path: root/deps/v8/src/codegen/arm/macro-assembler-arm.h

// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef INCLUDED_FROM_MACRO_ASSEMBLER_H
#error This header must be included via macro-assembler.h
#endif

#ifndef V8_CODEGEN_ARM_MACRO_ASSEMBLER_ARM_H_
#define V8_CODEGEN_ARM_MACRO_ASSEMBLER_ARM_H_

#include "src/codegen/arm/assembler-arm.h"
#include "src/codegen/bailout-reason.h"
#include "src/common/globals.h"
#include "src/objects/contexts.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);
}

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);

enum TargetAddressStorageMode {
  CAN_INLINE_TARGET_ADDRESS,
  NEVER_INLINE_TARGET_ADDRESS
};

class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
 public:
  using TurboAssemblerBase::TurboAssemblerBase;

  // Activation support.
  void EnterFrame(StackFrame::Type type,
                  bool load_constant_pool_pointer_reg = false);
  // Returns the pc offset at which the frame ends.
  int LeaveFrame(StackFrame::Type type);

// Allocate stack space of given size (i.e. decrement {sp} by the value
// stored in the given register, or by a constant). If you need to perform a
// stack check, do it before calling this function because this function may
// write into the newly allocated space. It may also overwrite the given
// register's value, in the version that takes a register.
#ifdef V8_OS_WIN
  void AllocateStackSpace(Register bytes_scratch);
  void AllocateStackSpace(int bytes);
#else
  void AllocateStackSpace(Register bytes) { sub(sp, sp, bytes); }
  void AllocateStackSpace(int bytes) { sub(sp, sp, Operand(bytes)); }
#endif

  // Push a fixed frame, consisting of lr, fp
  void PushCommonFrame(Register marker_reg = no_reg);

  // Generates function and stub prologue code.
  void StubPrologue(StackFrame::Type type);
  void Prologue();

  // Push a standard frame, consisting of lr, fp, context and JS function
  void PushStandardFrame(Register function_reg);

  void InitializeRootRegister();

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

  void Push(Handle<HeapObject> handle);
  void Push(Smi smi);

  // Push two registers.  Pushes leftmost register first (to highest address).
  void Push(Register src1, Register src2, Condition cond = al) {
    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) {
    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) {
    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);
    }
  }

  // Push five registers.  Pushes leftmost register first (to highest address).
  void Push(Register src1, Register src2, Register src3, Register src4,
            Register src5, Condition cond = al) {
    if (src1.code() > src2.code()) {
      if (src2.code() > src3.code()) {
        if (src3.code() > src4.code()) {
          if (src4.code() > src5.code()) {
            stm(db_w, sp,
                src1.bit() | src2.bit() | src3.bit() | src4.bit() | src5.bit(),
                cond);
          } else {
            stm(db_w, sp, src1.bit() | src2.bit() | src3.bit() | src4.bit(),
                cond);
            str(src5, MemOperand(sp, 4, NegPreIndex), cond);
          }
        } else {
          stm(db_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);
          Push(src4, src5, cond);
        }
      } else {
        stm(db_w, sp, src1.bit() | src2.bit(), cond);
        Push(src3, src4, src5, cond);
      }
    } else {
      str(src1, MemOperand(sp, 4, NegPreIndex), cond);
      Push(src2, src3, src4, src5, cond);
    }
  }

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

  // Pop two registers. Pops rightmost register first (from lower address).
  void Pop(Register src1, Register src2, Condition cond = al) {
    DCHECK(src1 != 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) {
    DCHECK(!AreAliased(src1, src2, 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);
      ldr(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) {
    DCHECK(!AreAliased(src1, src2, src3, 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);
    }
  }

  // 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 = 0,
                            Register scratch = no_reg);

  // Removes current frame and its arguments from the stack preserving
  // the arguments and a return address pushed to the stack for the next call.
  // Both |callee_args_count| and |caller_args_count_reg| do not include
  // receiver. |callee_args_count| is not modified, |caller_args_count_reg|
  // is trashed.
  void PrepareForTailCall(const ParameterCount& callee_args_count,
                          Register caller_args_count_reg, Register scratch0,
                          Register scratch1);

  // 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 MovToFloatParameter(DwVfpRegister src);
  void MovToFloatParameters(DwVfpRegister src1, DwVfpRegister src2);
  void MovToFloatResult(DwVfpRegister src);

  // 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 MovFromFloatParameter(DwVfpRegister dst);
  void MovFromFloatResult(DwVfpRegister dst);

  // Calls Abort(msg) if the condition cond is not satisfied.
  // Use --debug-code to enable.
  void Assert(Condition cond, AbortReason reason);

  // Like Assert(), but without condition.
  // Use --debug-code to enable.
  void AssertUnreachable(AbortReason reason);

  // Like Assert(), but always enabled.
  void Check(Condition cond, AbortReason reason);

  // Print a message to stdout and abort execution.
  void Abort(AbortReason msg);

  void LslPair(Register dst_low, Register dst_high, Register src_low,
               Register src_high, Register shift);
  void LslPair(Register dst_low, Register dst_high, Register src_low,
               Register src_high, uint32_t shift);
  void LsrPair(Register dst_low, Register dst_high, Register src_low,
               Register src_high, Register shift);
  void LsrPair(Register dst_low, Register dst_high, Register src_low,
               Register src_high, uint32_t shift);
  void AsrPair(Register dst_low, Register dst_high, Register src_low,
               Register src_high, Register shift);
  void AsrPair(Register dst_low, Register dst_high, Register src_low,
               Register src_high, uint32_t shift);

  void LoadFromConstantsTable(Register destination,
                              int constant_index) override;
  void LoadRootRegisterOffset(Register destination, intptr_t offset) override;
  void LoadRootRelative(Register destination, int32_t offset) override;

  // Call a runtime routine. This expects {centry} to contain a fitting CEntry
  // builtin for the target runtime function and uses an indirect call.
  void CallRuntimeWithCEntry(Runtime::FunctionId fid, Register centry);

  // Jump, Call, and Ret pseudo instructions implementing inter-working.
  void Call(Register target, Condition cond = al);
  void Call(Address target, RelocInfo::Mode rmode, Condition cond = al,
            TargetAddressStorageMode mode = CAN_INLINE_TARGET_ADDRESS,
            bool check_constant_pool = true);
  void Call(Handle<Code> code, RelocInfo::Mode rmode = RelocInfo::CODE_TARGET,
            Condition cond = al,
            TargetAddressStorageMode mode = CAN_INLINE_TARGET_ADDRESS,
            bool check_constant_pool = true);
  void Call(Label* target);

  // Load the builtin given by the Smi in |builtin_index| into the same
  // register.
  void LoadEntryFromBuiltinIndex(Register builtin_index);
  void CallBuiltinByIndex(Register builtin_index) override;

  void LoadCodeObjectEntry(Register destination, Register code_object) override;
  void CallCodeObject(Register code_object) override;
  void JumpCodeObject(Register code_object) override;

  // Generates an instruction sequence s.t. the return address points to the
  // instruction following the call.
  // The return address on the stack is used by frame iteration.
  void StoreReturnAddressAndCall(Register target);

  // This should only be used when assembling a deoptimizer call because of
  // the CheckConstPool invocation, which is only needed for deoptimization.
  void CallForDeoptimization(Address target, int deopt_id);

  // 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 Drop(Register count, Condition cond = al);

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

  // Compare single values and move the result to the normal condition flags.
  void VFPCompareAndSetFlags(const SwVfpRegister src1, const SwVfpRegister src2,
                             const Condition cond = al);
  void VFPCompareAndSetFlags(const SwVfpRegister src1, const float src2,
                             const Condition cond = al);

  // 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);

  // 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);
  }

  void VmovHigh(Register dst, DwVfpRegister src);
  void VmovHigh(DwVfpRegister dst, Register src);
  void VmovLow(Register dst, DwVfpRegister src);
  void VmovLow(DwVfpRegister dst, Register src);

  void CheckPageFlag(Register object, int mask, Condition cc,
                     Label* condition_met);

  // 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);

  void SaveRegisters(RegList registers);
  void RestoreRegisters(RegList registers);

  void CallRecordWriteStub(Register object, Operand offset,
                           RememberedSetAction remembered_set_action,
                           SaveFPRegsMode fp_mode);
  void CallRecordWriteStub(Register object, Operand offset,
                           RememberedSetAction remembered_set_action,
                           SaveFPRegsMode fp_mode, Address wasm_target);
  void CallEphemeronKeyBarrier(Register object, Operand offset,
                               SaveFPRegsMode fp_mode);

  // For a given |object| and |offset|:
  //   - Move |object| to |dst_object|.
  //   - Compute the address of the slot pointed to by |offset| in |object| and
  //     write it to |dst_slot|. |offset| can be either an immediate or a
  //     register.
  // This method makes sure |object| and |offset| are allowed to overlap with
  // the destination registers.
  void MoveObjectAndSlot(Register dst_object, Register dst_slot,
                         Register object, Operand offset);

  // 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);

  // Calculate how much stack space (in bytes) are required to store caller
  // registers excluding those specified in the arguments.
  int RequiredStackSizeForCallerSaved(SaveFPRegsMode fp_mode,
                                      Register exclusion1 = no_reg,
                                      Register exclusion2 = no_reg,
                                      Register exclusion3 = no_reg) const;

  // Push caller saved registers on the stack, and return the number of bytes
  // stack pointer is adjusted.
  int PushCallerSaved(SaveFPRegsMode fp_mode, Register exclusion1 = no_reg,
                      Register exclusion2 = no_reg,
                      Register exclusion3 = no_reg);
  // Restore caller saved registers from the stack, and return the number of
  // bytes stack pointer is adjusted.
  int PopCallerSaved(SaveFPRegsMode fp_mode, Register exclusion1 = no_reg,
                     Register exclusion2 = no_reg,
                     Register exclusion3 = no_reg);
  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);

  // Perform a floating-point min or max operation with the
  // (IEEE-754-compatible) semantics of ARM64's fmin/fmax. Some cases, typically
  // NaNs or +/-0.0, are expected to be rare and are handled in out-of-line
  // code. The specific behaviour depends on supported instructions.
  //
  // These functions assume (and assert) that left!=right. It is permitted
  // for the result to alias either input register.
  void FloatMax(SwVfpRegister result, SwVfpRegister left, SwVfpRegister right,
                Label* out_of_line);
  void FloatMin(SwVfpRegister result, SwVfpRegister left, SwVfpRegister right,
                Label* out_of_line);
  void FloatMax(DwVfpRegister result, DwVfpRegister left, DwVfpRegister right,
                Label* out_of_line);
  void FloatMin(DwVfpRegister result, DwVfpRegister left, DwVfpRegister right,
                Label* out_of_line);

  // Generate out-of-line cases for the macros above.
  void FloatMaxOutOfLine(SwVfpRegister result, SwVfpRegister left,
                         SwVfpRegister right);
  void FloatMinOutOfLine(SwVfpRegister result, SwVfpRegister left,
                         SwVfpRegister right);
  void FloatMaxOutOfLine(DwVfpRegister result, DwVfpRegister left,
                         DwVfpRegister right);
  void FloatMinOutOfLine(DwVfpRegister result, DwVfpRegister left,
                         DwVfpRegister right);

  void ExtractLane(Register dst, QwNeonRegister src, NeonDataType dt, int lane);
  void ExtractLane(Register dst, DwVfpRegister src, NeonDataType dt, int lane);
  void ExtractLane(SwVfpRegister dst, QwNeonRegister src, int lane);
  void ReplaceLane(QwNeonRegister dst, QwNeonRegister src, Register src_lane,
                   NeonDataType dt, int lane);
  void ReplaceLane(QwNeonRegister dst, QwNeonRegister src,
                   SwVfpRegister src_lane, int lane);

  // Register move. May do nothing if the registers are identical.
  void Move(Register dst, Smi smi);
  void Move(Register dst, Handle<HeapObject> value);
  void Move(Register dst, ExternalReference reference);
  void Move(Register dst, Register src, Condition cond = al);
  void Move(Register dst, const Operand& src, SBit sbit = LeaveCC,
            Condition cond = al) {
    if (!src.IsRegister() || src.rm() != dst || sbit != LeaveCC) {
      mov(dst, src, sbit, cond);
    }
  }
  // Move src0 to dst0 and src1 to dst1, handling possible overlaps.
  void MovePair(Register dst0, Register src0, Register dst1, Register src1);

  void Move(SwVfpRegister dst, SwVfpRegister src, Condition cond = al);
  void Move(DwVfpRegister dst, DwVfpRegister src, Condition cond = al);
  void Move(QwNeonRegister dst, QwNeonRegister src);

  // Simulate s-register moves for imaginary s32 - s63 registers.
  void VmovExtended(Register dst, int src_code);
  void VmovExtended(int dst_code, Register src);
  // Move between s-registers and imaginary s-registers.
  void VmovExtended(int dst_code, int src_code);
  void VmovExtended(int dst_code, const MemOperand& src);
  void VmovExtended(const MemOperand& dst, int src_code);

  // Register swap. Note that the register operands should be distinct.
  void Swap(Register srcdst0, Register srcdst1);
  void Swap(DwVfpRegister srcdst0, DwVfpRegister srcdst1);
  void Swap(QwNeonRegister srcdst0, QwNeonRegister srcdst1);

  // Get the actual activation frame alignment for target environment.
  static int ActivationFrameAlignment();

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

  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);
  }

  // Load an object from the root table.
  void LoadRoot(Register destination, RootIndex index) override {
    LoadRoot(destination, index, al);
  }
  void LoadRoot(Register destination, RootIndex index, Condition cond);

  // Jump if the register contains a smi.
  void JumpIfSmi(Register value, Label* smi_label);

  void JumpIfEqual(Register x, int32_t y, Label* dest);
  void JumpIfLessThan(Register x, int32_t y, Label* dest);

  // 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.
  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(Isolate* isolate, Zone* zone, Register result,
                         DwVfpRegister double_input, StubCallMode stub_mode);

  // EABI variant for double arguments in use.
  bool use_eabi_hardfloat() {
#ifdef __arm__
    return base::OS::ArmUsingHardFloat();
#elif USE_EABI_HARDFLOAT
    return true;
#else
    return false;
#endif
  }

  // Compute the start of the generated instruction stream from the current PC.
  // This is an alternative to embedding the {CodeObject} handle as a reference.
  void ComputeCodeStartAddress(Register dst);

  void ResetSpeculationPoisonRegister();

 private:
  // Compare single values and then load the fpscr flags to a register.
  void VFPCompareAndLoadFlags(const SwVfpRegister src1,
                              const SwVfpRegister src2,
                              const Register fpscr_flags,
                              const Condition cond = al);
  void VFPCompareAndLoadFlags(const SwVfpRegister src1, const float src2,
                              const Register fpscr_flags,
                              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 Jump(intptr_t target, RelocInfo::Mode rmode, Condition cond = al);

  // Implementation helpers for FloatMin and FloatMax.
  template <typename T>
  void FloatMaxHelper(T result, T left, T right, Label* out_of_line);
  template <typename T>
  void FloatMinHelper(T result, T left, T right, Label* out_of_line);
  template <typename T>
  void FloatMaxOutOfLineHelper(T result, T left, T right);
  template <typename T>
  void FloatMinOutOfLineHelper(T result, T left, T right);

  int CalculateStackPassedWords(int num_reg_arguments,
                                int num_double_arguments);

  void CallCFunctionHelper(Register function, int num_reg_arguments,
                           int num_double_arguments);

  void CallRecordWriteStub(Register object, Operand offset,
                           RememberedSetAction remembered_set_action,
                           SaveFPRegsMode fp_mode, Handle<Code> code_target,
                           Address wasm_target);
};

// MacroAssembler implements a collection of frequently used macros.
class V8_EXPORT_PRIVATE MacroAssembler : public TurboAssembler {
 public:
  using TurboAssembler::TurboAssembler;

  void Mls(Register dst, Register src1, Register src2, Register srcA,
           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);

  // ---------------------------------------------------------------------------
  // GC Support

  // 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.
  // The offset is the offset from the start of the object, not the offset from
  // the tagged HeapObject pointer.  For use with FieldMemOperand(reg, off).
  void RecordWriteField(
      Register object, int offset, Register value, LinkRegisterStatus lr_status,
      SaveFPRegsMode save_fp,
      RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
      SmiCheck smi_check = INLINE_SMI_CHECK);

  // For a given |object| notify the garbage collector that the slot at |offset|
  // has been written. |value| is the object being stored.
  void RecordWrite(
      Register object, Operand offset, Register value,
      LinkRegisterStatus lr_status, SaveFPRegsMode save_fp,
      RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,
      SmiCheck smi_check = INLINE_SMI_CHECK);

  // Enter exit frame.
  // stack_space - extra stack space, used for alignment before call to C.
  void EnterExitFrame(bool save_doubles, int stack_space = 0,
                      StackFrame::Type frame_type = StackFrame::EXIT);

  // 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 argument_count_is_length = false);

  // Load the global proxy from the current context.
  void LoadGlobalProxy(Register dst);

  void LoadNativeContextSlot(int index, Register dst);

  // ---------------------------------------------------------------------------
  // JavaScript invokes

  // Invoke the JavaScript function code by either calling or jumping.
  void InvokeFunctionCode(Register function, Register new_target,
                          const ParameterCount& expected,
                          const ParameterCount& actual, InvokeFlag flag);

  // On function call, call into the debugger if necessary.
  void CheckDebugHook(Register fun, Register new_target,
                      const ParameterCount& expected,
                      const ParameterCount& actual);

  // Invoke the JavaScript function in the given register. Changes the
  // current context to the context in the function before invoking.
  void InvokeFunction(Register function, Register new_target,
                      const ParameterCount& actual, InvokeFlag flag);

  void InvokeFunction(Register function, const ParameterCount& expected,
                      const ParameterCount& actual, InvokeFlag flag);

  // Frame restart support
  void MaybeDropFrames();

  // Exception handling

  // Push a new stack handler and link into stack handler chain.
  void PushStackHandler();

  // Unlink the stack handler on top of the stack from the stack handler chain.
  // Must preserve the result register.
  void PopStackHandler();

  // ---------------------------------------------------------------------------
  // Support functions.

  // 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.
  // Type_reg can be no_reg. In that case a scratch register is used.
  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);

  // Compare the object in a register to a value from the root list.
  // Acquires a scratch register.
  void CompareRoot(Register obj, RootIndex index);
  void PushRoot(RootIndex index) {
    UseScratchRegisterScope temps(this);
    Register scratch = temps.Acquire();
    LoadRoot(scratch, index);
    Push(scratch);
  }

  // Compare the object in a register to a value and jump if they are equal.
  void JumpIfRoot(Register with, RootIndex index, Label* if_equal) {
    CompareRoot(with, index);
    b(eq, if_equal);
  }

  // Compare the object in a register to a value and jump if they are not equal.
  void JumpIfNotRoot(Register with, RootIndex index, Label* if_not_equal) {
    CompareRoot(with, index);
    b(ne, if_not_equal);
  }

  // Checks if value is in range [lower_limit, higher_limit] using a single
  // comparison.
  void JumpIfIsInRange(Register value, unsigned lower_limit,
                       unsigned higher_limit, Label* on_in_range);

  // ---------------------------------------------------------------------------
  // Runtime calls

  // Call a runtime routine.
  void CallRuntime(const Runtime::Function* f, int num_arguments,
                   SaveFPRegsMode save_doubles = kDontSaveFPRegs);

  // Convenience function: Same as above, but takes the fid instead.
  void CallRuntime(Runtime::FunctionId fid,
                   SaveFPRegsMode save_doubles = kDontSaveFPRegs) {
    const Runtime::Function* function = Runtime::FunctionForId(fid);
    CallRuntime(function, function->nargs, save_doubles);
  }

  // Convenience function: Same as above, but takes the fid instead.
  void CallRuntime(Runtime::FunctionId fid, int num_arguments,
                   SaveFPRegsMode save_doubles = kDontSaveFPRegs) {
    CallRuntime(Runtime::FunctionForId(fid), num_arguments, save_doubles);
  }

  // Convenience function: tail call a runtime routine (jump).
  void TailCallRuntime(Runtime::FunctionId fid);

  // Jump to a runtime routine.
  void JumpToExternalReference(const ExternalReference& builtin,
                               bool builtin_exit_frame = false);

  // Generates a trampoline to jump to the off-heap instruction stream.
  void JumpToInstructionStream(Address entry);

  // ---------------------------------------------------------------------------
  // In-place weak references.
  void LoadWeakValue(Register out, Register in, Label* target_if_cleared);

  // ---------------------------------------------------------------------------
  // StatsCounter support

  void IncrementCounter(StatsCounter* counter, int value, Register scratch1,
                        Register scratch2);
  void DecrementCounter(StatsCounter* counter, int value, Register scratch1,
                        Register scratch2);

  // ---------------------------------------------------------------------------
  // Smi utilities

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

  // Test if the register contains a smi (Z == 0 (eq) if true).
  void SmiTst(Register value);
  // Jump if either of the registers contain a non-smi.
  void JumpIfNotSmi(Register value, Label* not_smi_label);

  // 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 Constructor, enabled via --debug-code.
  void AssertConstructor(Register object);

  // Abort execution if argument is not a JSFunction, enabled via --debug-code.
  void AssertFunction(Register object);

  // Abort execution if argument is not a JSBoundFunction,
  // enabled via --debug-code.
  void AssertBoundFunction(Register object);

  // Abort execution if argument is not a JSGeneratorObject (or subclass),
  // enabled via --debug-code.
  void AssertGeneratorObject(Register object);

  // Abort execution if argument is not undefined or an AllocationSite, enabled
  // via --debug-code.
  void AssertUndefinedOrAllocationSite(Register object, Register scratch);

  template <typename Field>
  void DecodeField(Register dst, Register src) {
    Ubfx(dst, src, Field::kShift, Field::kSize);
  }

  template <typename Field>
  void DecodeField(Register reg) {
    DecodeField<Field>(reg, reg);
  }

 private:
  // Helper functions for generating invokes.
  void InvokePrologue(const ParameterCount& expected,
                      const ParameterCount& actual, Label* done,
                      bool* definitely_mismatches, InvokeFlag flag);

  // Compute memory operands for safepoint stack slots.
  static int SafepointRegisterStackIndex(int reg_code);

  // Needs access to SafepointRegisterStackIndex for compiled frame
  // traversal.
  friend class StandardFrame;

  DISALLOW_IMPLICIT_CONSTRUCTORS(MacroAssembler);
};

// -----------------------------------------------------------------------------
// Static helper functions.

inline MemOperand ContextMemOperand(Register context, int index = 0) {
  return MemOperand(context, Context::SlotOffset(index));
}

inline MemOperand NativeContextMemOperand() {
  return ContextMemOperand(cp, Context::NATIVE_CONTEXT_INDEX);
}

#define ACCESS_MASM(masm) masm->

}  // namespace internal
}  // namespace v8

#endif  // V8_CODEGEN_ARM_MACRO_ASSEMBLER_ARM_H_