ_FUN_BC_CONTEXT);
          #if MICROPY_PERSISTENT_CODE_SAVE
          ASM_LOAD_REG_REG_OFFSET(emit->as, REG_QSTR_TABLE, REG_FUN_TABLE, OFFSETOF_MODULE_CONTEXT_QSTR_TABLE);
          #endif
          ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_FUN_TABLE, OFFSETOF_MODULE_CONTEXT_OBJ_TABLE);
          ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_FUN_TABLE, fun_table_off);
  
          // Store function object (passed as first arg) to stack if needed
          if (NEED_FUN_OBJ(emit)) {
              ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_FUN_OBJ(emit), REG_PARENT_ARG_1);
          }
  
          // Put n_args in REG_ARG_1, n_kw in REG_ARG_2, args array in REG_LOCAL_LAST
          #if N_X86
          asm_x86_mov_arg_to_r32(emit->as, 1, REG_ARG_1);
          asm_x86_mov_arg_to_r32(emit->as, 2, REG_ARG_2);
          asm_x86_mov_arg_to_r32(emit->as, 3, REG_LOCAL_LAST);
          #else
          ASM_MOV_REG_REG(emit->as, REG_ARG_1, REG_PARENT_ARG_2);
          ASM_MOV_REG_REG(emit->as, REG_ARG_2, REG_PARENT_ARG_3);
          ASM_MOV_REG_REG(emit->as, REG_LOCAL_LAST, REG_PARENT_ARG_4);
          #endif
  
          // Check number of args matches this function, and call mp_arg_check_num_sig if not
          ASM_JUMP_IF_REG_NONZERO(emit->as, REG_ARG_2, *emit->label_slot + 4, true);
          ASM_MOV_REG_IMM(emit->as, REG_ARG_3, scope->num_pos_args);
          ASM_JUMP_IF_REG_EQ(emit->as, REG_ARG_1, REG_ARG_3, *emit->label_slot + 5);
          mp_asm_base_label_assign(&emit->as->base, *emit->label_slot + 4);
          ASM_MOV_REG_IMM(emit->as, REG_ARG_3, MP_OBJ_FUN_MAKE_SIG(scope->num_pos_args, scope->num_pos_args, false));
          ASM_CALL_IND(emit->as, MP_F_ARG_CHECK_NUM_SIG);
          mp_asm_base_label_assign(&emit->as->base, *emit->label_slot + 5);
  
          // Store arguments into locals (reg or stack), converting to native if needed
          for (int i = 0; i < emit->scope->num_pos_args; i++) {
              int r = REG_ARG_1;
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_ARG_1, REG_LOCAL_LAST, i);
              if (emit->local_vtype[i] != VTYPE_PYOBJ) {
                  emit_call_with_imm_arg(emit, MP_F_CONVERT_OBJ_TO_NATIVE, emit->local_vtype[i], REG_ARG_2);
                  r = REG_RET;
              }
              // REG_LOCAL_LAST points to the args array so be sure not to overwrite it if it's still needed
              if (i < MAX_REGS_FOR_LOCAL_VARS && CAN_USE_REGS_FOR_LOCALS(emit) && (i != MAX_REGS_FOR_LOCAL_VARS - 1 || emit->scope->num_pos_args == MAX_REGS_FOR_LOCAL_VARS)) {
                  ASM_MOV_REG_REG(emit->as, reg_local_table[i], r);
              } else {
                  emit_native_mov_state_reg(emit, LOCAL_IDX_LOCAL_VAR(emit, i), r);
              }
          }
          // Get local from the stack back into REG_LOCAL_LAST if this reg couldn't be written to above
          if (emit->scope->num_pos_args >= MAX_REGS_FOR_LOCAL_VARS + 1 && CAN_USE_REGS_FOR_LOCALS(emit)) {
              ASM_MOV_REG_LOCAL(emit->as, REG_LOCAL_LAST, LOCAL_IDX_LOCAL_VAR(emit, MAX_REGS_FOR_LOCAL_VARS - 1));
          }
  
          emit_native_global_exc_entry(emit);
  
      } else {
          // work out size of state (locals plus stack)
          emit->n_state = scope->num_locals + scope->stack_size;
  
          if (emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR) {
              mp_asm_base_data(&emit->as->base, ASM_WORD_SIZE, (uintptr_t)emit->prelude_ptr_index);
              mp_asm_base_data(&emit->as->base, ASM_WORD_SIZE, (uintptr_t)emit->start_offset);
              ASM_ENTRY(emit->as, emit->code_state_start);
  
              // Reset the state size for the state pointed to by REG_GENERATOR_STATE
              emit->code_state_start = 0;
              emit->stack_start = SIZEOF_CODE_STATE;
  
              // Put address of code_state into REG_GENERATOR_STATE
              #if N_X86
              asm_x86_mov_arg_to_r32(emit->as, 0, REG_GENERATOR_STATE);
              #else
              ASM_MOV_REG_REG(emit->as, REG_GENERATOR_STATE, REG_PARENT_ARG_1);
              #endif
  
              // Put throw value into LOCAL_IDX_EXC_VAL slot, for yield/yield-from
              #if N_X86
              asm_x86_mov_arg_to_r32(emit->as, 1, REG_PARENT_ARG_2);
              #endif
              ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_PARENT_ARG_2);
  
              // Load REG_FUN_TABLE with a pointer to mp_fun_table, found in the const_table
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_GENERATOR_STATE, LOCAL_IDX_FUN_OBJ(emit));
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_TEMP0, OFFSETOF_OBJ_FUN_BC_CONTEXT);
              #if MICROPY_PERSISTENT_CODE_SAVE
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_QSTR_TABLE, REG_TEMP0, OFFSETOF_MODULE_CONTEXT_QSTR_TABLE);
              #endif
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_TEMP0, OFFSETOF_MODULE_CONTEXT_OBJ_TABLE);
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_TEMP0, fun_table_off);
          } else {
              // The locals and stack start after the code_state structure
              emit->stack_start = emit->code_state_start + SIZEOF_CODE_STATE;
  
              // Allocate space on C-stack for code_state structure, which includes state
              ASM_ENTRY(emit->as, emit->stack_start + emit->n_state);
  
              // Prepare incoming arguments for call to mp_setup_code_state
  
              #if N_X86
              asm_x86_mov_arg_to_r32(emit->as, 0, REG_PARENT_ARG_1);
              asm_x86_mov_arg_to_r32(emit->as, 1, REG_PARENT_ARG_2);
              asm_x86_mov_arg_to_r32(emit->as, 2, REG_PARENT_ARG_3);
              asm_x86_mov_arg_to_r32(emit->as, 3, REG_PARENT_ARG_4);
              #endif
  
              // Load REG_FUN_TABLE with a pointer to mp_fun_table, found in the const_table
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_PARENT_ARG_1, OFFSETOF_OBJ_FUN_BC_CONTEXT);
              #if MICROPY_PERSISTENT_CODE_SAVE
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_QSTR_TABLE, REG_FUN_TABLE, OFFSETOF_MODULE_CONTEXT_QSTR_TABLE);
              #endif
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_FUN_TABLE, OFFSETOF_MODULE_CONTEXT_OBJ_TABLE);
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_FUN_TABLE, REG_FUN_TABLE, fun_table_off);
  
              // Set code_state.fun_bc
              ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_FUN_OBJ(emit), REG_PARENT_ARG_1);
  
              // Set code_state.ip, a pointer to the beginning of the prelude.  This pointer is found
              // either directly in mp_obj_fun_bc_t.child_table (if there are no children), or in
              // mp_obj_fun_bc_t.child_table[num_children] (if num_children > 0).
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_PARENT_ARG_1, REG_PARENT_ARG_1, OFFSETOF_OBJ_FUN_BC_CHILD_TABLE);
              if (emit->prelude_ptr_index != 0) {
                  ASM_LOAD_REG_REG_OFFSET(emit->as, REG_PARENT_ARG_1, REG_PARENT_ARG_1, emit->prelude_ptr_index);
              }
              emit_native_mov_state_reg(emit, emit->code_state_start + OFFSETOF_CODE_STATE_IP, REG_PARENT_ARG_1);
  
              // Set code_state.n_state (only works on little endian targets due to n_state being uint16_t)
              emit_native_mov_state_imm_via(emit, emit->code_state_start + OFFSETOF_CODE_STATE_N_STATE, emit->n_state, REG_ARG_1);
  
              // Put address of code_state into first arg
              ASM_MOV_REG_LOCAL_ADDR(emit->as, REG_ARG_1, emit->code_state_start);
  
              // Copy next 3 args if needed
              #if REG_ARG_2 != REG_PARENT_ARG_2
              ASM_MOV_REG_REG(emit->as, REG_ARG_2, REG_PARENT_ARG_2);
              #endif
              #if REG_ARG_3 != REG_PARENT_ARG_3
              ASM_MOV_REG_REG(emit->as, REG_ARG_3, REG_PARENT_ARG_3);
              #endif
              #if REG_ARG_4 != REG_PARENT_ARG_4
              ASM_MOV_REG_REG(emit->as, REG_ARG_4, REG_PARENT_ARG_4);
              #endif
  
              // Call mp_setup_code_state to prepare code_state structure
              #if N_THUMB
              asm_thumb_bl_ind(emit->as, MP_F_SETUP_CODE_STATE, ASM_THUMB_REG_R4);
              #elif N_ARM
              asm_arm_bl_ind(emit->as, MP_F_SETUP_CODE_STATE, ASM_ARM_REG_R4);
              #else
              ASM_CALL_IND(emit->as, MP_F_SETUP_CODE_STATE);
              #endif
          }
  
          emit_native_global_exc_entry(emit);
  
          // cache some locals in registers, but only if no exception handlers
          if (CAN_USE_REGS_FOR_LOCALS(emit)) {
              for (int i = 0; i < MAX_REGS_FOR_LOCAL_VARS && i < scope->num_locals; ++i) {
                  ASM_MOV_REG_LOCAL(emit->as, reg_local_table[i], LOCAL_IDX_LOCAL_VAR(emit, i));
              }
          }
  
          // set the type of closed over variables
          for (mp_uint_t i = 0; i < scope->id_info_len; i++) {
              id_info_t *id = &scope->id_info[i];
              if (id->kind == ID_INFO_KIND_CELL) {
                  emit->local_vtype[id->local_num] = VTYPE_PYOBJ;
              }
          }
      }
  }
  
  static inline void emit_native_write_code_info_byte(emit_t *emit, byte val) {
      mp_asm_base_data(&emit->as->base, 1, val);
  }
  
  static inline void emit_native_write_code_info_qstr(emit_t *emit, qstr qst) {
      mp_encode_uint(&emit->as->base, mp_asm_base_get_cur_to_write_bytes, mp_emit_common_use_qstr(emit->emit_common, qst));
  }
  
  STATIC bool emit_native_end_pass(emit_t *emit) {
      emit_native_global_exc_exit(emit);
  
      if (!emit->do_viper_types) {
          emit->prelude_offset = mp_asm_base_get_code_pos(&emit->as->base);
          emit->prelude_ptr_index = emit->emit_common->ct_cur_child;
  
          size_t n_state = emit->n_state;
          size_t n_exc_stack = 0; // exc-stack not needed for native code
          MP_BC_PRELUDE_SIG_ENCODE(n_state, n_exc_stack, emit->scope, emit_native_write_code_info_byte, emit);
  
          size_t n_info = emit->n_info;
          size_t n_cell = emit->n_cell;
          MP_BC_PRELUDE_SIZE_ENCODE(n_info, n_cell, emit_native_write_code_info_byte, emit);
  
          // bytecode prelude: source info (function and argument qstrs)
          size_t info_start = mp_asm_base_get_code_pos(&emit->as->base);
          emit_native_write_code_info_qstr(emit, emit->scope->simple_name);
          for (int i = 0; i < emit->scope->num_pos_args + emit->scope->num_kwonly_args; i++) {
              qstr qst = MP_QSTR__star_;
              for (int j = 0; j < emit->scope->id_info_len; ++j) {
                  id_info_t *id = &emit->scope->id_info[j];
                  if ((id->flags & ID_FLAG_IS_PARAM) && id->local_num == i) {
                      qst = id->qst;
                      break;
                  }
              }
              emit_native_write_code_info_qstr(emit, qst);
          }
          emit->n_info = mp_asm_base_get_code_pos(&emit->as->base) - info_start;
  
          // bytecode prelude: initialise closed over variables
          size_t cell_start = mp_asm_base_get_code_pos(&emit->as->base);
          for (int i = 0; i < emit->scope->id_info_len; i++) {
              id_info_t *id = &emit->scope->id_info[i];
              if (id->kind == ID_INFO_KIND_CELL) {
                  assert(id->local_num <= 255);
                  mp_asm_base_data(&emit->as->base, 1, id->local_num); // write the local which should be converted to a cell
              }
          }
          emit->n_cell = mp_asm_base_get_code_pos(&emit->as->base) - cell_start;
  
      }
  
      ASM_END_PASS(emit->as);
  
      // check stack is back to zero size
      assert(emit->stack_size == 0);
      assert(emit->exc_stack_size == 0);
  
      if (emit->pass == MP_PASS_EMIT) {
          void *f = mp_asm_base_get_code(&emit->as->base);
          mp_uint_t f_len = mp_asm_base_get_code_size(&emit->as->base);
  
          mp_raw_code_t **children = emit->emit_common->children;
          if (!emit->do_viper_types) {
              #if MICROPY_EMIT_NATIVE_PRELUDE_SEPARATE_FROM_MACHINE_CODE
              // Executable code cannot be accessed byte-wise on this architecture, so copy
              // the prelude to a separate memory region that is byte-wise readable.
              void *buf = emit->as->base.code_base + emit->prelude_offset;
              size_t n = emit->as->base.code_offset - emit->prelude_offset;
              const uint8_t *prelude_ptr = memcpy(m_new(uint8_t, n), buf, n);
              #else
              // Point to the prelude directly, at the end of the machine code data.
              const uint8_t *prelude_ptr = (const uint8_t *)f + emit->prelude_offset;
              #endif
  
              // Store the pointer to the prelude using the child_table.
              assert(emit->prelude_ptr_index == emit->emit_common->ct_cur_child);
              if (emit->prelude_ptr_index == 0) {
                  children = (void *)prelude_ptr;
              } else {
                  children = m_renew(mp_raw_code_t *, children, emit->prelude_ptr_index, emit->prelude_ptr_index + 1);
                  children[emit->prelude_ptr_index] = (void *)prelude_ptr;
              }
          }
  
          mp_emit_glue_assign_native(emit->scope->raw_code,
              emit->do_viper_types ? MP_CODE_NATIVE_VIPER : MP_CODE_NATIVE_PY,
              f, f_len,
              children,
              #if MICROPY_PERSISTENT_CODE_SAVE
              emit->emit_common->ct_cur_child,
              emit->prelude_offset,
              #endif
              emit->scope->scope_flags, 0, 0);
      }
  
      return true;
  }
  
  STATIC bool emit_native_last_emit_was_return_value(emit_t *emit) {
      return emit->last_emit_was_return_value;
  }
  
  STATIC void ensure_extra_stack(emit_t *emit, size_t delta) {
      if (emit->stack_size + delta > emit->stack_info_alloc) {
          size_t new_alloc = (emit->stack_size + delta + 8) & ~3;
          emit->stack_info = m_renew(stack_info_t, emit->stack_info, emit->stack_info_alloc, new_alloc);
          emit->stack_info_alloc = new_alloc;
      }
  }
  
  STATIC void adjust_stack(emit_t *emit, mp_int_t stack_size_delta) {
      assert((mp_int_t)emit->stack_size + stack_size_delta >= 0);
      assert((mp_int_t)emit->stack_size + stack_size_delta <= (mp_int_t)emit->stack_info_alloc);
      emit->stack_size += stack_size_delta;
      if (emit->pass > MP_PASS_SCOPE && emit->stack_size > emit->scope->stack_size) {
          emit->scope->stack_size = emit->stack_size;
      }
      #ifdef DEBUG_PRINT
      DEBUG_printf("  adjust_stack; stack_size=%d+%d; stack now:", emit->stack_size - stack_size_delta, stack_size_delta);
      for (int i = 0; i < emit->stack_size; i++) {
          stack_info_t *si = &emit->stack_info[i];
          DEBUG_printf(" (v=%d k=%d %d)", si->vtype, si->kind, si->data.u_reg);
      }
      DEBUG_printf("\n");
      #endif
  }
  
  STATIC void emit_native_adjust_stack_size(emit_t *emit, mp_int_t delta) {
      DEBUG_printf("adjust_stack_size(" INT_FMT ")\n", delta);
      if (delta > 0) {
          ensure_extra_stack(emit, delta);
      }
      // If we are adjusting the stack in a positive direction (pushing) then we
      // need to fill in values for the stack kind and vtype of the newly-pushed
      // entries.  These should be set to "value" (ie not reg or imm) because we
      // should only need to adjust the stack due to a jump to this part in the
      // code (and hence we have settled the stack before the jump).
      for (mp_int_t i = 0; i < delta; i++) {
          stack_info_t *si = &emit->stack_info[emit->stack_size + i];
          si->kind = STACK_VALUE;
          // TODO we don't know the vtype to use here.  At the moment this is a
          // hack to get the case of multi comparison working.
          if (delta == 1) {
              si->vtype = emit->saved_stack_vtype;
          } else {
              si->vtype = VTYPE_PYOBJ;
          }
      }
      adjust_stack(emit, delta);
  }
  
  STATIC void emit_native_set_source_line(emit_t *emit, mp_uint_t source_line) {
      (void)emit;
      (void)source_line;
  }
  
  // this must be called at start of emit functions
  STATIC void emit_native_pre(emit_t *emit) {
      emit->last_emit_was_return_value = false;
  }
  
  // depth==0 is top, depth==1 is before top, etc
  STATIC stack_info_t *peek_stack(emit_t *emit, mp_uint_t depth) {
      return &emit->stack_info[emit->stack_size - 1 - depth];
  }
  
  // depth==0 is top, depth==1 is before top, etc
  STATIC vtype_kind_t peek_vtype(emit_t *emit, mp_uint_t depth) {
      if (emit->do_viper_types) {
          return peek_stack(emit, depth)->vtype;
      } else {
          // Type is always PYOBJ even if the intermediate stored value is not
          return VTYPE_PYOBJ;
      }
  }
  
  // pos=1 is TOS, pos=2 is next, etc
  // use pos=0 for no skipping
  STATIC void need_reg_single(emit_t *emit, int reg_needed, int skip_stack_pos) {
      skip_stack_pos = emit->stack_size - skip_stack_pos;
      for (int i = 0; i < emit->stack_size; i++) {
          if (i != skip_stack_pos) {
              stack_info_t *si = &emit->stack_info[i];
              if (si->kind == STACK_REG && si->data.u_reg == reg_needed) {
                  si->kind = STACK_VALUE;
                  emit_native_mov_state_reg(emit, emit->stack_start + i, si->data.u_reg);
              }
          }
      }
  }
  
  // Ensures all unsettled registers that hold Python values are copied to the
  // concrete Python stack.  All registers are then free to use.
  STATIC void need_reg_all(emit_t *emit) {
      for (int i = 0; i < emit->stack_size; i++) {
          stack_info_t *si = &emit->stack_info[i];
          if (si->kind == STACK_REG) {
              DEBUG_printf("    reg(%u) to local(%u)\n", si->data.u_reg, emit->stack_start + i);
              si->kind = STACK_VALUE;
              emit_native_mov_state_reg(emit, emit->stack_start + i, si->data.u_reg);
          }
      }
  }
  
  STATIC vtype_kind_t load_reg_stack_imm(emit_t *emit, int reg_dest, const stack_info_t *si, bool convert_to_pyobj) {
      if (!convert_to_pyobj && emit->do_viper_types) {
          ASM_MOV_REG_IMM(emit->as, reg_dest, si->data.u_imm);
          return si->vtype;
      } else {
          if (si->vtype == VTYPE_PYOBJ) {
              ASM_MOV_REG_IMM(emit->as, reg_dest, si->data.u_imm);
          } else if (si->vtype == VTYPE_BOOL) {
              emit_native_mov_reg_const(emit, reg_dest, MP_F_CONST_FALSE_OBJ + si->data.u_imm);
          } else if (si->vtype == VTYPE_INT || si->vtype == VTYPE_UINT) {
              ASM_MOV_REG_IMM(emit->as, reg_dest, (uintptr_t)MP_OBJ_NEW_SMALL_INT(si->data.u_imm));
          } else if (si->vtype == VTYPE_PTR_NONE) {
              emit_native_mov_reg_const(emit, reg_dest, MP_F_CONST_NONE_OBJ);
          } else {
              mp_raise_NotImplementedError(MP_ERROR_TEXT("conversion to object"));
          }
          return VTYPE_PYOBJ;
      }
  }
  
  // Copies all unsettled registers and immediates that are Python values into the
  // concrete Python stack.  This ensures the concrete Python stack holds valid
  // values for the current stack_size.
  // This function may clobber REG_TEMP1.
  STATIC void need_stack_settled(emit_t *emit) {
      DEBUG_printf("  need_stack_settled; stack_size=%d\n", emit->stack_size);
      need_reg_all(emit);
      for (int i = 0; i < emit->stack_size; i++) {
          stack_info_t *si = &emit->stack_info[i];
          if (si->kind == STACK_IMM) {
              DEBUG_printf("    imm(" INT_FMT ") to local(%u)\n", si->data.u_imm, emit->stack_start + i);
              si->kind = STACK_VALUE;
              // using REG_TEMP1 to avoid clobbering REG_TEMP0 (aka REG_RET)
              si->vtype = load_reg_stack_imm(emit, REG_TEMP1, si, false);
              emit_native_mov_state_reg(emit, emit->stack_start + i, REG_TEMP1);
          }
      }
  }
  
  // pos=1 is TOS, pos=2 is next, etc
  STATIC void emit_access_stack(emit_t *emit, int pos, vtype_kind_t *vtype, int reg_dest) {
      need_reg_single(emit, reg_dest, pos);
      stack_info_t *si = &emit->stack_info[emit->stack_size - pos];
      *vtype = si->vtype;
      switch (si->kind) {
          case STACK_VALUE:
              emit_native_mov_reg_state(emit, reg_dest, emit->stack_start + emit->stack_size - pos);
              break;
  
          case STACK_REG:
              if (si->data.u_reg != reg_dest) {
                  ASM_MOV_REG_REG(emit->as, reg_dest, si->data.u_reg);
              }
              break;
  
          case STACK_IMM:
              *vtype = load_reg_stack_imm(emit, reg_dest, si, false);
              break;
      }
  }
  
  // does an efficient X=pop(); discard(); push(X)
  // needs a (non-temp) register in case the poped element was stored in the stack
  STATIC void emit_fold_stack_top(emit_t *emit, int reg_dest) {
      stack_info_t *si = &emit->stack_info[emit->stack_size - 2];
      si[0] = si[1];
      if (si->kind == STACK_VALUE) {
          // if folded element was on the stack we need to put it in a register
          emit_native_mov_reg_state(emit, reg_dest, emit->stack_start + emit->stack_size - 1);
          si->kind = STACK_REG;
          si->data.u_reg = reg_dest;
      }
      adjust_stack(emit, -1);
  }
  
  // If stacked value is in a register and the register is not r1 or r2, then
  // *reg_dest is set to that register.  Otherwise the value is put in *reg_dest.
  STATIC void emit_pre_pop_reg_flexible(emit_t *emit, vtype_kind_t *vtype, int *reg_dest, int not_r1, int not_r2) {
      emit->last_emit_was_return_value = false;
      stack_info_t *si = peek_stack(emit, 0);
      if (si->kind == STACK_REG && si->data.u_reg != not_r1 && si->data.u_reg != not_r2) {
          *vtype = si->vtype;
          *reg_dest = si->data.u_reg;
          need_reg_single(emit, *reg_dest, 1);
      } else {
          emit_access_stack(emit, 1, vtype, *reg_dest);
      }
      adjust_stack(emit, -1);
  }
  
  STATIC void emit_pre_pop_discard(emit_t *emit) {
      emit->last_emit_was_return_value = false;
      adjust_stack(emit, -1);
  }
  
  STATIC void emit_pre_pop_reg(emit_t *emit, vtype_kind_t *vtype, int reg_dest) {
      emit->last_emit_was_return_value = false;
      emit_access_stack(emit, 1, vtype, reg_dest);
      adjust_stack(emit, -1);
  }
  
  STATIC void emit_pre_pop_reg_reg(emit_t *emit, vtype_kind_t *vtypea, int rega, vtype_kind_t *vtypeb, int regb) {
      emit_pre_pop_reg(emit, vtypea, rega);
      emit_pre_pop_reg(emit, vtypeb, regb);
  }
  
  STATIC void emit_pre_pop_reg_reg_reg(emit_t *emit, vtype_kind_t *vtypea, int rega, vtype_kind_t *vtypeb, int regb, vtype_kind_t *vtypec, int regc) {
      emit_pre_pop_reg(emit, vtypea, rega);
      emit_pre_pop_reg(emit, vtypeb, regb);
      emit_pre_pop_reg(emit, vtypec, regc);
  }
  
  STATIC void emit_post(emit_t *emit) {
      (void)emit;
  }
  
  STATIC void emit_post_top_set_vtype(emit_t *emit, vtype_kind_t new_vtype) {
      stack_info_t *si = &emit->stack_info[emit->stack_size - 1];
      si->vtype = new_vtype;
  }
  
  STATIC void emit_post_push_reg(emit_t *emit, vtype_kind_t vtype, int reg) {
      ensure_extra_stack(emit, 1);
      stack_info_t *si = &emit->stack_info[emit->stack_size];
      si->vtype = vtype;
      si->kind = STACK_REG;
      si->data.u_reg = reg;
      adjust_stack(emit, 1);
  }
  
  STATIC void emit_post_push_imm(emit_t *emit, vtype_kind_t vtype, mp_int_t imm) {
      ensure_extra_stack(emit, 1);
      stack_info_t *si = &emit->stack_info[emit->stack_size];
      si->vtype = vtype;
      si->kind = STACK_IMM;
      si->data.u_imm = imm;
      adjust_stack(emit, 1);
  }
  
  STATIC void emit_post_push_reg_reg(emit_t *emit, vtype_kind_t vtypea, int rega, vtype_kind_t vtypeb, int regb) {
      emit_post_push_reg(emit, vtypea, rega);
      emit_post_push_reg(emit, vtypeb, regb);
  }
  
  STATIC void emit_post_push_reg_reg_reg(emit_t *emit, vtype_kind_t vtypea, int rega, vtype_kind_t vtypeb, int regb, vtype_kind_t vtypec, int regc) {
      emit_post_push_reg(emit, vtypea, rega);
      emit_post_push_reg(emit, vtypeb, regb);
      emit_post_push_reg(emit, vtypec, regc);
  }
  
  STATIC void emit_post_push_reg_reg_reg_reg(emit_t *emit, vtype_kind_t vtypea, int rega, vtype_kind_t vtypeb, int regb, vtype_kind_t vtypec, int regc, vtype_kind_t vtyped, int regd) {
      emit_post_push_reg(emit, vtypea, rega);
      emit_post_push_reg(emit, vtypeb, regb);
      emit_post_push_reg(emit, vtypec, regc);
      emit_post_push_reg(emit, vtyped, regd);
  }
  
  STATIC void emit_call(emit_t *emit, mp_fun_kind_t fun_kind) {
      need_reg_all(emit);
      ASM_CALL_IND(emit->as, fun_kind);
  }
  
  STATIC void emit_call_with_imm_arg(emit_t *emit, mp_fun_kind_t fun_kind, mp_int_t arg_val, int arg_reg) {
      need_reg_all(emit);
      ASM_MOV_REG_IMM(emit->as, arg_reg, arg_val);
      ASM_CALL_IND(emit->as, fun_kind);
  }
  
  STATIC void emit_call_with_2_imm_args(emit_t *emit, mp_fun_kind_t fun_kind, mp_int_t arg_val1, int arg_reg1, mp_int_t arg_val2, int arg_reg2) {
      need_reg_all(emit);
      ASM_MOV_REG_IMM(emit->as, arg_reg1, arg_val1);
      ASM_MOV_REG_IMM(emit->as, arg_reg2, arg_val2);
      ASM_CALL_IND(emit->as, fun_kind);
  }
  
  STATIC void emit_call_with_qstr_arg(emit_t *emit, mp_fun_kind_t fun_kind, qstr qst, int arg_reg) {
      need_reg_all(emit);
      emit_native_mov_reg_qstr(emit, arg_reg, qst);
      ASM_CALL_IND(emit->as, fun_kind);
  }
  
  // vtype of all n_pop objects is VTYPE_PYOBJ
  // Will convert any items that are not VTYPE_PYOBJ to this type and put them back on the stack.
  // If any conversions of non-immediate values are needed, then it uses REG_ARG_1, REG_ARG_2 and REG_RET.
  // Otherwise, it does not use any temporary registers (but may use reg_dest before loading it with stack pointer).
  STATIC void emit_get_stack_pointer_to_reg_for_pop(emit_t *emit, mp_uint_t reg_dest, mp_uint_t n_pop) {
      need_reg_all(emit);
  
      // First, store any immediate values to their respective place on the stack.
      for (mp_uint_t i = 0; i < n_pop; i++) {
          stack_info_t *si = &emit->stack_info[emit->stack_size - 1 - i];
          // must push any imm's to stack
          // must convert them to VTYPE_PYOBJ for viper code
          if (si->kind == STACK_IMM) {
              si->kind = STACK_VALUE;
              si->vtype = load_reg_stack_imm(emit, reg_dest, si, true);
              emit_native_mov_state_reg(emit, emit->stack_start + emit->stack_size - 1 - i, reg_dest);
          }
  
          // verify that this value is on the stack
          assert(si->kind == STACK_VALUE);
      }
  
      // Second, convert any non-VTYPE_PYOBJ to that type.
      for (mp_uint_t i = 0; i < n_pop; i++) {
          stack_info_t *si = &emit->stack_info[emit->stack_size - 1 - i];
          if (si->vtype != VTYPE_PYOBJ) {
              mp_uint_t local_num = emit->stack_start + emit->stack_size - 1 - i;
              emit_native_mov_reg_state(emit, REG_ARG_1, local_num);
              emit_call_with_imm_arg(emit, MP_F_CONVERT_NATIVE_TO_OBJ, si->vtype, REG_ARG_2); // arg2 = type
              emit_native_mov_state_reg(emit, local_num, REG_RET);
              si->vtype = VTYPE_PYOBJ;
              DEBUG_printf("  convert_native_to_obj(local_num=" UINT_FMT ")\n", local_num);
          }
      }
  
      // Adujust the stack for a pop of n_pop items, and load the stack pointer into reg_dest.
      adjust_stack(emit, -n_pop);
      emit_native_mov_reg_state_addr(emit, reg_dest, emit->stack_start + emit->stack_size);
  }
  
  // vtype of all n_push objects is VTYPE_PYOBJ
  STATIC void emit_get_stack_pointer_to_reg_for_push(emit_t *emit, mp_uint_t reg_dest, mp_uint_t n_push) {
      need_reg_all(emit);
      ensure_extra_stack(emit, n_push);
      for (mp_uint_t i = 0; i < n_push; i++) {
          emit->stack_info[emit->stack_size + i].kind = STACK_VALUE;
          emit->stack_info[emit->stack_size + i].vtype = VTYPE_PYOBJ;
      }
      emit_native_mov_reg_state_addr(emit, reg_dest, emit->stack_start + emit->stack_size);
      adjust_stack(emit, n_push);
  }
  
  STATIC void emit_native_push_exc_stack(emit_t *emit, uint label, bool is_finally) {
      if (emit->exc_stack_size + 1 > emit->exc_stack_alloc) {
          size_t new_alloc = emit->exc_stack_alloc + 4;
          emit->exc_stack = m_renew(exc_stack_entry_t, emit->exc_stack, emit->exc_stack_alloc, new_alloc);
          emit->exc_stack_alloc = new_alloc;
      }
  
      exc_stack_entry_t *e = &emit->exc_stack[emit->exc_stack_size++];
      e->label = label;
      e->is_finally = is_finally;
      e->unwind_label = UNWIND_LABEL_UNUSED;
      e->is_active = true;
  
      ASM_MOV_REG_PCREL(emit->as, REG_RET, label);
      ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_HANDLER_PC(emit), REG_RET);
  }
  
  STATIC void emit_native_leave_exc_stack(emit_t *emit, bool start_of_handler) {
      assert(emit->exc_stack_size > 0);
  
      // Get current exception handler and deactivate it
      exc_stack_entry_t *e = &emit->exc_stack[emit->exc_stack_size - 1];
      e->is_active = false;
  
      // Find next innermost active exception handler, to restore as current handler
      for (--e; e >= emit->exc_stack && !e->is_active; --e) {
      }
  
      // Update the PC of the new exception handler
      if (e < emit->exc_stack) {
          // No active handler, clear handler PC to zero
          if (start_of_handler) {
              // Optimisation: PC is already cleared by global exc handler
              return;
          }
          ASM_XOR_REG_REG(emit->as, REG_RET, REG_RET);
      } else {
          // Found new active handler, get its PC
          ASM_MOV_REG_PCREL(emit->as, REG_RET, e->label);
      }
      ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_HANDLER_PC(emit), REG_RET);
  }
  
  STATIC exc_stack_entry_t *emit_native_pop_exc_stack(emit_t *emit) {
      assert(emit->exc_stack_size > 0);
      exc_stack_entry_t *e = &emit->exc_stack[--emit->exc_stack_size];
      assert(e->is_active == false);
      return e;
  }
  
  STATIC void emit_load_reg_with_object(emit_t *emit, int reg, mp_obj_t obj) {
      emit->scope->scope_flags |= MP_SCOPE_FLAG_HASCONSTS;
      size_t table_off = mp_emit_common_use_const_obj(emit->emit_common, obj);
      emit_native_mov_reg_state(emit, REG_TEMP0, LOCAL_IDX_FUN_OBJ(emit));
      ASM_LOAD_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_TEMP0, OFFSETOF_OBJ_FUN_BC_CONTEXT);
      ASM_LOAD_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_TEMP0, OFFSETOF_MODULE_CONTEXT_OBJ_TABLE);
      ASM_LOAD_REG_REG_OFFSET(emit->as, reg, REG_TEMP0, table_off);
  }
  
  STATIC void emit_load_reg_with_child(emit_t *emit, int reg, mp_raw_code_t *rc) {
      size_t table_off = mp_emit_common_alloc_const_child(emit->emit_common, rc);
      emit_native_mov_reg_state(emit, REG_TEMP0, LOCAL_IDX_FUN_OBJ(emit));
      ASM_LOAD_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_TEMP0, OFFSETOF_OBJ_FUN_BC_CHILD_TABLE);
      ASM_LOAD_REG_REG_OFFSET(emit->as, reg, REG_TEMP0, table_off);
  }
  
  STATIC void emit_native_label_assign(emit_t *emit, mp_uint_t l) {
      DEBUG_printf("label_assign(" UINT_FMT ")\n", l);
  
      bool is_finally = false;
      if (emit->exc_stack_size > 0) {
          exc_stack_entry_t *e = &emit->exc_stack[emit->exc_stack_size - 1];
          is_finally = e->is_finally && e->label == l;
      }
  
      if (is_finally) {
          // Label is at start of finally handler: store TOS into exception slot
          vtype_kind_t vtype;
          emit_pre_pop_reg(emit, &vtype, REG_TEMP0);
          ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_TEMP0);
      }
  
      emit_native_pre(emit);
      // need to commit stack because we can jump here from elsewhere
      need_stack_settled(emit);
      mp_asm_base_label_assign(&emit->as->base, l);
      emit_post(emit);
  
      if (is_finally) {
          // Label is at start of finally handler: pop exception stack
          emit_native_leave_exc_stack(emit, false);
      }
  }
  
  STATIC void emit_native_global_exc_entry(emit_t *emit) {
      // Note: 4 labels are reserved for this function, starting at *emit->label_slot
  
      emit->exit_label = *emit->label_slot;
  
      if (NEED_GLOBAL_EXC_HANDLER(emit)) {
          mp_uint_t nlr_label = *emit->label_slot + 1;
          mp_uint_t start_label = *emit->label_slot + 2;
          mp_uint_t global_except_label = *emit->label_slot + 3;
  
          if (!(emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR)) {
              // Set new globals
              emit_native_mov_reg_state(emit, REG_ARG_1, LOCAL_IDX_FUN_OBJ(emit));
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_ARG_1, REG_ARG_1, OFFSETOF_OBJ_FUN_BC_CONTEXT);
              ASM_LOAD_REG_REG_OFFSET(emit->as, REG_ARG_1, REG_ARG_1, OFFSETOF_MODULE_CONTEXT_GLOBALS);
              emit_call(emit, MP_F_NATIVE_SWAP_GLOBALS);
  
              // Save old globals (or NULL if globals didn't change)
              emit_native_mov_state_reg(emit, LOCAL_IDX_OLD_GLOBALS(emit), REG_RET);
          }
  
          if (emit->scope->exc_stack_size == 0) {
              if (!(emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR)) {
                  // Optimisation: if globals didn't change don't push the nlr context
                  ASM_JUMP_IF_REG_ZERO(emit->as, REG_RET, start_label, false);
              }
  
              // Wrap everything in an nlr context
              ASM_MOV_REG_LOCAL_ADDR(emit->as, REG_ARG_1, 0);
              emit_call(emit, MP_F_NLR_PUSH);
              #if N_NLR_SETJMP
              ASM_MOV_REG_LOCAL_ADDR(emit->as, REG_ARG_1, 2);
              emit_call(emit, MP_F_SETJMP);
              #endif
              ASM_JUMP_IF_REG_ZERO(emit->as, REG_RET, start_label, true);
          } else {
              // Clear the unwind state
              ASM_XOR_REG_REG(emit->as, REG_TEMP0, REG_TEMP0);
              ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_HANDLER_UNWIND(emit), REG_TEMP0);
  
              // Put PC of start code block into REG_LOCAL_1
              ASM_MOV_REG_PCREL(emit->as, REG_LOCAL_1, start_label);
  
              // Wrap everything in an nlr context
              emit_native_label_assign(emit, nlr_label);
              ASM_MOV_REG_LOCAL_ADDR(emit->as, REG_ARG_1, 0);
              emit_call(emit, MP_F_NLR_PUSH);
              #if N_NLR_SETJMP
              ASM_MOV_REG_LOCAL_ADDR(emit->as, REG_ARG_1, 2);
              emit_call(emit, MP_F_SETJMP);
              #endif
              ASM_JUMP_IF_REG_NONZERO(emit->as, REG_RET, global_except_label, true);
  
              // Clear PC of current code block, and jump there to resume execution
              ASM_XOR_REG_REG(emit->as, REG_TEMP0, REG_TEMP0);
              ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_HANDLER_PC(emit), REG_TEMP0);
              ASM_JUMP_REG(emit->as, REG_LOCAL_1);
  
              // Global exception handler: check for valid exception handler
              emit_native_label_assign(emit, global_except_label);
              ASM_MOV_REG_LOCAL(emit->as, REG_LOCAL_1, LOCAL_IDX_EXC_HANDLER_PC(emit));
              ASM_JUMP_IF_REG_NONZERO(emit->as, REG_LOCAL_1, nlr_label, false);
          }
  
          if (!(emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR)) {
              // Restore old globals
              emit_native_mov_reg_state(emit, REG_ARG_1, LOCAL_IDX_OLD_GLOBALS(emit));
              emit_call(emit, MP_F_NATIVE_SWAP_GLOBALS);
          }
  
          if (emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR) {
              // Store return value in state[0]
              ASM_MOV_REG_LOCAL(emit->as, REG_TEMP0, LOCAL_IDX_EXC_VAL(emit));
              ASM_STORE_REG_REG_OFFSET(emit->as, REG_TEMP0, REG_GENERATOR_STATE, OFFSETOF_CODE_STATE_STATE);
  
              // Load return kind
              ASM_MOV_REG_IMM(emit->as, REG_PARENT_RET, MP_VM_RETURN_EXCEPTION);
  
              ASM_EXIT(emit->as);
          } else {
              // Re-raise exception out to caller
              ASM_MOV_REG_LOCAL(emit->as, REG_ARG_1, LOCAL_IDX_EXC_VAL(emit));
              emit_call(emit, MP_F_NATIVE_RAISE);
          }
  
          // Label for start of function
          emit_native_label_assign(emit, start_label);
  
          if (emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR) {
              emit_native_mov_reg_state(emit, REG_TEMP0, LOCAL_IDX_GEN_PC(emit));
              ASM_JUMP_REG(emit->as, REG_TEMP0);
              emit->start_offset = mp_asm_base_get_code_pos(&emit->as->base);
  
              // This is the first entry of the generator
  
              // Check LOCAL_IDX_EXC_VAL for any injected value
              ASM_MOV_REG_LOCAL(emit->as, REG_ARG_1, LOCAL_IDX_EXC_VAL(emit));
              emit_call(emit, MP_F_NATIVE_RAISE);
          }
      }
  }
  
  STATIC void emit_native_global_exc_exit(emit_t *emit) {
      // Label for end of function
      emit_native_label_assign(emit, emit->exit_label);
  
      if (NEED_GLOBAL_EXC_HANDLER(emit)) {
          // Get old globals
          if (!(emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR)) {
              emit_native_mov_reg_state(emit, REG_ARG_1, LOCAL_IDX_OLD_GLOBALS(emit));
  
              if (emit->scope->exc_stack_size == 0) {
                  // Optimisation: if globals didn't change then don't restore them and don't do nlr_pop
                  ASM_JUMP_IF_REG_ZERO(emit->as, REG_ARG_1, emit->exit_label + 1, false);
              }
  
              // Restore old globals
              emit_call(emit, MP_F_NATIVE_SWAP_GLOBALS);
          }
  
          // Pop the nlr context
          emit_call(emit, MP_F_NLR_POP);
  
          if (!(emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR)) {
              if (emit->scope->exc_stack_size == 0) {
                  // Destination label for above optimisation
                  emit_native_label_assign(emit, emit->exit_label + 1);
              }
          }
  
          // Load return value
          ASM_MOV_REG_LOCAL(emit->as, REG_PARENT_RET, LOCAL_IDX_RET_VAL(emit));
      }
  
      ASM_EXIT(emit->as);
  }
  
  STATIC void emit_native_import_name(emit_t *emit, qstr qst) {
      DEBUG_printf("import_name %s\n", qstr_str(qst));
  
      // get arguments from stack: arg2 = fromlist, arg3 = level
      // If using viper types these arguments must be converted to proper objects, and
      // to accomplish this viper types are turned off for the emit_pre_pop_reg_reg call.
      bool orig_do_viper_types = emit->do_viper_types;
      emit->do_viper_types = false;
      vtype_kind_t vtype_fromlist;
      vtype_kind_t vtype_level;
      emit_pre_pop_reg_reg(emit, &vtype_fromlist, REG_ARG_2, &vtype_level, REG_ARG_3);
      assert(vtype_fromlist == VTYPE_PYOBJ);
      assert(vtype_level == VTYPE_PYOBJ);
      emit->do_viper_types = orig_do_viper_types;
  
      emit_call_with_qstr_arg(emit, MP_F_IMPORT_NAME, qst, REG_ARG_1); // arg1 = import name
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_import_from(emit_t *emit, qstr qst) {
      DEBUG_printf("import_from %s\n", qstr_str(qst));
      emit_native_pre(emit);
      vtype_kind_t vtype_module;
      emit_access_stack(emit, 1, &vtype_module, REG_ARG_1); // arg1 = module
      assert(vtype_module == VTYPE_PYOBJ);
      emit_call_with_qstr_arg(emit, MP_F_IMPORT_FROM, qst, REG_ARG_2); // arg2 = import name
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_import_star(emit_t *emit) {
      DEBUG_printf("import_star\n");
      vtype_kind_t vtype_module;
      emit_pre_pop_reg(emit, &vtype_module, REG_ARG_1); // arg1 = module
      assert(vtype_module == VTYPE_PYOBJ);
      emit_call(emit, MP_F_IMPORT_ALL);
      emit_post(emit);
  }
  
  STATIC void emit_native_import(emit_t *emit, qstr qst, int kind) {
      if (kind == MP_EMIT_IMPORT_NAME) {
          emit_native_import_name(emit, qst);
      } else if (kind == MP_EMIT_IMPORT_FROM) {
          emit_native_import_from(emit, qst);
      } else {
          emit_native_import_star(emit);
      }
  }
  
  STATIC void emit_native_load_const_tok(emit_t *emit, mp_token_kind_t tok) {
      DEBUG_printf("load_const_tok(tok=%u)\n", tok);
      if (tok == MP_TOKEN_ELLIPSIS) {
          emit_native_load_const_obj(emit, MP_OBJ_FROM_PTR(&mp_const_ellipsis_obj));
      } else {
          emit_native_pre(emit);
          if (tok == MP_TOKEN_KW_NONE) {
              emit_post_push_imm(emit, VTYPE_PTR_NONE, 0);
          } else {
              emit_post_push_imm(emit, VTYPE_BOOL, tok == MP_TOKEN_KW_FALSE ? 0 : 1);
          }
      }
  }
  
  STATIC void emit_native_load_const_small_int(emit_t *emit, mp_int_t arg) {
      DEBUG_printf("load_const_small_int(int=" INT_FMT ")\n", arg);
      emit_native_pre(emit);
      emit_post_push_imm(emit, VTYPE_INT, arg);
  }
  
  STATIC void emit_native_load_const_str(emit_t *emit, qstr qst) {
      emit_native_pre(emit);
      // TODO: Eventually we want to be able to work with raw pointers in viper to
      // do native array access.  For now we just load them as any other object.
      /*
      if (emit->do_viper_types) {
          // load a pointer to the asciiz string?
          emit_post_push_imm(emit, VTYPE_PTR, (mp_uint_t)qstr_str(qst));
      } else
      */
      {
          need_reg_single(emit, REG_TEMP0, 0);
          emit_native_mov_reg_qstr_obj(emit, REG_TEMP0, qst);
          emit_post_push_reg(emit, VTYPE_PYOBJ, REG_TEMP0);
      }
  }
  
  STATIC void emit_native_load_const_obj(emit_t *emit, mp_obj_t obj) {
      emit_native_pre(emit);
      need_reg_single(emit, REG_RET, 0);
      emit_load_reg_with_object(emit, REG_RET, obj);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_load_null(emit_t *emit) {
      emit_native_pre(emit);
      emit_post_push_imm(emit, VTYPE_PYOBJ, 0);
  }
  
  STATIC void emit_native_load_fast(emit_t *emit, qstr qst, mp_uint_t local_num) {
      DEBUG_printf("load_fast(%s, " UINT_FMT ")\n", qstr_str(qst), local_num);
      vtype_kind_t vtype = emit->local_vtype[local_num];
      if (vtype == VTYPE_UNBOUND) {
          EMIT_NATIVE_VIPER_TYPE_ERROR(emit, MP_ERROR_TEXT("local '%q' used before type known"), qst);
      }
      emit_native_pre(emit);
      if (local_num < MAX_REGS_FOR_LOCAL_VARS && CAN_USE_REGS_FOR_LOCALS(emit)) {
          emit_post_push_reg(emit, vtype, reg_local_table[local_num]);
      } else {
          need_reg_single(emit, REG_TEMP0, 0);
          emit_native_mov_reg_state(emit, REG_TEMP0, LOCAL_IDX_LOCAL_VAR(emit, local_num));
          emit_post_push_reg(emit, vtype, REG_TEMP0);
      }
  }
  
  STATIC void emit_native_load_deref(emit_t *emit, qstr qst, mp_uint_t local_num) {
      DEBUG_printf("load_deref(%s, " UINT_FMT ")\n", qstr_str(qst), local_num);
      need_reg_single(emit, REG_RET, 0);
      emit_native_load_fast(emit, qst, local_num);
      vtype_kind_t vtype;
      int reg_base = REG_RET;
      emit_pre_pop_reg_flexible(emit, &vtype, &reg_base, -1, -1);
      ASM_LOAD_REG_REG_OFFSET(emit->as, REG_RET, reg_base, 1);
      // closed over vars are always Python objects
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_load_local(emit_t *emit, qstr qst, mp_uint_t local_num, int kind) {
      if (kind == MP_EMIT_IDOP_LOCAL_FAST) {
          emit_native_load_fast(emit, qst, local_num);
      } else {
          emit_native_load_deref(emit, qst, local_num);
      }
  }
  
  STATIC void emit_native_load_global(emit_t *emit, qstr qst, int kind) {
      MP_STATIC_ASSERT(MP_F_LOAD_NAME + MP_EMIT_IDOP_GLOBAL_NAME == MP_F_LOAD_NAME);
      MP_STATIC_ASSERT(MP_F_LOAD_NAME + MP_EMIT_IDOP_GLOBAL_GLOBAL == MP_F_LOAD_GLOBAL);
      emit_native_pre(emit);
      if (kind == MP_EMIT_IDOP_GLOBAL_NAME) {
          DEBUG_printf("load_name(%s)\n", qstr_str(qst));
      } else {
          DEBUG_printf("load_global(%s)\n", qstr_str(qst));
          if (emit->do_viper_types) {
              // check for builtin casting operators
              int native_type = mp_native_type_from_qstr(qst);
              if (native_type >= MP_NATIVE_TYPE_BOOL) {
                  emit_post_push_imm(emit, VTYPE_BUILTIN_CAST, native_type);
                  return;
              }
          }
      }
      emit_call_with_qstr_arg(emit, MP_F_LOAD_NAME + kind, qst, REG_ARG_1);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_load_attr(emit_t *emit, qstr qst) {
      // depends on type of subject:
      //  - integer, function, pointer to integers: error
      //  - pointer to structure: get member, quite easy
      //  - Python object: call mp_load_attr, and needs to be typed to convert result
      vtype_kind_t vtype_base;
      emit_pre_pop_reg(emit, &vtype_base, REG_ARG_1); // arg1 = base
      assert(vtype_base == VTYPE_PYOBJ);
      emit_call_with_qstr_arg(emit, MP_F_LOAD_ATTR, qst, REG_ARG_2); // arg2 = attribute name
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_load_method(emit_t *emit, qstr qst, bool is_super) {
      if (is_super) {
          emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_2, 3); // arg2 = dest ptr
          emit_get_stack_pointer_to_reg_for_push(emit, REG_ARG_2, 2); // arg2 = dest ptr
          emit_call_with_qstr_arg(emit, MP_F_LOAD_SUPER_METHOD, qst, REG_ARG_1); // arg1 = method name
      } else {
          vtype_kind_t vtype_base;
          emit_pre_pop_reg(emit, &vtype_base, REG_ARG_1); // arg1 = base
          assert(vtype_base == VTYPE_PYOBJ);
          emit_get_stack_pointer_to_reg_for_push(emit, REG_ARG_3, 2); // arg3 = dest ptr
          emit_call_with_qstr_arg(emit, MP_F_LOAD_METHOD, qst, REG_ARG_2); // arg2 = method name
      }
  }
  
  STATIC void emit_native_load_build_class(emit_t *emit) {
      emit_native_pre(emit);
      emit_call(emit, MP_F_LOAD_BUILD_CLASS);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_load_subscr(emit_t *emit) {
      DEBUG_printf("load_subscr\n");
      // need to compile: base[index]
  
      // pop: index, base
      // optimise case where index is an immediate
      vtype_kind_t vtype_base = peek_vtype(emit, 1);
  
      if (vtype_base == VTYPE_PYOBJ) {
          // standard Python subscr
          // TODO factor this implicit cast code with other uses of it
          vtype_kind_t vtype_index = peek_vtype(emit, 0);
          if (vtype_index == VTYPE_PYOBJ) {
              emit_pre_pop_reg(emit, &vtype_index, REG_ARG_2);
          } else {
              emit_pre_pop_reg(emit, &vtype_index, REG_ARG_1);
              emit_call_with_imm_arg(emit, MP_F_CONVERT_NATIVE_TO_OBJ, vtype_index, REG_ARG_2); // arg2 = type
              ASM_MOV_REG_REG(emit->as, REG_ARG_2, REG_RET);
          }
          emit_pre_pop_reg(emit, &vtype_base, REG_ARG_1);
          emit_call_with_imm_arg(emit, MP_F_OBJ_SUBSCR, (mp_uint_t)MP_OBJ_SENTINEL, REG_ARG_3);
          emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
      } else {
          // viper load
          // TODO The different machine architectures have very different
          // capabilities and requirements for loads, so probably best to
          // write a completely separate load-optimiser for each one.
          stack_info_t *top = peek_stack(emit, 0);
          if (top->vtype == VTYPE_INT && top->kind == STACK_IMM) {
              // index is an immediate
              mp_int_t index_value = top->data.u_imm;
              emit_pre_pop_discard(emit); // discard index
              int reg_base = REG_ARG_1;
              int reg_index = REG_ARG_2;
              emit_pre_pop_reg_flexible(emit, &vtype_base, &reg_base, reg_index, reg_index);
              need_reg_single(emit, REG_RET, 0);
              switch (vtype_base) {
                  case VTYPE_PTR8: {
                      // pointer to 8-bit memory
                      // TODO optimise to use thumb ldrb r1, [r2, r3]
                      if (index_value != 0) {
                          // index is non-zero
                          #if N_THUMB
                          if (index_value > 0 && index_value < 32) {
                              asm_thumb_ldrb_rlo_rlo_i5(emit->as, REG_RET, reg_base, index_value);
                              break;
                          }
                          #endif
                          ASM_MOV_REG_IMM(emit->as, reg_index, index_value);
                          ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add index to base
                          reg_base = reg_index;
                      }
                      ASM_LOAD8_REG_REG(emit->as, REG_RET, reg_base); // load from (base+index)
                      break;
                  }
                  case VTYPE_PTR16: {
                      // pointer to 16-bit memory
                      if (index_value != 0) {
                          // index is a non-zero immediate
                          #if N_THUMB
                          if (index_value > 0 && index_value < 32) {
                              asm_thumb_ldrh_rlo_rlo_i5(emit->as, REG_RET, reg_base, index_value);
                              break;
                          }
                          #endif
                          ASM_MOV_REG_IMM(emit->as, reg_index, index_value << 1);
                          ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add 2*index to base
                          reg_base = reg_index;
                      }
                      ASM_LOAD16_REG_REG(emit->as, REG_RET, reg_base); // load from (base+2*index)
                      break;
                  }
                  case VTYPE_PTR32: {
                      // pointer to 32-bit memory
                      if (index_value != 0) {
                          // index is a non-zero immediate
                          #if N_THUMB
                          if (index_value > 0 && index_value < 32) {
                              asm_thumb_ldr_rlo_rlo_i5(emit->as, REG_RET, reg_base, index_value);
                              break;
                          }
                          #endif
                          ASM_MOV_REG_IMM(emit->as, reg_index, index_value << 2);
                          ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add 4*index to base
                          reg_base = reg_index;
                      }
                      ASM_LOAD32_REG_REG(emit->as, REG_RET, reg_base); // load from (base+4*index)
                      break;
                  }
                  default:
                      EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                          MP_ERROR_TEXT("can't load from '%q'"), vtype_to_qstr(vtype_base));
              }
          } else {
              // index is not an immediate
              vtype_kind_t vtype_index;
              int reg_index = REG_ARG_2;
              emit_pre_pop_reg_flexible(emit, &vtype_index, &reg_index, REG_ARG_1, REG_ARG_1);
              emit_pre_pop_reg(emit, &vtype_base, REG_ARG_1);
              need_reg_single(emit, REG_RET, 0);
              if (vtype_index != VTYPE_INT && vtype_index != VTYPE_UINT) {
                  EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                      MP_ERROR_TEXT("can't load with '%q' index"), vtype_to_qstr(vtype_index));
              }
              switch (vtype_base) {
                  case VTYPE_PTR8: {
                      // pointer to 8-bit memory
                      // TODO optimise to use thumb ldrb r1, [r2, r3]
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_LOAD8_REG_REG(emit->as, REG_RET, REG_ARG_1); // store value to (base+index)
                      break;
                  }
                  case VTYPE_PTR16: {
                      // pointer to 16-bit memory
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_LOAD16_REG_REG(emit->as, REG_RET, REG_ARG_1); // load from (base+2*index)
                      break;
                  }
                  case VTYPE_PTR32: {
                      // pointer to word-size memory
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_LOAD32_REG_REG(emit->as, REG_RET, REG_ARG_1); // load from (base+4*index)
                      break;
                  }
                  default:
                      EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                          MP_ERROR_TEXT("can't load from '%q'"), vtype_to_qstr(vtype_base));
              }
          }
          emit_post_push_reg(emit, VTYPE_INT, REG_RET);
      }
  }
  
  STATIC void emit_native_store_fast(emit_t *emit, qstr qst, mp_uint_t local_num) {
      vtype_kind_t vtype;
      if (local_num < MAX_REGS_FOR_LOCAL_VARS && CAN_USE_REGS_FOR_LOCALS(emit)) {
          emit_pre_pop_reg(emit, &vtype, reg_local_table[local_num]);
      } else {
          emit_pre_pop_reg(emit, &vtype, REG_TEMP0);
          emit_native_mov_state_reg(emit, LOCAL_IDX_LOCAL_VAR(emit, local_num), REG_TEMP0);
      }
      emit_post(emit);
  
      // check types
      if (emit->local_vtype[local_num] == VTYPE_UNBOUND) {
          // first time this local is assigned, so give it a type of the object stored in it
          emit->local_vtype[local_num] = vtype;
      } else if (emit->local_vtype[local_num] != vtype) {
          // type of local is not the same as object stored in it
          EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
              MP_ERROR_TEXT("local '%q' has type '%q' but source is '%q'"),
              qst, vtype_to_qstr(emit->local_vtype[local_num]), vtype_to_qstr(vtype));
      }
  }
  
  STATIC void emit_native_store_deref(emit_t *emit, qstr qst, mp_uint_t local_num) {
      DEBUG_printf("store_deref(%s, " UINT_FMT ")\n", qstr_str(qst), local_num);
      need_reg_single(emit, REG_TEMP0, 0);
      need_reg_single(emit, REG_TEMP1, 0);
      emit_native_load_fast(emit, qst, local_num);
      vtype_kind_t vtype;
      int reg_base = REG_TEMP0;
      emit_pre_pop_reg_flexible(emit, &vtype, &reg_base, -1, -1);
      int reg_src = REG_TEMP1;
      emit_pre_pop_reg_flexible(emit, &vtype, &reg_src, reg_base, reg_base);
      ASM_STORE_REG_REG_OFFSET(emit->as, reg_src, reg_base, 1);
      emit_post(emit);
  }
  
  STATIC void emit_native_store_local(emit_t *emit, qstr qst, mp_uint_t local_num, int kind) {
      if (kind == MP_EMIT_IDOP_LOCAL_FAST) {
          emit_native_store_fast(emit, qst, local_num);
      } else {
          emit_native_store_deref(emit, qst, local_num);
      }
  }
  
  STATIC void emit_native_store_global(emit_t *emit, qstr qst, int kind) {
      MP_STATIC_ASSERT(MP_F_STORE_NAME + MP_EMIT_IDOP_GLOBAL_NAME == MP_F_STORE_NAME);
      MP_STATIC_ASSERT(MP_F_STORE_NAME + MP_EMIT_IDOP_GLOBAL_GLOBAL == MP_F_STORE_GLOBAL);
      if (kind == MP_EMIT_IDOP_GLOBAL_NAME) {
          // mp_store_name, but needs conversion of object (maybe have mp_viper_store_name(obj, type))
          vtype_kind_t vtype;
          emit_pre_pop_reg(emit, &vtype, REG_ARG_2);
          assert(vtype == VTYPE_PYOBJ);
      } else {
          vtype_kind_t vtype = peek_vtype(emit, 0);
          if (vtype == VTYPE_PYOBJ) {
              emit_pre_pop_reg(emit, &vtype, REG_ARG_2);
          } else {
              emit_pre_pop_reg(emit, &vtype, REG_ARG_1);
              emit_call_with_imm_arg(emit, MP_F_CONVERT_NATIVE_TO_OBJ, vtype, REG_ARG_2); // arg2 = type
              ASM_MOV_REG_REG(emit->as, REG_ARG_2, REG_RET);
          }
      }
      emit_call_with_qstr_arg(emit, MP_F_STORE_NAME + kind, qst, REG_ARG_1); // arg1 = name
      emit_post(emit);
  }
  
  STATIC void emit_native_store_attr(emit_t *emit, qstr qst) {
      vtype_kind_t vtype_base, vtype_val;
      emit_pre_pop_reg_reg(emit, &vtype_base, REG_ARG_1, &vtype_val, REG_ARG_3); // arg1 = base, arg3 = value
      assert(vtype_base == VTYPE_PYOBJ);
      assert(vtype_val == VTYPE_PYOBJ);
      emit_call_with_qstr_arg(emit, MP_F_STORE_ATTR, qst, REG_ARG_2); // arg2 = attribute name
      emit_post(emit);
  }
  
  STATIC void emit_native_store_subscr(emit_t *emit) {
      DEBUG_printf("store_subscr\n");
      // need to compile: base[index] = value
  
      // pop: index, base, value
      // optimise case where index is an immediate
      vtype_kind_t vtype_base = peek_vtype(emit, 1);
  
      if (vtype_base == VTYPE_PYOBJ) {
          // standard Python subscr
          vtype_kind_t vtype_index = peek_vtype(emit, 0);
          vtype_kind_t vtype_value = peek_vtype(emit, 2);
          if (vtype_index != VTYPE_PYOBJ || vtype_value != VTYPE_PYOBJ) {
              // need to implicitly convert non-objects to objects
              // TODO do this properly
              emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_1, 3);
              adjust_stack(emit, 3);
          }
          emit_pre_pop_reg_reg_reg(emit, &vtype_index, REG_ARG_2, &vtype_base, REG_ARG_1, &vtype_value, REG_ARG_3);
          emit_call(emit, MP_F_OBJ_SUBSCR);
      } else {
          // viper store
          // TODO The different machine architectures have very different
          // capabilities and requirements for stores, so probably best to
          // write a completely separate store-optimiser for each one.
          stack_info_t *top = peek_stack(emit, 0);
          if (top->vtype == VTYPE_INT && top->kind == STACK_IMM) {
              // index is an immediate
              mp_int_t index_value = top->data.u_imm;
              emit_pre_pop_discard(emit); // discard index
              vtype_kind_t vtype_value;
              int reg_base = REG_ARG_1;
              int reg_index = REG_ARG_2;
              int reg_value = REG_ARG_3;
              emit_pre_pop_reg_flexible(emit, &vtype_base, &reg_base, reg_index, reg_value);
              #if N_X64 || N_X86
              // special case: x86 needs byte stores to be from lower 4 regs (REG_ARG_3 is EDX)
              emit_pre_pop_reg(emit, &vtype_value, reg_value);
              #else
              emit_pre_pop_reg_flexible(emit, &vtype_value, &reg_value, reg_base, reg_index);
              #endif
              if (vtype_value != VTYPE_BOOL && vtype_value != VTYPE_INT && vtype_value != VTYPE_UINT) {
                  EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                      MP_ERROR_TEXT("can't store '%q'"), vtype_to_qstr(vtype_value));
              }
              switch (vtype_base) {
                  case VTYPE_PTR8: {
                      // pointer to 8-bit memory
                      // TODO optimise to use thumb strb r1, [r2, r3]
                      if (index_value != 0) {
                          // index is non-zero
                          #if N_THUMB
                          if (index_value > 0 && index_value < 32) {
                              asm_thumb_strb_rlo_rlo_i5(emit->as, reg_value, reg_base, index_value);
                              break;
                          }
                          #endif
                          ASM_MOV_REG_IMM(emit->as, reg_index, index_value);
                          #if N_ARM
                          asm_arm_strb_reg_reg_reg(emit->as, reg_value, reg_base, reg_index);
                          return;
                          #endif
                          ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add index to base
                          reg_base = reg_index;
                      }
                      ASM_STORE8_REG_REG(emit->as, reg_value, reg_base); // store value to (base+index)
                      break;
                  }
                  case VTYPE_PTR16: {
                      // pointer to 16-bit memory
                      if (index_value != 0) {
                          // index is a non-zero immediate
                          #if N_THUMB
                          if (index_value > 0 && index_value < 32) {
                              asm_thumb_strh_rlo_rlo_i5(emit->as, reg_value, reg_base, index_value);
                              break;
                          }
                          #endif
                          ASM_MOV_REG_IMM(emit->as, reg_index, index_value << 1);
                          ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add 2*index to base
                          reg_base = reg_index;
                      }
                      ASM_STORE16_REG_REG(emit->as, reg_value, reg_base); // store value to (base+2*index)
                      break;
                  }
                  case VTYPE_PTR32: {
                      // pointer to 32-bit memory
                      if (index_value != 0) {
                          // index is a non-zero immediate
                          #if N_THUMB
                          if (index_value > 0 && index_value < 32) {
                              asm_thumb_str_rlo_rlo_i5(emit->as, reg_value, reg_base, index_value);
                              break;
                          }
                          #endif
                          #if N_ARM
                          ASM_MOV_REG_IMM(emit->as, reg_index, index_value);
                          asm_arm_str_reg_reg_reg(emit->as, reg_value, reg_base, reg_index);
                          return;
                          #endif
                          ASM_MOV_REG_IMM(emit->as, reg_index, index_value << 2);
                          ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add 4*index to base
                          reg_base = reg_index;
                      }
                      ASM_STORE32_REG_REG(emit->as, reg_value, reg_base); // store value to (base+4*index)
                      break;
                  }
                  default:
                      EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                          MP_ERROR_TEXT("can't store to '%q'"), vtype_to_qstr(vtype_base));
              }
          } else {
              // index is not an immediate
              vtype_kind_t vtype_index, vtype_value;
              int reg_index = REG_ARG_2;
              int reg_value = REG_ARG_3;
              emit_pre_pop_reg_flexible(emit, &vtype_index, &reg_index, REG_ARG_1, reg_value);
              emit_pre_pop_reg(emit, &vtype_base, REG_ARG_1);
              if (vtype_index != VTYPE_INT && vtype_index != VTYPE_UINT) {
                  EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                      MP_ERROR_TEXT("can't store with '%q' index"), vtype_to_qstr(vtype_index));
              }
              #if N_X64 || N_X86
              // special case: x86 needs byte stores to be from lower 4 regs (REG_ARG_3 is EDX)
              emit_pre_pop_reg(emit, &vtype_value, reg_value);
              #else
              emit_pre_pop_reg_flexible(emit, &vtype_value, &reg_value, REG_ARG_1, reg_index);
              #endif
              if (vtype_value != VTYPE_BOOL && vtype_value != VTYPE_INT && vtype_value != VTYPE_UINT) {
                  EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                      MP_ERROR_TEXT("can't store '%q'"), vtype_to_qstr(vtype_value));
              }
              switch (vtype_base) {
                  case VTYPE_PTR8: {
                      // pointer to 8-bit memory
                      // TODO optimise to use thumb strb r1, [r2, r3]
                      #if N_ARM
                      asm_arm_strb_reg_reg_reg(emit->as, reg_value, REG_ARG_1, reg_index);
                      break;
                      #endif
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_STORE8_REG_REG(emit->as, reg_value, REG_ARG_1); // store value to (base+index)
                      break;
                  }
                  case VTYPE_PTR16: {
                      // pointer to 16-bit memory
                      #if N_ARM
                      asm_arm_strh_reg_reg_reg(emit->as, reg_value, REG_ARG_1, reg_index);
                      break;
                      #endif
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_STORE16_REG_REG(emit->as, reg_value, REG_ARG_1); // store value to (base+2*index)
                      break;
                  }
                  case VTYPE_PTR32: {
                      // pointer to 32-bit memory
                      #if N_ARM
                      asm_arm_str_reg_reg_reg(emit->as, reg_value, REG_ARG_1, reg_index);
                      break;
                      #endif
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                      ASM_STORE32_REG_REG(emit->as, reg_value, REG_ARG_1); // store value to (base+4*index)
                      break;
                  }
                  default:
                      EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                          MP_ERROR_TEXT("can't store to '%q'"), vtype_to_qstr(vtype_base));
              }
          }
  
      }
  }
  
  STATIC void emit_native_delete_local(emit_t *emit, qstr qst, mp_uint_t local_num, int kind) {
      if (kind == MP_EMIT_IDOP_LOCAL_FAST) {
          // TODO: This is not compliant implementation. We could use MP_OBJ_SENTINEL
          // to mark deleted vars but then every var would need to be checked on
          // each access. Very inefficient, so just set value to None to enable GC.
          emit_native_load_const_tok(emit, MP_TOKEN_KW_NONE);
          emit_native_store_fast(emit, qst, local_num);
      } else {
          // TODO implement me!
      }
  }
  
  STATIC void emit_native_delete_global(emit_t *emit, qstr qst, int kind) {
      MP_STATIC_ASSERT(MP_F_DELETE_NAME + MP_EMIT_IDOP_GLOBAL_NAME == MP_F_DELETE_NAME);
      MP_STATIC_ASSERT(MP_F_DELETE_NAME + MP_EMIT_IDOP_GLOBAL_GLOBAL == MP_F_DELETE_GLOBAL);
      emit_native_pre(emit);
      emit_call_with_qstr_arg(emit, MP_F_DELETE_NAME + kind, qst, REG_ARG_1);
      emit_post(emit);
  }
  
  STATIC void emit_native_delete_attr(emit_t *emit, qstr qst) {
      vtype_kind_t vtype_base;
      emit_pre_pop_reg(emit, &vtype_base, REG_ARG_1); // arg1 = base
      assert(vtype_base == VTYPE_PYOBJ);
      ASM_XOR_REG_REG(emit->as, REG_ARG_3, REG_ARG_3); // arg3 = value (null for delete)
      emit_call_with_qstr_arg(emit, MP_F_STORE_ATTR, qst, REG_ARG_2); // arg2 = attribute name
      emit_post(emit);
  }
  
  STATIC void emit_native_delete_subscr(emit_t *emit) {
      vtype_kind_t vtype_index, vtype_base;
      emit_pre_pop_reg_reg(emit, &vtype_index, REG_ARG_2, &vtype_base, REG_ARG_1); // index, base
      assert(vtype_index == VTYPE_PYOBJ);
      assert(vtype_base == VTYPE_PYOBJ);
      emit_call_with_imm_arg(emit, MP_F_OBJ_SUBSCR, (mp_uint_t)MP_OBJ_NULL, REG_ARG_3);
  }
  
  STATIC void emit_native_subscr(emit_t *emit, int kind) {
      if (kind == MP_EMIT_SUBSCR_LOAD) {
          emit_native_load_subscr(emit);
      } else if (kind == MP_EMIT_SUBSCR_STORE) {
          emit_native_store_subscr(emit);
      } else {
          emit_native_delete_subscr(emit);
      }
  }
  
  STATIC void emit_native_attr(emit_t *emit, qstr qst, int kind) {
      if (kind == MP_EMIT_ATTR_LOAD) {
          emit_native_load_attr(emit, qst);
      } else if (kind == MP_EMIT_ATTR_STORE) {
          emit_native_store_attr(emit, qst);
      } else {
          emit_native_delete_attr(emit, qst);
      }
  }
  
  STATIC void emit_native_dup_top(emit_t *emit) {
      DEBUG_printf("dup_top\n");
      vtype_kind_t vtype;
      int reg = REG_TEMP0;
      emit_pre_pop_reg_flexible(emit, &vtype, &reg, -1, -1);
      emit_post_push_reg_reg(emit, vtype, reg, vtype, reg);
  }
  
  STATIC void emit_native_dup_top_two(emit_t *emit) {
      vtype_kind_t vtype0, vtype1;
      emit_pre_pop_reg_reg(emit, &vtype0, REG_TEMP0, &vtype1, REG_TEMP1);
      emit_post_push_reg_reg_reg_reg(emit, vtype1, REG_TEMP1, vtype0, REG_TEMP0, vtype1, REG_TEMP1, vtype0, REG_TEMP0);
  }
  
  STATIC void emit_native_pop_top(emit_t *emit) {
      DEBUG_printf("pop_top\n");
      emit_pre_pop_discard(emit);
      emit_post(emit);
  }
  
  STATIC void emit_native_rot_two(emit_t *emit) {
      DEBUG_printf("rot_two\n");
      vtype_kind_t vtype0, vtype1;
      emit_pre_pop_reg_reg(emit, &vtype0, REG_TEMP0, &vtype1, REG_TEMP1);
      emit_post_push_reg_reg(emit, vtype0, REG_TEMP0, vtype1, REG_TEMP1);
  }
  
  STATIC void emit_native_rot_three(emit_t *emit) {
      DEBUG_printf("rot_three\n");
      vtype_kind_t vtype0, vtype1, vtype2;
      emit_pre_pop_reg_reg_reg(emit, &vtype0, REG_TEMP0, &vtype1, REG_TEMP1, &vtype2, REG_TEMP2);
      emit_post_push_reg_reg_reg(emit, vtype0, REG_TEMP0, vtype2, REG_TEMP2, vtype1, REG_TEMP1);
  }
  
  STATIC void emit_native_jump(emit_t *emit, mp_uint_t label) {
      DEBUG_printf("jump(label=" UINT_FMT ")\n", label);
      emit_native_pre(emit);
      // need to commit stack because we are jumping elsewhere
      need_stack_settled(emit);
      ASM_JUMP(emit->as, label);
      emit_post(emit);
  }
  
  STATIC void emit_native_jump_helper(emit_t *emit, bool cond, mp_uint_t label, bool pop) {
      vtype_kind_t vtype = peek_vtype(emit, 0);
      if (vtype == VTYPE_PYOBJ) {
          emit_pre_pop_reg(emit, &vtype, REG_ARG_1);
          if (!pop) {
              adjust_stack(emit, 1);
          }
          emit_call(emit, MP_F_OBJ_IS_TRUE);
      } else {
          emit_pre_pop_reg(emit, &vtype, REG_RET);
          if (!pop) {
              adjust_stack(emit, 1);
          }
          if (!(vtype == VTYPE_BOOL || vtype == VTYPE_INT || vtype == VTYPE_UINT)) {
              EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                  MP_ERROR_TEXT("can't implicitly convert '%q' to 'bool'"), vtype_to_qstr(vtype));
          }
      }
      // For non-pop need to save the vtype so that emit_native_adjust_stack_size
      // can use it.  This is a bit of a hack.
      if (!pop) {
          emit->saved_stack_vtype = vtype;
      }
      // need to commit stack because we may jump elsewhere
      need_stack_settled(emit);
      // Emit the jump
      if (cond) {
          ASM_JUMP_IF_REG_NONZERO(emit->as, REG_RET, label, vtype == VTYPE_PYOBJ);
      } else {
          ASM_JUMP_IF_REG_ZERO(emit->as, REG_RET, label, vtype == VTYPE_PYOBJ);
      }
      if (!pop) {
          adjust_stack(emit, -1);
      }
      emit_post(emit);
  }
  
  STATIC void emit_native_pop_jump_if(emit_t *emit, bool cond, mp_uint_t label) {
      DEBUG_printf("pop_jump_if(cond=%u, label=" UINT_FMT ")\n", cond, label);
      emit_native_jump_helper(emit, cond, label, true);
  }
  
  STATIC void emit_native_jump_if_or_pop(emit_t *emit, bool cond, mp_uint_t label) {
      DEBUG_printf("jump_if_or_pop(cond=%u, label=" UINT_FMT ")\n", cond, label);
      emit_native_jump_helper(emit, cond, label, false);
  }
  
  STATIC void emit_native_unwind_jump(emit_t *emit, mp_uint_t label, mp_uint_t except_depth) {
      if (except_depth > 0) {
          exc_stack_entry_t *first_finally = NULL;
          exc_stack_entry_t *prev_finally = NULL;
          exc_stack_entry_t *e = &emit->exc_stack[emit->exc_stack_size - 1];
          for (; except_depth > 0; --except_depth, --e) {
              if (e->is_finally && e->is_active) {
                  // Found an active finally handler
                  if (first_finally == NULL) {
                      first_finally = e;
                  }
                  if (prev_finally != NULL) {
                      // Mark prev finally as needed to unwind a jump
                      prev_finally->unwind_label = e->label;
                  }
                  prev_finally = e;
              }
          }
          if (prev_finally == NULL) {
              // No finally, handle the jump ourselves
              // First, restore the exception handler address for the jump
              if (e < emit->exc_stack) {
                  ASM_XOR_REG_REG(emit->as, REG_RET, REG_RET);
              } else {
                  ASM_MOV_REG_PCREL(emit->as, REG_RET, e->label);
              }
              ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_HANDLER_PC(emit), REG_RET);
          } else {
              // Last finally should do our jump for us
              // Mark finally as needing to decide the type of jump
              prev_finally->unwind_label = UNWIND_LABEL_DO_FINAL_UNWIND;
              ASM_MOV_REG_PCREL(emit->as, REG_RET, label & ~MP_EMIT_BREAK_FROM_FOR);
              ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_HANDLER_UNWIND(emit), REG_RET);
              // Cancel any active exception (see also emit_native_pop_except_jump)
              ASM_MOV_REG_IMM(emit->as, REG_RET, (mp_uint_t)MP_OBJ_NULL);
              ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_RET);
              // Jump to the innermost active finally
              label = first_finally->label;
          }
      }
      emit_native_jump(emit, label & ~MP_EMIT_BREAK_FROM_FOR);
  }
  
  STATIC void emit_native_setup_with(emit_t *emit, mp_uint_t label) {
      // the context manager is on the top of the stack
      // stack: (..., ctx_mgr)
  
      // get __exit__ method
      vtype_kind_t vtype;
      emit_access_stack(emit, 1, &vtype, REG_ARG_1); // arg1 = ctx_mgr
      assert(vtype == VTYPE_PYOBJ);
      emit_get_stack_pointer_to_reg_for_push(emit, REG_ARG_3, 2); // arg3 = dest ptr
      emit_call_with_qstr_arg(emit, MP_F_LOAD_METHOD, MP_QSTR___exit__, REG_ARG_2);
      // stack: (..., ctx_mgr, __exit__, self)
  
      emit_pre_pop_reg(emit, &vtype, REG_ARG_3); // self
      emit_pre_pop_reg(emit, &vtype, REG_ARG_2); // __exit__
      emit_pre_pop_reg(emit, &vtype, REG_ARG_1); // ctx_mgr
      emit_post_push_reg(emit, vtype, REG_ARG_2); // __exit__
      emit_post_push_reg(emit, vtype, REG_ARG_3); // self
      // stack: (..., __exit__, self)
      // REG_ARG_1=ctx_mgr
  
      // get __enter__ method
      emit_get_stack_pointer_to_reg_for_push(emit, REG_ARG_3, 2); // arg3 = dest ptr
      emit_call_with_qstr_arg(emit, MP_F_LOAD_METHOD, MP_QSTR___enter__, REG_ARG_2); // arg2 = method name
      // stack: (..., __exit__, self, __enter__, self)
  
      // call __enter__ method
      emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, 2); // pointer to items, including meth and self
      emit_call_with_2_imm_args(emit, MP_F_CALL_METHOD_N_KW, 0, REG_ARG_1, 0, REG_ARG_2);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET); // push return value of __enter__
      // stack: (..., __exit__, self, as_value)
  
      // need to commit stack because we may jump elsewhere
      need_stack_settled(emit);
      emit_native_push_exc_stack(emit, label, true);
  
      emit_native_dup_top(emit);
      // stack: (..., __exit__, self, as_value, as_value)
  }
  
  STATIC void emit_native_setup_block(emit_t *emit, mp_uint_t label, int kind) {
      if (kind == MP_EMIT_SETUP_BLOCK_WITH) {
          emit_native_setup_with(emit, label);
      } else {
          // Set up except and finally
          emit_native_pre(emit);
          need_stack_settled(emit);
          emit_native_push_exc_stack(emit, label, kind == MP_EMIT_SETUP_BLOCK_FINALLY);
          emit_post(emit);
      }
  }
  
  STATIC void emit_native_with_cleanup(emit_t *emit, mp_uint_t label) {
      // Note: 3 labels are reserved for this function, starting at *emit->label_slot
  
      // stack: (..., __exit__, self, as_value)
      emit_native_pre(emit);
      emit_native_leave_exc_stack(emit, false);
      adjust_stack(emit, -1);
      // stack: (..., __exit__, self)
  
      // Label for case where __exit__ is called from an unwind jump
      emit_native_label_assign(emit, *emit->label_slot + 2);
  
      // call __exit__
      emit_post_push_imm(emit, VTYPE_PTR_NONE, 0);
      emit_post_push_imm(emit, VTYPE_PTR_NONE, 0);
      emit_post_push_imm(emit, VTYPE_PTR_NONE, 0);
      emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, 5);
      emit_call_with_2_imm_args(emit, MP_F_CALL_METHOD_N_KW, 3, REG_ARG_1, 0, REG_ARG_2);
  
      // Replace exc with None and finish
      emit_native_jump(emit, *emit->label_slot);
  
      // nlr_catch
      // Don't use emit_native_label_assign because this isn't a real finally label
      mp_asm_base_label_assign(&emit->as->base, label);
  
      // Leave with's exception handler
      emit_native_leave_exc_stack(emit, true);
  
      // Adjust stack counter for: __exit__, self (implicitly discard as_value which is above self)
      emit_native_adjust_stack_size(emit, 2);
      // stack: (..., __exit__, self)
  
      ASM_MOV_REG_LOCAL(emit->as, REG_ARG_1, LOCAL_IDX_EXC_VAL(emit)); // get exc
  
      // Check if exc is MP_OBJ_NULL (i.e. zero) and jump to non-exc handler if it is
      ASM_JUMP_IF_REG_ZERO(emit->as, REG_ARG_1, *emit->label_slot + 2, false);
  
      ASM_LOAD_REG_REG_OFFSET(emit->as, REG_ARG_2, REG_ARG_1, 0); // get type(exc)
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_ARG_2); // push type(exc)
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_ARG_1); // push exc value
      emit_post_push_imm(emit, VTYPE_PTR_NONE, 0); // traceback info
      // Stack: (..., __exit__, self, type(exc), exc, traceback)
  
      // call __exit__ method
      emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, 5);
      emit_call_with_2_imm_args(emit, MP_F_CALL_METHOD_N_KW, 3, REG_ARG_1, 0, REG_ARG_2);
      // Stack: (...)
  
      // If REG_RET is true then we need to replace exception with None (swallow exception)
      if (REG_ARG_1 != REG_RET) {
          ASM_MOV_REG_REG(emit->as, REG_ARG_1, REG_RET);
      }
      emit_call(emit, MP_F_OBJ_IS_TRUE);
      ASM_JUMP_IF_REG_ZERO(emit->as, REG_RET, *emit->label_slot + 1, true);
  
      // Replace exception with MP_OBJ_NULL.
      emit_native_label_assign(emit, *emit->label_slot);
      ASM_MOV_REG_IMM(emit->as, REG_TEMP0, (mp_uint_t)MP_OBJ_NULL);
      ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_TEMP0);
  
      // end of with cleanup nlr_catch block
      emit_native_label_assign(emit, *emit->label_slot + 1);
  
      // Exception is in nlr_buf.ret_val slot
  }
  
  STATIC void emit_native_end_finally(emit_t *emit) {
      // logic:
      //   exc = pop_stack
      //   if exc == None: pass
      //   else: raise exc
      // the check if exc is None is done in the MP_F_NATIVE_RAISE stub
      emit_native_pre(emit);
      ASM_MOV_REG_LOCAL(emit->as, REG_ARG_1, LOCAL_IDX_EXC_VAL(emit));
      emit_call(emit, MP_F_NATIVE_RAISE);
  
      // Get state for this finally and see if we need to unwind
      exc_stack_entry_t *e = emit_native_pop_exc_stack(emit);
      if (e->unwind_label != UNWIND_LABEL_UNUSED) {
          ASM_MOV_REG_LOCAL(emit->as, REG_RET, LOCAL_IDX_EXC_HANDLER_UNWIND(emit));
          ASM_JUMP_IF_REG_ZERO(emit->as, REG_RET, *emit->label_slot, false);
          if (e->unwind_label == UNWIND_LABEL_DO_FINAL_UNWIND) {
              ASM_JUMP_REG(emit->as, REG_RET);
          } else {
              emit_native_jump(emit, e->unwind_label);
          }
          emit_native_label_assign(emit, *emit->label_slot);
      }
  
      emit_post(emit);
  }
  
  STATIC void emit_native_get_iter(emit_t *emit, bool use_stack) {
      // perhaps the difficult one, as we want to rewrite for loops using native code
      // in cases where we iterate over a Python object, can we use normal runtime calls?
  
      vtype_kind_t vtype;
      emit_pre_pop_reg(emit, &vtype, REG_ARG_1);
      assert(vtype == VTYPE_PYOBJ);
      if (use_stack) {
          emit_get_stack_pointer_to_reg_for_push(emit, REG_ARG_2, MP_OBJ_ITER_BUF_NSLOTS);
          emit_call(emit, MP_F_NATIVE_GETITER);
      } else {
          // mp_getiter will allocate the iter_buf on the heap
          ASM_MOV_REG_IMM(emit->as, REG_ARG_2, 0);
          emit_call(emit, MP_F_NATIVE_GETITER);
          emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
      }
  }
  
  STATIC void emit_native_for_iter(emit_t *emit, mp_uint_t label) {
      emit_native_pre(emit);
      emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_1, MP_OBJ_ITER_BUF_NSLOTS);
      adjust_stack(emit, MP_OBJ_ITER_BUF_NSLOTS);
      emit_call(emit, MP_F_NATIVE_ITERNEXT);
      #if MICROPY_DEBUG_MP_OBJ_SENTINELS
      ASM_MOV_REG_IMM(emit->as, REG_TEMP1, (mp_uint_t)MP_OBJ_STOP_ITERATION);
      ASM_JUMP_IF_REG_EQ(emit->as, REG_RET, REG_TEMP1, label);
      #else
      MP_STATIC_ASSERT(MP_OBJ_STOP_ITERATION == 0);
      ASM_JUMP_IF_REG_ZERO(emit->as, REG_RET, label, false);
      #endif
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_for_iter_end(emit_t *emit) {
      // adjust stack counter (we get here from for_iter ending, which popped the value for us)
      emit_native_pre(emit);
      adjust_stack(emit, -MP_OBJ_ITER_BUF_NSLOTS);
      emit_post(emit);
  }
  
  STATIC void emit_native_pop_except_jump(emit_t *emit, mp_uint_t label, bool within_exc_handler) {
      if (within_exc_handler) {
          // Cancel any active exception so subsequent handlers don't see it
          ASM_MOV_REG_IMM(emit->as, REG_TEMP0, (mp_uint_t)MP_OBJ_NULL);
          ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_TEMP0);
      } else {
          emit_native_leave_exc_stack(emit, false);
      }
      emit_native_jump(emit, label);
  }
  
  STATIC void emit_native_unary_op(emit_t *emit, mp_unary_op_t op) {
      vtype_kind_t vtype;
      emit_pre_pop_reg(emit, &vtype, REG_ARG_2);
      if (vtype == VTYPE_PYOBJ) {
          emit_call_with_imm_arg(emit, MP_F_UNARY_OP, op, REG_ARG_1);
          emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
      } else {
          adjust_stack(emit, 1);
          EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
              MP_ERROR_TEXT("unary op %q not implemented"), mp_unary_op_method_name[op]);
      }
  }
  
  STATIC void emit_native_binary_op(emit_t *emit, mp_binary_op_t op) {
      DEBUG_printf("binary_op(" UINT_FMT ")\n", op);
      vtype_kind_t vtype_lhs = peek_vtype(emit, 1);
      vtype_kind_t vtype_rhs = peek_vtype(emit, 0);
      if ((vtype_lhs == VTYPE_INT || vtype_lhs == VTYPE_UINT)
          && (vtype_rhs == VTYPE_INT || vtype_rhs == VTYPE_UINT)) {
          // for integers, inplace and normal ops are equivalent, so use just normal ops
          if (MP_BINARY_OP_INPLACE_OR <= op && op <= MP_BINARY_OP_INPLACE_POWER) {
              op += MP_BINARY_OP_OR - MP_BINARY_OP_INPLACE_OR;
          }
  
          #if N_X64 || N_X86
          // special cases for x86 and shifting
          if (op == MP_BINARY_OP_LSHIFT || op == MP_BINARY_OP_RSHIFT) {
              #if N_X64
              emit_pre_pop_reg_reg(emit, &vtype_rhs, ASM_X64_REG_RCX, &vtype_lhs, REG_RET);
              #else
              emit_pre_pop_reg_reg(emit, &vtype_rhs, ASM_X86_REG_ECX, &vtype_lhs, REG_RET);
              #endif
              if (op == MP_BINARY_OP_LSHIFT) {
                  ASM_LSL_REG(emit->as, REG_RET);
              } else {
                  if (vtype_lhs == VTYPE_UINT) {
                      ASM_LSR_REG(emit->as, REG_RET);
                  } else {
                      ASM_ASR_REG(emit->as, REG_RET);
                  }
              }
              emit_post_push_reg(emit, vtype_lhs, REG_RET);
              return;
          }
          #endif
  
          // special cases for floor-divide and module because we dispatch to helper functions
          if (op == MP_BINARY_OP_FLOOR_DIVIDE || op == MP_BINARY_OP_MODULO) {
              emit_pre_pop_reg_reg(emit, &vtype_rhs, REG_ARG_2, &vtype_lhs, REG_ARG_1);
              if (vtype_lhs != VTYPE_INT) {
                  EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                      MP_ERROR_TEXT("div/mod not implemented for uint"), mp_binary_op_method_name[op]);
              }
              if (op == MP_BINARY_OP_FLOOR_DIVIDE) {
                  emit_call(emit, MP_F_SMALL_INT_FLOOR_DIVIDE);
              } else {
                  emit_call(emit, MP_F_SMALL_INT_MODULO);
              }
              emit_post_push_reg(emit, VTYPE_INT, REG_RET);
              return;
          }
  
          int reg_rhs = REG_ARG_3;
          emit_pre_pop_reg_flexible(emit, &vtype_rhs, &reg_rhs, REG_RET, REG_ARG_2);
          emit_pre_pop_reg(emit, &vtype_lhs, REG_ARG_2);
  
          #if !(N_X64 || N_X86)
          if (op == MP_BINARY_OP_LSHIFT || op == MP_BINARY_OP_RSHIFT) {
              if (op == MP_BINARY_OP_LSHIFT) {
                  ASM_LSL_REG_REG(emit->as, REG_ARG_2, reg_rhs);
              } else {
                  if (vtype_lhs == VTYPE_UINT) {
                      ASM_LSR_REG_REG(emit->as, REG_ARG_2, reg_rhs);
                  } else {
                      ASM_ASR_REG_REG(emit->as, REG_ARG_2, reg_rhs);
                  }
              }
              emit_post_push_reg(emit, vtype_lhs, REG_ARG_2);
              return;
          }
          #endif
  
          if (op == MP_BINARY_OP_OR) {
              ASM_OR_REG_REG(emit->as, REG_ARG_2, reg_rhs);
              emit_post_push_reg(emit, vtype_lhs, REG_ARG_2);
          } else if (op == MP_BINARY_OP_XOR) {
              ASM_XOR_REG_REG(emit->as, REG_ARG_2, reg_rhs);
              emit_post_push_reg(emit, vtype_lhs, REG_ARG_2);
          } else if (op == MP_BINARY_OP_AND) {
              ASM_AND_REG_REG(emit->as, REG_ARG_2, reg_rhs);
              emit_post_push_reg(emit, vtype_lhs, REG_ARG_2);
          } else if (op == MP_BINARY_OP_ADD) {
              ASM_ADD_REG_REG(emit->as, REG_ARG_2, reg_rhs);
              emit_post_push_reg(emit, vtype_lhs, REG_ARG_2);
          } else if (op == MP_BINARY_OP_SUBTRACT) {
              ASM_SUB_REG_REG(emit->as, REG_ARG_2, reg_rhs);
              emit_post_push_reg(emit, vtype_lhs, REG_ARG_2);
          } else if (op == MP_BINARY_OP_MULTIPLY) {
              ASM_MUL_REG_REG(emit->as, REG_ARG_2, reg_rhs);
              emit_post_push_reg(emit, vtype_lhs, REG_ARG_2);
          } else if (MP_BINARY_OP_LESS <= op && op <= MP_BINARY_OP_NOT_EQUAL) {
              // comparison ops are (in enum order):
              //  MP_BINARY_OP_LESS
              //  MP_BINARY_OP_MORE
              //  MP_BINARY_OP_EQUAL
              //  MP_BINARY_OP_LESS_EQUAL
              //  MP_BINARY_OP_MORE_EQUAL
              //  MP_BINARY_OP_NOT_EQUAL
  
              if (vtype_lhs != vtype_rhs) {
                  EMIT_NATIVE_VIPER_TYPE_ERROR(emit, MP_ERROR_TEXT("comparison of int and uint"));
              }
  
              size_t op_idx = op - MP_BINARY_OP_LESS + (vtype_lhs == VTYPE_UINT ? 0 : 6);
  
              need_reg_single(emit, REG_RET, 0);
              #if N_X64
              asm_x64_xor_r64_r64(emit->as, REG_RET, REG_RET);
              asm_x64_cmp_r64_with_r64(emit->as, reg_rhs, REG_ARG_2);
              static byte ops[6 + 6] = {
                  // unsigned
                  ASM_X64_CC_JB,
                  ASM_X64_CC_JA,
                  ASM_X64_CC_JE,
                  ASM_X64_CC_JBE,
                  ASM_X64_CC_JAE,
                  ASM_X64_CC_JNE,
                  // signed
                  ASM_X64_CC_JL,
                  ASM_X64_CC_JG,
                  ASM_X64_CC_JE,
                  ASM_X64_CC_JLE,
                  ASM_X64_CC_JGE,
                  ASM_X64_CC_JNE,
              };
              asm_x64_setcc_r8(emit->as, ops[op_idx], REG_RET);
              #elif N_X86
              asm_x86_xor_r32_r32(emit->as, REG_RET, REG_RET);
              asm_x86_cmp_r32_with_r32(emit->as, reg_rhs, REG_ARG_2);
              static byte ops[6 + 6] = {
                  // unsigned
                  ASM_X86_CC_JB,
                  ASM_X86_CC_JA,
                  ASM_X86_CC_JE,
                  ASM_X86_CC_JBE,
                  ASM_X86_CC_JAE,
                  ASM_X86_CC_JNE,
                  // signed
                  ASM_X86_CC_JL,
                  ASM_X86_CC_JG,
                  ASM_X86_CC_JE,
                  ASM_X86_CC_JLE,
                  ASM_X86_CC_JGE,
                  ASM_X86_CC_JNE,
              };
              asm_x86_setcc_r8(emit->as, ops[op_idx], REG_RET);
              #elif N_THUMB
              asm_thumb_cmp_rlo_rlo(emit->as, REG_ARG_2, reg_rhs);
              if (asm_thumb_allow_armv7m(emit->as)) {
                  static uint16_t ops[6 + 6] = {
                      // unsigned
                      ASM_THUMB_OP_ITE_CC,
                      ASM_THUMB_OP_ITE_HI,
                      ASM_THUMB_OP_ITE_EQ,
                      ASM_THUMB_OP_ITE_LS,
                      ASM_THUMB_OP_ITE_CS,
                      ASM_THUMB_OP_ITE_NE,
                      // signed
                      ASM_THUMB_OP_ITE_LT,
                      ASM_THUMB_OP_ITE_GT,
                      ASM_THUMB_OP_ITE_EQ,
                      ASM_THUMB_OP_ITE_LE,
                      ASM_THUMB_OP_ITE_GE,
                      ASM_THUMB_OP_ITE_NE,
                  };
                  asm_thumb_op16(emit->as, ops[op_idx]);
                  asm_thumb_mov_rlo_i8(emit->as, REG_RET, 1);
                  asm_thumb_mov_rlo_i8(emit->as, REG_RET, 0);
              } else {
                  static uint16_t ops[6 + 6] = {
                      // unsigned
                      ASM_THUMB_CC_CC,
                      ASM_THUMB_CC_HI,
                      ASM_THUMB_CC_EQ,
                      ASM_THUMB_CC_LS,
                      ASM_THUMB_CC_CS,
                      ASM_THUMB_CC_NE,
                      // signed
                      ASM_THUMB_CC_LT,
                      ASM_THUMB_CC_GT,
                      ASM_THUMB_CC_EQ,
                      ASM_THUMB_CC_LE,
                      ASM_THUMB_CC_GE,
                      ASM_THUMB_CC_NE,
                  };
                  asm_thumb_bcc_rel9(emit->as, ops[op_idx], 6);
                  asm_thumb_mov_rlo_i8(emit->as, REG_RET, 0);
                  asm_thumb_b_rel12(emit->as, 4);
                  asm_thumb_mov_rlo_i8(emit->as, REG_RET, 1);
              }
              #elif N_ARM
              asm_arm_cmp_reg_reg(emit->as, REG_ARG_2, reg_rhs);
              static uint ccs[6 + 6] = {
                  // unsigned
                  ASM_ARM_CC_CC,
                  ASM_ARM_CC_HI,
                  ASM_ARM_CC_EQ,
                  ASM_ARM_CC_LS,
                  ASM_ARM_CC_CS,
                  ASM_ARM_CC_NE,
                  // signed
                  ASM_ARM_CC_LT,
                  ASM_ARM_CC_GT,
                  ASM_ARM_CC_EQ,
                  ASM_ARM_CC_LE,
                  ASM_ARM_CC_GE,
                  ASM_ARM_CC_NE,
              };
              asm_arm_setcc_reg(emit->as, REG_RET, ccs[op_idx]);
              #elif N_XTENSA || N_XTENSAWIN
              static uint8_t ccs[6 + 6] = {
                  // unsigned
                  ASM_XTENSA_CC_LTU,
                  0x80 | ASM_XTENSA_CC_LTU, // for GTU we'll swap args
                  ASM_XTENSA_CC_EQ,
                  0x80 | ASM_XTENSA_CC_GEU, // for LEU we'll swap args
                  ASM_XTENSA_CC_GEU,
                  ASM_XTENSA_CC_NE,
                  // signed
                  ASM_XTENSA_CC_LT,
                  0x80 | ASM_XTENSA_CC_LT, // for GT we'll swap args
                  ASM_XTENSA_CC_EQ,
                  0x80 | ASM_XTENSA_CC_GE, // for LE we'll swap args
                  ASM_XTENSA_CC_GE,
                  ASM_XTENSA_CC_NE,
              };
              uint8_t cc = ccs[op_idx];
              if ((cc & 0x80) == 0) {
                  asm_xtensa_setcc_reg_reg_reg(emit->as, cc, REG_RET, REG_ARG_2, reg_rhs);
              } else {
                  asm_xtensa_setcc_reg_reg_reg(emit->as, cc & ~0x80, REG_RET, reg_rhs, REG_ARG_2);
              }
              #else
              #error not implemented
              #endif
              emit_post_push_reg(emit, VTYPE_BOOL, REG_RET);
          } else {
              // TODO other ops not yet implemented
              adjust_stack(emit, 1);
              EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                  MP_ERROR_TEXT("binary op %q not implemented"), mp_binary_op_method_name[op]);
          }
      } else if (vtype_lhs == VTYPE_PYOBJ && vtype_rhs == VTYPE_PYOBJ) {
          emit_pre_pop_reg_reg(emit, &vtype_rhs, REG_ARG_3, &vtype_lhs, REG_ARG_2);
          bool invert = false;
          if (op == MP_BINARY_OP_NOT_IN) {
              invert = true;
              op = MP_BINARY_OP_IN;
          } else if (op == MP_BINARY_OP_IS_NOT) {
              invert = true;
              op = MP_BINARY_OP_IS;
          }
          emit_call_with_imm_arg(emit, MP_F_BINARY_OP, op, REG_ARG_1);
          if (invert) {
              ASM_MOV_REG_REG(emit->as, REG_ARG_2, REG_RET);
              emit_call_with_imm_arg(emit, MP_F_UNARY_OP, MP_UNARY_OP_NOT, REG_ARG_1);
          }
          emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
      } else {
          adjust_stack(emit, -1);
          EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
              MP_ERROR_TEXT("can't do binary op between '%q' and '%q'"),
              vtype_to_qstr(vtype_lhs), vtype_to_qstr(vtype_rhs));
      }
  }
  
  #if MICROPY_PY_BUILTINS_SLICE
  STATIC void emit_native_build_slice(emit_t *emit, mp_uint_t n_args);
  #endif
  
  STATIC void emit_native_build(emit_t *emit, mp_uint_t n_args, int kind) {
      // for viper: call runtime, with types of args
      //   if wrapped in byte_array, or something, allocates memory and fills it
      MP_STATIC_ASSERT(MP_F_BUILD_TUPLE + MP_EMIT_BUILD_TUPLE == MP_F_BUILD_TUPLE);
      MP_STATIC_ASSERT(MP_F_BUILD_TUPLE + MP_EMIT_BUILD_LIST == MP_F_BUILD_LIST);
      MP_STATIC_ASSERT(MP_F_BUILD_TUPLE + MP_EMIT_BUILD_MAP == MP_F_BUILD_MAP);
      MP_STATIC_ASSERT(MP_F_BUILD_TUPLE + MP_EMIT_BUILD_SET == MP_F_BUILD_SET);
      #if MICROPY_PY_BUILTINS_SLICE
      if (kind == MP_EMIT_BUILD_SLICE) {
          emit_native_build_slice(emit, n_args);
          return;
      }
      #endif
      emit_native_pre(emit);
      if (kind == MP_EMIT_BUILD_TUPLE || kind == MP_EMIT_BUILD_LIST || kind == MP_EMIT_BUILD_SET) {
          emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_2, n_args); // pointer to items
      }
      emit_call_with_imm_arg(emit, MP_F_BUILD_TUPLE + kind, n_args, REG_ARG_1);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET); // new tuple/list/map/set
  }
  
  STATIC void emit_native_store_map(emit_t *emit) {
      vtype_kind_t vtype_key, vtype_value, vtype_map;
      emit_pre_pop_reg_reg_reg(emit, &vtype_key, REG_ARG_2, &vtype_value, REG_ARG_3, &vtype_map, REG_ARG_1); // key, value, map
      assert(vtype_key == VTYPE_PYOBJ);
      assert(vtype_value == VTYPE_PYOBJ);
      assert(vtype_map == VTYPE_PYOBJ);
      emit_call(emit, MP_F_STORE_MAP);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET); // map
  }
  
  #if MICROPY_PY_BUILTINS_SLICE
  STATIC void emit_native_build_slice(emit_t *emit, mp_uint_t n_args) {
      DEBUG_printf("build_slice %d\n", n_args);
      if (n_args == 2) {
          vtype_kind_t vtype_start, vtype_stop;
          emit_pre_pop_reg_reg(emit, &vtype_stop, REG_ARG_2, &vtype_start, REG_ARG_1); // arg1 = start, arg2 = stop
          assert(vtype_start == VTYPE_PYOBJ);
          assert(vtype_stop == VTYPE_PYOBJ);
          emit_native_mov_reg_const(emit, REG_ARG_3, MP_F_CONST_NONE_OBJ); // arg3 = step
      } else {
          assert(n_args == 3);
          vtype_kind_t vtype_start, vtype_stop, vtype_step;
          emit_pre_pop_reg_reg_reg(emit, &vtype_step, REG_ARG_3, &vtype_stop, REG_ARG_2, &vtype_start, REG_ARG_1); // arg1 = start, arg2 = stop, arg3 = step
          assert(vtype_start == VTYPE_PYOBJ);
          assert(vtype_stop == VTYPE_PYOBJ);
          assert(vtype_step == VTYPE_PYOBJ);
      }
      emit_call(emit, MP_F_NEW_SLICE);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  #endif
  
  STATIC void emit_native_store_comp(emit_t *emit, scope_kind_t kind, mp_uint_t collection_index) {
      mp_fun_kind_t f;
      if (kind == SCOPE_LIST_COMP) {
          vtype_kind_t vtype_item;
          emit_pre_pop_reg(emit, &vtype_item, REG_ARG_2);
          assert(vtype_item == VTYPE_PYOBJ);
          f = MP_F_LIST_APPEND;
      #if MICROPY_PY_BUILTINS_SET
      } else if (kind == SCOPE_SET_COMP) {
          vtype_kind_t vtype_item;
          emit_pre_pop_reg(emit, &vtype_item, REG_ARG_2);
          assert(vtype_item == VTYPE_PYOBJ);
          f = MP_F_STORE_SET;
      #endif
      } else {
          // SCOPE_DICT_COMP
          vtype_kind_t vtype_key, vtype_value;
          emit_pre_pop_reg_reg(emit, &vtype_key, REG_ARG_2, &vtype_value, REG_ARG_3);
          assert(vtype_key == VTYPE_PYOBJ);
          assert(vtype_value == VTYPE_PYOBJ);
          f = MP_F_STORE_MAP;
      }
      vtype_kind_t vtype_collection;
      emit_access_stack(emit, collection_index, &vtype_collection, REG_ARG_1);
      assert(vtype_collection == VTYPE_PYOBJ);
      emit_call(emit, f);
      emit_post(emit);
  }
  
  STATIC void emit_native_unpack_sequence(emit_t *emit, mp_uint_t n_args) {
      DEBUG_printf("unpack_sequence %d\n", n_args);
      vtype_kind_t vtype_base;
      emit_pre_pop_reg(emit, &vtype_base, REG_ARG_1); // arg1 = seq
      assert(vtype_base == VTYPE_PYOBJ);
      emit_get_stack_pointer_to_reg_for_push(emit, REG_ARG_3, n_args); // arg3 = dest ptr
      emit_call_with_imm_arg(emit, MP_F_UNPACK_SEQUENCE, n_args, REG_ARG_2); // arg2 = n_args
  }
  
  STATIC void emit_native_unpack_ex(emit_t *emit, mp_uint_t n_left, mp_uint_t n_right) {
      DEBUG_printf("unpack_ex %d %d\n", n_left, n_right);
      vtype_kind_t vtype_base;
      emit_pre_pop_reg(emit, &vtype_base, REG_ARG_1); // arg1 = seq
      assert(vtype_base == VTYPE_PYOBJ);
      emit_get_stack_pointer_to_reg_for_push(emit, REG_ARG_3, n_left + n_right + 1); // arg3 = dest ptr
      emit_call_with_imm_arg(emit, MP_F_UNPACK_EX, n_left | (n_right << 8), REG_ARG_2); // arg2 = n_left + n_right
  }
  
  STATIC void emit_native_make_function(emit_t *emit, scope_t *scope, mp_uint_t n_pos_defaults, mp_uint_t n_kw_defaults) {
      // call runtime, with type info for args, or don't support dict/default params, or only support Python objects for them
      emit_native_pre(emit);
      emit_native_mov_reg_state(emit, REG_ARG_2, LOCAL_IDX_FUN_OBJ(emit));
      ASM_LOAD_REG_REG_OFFSET(emit->as, REG_ARG_2, REG_ARG_2, OFFSETOF_OBJ_FUN_BC_CONTEXT);
      if (n_pos_defaults == 0 && n_kw_defaults == 0) {
          need_reg_all(emit);
          ASM_MOV_REG_IMM(emit->as, REG_ARG_3, 0);
      } else {
          emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, 2);
          need_reg_all(emit);
      }
      emit_load_reg_with_child(emit, REG_ARG_1, scope->raw_code);
      ASM_CALL_IND(emit->as, MP_F_MAKE_FUNCTION_FROM_RAW_CODE);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_make_closure(emit_t *emit, scope_t *scope, mp_uint_t n_closed_over, mp_uint_t n_pos_defaults, mp_uint_t n_kw_defaults) {
      // make function
      emit_native_pre(emit);
      emit_native_mov_reg_state(emit, REG_ARG_2, LOCAL_IDX_FUN_OBJ(emit));
      ASM_LOAD_REG_REG_OFFSET(emit->as, REG_ARG_2, REG_ARG_2, OFFSETOF_OBJ_FUN_BC_CONTEXT);
      if (n_pos_defaults == 0 && n_kw_defaults == 0) {
          need_reg_all(emit);
          ASM_MOV_REG_IMM(emit->as, REG_ARG_3, 0);
      } else {
          emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, 2 + n_closed_over);
          adjust_stack(emit, 2 + n_closed_over);
          need_reg_all(emit);
      }
      emit_load_reg_with_child(emit, REG_ARG_1, scope->raw_code);
      ASM_CALL_IND(emit->as, MP_F_MAKE_FUNCTION_FROM_RAW_CODE);
  
      // make closure
      #if REG_ARG_1 != REG_RET
      ASM_MOV_REG_REG(emit->as, REG_ARG_1, REG_RET);
      #endif
      ASM_MOV_REG_IMM(emit->as, REG_ARG_2, n_closed_over);
      emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, n_closed_over);
      if (n_pos_defaults != 0 || n_kw_defaults != 0) {
          adjust_stack(emit, -2);
      }
      ASM_CALL_IND(emit->as, MP_F_NEW_CLOSURE);
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
  }
  
  STATIC void emit_native_call_function(emit_t *emit, mp_uint_t n_positional, mp_uint_t n_keyword, mp_uint_t star_flags) {
      DEBUG_printf("call_function(n_pos=" UINT_FMT ", n_kw=" UINT_FMT ", star_flags=" UINT_FMT ")\n", n_positional, n_keyword, star_flags);
  
      // TODO: in viper mode, call special runtime routine with type info for args,
      // and wanted type info for return, to remove need for boxing/unboxing
  
      emit_native_pre(emit);
      vtype_kind_t vtype_fun = peek_vtype(emit, n_positional + 2 * n_keyword);
      if (vtype_fun == VTYPE_BUILTIN_CAST) {
          // casting operator
          assert(n_positional == 1 && n_keyword == 0);
          assert(!star_flags);
          DEBUG_printf("  cast to %d\n", vtype_fun);
          vtype_kind_t vtype_cast = peek_stack(emit, 1)->data.u_imm;
          switch (peek_vtype(emit, 0)) {
              case VTYPE_PYOBJ: {
                  vtype_kind_t vtype;
                  emit_pre_pop_reg(emit, &vtype, REG_ARG_1);
                  emit_pre_pop_discard(emit);
                  emit_call_with_imm_arg(emit, MP_F_CONVERT_OBJ_TO_NATIVE, vtype_cast, REG_ARG_2); // arg2 = type
                  emit_post_push_reg(emit, vtype_cast, REG_RET);
                  break;
              }
              case VTYPE_BOOL:
              case VTYPE_INT:
              case VTYPE_UINT:
              case VTYPE_PTR:
              case VTYPE_PTR8:
              case VTYPE_PTR16:
              case VTYPE_PTR32:
              case VTYPE_PTR_NONE:
                  emit_fold_stack_top(emit, REG_ARG_1);
                  emit_post_top_set_vtype(emit, vtype_cast);
                  break;
              default:
                  // this can happen when casting a cast: int(int)
                  mp_raise_NotImplementedError(MP_ERROR_TEXT("casting"));
          }
      } else {
          assert(vtype_fun == VTYPE_PYOBJ);
          if (star_flags) {
              emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, n_positional + 2 * n_keyword + 2); // pointer to args
              emit_call_with_2_imm_args(emit, MP_F_CALL_METHOD_N_KW_VAR, 0, REG_ARG_1, n_positional | (n_keyword << 8), REG_ARG_2);
              emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
          } else {
              if (n_positional != 0 || n_keyword != 0) {
                  emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, n_positional + 2 * n_keyword); // pointer to args
              }
              emit_pre_pop_reg(emit, &vtype_fun, REG_ARG_1); // the function
              emit_call_with_imm_arg(emit, MP_F_NATIVE_CALL_FUNCTION_N_KW, n_positional | (n_keyword << 8), REG_ARG_2);
              emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
          }
      }
  }
  
  STATIC void emit_native_call_method(emit_t *emit, mp_uint_t n_positional, mp_uint_t n_keyword, mp_uint_t star_flags) {
      if (star_flags) {
          emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, n_positional + 2 * n_keyword + 3); // pointer to args
          emit_call_with_2_imm_args(emit, MP_F_CALL_METHOD_N_KW_VAR, 1, REG_ARG_1, n_positional | (n_keyword << 8), REG_ARG_2);
          emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
      } else {
          emit_native_pre(emit);
          emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, 2 + n_positional + 2 * n_keyword); // pointer to items, including meth and self
          emit_call_with_2_imm_args(emit, MP_F_CALL_METHOD_N_KW, n_positional, REG_ARG_1, n_keyword, REG_ARG_2);
          emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
      }
  }
  
  STATIC void emit_native_return_value(emit_t *emit) {
      DEBUG_printf("return_value\n");
  
      if (emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR) {
          // Save pointer to current stack position for caller to access return value
          emit_get_stack_pointer_to_reg_for_pop(emit, REG_TEMP0, 1);
          emit_native_mov_state_reg(emit, OFFSETOF_CODE_STATE_SP, REG_TEMP0);
  
          // Put return type in return value slot
          ASM_MOV_REG_IMM(emit->as, REG_TEMP0, MP_VM_RETURN_NORMAL);
          ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_RET_VAL(emit), REG_TEMP0);
  
          // Do the unwinding jump to get to the return handler
          emit_native_unwind_jump(emit, emit->exit_label, emit->exc_stack_size);
          emit->last_emit_was_return_value = true;
          return;
      }
  
      if (emit->do_viper_types) {
          vtype_kind_t return_vtype = emit->scope->scope_flags >> MP_SCOPE_FLAG_VIPERRET_POS;
          if (peek_vtype(emit, 0) == VTYPE_PTR_NONE) {
              emit_pre_pop_discard(emit);
              if (return_vtype == VTYPE_PYOBJ) {
                  emit_native_mov_reg_const(emit, REG_PARENT_RET, MP_F_CONST_NONE_OBJ);
              } else {
                  ASM_MOV_REG_IMM(emit->as, REG_ARG_1, 0);
              }
          } else {
              vtype_kind_t vtype;
              emit_pre_pop_reg(emit, &vtype, return_vtype == VTYPE_PYOBJ ? REG_PARENT_RET : REG_ARG_1);
              if (vtype != return_vtype) {
                  EMIT_NATIVE_VIPER_TYPE_ERROR(emit,
                      MP_ERROR_TEXT("return expected '%q' but got '%q'"),
                      vtype_to_qstr(return_vtype), vtype_to_qstr(vtype));
              }
          }
          if (return_vtype != VTYPE_PYOBJ) {
              emit_call_with_imm_arg(emit, MP_F_CONVERT_NATIVE_TO_OBJ, return_vtype, REG_ARG_2);
              #if REG_RET != REG_PARENT_RET
              ASM_MOV_REG_REG(emit->as, REG_PARENT_RET, REG_RET);
              #endif
          }
      } else {
          vtype_kind_t vtype;
          emit_pre_pop_reg(emit, &vtype, REG_PARENT_RET);
          assert(vtype == VTYPE_PYOBJ);
      }
      if (NEED_GLOBAL_EXC_HANDLER(emit)) {
          // Save return value for the global exception handler to use
          ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_RET_VAL(emit), REG_PARENT_RET);
      }
      emit_native_unwind_jump(emit, emit->exit_label, emit->exc_stack_size);
      emit->last_emit_was_return_value = true;
  }
  
  STATIC void emit_native_raise_varargs(emit_t *emit, mp_uint_t n_args) {
      (void)n_args;
      assert(n_args == 1);
      vtype_kind_t vtype_exc;
      emit_pre_pop_reg(emit, &vtype_exc, REG_ARG_1); // arg1 = object to raise
      if (vtype_exc != VTYPE_PYOBJ) {
          EMIT_NATIVE_VIPER_TYPE_ERROR(emit, MP_ERROR_TEXT("must raise an object"));
      }
      // TODO probably make this 1 call to the runtime (which could even call convert, native_raise(obj, type))
      emit_call(emit, MP_F_NATIVE_RAISE);
  }
  
  STATIC void emit_native_yield(emit_t *emit, int kind) {
      // Note: 1 (yield) or 3 (yield from) labels are reserved for this function, starting at *emit->label_slot
  
      if (emit->do_viper_types) {
          mp_raise_NotImplementedError(MP_ERROR_TEXT("native yield"));
      }
      emit->scope->scope_flags |= MP_SCOPE_FLAG_GENERATOR;
  
      need_stack_settled(emit);
  
      if (kind == MP_EMIT_YIELD_FROM) {
  
          // Top of yield-from loop, conceptually implementing:
          //     for item in generator:
          //         yield item
  
          // Jump to start of loop
          emit_native_jump(emit, *emit->label_slot + 2);
  
          // Label for top of loop
          emit_native_label_assign(emit, *emit->label_slot + 1);
      }
  
      // Save pointer to current stack position for caller to access yielded value
      emit_get_stack_pointer_to_reg_for_pop(emit, REG_TEMP0, 1);
      emit_native_mov_state_reg(emit, OFFSETOF_CODE_STATE_SP, REG_TEMP0);
  
      // Put return type in return value slot
      ASM_MOV_REG_IMM(emit->as, REG_TEMP0, MP_VM_RETURN_YIELD);
      ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_RET_VAL(emit), REG_TEMP0);
  
      // Save re-entry PC
      ASM_MOV_REG_PCREL(emit->as, REG_TEMP0, *emit->label_slot);
      emit_native_mov_state_reg(emit, LOCAL_IDX_GEN_PC(emit), REG_TEMP0);
  
      // Jump to exit handler
      ASM_JUMP(emit->as, emit->exit_label);
  
      // Label re-entry point
      mp_asm_base_label_assign(&emit->as->base, *emit->label_slot);
  
      // Re-open any active exception handler
      if (emit->exc_stack_size > 0) {
          // Find innermost active exception handler, to restore as current handler
          exc_stack_entry_t *e = &emit->exc_stack[emit->exc_stack_size - 1];
          for (; e >= emit->exc_stack; --e) {
              if (e->is_active) {
                  // Found active handler, get its PC
                  ASM_MOV_REG_PCREL(emit->as, REG_RET, e->label);
                  ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_HANDLER_PC(emit), REG_RET);
                  break;
              }
          }
      }
  
      emit_native_adjust_stack_size(emit, 1); // send_value
  
      if (kind == MP_EMIT_YIELD_VALUE) {
          // Check LOCAL_IDX_EXC_VAL for any injected value
          ASM_MOV_REG_LOCAL(emit->as, REG_ARG_1, LOCAL_IDX_EXC_VAL(emit));
          emit_call(emit, MP_F_NATIVE_RAISE);
      } else {
          // Label loop entry
          emit_native_label_assign(emit, *emit->label_slot + 2);
  
          // Get the next item from the delegate generator
          vtype_kind_t vtype;
          emit_pre_pop_reg(emit, &vtype, REG_ARG_2); // send_value
          emit_access_stack(emit, 1, &vtype, REG_ARG_1); // generator
          ASM_MOV_REG_LOCAL(emit->as, REG_ARG_3, LOCAL_IDX_EXC_VAL(emit)); // throw_value
          emit_post_push_reg(emit, VTYPE_PYOBJ, REG_ARG_3);
          emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, 1); // ret_value
          emit_call(emit, MP_F_NATIVE_YIELD_FROM);
  
          // If returned non-zero then generator continues
          ASM_JUMP_IF_REG_NONZERO(emit->as, REG_RET, *emit->label_slot + 1, true);
  
          // Pop exhausted gen, replace with ret_value
          emit_native_adjust_stack_size(emit, 1); // ret_value
          emit_fold_stack_top(emit, REG_ARG_1);
      }
  }
  
  STATIC void emit_native_start_except_handler(emit_t *emit) {
      // Protected block has finished so leave the current exception handler
      emit_native_leave_exc_stack(emit, true);
  
      // Get and push nlr_buf.ret_val
      ASM_MOV_REG_LOCAL(emit->as, REG_TEMP0, LOCAL_IDX_EXC_VAL(emit));
      emit_post_push_reg(emit, VTYPE_PYOBJ, REG_TEMP0);
  }
  
  STATIC void emit_native_end_except_handler(emit_t *emit) {
      adjust_stack(emit, -1); // pop the exception (end_finally didn't use it)
  }
  
  const emit_method_table_t EXPORT_FUN(method_table) = {
      #if MICROPY_DYNAMIC_COMPILER
      EXPORT_FUN(new),
      EXPORT_FUN(free),
      #endif
  
      emit_native_start_pass,
      emit_native_end_pass,
      emit_native_last_emit_was_return_value,
      emit_native_adjust_stack_size,
      emit_native_set_source_line,
  
      {
          emit_native_load_local,
          emit_native_load_global,
      },
      {
          emit_native_store_local,
          emit_native_store_global,
      },
      {
          emit_native_delete_local,
          emit_native_delete_global,
      },
  
      emit_native_label_assign,
      emit_native_import,
      emit_native_load_const_tok,
      emit_native_load_const_small_int,
      emit_native_load_const_str,
      emit_native_load_const_obj,
      emit_native_load_null,
      emit_native_load_method,
      emit_native_load_build_class,
      emit_native_subscr,
      emit_native_attr,
      emit_native_dup_top,
      emit_native_dup_top_two,
      emit_native_pop_top,
      emit_native_rot_two,
      emit_native_rot_three,
      emit_native_jump,
      emit_native_pop_jump_if,
      emit_native_jump_if_or_pop,
      emit_native_unwind_jump,
      emit_native_setup_block,
      emit_native_with_cleanup,
      emit_native_end_finally,
      emit_native_get_iter,
      emit_native_for_iter,
      emit_native_for_iter_end,
      emit_native_pop_except_jump,
      emit_native_unary_op,
      emit_native_binary_op,
      emit_native_build,
      emit_native_store_map,
      emit_native_store_comp,
      emit_native_unpack_sequence,
      emit_native_unpack_ex,
      emit_native_make_function,
      emit_native_make_closure,
      emit_native_call_function,
      emit_native_call_method,
      emit_native_return_value,
      emit_native_raise_varargs,
      emit_native_yield,
  
      emit_native_start_except_handler,
      emit_native_end_except_handler,
  };
  
  #endif
  