CSE2410 Fall 2014 Bounce

// Copyright 2012 the V8 project authors. All rights reserved.

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

//       notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

//       copyright notice, this list of conditions and the following

//       disclaimer in the documentation and/or other materials provided

//       with the distribution.

//     * Neither the name of Google Inc. nor the names of its

//       contributors may be used to endorse or promote products derived

//       from this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_ARM_MACRO_ASSEMBLER_ARM_H_

#define V8_ARM_MACRO_ASSEMBLER_ARM_H_

#include "assembler.h"

#include "frames.h"

#include "v8globals.h"

namespace v8 {

namespace internal {

// ----------------------------------------------------------------------------

// Static helper functions

// Generate a MemOperand for loading a field from an object.

inline MemOperand FieldMemOperand(Register object, int offset) {

  return MemOperand(object, offset - kHeapObjectTag);

}

// Give alias names to registers

const Register pp = { kRegister_r7_Code };  // Constant pool pointer.

const Register cp = { kRegister_r8_Code };  // JavaScript context pointer.

const Register kRootRegister = { kRegister_r10_Code };  // Roots array pointer.

// Flags used for AllocateHeapNumber

enum TaggingMode {

  // Tag the result.

  TAG_RESULT,

  // Don't tag

  DONT_TAG_RESULT

};

enum RememberedSetAction { EMIT_REMEMBERED_SET, OMIT_REMEMBERED_SET };

enum SmiCheck { INLINE_SMI_CHECK, OMIT_SMI_CHECK };

enum LinkRegisterStatus { kLRHasNotBeenSaved, kLRHasBeenSaved };

Register GetRegisterThatIsNotOneOf(Register reg1,

                                   Register reg2 = no_reg,

                                   Register reg3 = no_reg,

                                   Register reg4 = no_reg,

                                   Register reg5 = no_reg,

                                   Register reg6 = no_reg);

#ifdef DEBUG

bool AreAliased(Register reg1,

                Register reg2,

                Register reg3 = no_reg,

                Register reg4 = no_reg,

                Register reg5 = no_reg,

                Register reg6 = no_reg);

#endif

enum TargetAddressStorageMode {

  CAN_INLINE_TARGET_ADDRESS,

  NEVER_INLINE_TARGET_ADDRESS

};

// MacroAssembler implements a collection of frequently used macros.

class MacroAssembler: public Assembler {

 public:

  // The isolate parameter can be NULL if the macro assembler should

  // not use isolate-dependent functionality. In this case, it's the

  // responsibility of the caller to never invoke such function on the

  // macro assembler.

  MacroAssembler(Isolate* isolate, void* buffer, int size);

  // Jump, Call, and Ret pseudo instructions implementing inter-working.

  void Jump(Register target, Condition cond = al);

  void Jump(Address target, RelocInfo::Mode rmode, Condition cond = al);

  void Jump(Handle<Code> code, RelocInfo::Mode rmode, Condition cond = al);

  static int CallSize(Register target, Condition cond = al);

  void Call(Register target, Condition cond = al);

  int CallSize(Address target, RelocInfo::Mode rmode, Condition cond = al);

  static int CallSizeNotPredictableCodeSize(Address target,

                                            RelocInfo::Mode rmode,

                                            Condition cond = al);

  void Call(Address target, RelocInfo::Mode rmode,

            Condition cond = al,

            TargetAddressStorageMode mode = CAN_INLINE_TARGET_ADDRESS);

  int CallSize(Handle<Code> code,

               RelocInfo::Mode rmode = RelocInfo::CODE_TARGET,

               TypeFeedbackId ast_id = TypeFeedbackId::None(),

               Condition cond = al);

  void Call(Handle<Code> code,

            RelocInfo::Mode rmode = RelocInfo::CODE_TARGET,

            TypeFeedbackId ast_id = TypeFeedbackId::None(),

            Condition cond = al,

            TargetAddressStorageMode mode = CAN_INLINE_TARGET_ADDRESS);

  void Ret(Condition cond = al);

  // Emit code to discard a non-negative number of pointer-sized elements

  // from the stack, clobbering only the sp register.

  void Drop(int count, Condition cond = al);

  void Ret(int drop, Condition cond = al);

  // Swap two registers.  If the scratch register is omitted then a slightly

  // less efficient form using xor instead of mov is emitted.

  void Swap(Register reg1,

            Register reg2,

            Register scratch = no_reg,

            Condition cond = al);

  void And(Register dst, Register src1, const Operand& src2,

           Condition cond = al);

  void Ubfx(Register dst, Register src, int lsb, int width,

            Condition cond = al);

  void Sbfx(Register dst, Register src, int lsb, int width,

            Condition cond = al);

  // The scratch register is not used for ARMv7.

  // scratch can be the same register as src (in which case it is trashed), but

  // not the same as dst.

  void Bfi(Register dst,

           Register src,

           Register scratch,

           int lsb,

           int width,

           Condition cond = al);

  void Bfc(Register dst, Register src, int lsb, int width, Condition cond = al);

  void Usat(Register dst, int satpos, const Operand& src,

            Condition cond = al);

  void Call(Label* target);

  void Push(Register src) { push(src); }

  void Pop(Register dst) { pop(dst); }

  // Register move. May do nothing if the registers are identical.

  void Move(Register dst, Handle<Object> value);

  void Move(Register dst, Register src, Condition cond = al);

  void Move(DwVfpRegister dst, DwVfpRegister src);

  // Load an object from the root table.

  void LoadRoot(Register destination,

                Heap::RootListIndex index,

                Condition cond = al);

  // Store an object to the root table.

  void StoreRoot(Register source,

                 Heap::RootListIndex index,

                 Condition cond = al);

  // ---------------------------------------------------------------------------

  // GC Support

  void IncrementalMarkingRecordWriteHelper(Register object,

                                           Register value,

                                           Register address);

  enum RememberedSetFinalAction {

    kReturnAtEnd,

    kFallThroughAtEnd

  };

  // Record in the remembered set the fact that we have a pointer to new space

  // at the address pointed to by the addr register.  Only works if addr is not

  // in new space.

  void RememberedSetHelper(Register object,  // Used for debug code.

                           Register addr,

                           Register scratch,

                           SaveFPRegsMode save_fp,

                           RememberedSetFinalAction and_then);

  void CheckPageFlag(Register object,

                     Register scratch,

                     int mask,

                     Condition cc,

                     Label* condition_met);

  void CheckMapDeprecated(Handle<Map> map,

                          Register scratch,

                          Label* if_deprecated);

  // Check if object is in new space.  Jumps if the object is not in new space.

  // The register scratch can be object itself, but scratch will be clobbered.

  void JumpIfNotInNewSpace(Register object,

                           Register scratch,

                           Label* branch) {

    InNewSpace(object, scratch, ne, branch);

  }

  // Check if object is in new space.  Jumps if the object is in new space.

  // The register scratch can be object itself, but it will be clobbered.

  void JumpIfInNewSpace(Register object,

                        Register scratch,

                        Label* branch) {

    InNewSpace(object, scratch, eq, branch);

  }

  // Check if an object has a given incremental marking color.

  void HasColor(Register object,

                Register scratch0,

                Register scratch1,

                Label* has_color,

                int first_bit,

                int second_bit);

  void JumpIfBlack(Register object,

                   Register scratch0,

                   Register scratch1,

                   Label* on_black);

  // Checks the color of an object.  If the object is already grey or black

  // then we just fall through, since it is already live.  If it is white and

  // we can determine that it doesn't need to be scanned, then we just mark it

  // black and fall through.  For the rest we jump to the label so the

  // incremental marker can fix its assumptions.

  void EnsureNotWhite(Register object,

                      Register scratch1,

                      Register scratch2,

                      Register scratch3,

                      Label* object_is_white_and_not_data);

  // Detects conservatively whether an object is data-only, i.e. it does need to

  // be scanned by the garbage collector.

  void JumpIfDataObject(Register value,

                        Register scratch,

                        Label* not_data_object);

  // Notify the garbage collector that we wrote a pointer into an object.

  // |object| is the object being stored into, |value| is the object being

  // stored.  value and scratch registers are clobbered by the operation.

  // The offset is the offset from the start of the object, not the offset from

  // the tagged HeapObject pointer.  For use with FieldOperand(reg, off).

  void RecordWriteField(

      Register object,

      int offset,

      Register value,

      Register scratch,

      LinkRegisterStatus lr_status,

      SaveFPRegsMode save_fp,

      RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,

      SmiCheck smi_check = INLINE_SMI_CHECK);

  // As above, but the offset has the tag presubtracted.  For use with

  // MemOperand(reg, off).

  inline void RecordWriteContextSlot(

      Register context,

      int offset,

      Register value,

      Register scratch,

      LinkRegisterStatus lr_status,

      SaveFPRegsMode save_fp,

      RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,

      SmiCheck smi_check = INLINE_SMI_CHECK) {

    RecordWriteField(context,

                     offset + kHeapObjectTag,

                     value,

                     scratch,

                     lr_status,

                     save_fp,

                     remembered_set_action,

                     smi_check);

  }

  // For a given |object| notify the garbage collector that the slot |address|

  // has been written.  |value| is the object being stored. The value and

  // address registers are clobbered by the operation.

  void RecordWrite(

      Register object,

      Register address,

      Register value,

      LinkRegisterStatus lr_status,

      SaveFPRegsMode save_fp,

      RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,

      SmiCheck smi_check = INLINE_SMI_CHECK);

  // Push a handle.

  void Push(Handle<Object> handle);

  void Push(Smi* smi) { Push(Handle<Smi>(smi, isolate())); }

  // Push two registers.  Pushes leftmost register first (to highest address).

  void Push(Register src1, Register src2, Condition cond = al) {

    ASSERT(!src1.is(src2));

    if (src1.code() > src2.code()) {

      stm(db_w, sp, src1.bit() | src2.bit(), cond);

    } else {

      str(src1, MemOperand(sp, 4, NegPreIndex), cond);

      str(src2, MemOperand(sp, 4, NegPreIndex), cond);

    }

  }

  // Push three registers.  Pushes leftmost register first (to highest address).

  void Push(Register src1, Register src2, Register src3, Condition cond = al) {

    ASSERT(!src1.is(src2));

    ASSERT(!src2.is(src3));

    ASSERT(!src1.is(src3));

    if (src1.code() > src2.code()) {

      if (src2.code() > src3.code()) {

        stm(db_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);

      } else {

        stm(db_w, sp, src1.bit() | src2.bit(), cond);

        str(src3, MemOperand(sp, 4, NegPreIndex), cond);

      }

    } else {

      str(src1, MemOperand(sp, 4, NegPreIndex), cond);

      Push(src2, src3, cond);

    }

  }

  // Push four registers.  Pushes leftmost register first (to highest address).

  void Push(Register src1,

            Register src2,

            Register src3,

            Register src4,

            Condition cond = al) {

    ASSERT(!src1.is(src2));

    ASSERT(!src2.is(src3));

    ASSERT(!src1.is(src3));

    ASSERT(!src1.is(src4));

    ASSERT(!src2.is(src4));

    ASSERT(!src3.is(src4));

    if (src1.code() > src2.code()) {

      if (src2.code() > src3.code()) {

        if (src3.code() > src4.code()) {

          stm(db_w,

              sp,

              src1.bit() | src2.bit() | src3.bit() | src4.bit(),

              cond);

        } else {

          stm(db_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);

          str(src4, MemOperand(sp, 4, NegPreIndex), cond);

        }

      } else {

        stm(db_w, sp, src1.bit() | src2.bit(), cond);

        Push(src3, src4, cond);

      }

    } else {

      str(src1, MemOperand(sp, 4, NegPreIndex), cond);

      Push(src2, src3, src4, cond);

    }

  }

  // Pop two registers. Pops rightmost register first (from lower address).

  void Pop(Register src1, Register src2, Condition cond = al) {

    ASSERT(!src1.is(src2));

    if (src1.code() > src2.code()) {

      ldm(ia_w, sp, src1.bit() | src2.bit(), cond);

    } else {

      ldr(src2, MemOperand(sp, 4, PostIndex), cond);

      ldr(src1, MemOperand(sp, 4, PostIndex), cond);

    }

  }

  // Pop three registers.  Pops rightmost register first (from lower address).

  void Pop(Register src1, Register src2, Register src3, Condition cond = al) {

    ASSERT(!src1.is(src2));

    ASSERT(!src2.is(src3));

    ASSERT(!src1.is(src3));

    if (src1.code() > src2.code()) {

      if (src2.code() > src3.code()) {

        ldm(ia_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);

      } else {

        ldr(src3, MemOperand(sp, 4, PostIndex), cond);

        ldm(ia_w, sp, src1.bit() | src2.bit(), cond);

      }

    } else {

      Pop(src2, src3, cond);

      str(src1, MemOperand(sp, 4, PostIndex), cond);

    }

  }

  // Pop four registers.  Pops rightmost register first (from lower address).

  void Pop(Register src1,

           Register src2,

           Register src3,

           Register src4,

           Condition cond = al) {

    ASSERT(!src1.is(src2));

    ASSERT(!src2.is(src3));

    ASSERT(!src1.is(src3));

    ASSERT(!src1.is(src4));

    ASSERT(!src2.is(src4));

    ASSERT(!src3.is(src4));

    if (src1.code() > src2.code()) {

      if (src2.code() > src3.code()) {

        if (src3.code() > src4.code()) {

          ldm(ia_w,

              sp,

              src1.bit() | src2.bit() | src3.bit() | src4.bit(),

              cond);

        } else {

          ldr(src4, MemOperand(sp, 4, PostIndex), cond);

          ldm(ia_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);

        }

      } else {

        Pop(src3, src4, cond);

        ldm(ia_w, sp, src1.bit() | src2.bit(), cond);

      }

    } else {

      Pop(src2, src3, src4, cond);

      ldr(src1, MemOperand(sp, 4, PostIndex), cond);

    }

  }

  // Push and pop the registers that can hold pointers, as defined by the

  // RegList constant kSafepointSavedRegisters.

  void PushSafepointRegisters();

  void PopSafepointRegisters();

  void PushSafepointRegistersAndDoubles();

  void PopSafepointRegistersAndDoubles();

  // Store value in register src in the safepoint stack slot for

  // register dst.

  void StoreToSafepointRegisterSlot(Register src, Register dst);

  void StoreToSafepointRegistersAndDoublesSlot(Register src, Register dst);

  // Load the value of the src register from its safepoint stack slot

  // into register dst.

  void LoadFromSafepointRegisterSlot(Register dst, Register src);

  // Load two consecutive registers with two consecutive memory locations.

  void Ldrd(Register dst1,

            Register dst2,

            const MemOperand& src,

            Condition cond = al);

  // Store two consecutive registers to two consecutive memory locations.

  void Strd(Register src1,

            Register src2,

            const MemOperand& dst,

            Condition cond = al);

  // Ensure that FPSCR contains values needed by JavaScript.

  // We need the NaNModeControlBit to be sure that operations like

  // vadd and vsub generate the Canonical NaN (if a NaN must be generated).

  // In VFP3 it will be always the Canonical NaN.

  // In VFP2 it will be either the Canonical NaN or the negative version

  // of the Canonical NaN. It doesn't matter if we have two values. The aim

  // is to be sure to never generate the hole NaN.

  void VFPEnsureFPSCRState(Register scratch);

  // If the value is a NaN, canonicalize the value else, do nothing.

  void VFPCanonicalizeNaN(const DwVfpRegister dst,

                          const DwVfpRegister src,

                          const Condition cond = al);

  void VFPCanonicalizeNaN(const DwVfpRegister value,

                          const Condition cond = al) {

    VFPCanonicalizeNaN(value, value, cond);

  }

  // Compare double values and move the result to the normal condition flags.

  void VFPCompareAndSetFlags(const DwVfpRegister src1,

                             const DwVfpRegister src2,

                             const Condition cond = al);

  void VFPCompareAndSetFlags(const DwVfpRegister src1,

                             const double src2,

                             const Condition cond = al);

  // Compare double values and then load the fpscr flags to a register.

  void VFPCompareAndLoadFlags(const DwVfpRegister src1,

                              const DwVfpRegister src2,

                              const Register fpscr_flags,

                              const Condition cond = al);

  void VFPCompareAndLoadFlags(const DwVfpRegister src1,

                              const double src2,

                              const Register fpscr_flags,

                              const Condition cond = al);

  void Vmov(const DwVfpRegister dst,

            const double imm,

            const Register scratch = no_reg);

  void VmovHigh(Register dst, DwVfpRegister src);

  void VmovHigh(DwVfpRegister dst, Register src);

  void VmovLow(Register dst, DwVfpRegister src);

  void VmovLow(DwVfpRegister dst, Register src);

  // Loads the number from object into dst register.

  // If |object| is neither smi nor heap number, |not_number| is jumped to

  // with |object| still intact.

  void LoadNumber(Register object,

                  LowDwVfpRegister dst,

                  Register heap_number_map,

                  Register scratch,

                  Label* not_number);

  // Loads the number from object into double_dst in the double format.

  // Control will jump to not_int32 if the value cannot be exactly represented

  // by a 32-bit integer.

  // Floating point value in the 32-bit integer range that are not exact integer

  // won't be loaded.

  void LoadNumberAsInt32Double(Register object,

                               DwVfpRegister double_dst,

                               Register heap_number_map,

                               Register scratch,

                               LowDwVfpRegister double_scratch,

                               Label* not_int32);

  // Loads the number from object into dst as a 32-bit integer.

  // Control will jump to not_int32 if the object cannot be exactly represented

  // by a 32-bit integer.

  // Floating point value in the 32-bit integer range that are not exact integer

  // won't be converted.

  void LoadNumberAsInt32(Register object,

                         Register dst,

                         Register heap_number_map,

                         Register scratch,

                         DwVfpRegister double_scratch0,

                         LowDwVfpRegister double_scratch1,

                         Label* not_int32);

  // Generates function and stub prologue code.

  void Prologue(PrologueFrameMode frame_mode);

  // Enter exit frame.

  // stack_space - extra stack space, used for alignment before call to C.

  void EnterExitFrame(bool save_doubles, int stack_space = 0);

  // Leave the current exit frame. Expects the return value in r0.

  // Expect the number of values, pushed prior to the exit frame, to

  // remove in a register (or no_reg, if there is nothing to remove).

  void LeaveExitFrame(bool save_doubles,

                      Register argument_count,

                      bool restore_context);

  // Get the actual activation frame alignment for target environment.

  static int ActivationFrameAlignment();

  void LoadContext(Register dst, int context_chain_length);

  // Conditionally load the cached Array transitioned map of type

  // transitioned_kind from the native context if the map in register

  // map_in_out is the cached Array map in the native context of

  // expected_kind.

  void LoadTransitionedArrayMapConditional(

      ElementsKind expected_kind,

      ElementsKind transitioned_kind,

      Register map_in_out,

      Register scratch,

      Label* no_map_match);

  // Load the initial map for new Arrays from a JSFunction.

  void LoadInitialArrayMap(Register function_in,

                           Register scratch,

                           Register map_out,

                           bool can_have_holes);

  void LoadGlobalFunction(int index, Register function);

  void LoadArrayFunction(Register function);

  // Load the initial map from the global function. The registers

  // function and map can be the same, function is then overwritten.

  void LoadGlobalFunctionInitialMap(Register function,

                                    Register map,

                                    Register scratch);

  void InitializeRootRegister() {

    ExternalReference roots_array_start =

        ExternalReference::roots_array_start(isolate());

    mov(kRootRegister, Operand(roots_array_start));

  }

  // ---------------------------------------------------------------------------

  // JavaScript invokes

  // Set up call kind marking in ecx. The method takes ecx as an

  // explicit first parameter to make the code more readable at the

  // call sites.

  void SetCallKind(Register dst, CallKind kind);

  // Invoke the JavaScript function code by either calling or jumping.

  void InvokeCode(Register code,

                  const ParameterCount& expected,

                  const ParameterCount& actual,

                  InvokeFlag flag,

                  const CallWrapper& call_wrapper,

                  CallKind call_kind);

  void InvokeCode(Handle<Code> code,

                  const ParameterCount& expected,

                  const ParameterCount& actual,

                  RelocInfo::Mode rmode,

                  InvokeFlag flag,

                  CallKind call_kind);

  // Invoke the JavaScript function in the given register. Changes the

  // current context to the context in the function before invoking.

  void InvokeFunction(Register function,

                      const ParameterCount& actual,

                      InvokeFlag flag,

                      const CallWrapper& call_wrapper,

                      CallKind call_kind);

  void InvokeFunction(Handle<JSFunction> function,

                      const ParameterCount& expected,

                      const ParameterCount& actual,

                      InvokeFlag flag,

                      const CallWrapper& call_wrapper,

                      CallKind call_kind);

  void IsObjectJSObjectType(Register heap_object,

                            Register map,

                            Register scratch,

                            Label* fail);

  void IsInstanceJSObjectType(Register map,

                              Register scratch,

                              Label* fail);

  void IsObjectJSStringType(Register object,

                            Register scratch,

                            Label* fail);

  void IsObjectNameType(Register object,

                        Register scratch,

                        Label* fail);

#ifdef ENABLE_DEBUGGER_SUPPORT

  // ---------------------------------------------------------------------------

  // Debugger Support

  void DebugBreak();

#endif

  // ---------------------------------------------------------------------------

  // Exception handling

  // Push a new try handler and link into try handler chain.

  void PushTryHandler(StackHandler::Kind kind, int handler_index);

  // Unlink the stack handler on top of the stack from the try handler chain.

  // Must preserve the result register.

  void PopTryHandler();

  // Passes thrown value to the handler of top of the try handler chain.

  void Throw(Register value);

  // Propagates an uncatchable exception to the top of the current JS stack's

  // handler chain.

  void ThrowUncatchable(Register value);

  // ---------------------------------------------------------------------------

  // Inline caching support

  // Generate code for checking access rights - used for security checks

  // on access to global objects across environments. The holder register

  // is left untouched, whereas both scratch registers are clobbered.

  void CheckAccessGlobalProxy(Register holder_reg,

                              Register scratch,

                              Label* miss);

  void GetNumberHash(Register t0, Register scratch);

  void LoadFromNumberDictionary(Label* miss,

                                Register elements,

                                Register key,

                                Register result,

                                Register t0,

                                Register t1,

                                Register t2);

  inline void MarkCode(NopMarkerTypes type) {

    nop(type);

  }

  // Check if the given instruction is a 'type' marker.

  // i.e. check if is is a mov r<type>, r<type> (referenced as nop(type))

  // These instructions are generated to mark special location in the code,

  // like some special IC code.

  static inline bool IsMarkedCode(Instr instr, int type) {

    ASSERT((FIRST_IC_MARKER <= type) && (type < LAST_CODE_MARKER));

    return IsNop(instr, type);

  }

  static inline int GetCodeMarker(Instr instr) {

    int dst_reg_offset = 12;

    int dst_mask = 0xf << dst_reg_offset;

    int src_mask = 0xf;

    int dst_reg = (instr & dst_mask) >> dst_reg_offset;

    int src_reg = instr & src_mask;

    uint32_t non_register_mask = ~(dst_mask | src_mask);

    uint32_t mov_mask = al | 13 << 21;

    // Return <n> if we have a mov rn rn, else return -1.

    int type = ((instr & non_register_mask) == mov_mask) &&

               (dst_reg == src_reg) &&

               (FIRST_IC_MARKER <= dst_reg) && (dst_reg < LAST_CODE_MARKER)

                   ? src_reg

                   : -1;

    ASSERT((type == -1) ||

           ((FIRST_IC_MARKER <= type) && (type < LAST_CODE_MARKER)));

    return type;

  }

  // ---------------------------------------------------------------------------

  // Allocation support

  // Allocate an object in new space or old pointer space. The object_size is

  // specified either in bytes or in words if the allocation flag SIZE_IN_WORDS

  // is passed. If the space is exhausted control continues at the gc_required

  // label. The allocated object is returned in result. If the flag

  // tag_allocated_object is true the result is tagged as as a heap object.

  // All registers are clobbered also when control continues at the gc_required

  // label.

  void Allocate(int object_size,

                Register result,

                Register scratch1,

                Register scratch2,

                Label* gc_required,

                AllocationFlags flags);

  void Allocate(Register object_size,

                Register result,

                Register scratch1,

                Register scratch2,

                Label* gc_required,

                AllocationFlags flags);

  // Undo allocation in new space. The object passed and objects allocated after

  // it will no longer be allocated. The caller must make sure that no pointers

  // are left to the object(s) no longer allocated as they would be invalid when

  // allocation is undone.

  void UndoAllocationInNewSpace(Register object, Register scratch);

  void AllocateTwoByteString(Register result,

                             Register length,

                             Register scratch1,

                             Register scratch2,

                             Register scratch3,

                             Label* gc_required);

  void AllocateAsciiString(Register result,

                           Register length,

                           Register scratch1,

                           Register scratch2,

                           Register scratch3,

                           Label* gc_required);

  void AllocateTwoByteConsString(Register result,

                                 Register length,

                                 Register scratch1,

                                 Register scratch2,

                                 Label* gc_required);

  void AllocateAsciiConsString(Register result,

                               Register length,

                               Register scratch1,

                               Register scratch2,

                               Label* gc_required);

  void AllocateTwoByteSlicedString(Register result,

                                   Register length,

                                   Register scratch1,

                                   Register scratch2,

                                   Label* gc_required);

  void AllocateAsciiSlicedString(Register result,

                                 Register length,

                                 Register scratch1,

                                 Register scratch2,

                                 Label* gc_required);

  // Allocates a heap number or jumps to the gc_required label if the young

  // space is full and a scavenge is needed. All registers are clobbered also

  // when control continues at the gc_required label.

  void AllocateHeapNumber(Register result,

                          Register scratch1,

                          Register scratch2,

                          Register heap_number_map,

                          Label* gc_required,

                          TaggingMode tagging_mode = TAG_RESULT);

  void AllocateHeapNumberWithValue(Register result,

                                   DwVfpRegister value,

                                   Register scratch1,

                                   Register scratch2,

                                   Register heap_number_map,

                                   Label* gc_required);

  // Copies a fixed number of fields of heap objects from src to dst.

  void CopyFields(Register dst,

                  Register src,

                  LowDwVfpRegister double_scratch,

                  int field_count);

  // Copies a number of bytes from src to dst. All registers are clobbered. On

  // exit src and dst will point to the place just after where the last byte was

  // read or written and length will be zero.

  void CopyBytes(Register src,

                 Register dst,

                 Register length,

                 Register scratch);

  // Initialize fields with filler values.  Fields starting at |start_offset|

  // not including end_offset are overwritten with the value in |filler|.  At

  // the end the loop, |start_offset| takes the value of |end_offset|.

  void InitializeFieldsWithFiller(Register start_offset,

                                  Register end_offset,

                                  Register filler);

  // ---------------------------------------------------------------------------

  // Support functions.

  // Try to get function prototype of a function and puts the value in

  // the result register. Checks that the function really is a

  // function and jumps to the miss label if the fast checks fail. The

  // function register will be untouched; the other registers may be

  // clobbered.

  void TryGetFunctionPrototype(Register function,

                               Register result,

                               Register scratch,

                               Label* miss,

                               bool miss_on_bound_function = false);

  // Compare object type for heap object.  heap_object contains a non-Smi

  // whose object type should be compared with the given type.  This both

  // sets the flags and leaves the object type in the type_reg register.

  // It leaves the map in the map register (unless the type_reg and map register

  // are the same register).  It leaves the heap object in the heap_object

  // register unless the heap_object register is the same register as one of the

  // other registers.

  void CompareObjectType(Register heap_object,

                         Register map,

                         Register type_reg,

                         InstanceType type);

  // Compare instance type in a map.  map contains a valid map object whose

  // object type should be compared with the given type.  This both

  // sets the flags and leaves the object type in the type_reg register.

  void CompareInstanceType(Register map,

                           Register type_reg,

                           InstanceType type);

  // Check if a map for a JSObject indicates that the object has fast elements.

  // Jump to the specified label if it does not.

  void CheckFastElements(Register map,

                         Register scratch,

                         Label* fail);

  // Check if a map for a JSObject indicates that the object can have both smi

  // and HeapObject elements.  Jump to the specified label if it does not.

  void CheckFastObjectElements(Register map,

                               Register scratch,

                               Label* fail);

  // Check if a map for a JSObject indicates that the object has fast smi only

  // elements.  Jump to the specified label if it does not.

  void CheckFastSmiElements(Register map,

                            Register scratch,

                            Label* fail);

  // Check to see if maybe_number can be stored as a double in

  // FastDoubleElements. If it can, store it at the index specified by key in

  // the FastDoubleElements array elements. Otherwise jump to fail.

  void StoreNumberToDoubleElements(Register value_reg,

                                   Register key_reg,

                                   Register elements_reg,

                                   Register scratch1,

                                   LowDwVfpRegister double_scratch,

                                   Label* fail,

                                   int elements_offset = 0);

  // Compare an object's map with the specified map and its transitioned

  // elements maps if mode is ALLOW_ELEMENT_TRANSITION_MAPS. Condition flags are

  // set with result of map compare. If multiple map compares are required, the

  // compare sequences branches to early_success.

  void CompareMap(Register obj,

                  Register scratch,

                  Handle<Map> map,

                  Label* early_success);

  // As above, but the map of the object is already loaded into the register

  // which is preserved by the code generated.

  void CompareMap(Register obj_map,

                  Handle<Map> map,

                  Label* early_success);

  // Check if the map of an object is equal to a specified map and branch to

  // label if not. Skip the smi check if not required (object is known to be a

  // heap object). If mode is ALLOW_ELEMENT_TRANSITION_MAPS, then also match

  // against maps that are ElementsKind transition maps of the specified map.

  void CheckMap(Register obj,

                Register scratch,

                Handle<Map> map,

                Label* fail,

                SmiCheckType smi_check_type);

  void CheckMap(Register obj,

                Register scratch,

                Heap::RootListIndex index,

                Label* fail,

                SmiCheckType smi_check_type);

  // Check if the map of an object is equal to a specified map and branch to a

  // specified target if equal. Skip the smi check if not required (object is

  // known to be a heap object)

  void DispatchMap(Register obj,

                   Register scratch,

                   Handle<Map> map,

                   Handle<Code> success,

                   SmiCheckType smi_check_type);

  // Compare the object in a register to a value from the root list.

  // Uses the ip register as scratch.

  void CompareRoot(Register obj, Heap::RootListIndex index);

  // Load and check the instance type of an object for being a string.

  // Loads the type into the second argument register.

  // Returns a condition that will be enabled if the object was a string

  // and the passed-in condition passed. If the passed-in condition failed

  // then flags remain unchanged.

  Condition IsObjectStringType(Register obj,

                               Register type,

                               Condition cond = al) {

    ldr(type, FieldMemOperand(obj, HeapObject::kMapOffset), cond);

    ldrb(type, FieldMemOperand(type, Map::kInstanceTypeOffset), cond);

    tst(type, Operand(kIsNotStringMask), cond);

    ASSERT_EQ(0, kStringTag);

    return eq;

  }

  // Generates code for reporting that an illegal operation has

  // occurred.

  void IllegalOperation(int num_arguments);

  // Picks out an array index from the hash field.

  // Register use:

  //   hash - holds the index's hash. Clobbered.

  //   index - holds the overwritten index on exit.

  void IndexFromHash(Register hash, Register index);

  // Get the number of least significant bits from a register

  void GetLeastBitsFromSmi(Register dst, Register src, int num_least_bits);

  void GetLeastBitsFromInt32(Register dst, Register src, int mun_least_bits);

  // Load the value of a smi object into a double register.

  // The register value must be between d0 and d15.

  void SmiToDouble(LowDwVfpRegister value, Register smi);

  // Check if a double can be exactly represented as a signed 32-bit integer.

  // Z flag set to one if true.

  void TestDoubleIsInt32(DwVfpRegister double_input,

                         LowDwVfpRegister double_scratch);

  // Try to convert a double to a signed 32-bit integer.

  // Z flag set to one and result assigned if the conversion is exact.

  void TryDoubleToInt32Exact(Register result,

                             DwVfpRegister double_input,

                             LowDwVfpRegister double_scratch);

  // Floor a double and writes the value to the result register.

  // Go to exact if the conversion is exact (to be able to test -0),

  // fall through calling code if an overflow occurred, else go to done.

  // In return, input_high is loaded with high bits of input.

  void TryInt32Floor(Register result,

                     DwVfpRegister double_input,

                     Register input_high,

                     LowDwVfpRegister double_scratch,

                     Label* done,

                     Label* exact);

  // Performs a truncating conversion of a floating point number as used by

  // the JS bitwise operations. See ECMA-262 9.5: ToInt32. Goes to 'done' if it

  // succeeds, otherwise falls through if result is saturated. On return

  // 'result' either holds answer, or is clobbered on fall through.

  //

  // Only public for the test code in test-code-stubs-arm.cc.

  void TryInlineTruncateDoubleToI(Register result,

                                  DwVfpRegister input,

                                  Label* done);

  // Performs a truncating conversion of a floating point number as used by

  // the JS bitwise operations. See ECMA-262 9.5: ToInt32.

  // Exits with 'result' holding the answer.

  void TruncateDoubleToI(Register result, DwVfpRegister double_input);

  // Performs a truncating conversion of a heap number as used by

  // the JS bitwise operations. See ECMA-262 9.5: ToInt32. 'result' and 'input'

  // must be different registers.  Exits with 'result' holding the answer.

  void TruncateHeapNumberToI(Register result, Register object);

  // Converts the smi or heap number in object to an int32 using the rules

  // for ToInt32 as described in ECMAScript 9.5.: the value is truncated

  // and brought into the range -2^31 .. +2^31 - 1. 'result' and 'input' must be

  // different registers.

  void TruncateNumberToI(Register object,

                         Register result,

                         Register heap_number_map,

                         Register scratch1,

                         Label* not_int32);

  // Check whether d16-d31 are available on the CPU. The result is given by the

  // Z condition flag: Z==0 if d16-d31 available, Z==1 otherwise.

  void CheckFor32DRegs(Register scratch);

  // Does a runtime check for 16/32 FP registers. Either way, pushes 32 double

  // values to location, saving [d0..(d15|d31)].

  void SaveFPRegs(Register location, Register scratch);

  // Does a runtime check for 16/32 FP registers. Either way, pops 32 double

  // values to location, restoring [d0..(d15|d31)].

  void RestoreFPRegs(Register location, Register scratch);

  // ---------------------------------------------------------------------------

  // Runtime calls

  // Call a code stub.

  void CallStub(CodeStub* stub,

                TypeFeedbackId ast_id = TypeFeedbackId::None(),

                Condition cond = al);

  // Call a code stub.

  void TailCallStub(CodeStub* stub, Condition cond = al);

  // Call a runtime routine.

  void CallRuntime(const Runtime::Function* f,

                   int num_arguments,

                   SaveFPRegsMode save_doubles = kDontSaveFPRegs);

  void CallRuntimeSaveDoubles(Runtime::FunctionId id) {

    const Runtime::Function* function = Runtime::FunctionForId(id);

    CallRuntime(function, function->nargs, kSaveFPRegs);

  }

  // Convenience function: Same as above, but takes the fid instead.

  void CallRuntime(Runtime::FunctionId id, int num_arguments) {

    CallRuntime(Runtime::FunctionForId(id), num_arguments);

  }

  // Convenience function: call an external reference.

  void CallExternalReference(const ExternalReference& ext,

                             int num_arguments);

  // Tail call of a runtime routine (jump).

  // Like JumpToExternalReference, but also takes care of passing the number

  // of parameters.

  void TailCallExternalReference(const ExternalReference& ext,

                                 int num_arguments,

                                 int result_size);

  // Convenience function: tail call a runtime routine (jump).

  void TailCallRuntime(Runtime::FunctionId fid,

                       int num_arguments,

                       int result_size);

  int CalculateStackPassedWords(int num_reg_arguments,

                                int num_double_arguments);

  // Before calling a C-function from generated code, align arguments on stack.

  // After aligning the frame, non-register arguments must be stored in

  // sp[0], sp[4], etc., not pushed. The argument count assumes all arguments

  // are word sized. If double arguments are used, this function assumes that

  // all double arguments are stored before core registers; otherwise the

  // correct alignment of the double values is not guaranteed.

  // Some compilers/platforms require the stack to be aligned when calling

  // C++ code.

  // Needs a scratch register to do some arithmetic. This register will be

  // trashed.

  void PrepareCallCFunction(int num_reg_arguments,

                            int num_double_registers,

                            Register scratch);

  void PrepareCallCFunction(int num_reg_arguments,

                            Register scratch);

  // There are two ways of passing double arguments on ARM, depending on

  // whether soft or hard floating point ABI is used. These functions

  // abstract parameter passing for the three different ways we call

  // C functions from generated code.

  void SetCallCDoubleArguments(DwVfpRegister dreg);

  void SetCallCDoubleArguments(DwVfpRegister dreg1, DwVfpRegister dreg2);

  void SetCallCDoubleArguments(DwVfpRegister dreg, Register reg);

  // Calls a C function and cleans up the space for arguments allocated

  // by PrepareCallCFunction. The called function is not allowed to trigger a

  // garbage collection, since that might move the code and invalidate the

  // return address (unless this is somehow accounted for by the called

  // function).

  void CallCFunction(ExternalReference function, int num_arguments);

  void CallCFunction(Register function, int num_arguments);

  void CallCFunction(ExternalReference function,

                     int num_reg_arguments,

                     int num_double_arguments);

  void CallCFunction(Register function,

                     int num_reg_arguments,

                     int num_double_arguments);

  void GetCFunctionDoubleResult(const DwVfpRegister dst);

  // Calls an API function.  Allocates HandleScope, extracts returned value

  // from handle and propagates exceptions.  Restores context.  stack_space

  // - space to be unwound on exit (includes the call JS arguments space and

  // the additional space allocated for the fast call).

  void CallApiFunctionAndReturn(ExternalReference function,

                                Address function_address,

                                ExternalReference thunk_ref,

                                Register thunk_last_arg,

                                int stack_space,

                                MemOperand return_value_operand,

                                MemOperand* context_restore_operand);

  // Jump to a runtime routine.

  void JumpToExternalReference(const ExternalReference& builtin);

  // Invoke specified builtin JavaScript function. Adds an entry to

  // the unresolved list if the name does not resolve.

  void InvokeBuiltin(Builtins::JavaScript id,

                     InvokeFlag flag,

                     const CallWrapper& call_wrapper = NullCallWrapper());

  // Store the code object for the given builtin in the target register and

  // setup the function in r1.

  void GetBuiltinEntry(Register target, Builtins::JavaScript id);

  // Store the function for the given builtin in the target register.

  void GetBuiltinFunction(Register target, Builtins::JavaScript id);

  Handle<Object> CodeObject() {

    ASSERT(!code_object_.is_null());

    return code_object_;

  }

  // ---------------------------------------------------------------------------

  // StatsCounter support

  void SetCounter(StatsCounter* counter, int value,

                  Register scratch1, Register scratch2);

  void IncrementCounter(StatsCounter* counter, int value,

                        Register scratch1, Register scratch2);

  void DecrementCounter(StatsCounter* counter, int value,

                        Register scratch1, Register scratch2);

  // ---------------------------------------------------------------------------

  // Debugging

  // Calls Abort(msg) if the condition cond is not satisfied.

  // Use --debug_code to enable.

  void Assert(Condition cond, BailoutReason reason);

  void AssertFastElements(Register elements);

  // Like Assert(), but always enabled.

  void Check(Condition cond, BailoutReason reason);

  // Print a message to stdout and abort execution.

  void Abort(BailoutReason msg);

  // Verify restrictions about code generated in stubs.

  void set_generating_stub(bool value) { generating_stub_ = value; }

  bool generating_stub() { return generating_stub_; }

  void set_allow_stub_calls(bool value) { allow_stub_calls_ = value; }

  bool allow_stub_calls() { return allow_stub_calls_; }

  void set_has_frame(bool value) { has_frame_ = value; }

  bool has_frame() { return has_frame_; }

  inline bool AllowThisStubCall(CodeStub* stub);

  // EABI variant for double arguments in use.

  bool use_eabi_hardfloat() {

#ifdef __arm__

    return OS::ArmUsingHardFloat();

#elif USE_EABI_HARDFLOAT

    return true;

#else

    return false;

#endif

  }

  // ---------------------------------------------------------------------------

  // Number utilities

  // Check whether the value of reg is a power of two and not zero. If not

  // control continues at the label not_power_of_two. If reg is a power of two

  // the register scratch contains the value of (reg - 1) when control falls

  // through.

  void JumpIfNotPowerOfTwoOrZero(Register reg,

                                 Register scratch,

                                 Label* not_power_of_two_or_zero);

  // Check whether the value of reg is a power of two and not zero.

  // Control falls through if it is, with scratch containing the mask

  // value (reg - 1).

  // Otherwise control jumps to the 'zero_and_neg' label if the value of reg is

  // zero or negative, or jumps to the 'not_power_of_two' label if the value is

  // strictly positive but not a power of two.

  void JumpIfNotPowerOfTwoOrZeroAndNeg(Register reg,

                                       Register scratch,

                                       Label* zero_and_neg,

                                       Label* not_power_of_two);

  // ---------------------------------------------------------------------------

  // Smi utilities

  void SmiTag(Register reg, SBit s = LeaveCC) {

    add(reg, reg, Operand(reg), s);

  }

  void SmiTag(Register dst, Register src, SBit s = LeaveCC) {

    add(dst, src, Operand(src), s);

  }

  // Try to convert int32 to smi. If the value is to large, preserve

  // the original value and jump to not_a_smi. Destroys scratch and

  // sets flags.

  void TrySmiTag(Register reg, Label* not_a_smi) {

    TrySmiTag(reg, reg, not_a_smi);

  }

  void TrySmiTag(Register reg, Register src, Label* not_a_smi) {

    SmiTag(ip, src, SetCC);

    b(vs, not_a_smi);

    mov(reg, ip);

  }

  void SmiUntag(Register reg, SBit s = LeaveCC) {

    mov(reg, Operand::SmiUntag(reg), s);

  }

  void SmiUntag(Register dst, Register src, SBit s = LeaveCC) {

    mov(dst, Operand::SmiUntag(src), s);

  }

  // Untag the source value into destination and jump if source is a smi.

  // Souce and destination can be the same register.

  void UntagAndJumpIfSmi(Register dst, Register src, Label* smi_case);

  // Untag the source value into destination and jump if source is not a smi.

  // Souce and destination can be the same register.

  void UntagAndJumpIfNotSmi(Register dst, Register src, Label* non_smi_case);

  // Test if the register contains a smi (Z == 0 (eq) if true).

  inline void SmiTst(Register value) {

    tst(value, Operand(kSmiTagMask));

  }

  inline void NonNegativeSmiTst(Register value) {

    tst(value, Operand(kSmiTagMask | kSmiSignMask));

  }

  // Jump if the register contains a smi.

  inline void JumpIfSmi(Register value, Label* smi_label) {

    tst(value, Operand(kSmiTagMask));

    b(eq, smi_label);

  }

  // Jump if either of the registers contain a non-smi.

  inline void JumpIfNotSmi(Register value, Label* not_smi_label) {

    tst(value, Operand(kSmiTagMask));

    b(ne, not_smi_label);

  }

  // Jump if either of the registers contain a non-smi.

  void JumpIfNotBothSmi(Register reg1, Register reg2, Label* on_not_both_smi);

  // Jump if either of the registers contain a smi.

  void JumpIfEitherSmi(Register reg1, Register reg2, Label* on_either_smi);

  // Abort execution if argument is a smi, enabled via --debug-code.

  void AssertNotSmi(Register object);

  void AssertSmi(Register object);

  // Abort execution if argument is not a string, enabled via --debug-code.

  void AssertString(Register object);

  // Abort execution if argument is not a name, enabled via --debug-code.

  void AssertName(Register object);

  // Abort execution if reg is not the root value with the given index,

  // enabled via --debug-code.

  void AssertIsRoot(Register reg, Heap::RootListIndex index);

  // ---------------------------------------------------------------------------

  // HeapNumber utilities

  void JumpIfNotHeapNumber(Register object,

                           Register heap_number_map,

                           Register scratch,

                           Label* on_not_heap_number);

  // ---------------------------------------------------------------------------

  // String utilities

  // Generate code to do a lookup in the number string cache. If the number in

  // the register object is found in the cache the generated code falls through

  // with the result in the result register. The object and the result register

  // can be the same. If the number is not found in the cache the code jumps to

  // the label not_found with only the content of register object unchanged.

  void LookupNumberStringCache(Register object,

                               Register result,

                               Register scratch1,

                               Register scratch2,

                               Register scratch3,

                               Label* not_found);

  // Checks if both objects are sequential ASCII strings and jumps to label

  // if either is not. Assumes that neither object is a smi.

  void JumpIfNonSmisNotBothSequentialAsciiStrings(Register object1,

                                                  Register object2,

                                                  Register scratch1,

                                                  Register scratch2,

                                                  Label* failure);

  // Checks if both objects are sequential ASCII strings and jumps to label

  // if either is not.

  void JumpIfNotBothSequentialAsciiStrings(Register first,

                                           Register second,

                                           Register scratch1,

                                           Register scratch2,

                                           Label* not_flat_ascii_strings);

  // Checks if both instance types are sequential ASCII strings and jumps to

  // label if either is not.

  void JumpIfBothInstanceTypesAreNotSequentialAscii(

      Register first_object_instance_type,

      Register second_object_instance_type,

      Register scratch1,

      Register scratch2,

      Label* failure);

  // Check if instance type is sequential ASCII string and jump to label if

  // it is not.

  void JumpIfInstanceTypeIsNotSequentialAscii(Register type,

                                              Register scratch,

                                              Label* failure);

  void JumpIfNotUniqueName(Register reg, Label* not_unique_name);

  // ---------------------------------------------------------------------------

  // Patching helpers.

  // Get the location of a relocated constant (its address in the constant pool)

  // from its load site.

  void GetRelocatedValueLocation(Register ldr_location,

                                 Register result);

  void ClampUint8(Register output_reg, Register input_reg);

  void ClampDoubleToUint8(Register result_reg,

                          DwVfpRegister input_reg,

                          LowDwVfpRegister double_scratch);

  void LoadInstanceDescriptors(Register map, Register descriptors);

  void EnumLength(Register dst, Register map);

  void NumberOfOwnDescriptors(Register dst, Register map);

  template<typename Field>

  void DecodeField(Register reg) {

    static const int shift = Field::kShift;

    static const int mask = (Field::kMask >> shift) << kSmiTagSize;

    mov(reg, Operand(reg, LSR, shift));

    and_(reg, reg, Operand(mask));

  }

  // Activation support.

  void EnterFrame(StackFrame::Type type);

  void LeaveFrame(StackFrame::Type type);

  // Expects object in r0 and returns map with validated enum cache

  // in r0.  Assumes that any other register can be used as a scratch.

  void CheckEnumCache(Register null_value, Label* call_runtime);

  // AllocationMemento support. Arrays may have an associated

  // AllocationMemento object that can be checked for in order to pretransition

  // to another type.

  // On entry, receiver_reg should point to the array object.

  // scratch_reg gets clobbered.

  // If allocation info is present, condition flags are set to eq.

  void TestJSArrayForAllocationMemento(Register receiver_reg,

                                       Register scratch_reg,

                                       Label* no_memento_found);

  void JumpIfJSArrayHasAllocationMemento(Register receiver_reg,

                                         Register scratch_reg,

                                         Label* memento_found) {

    Label no_memento_found;

    TestJSArrayForAllocationMemento(receiver_reg, scratch_reg,

                                    &no_memento_found);

    b(eq, memento_found);

    bind(&no_memento_found);

  }

 private:

  void CallCFunctionHelper(Register function,

                           int num_reg_arguments,

                           int num_double_arguments);

  void Jump(intptr_t target, RelocInfo::Mode rmode, Condition cond = al);

  // Helper functions for generating invokes.

  void InvokePrologue(const ParameterCount& expected,

                      const ParameterCount& actual,

                      Handle<Code> code_constant,

                      Register code_reg,

                      Label* done,

                      bool* definitely_mismatches,

                      InvokeFlag flag,

                      const CallWrapper& call_wrapper,

                      CallKind call_kind);

  void InitializeNewString(Register string,

                           Register length,