text: // 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.
  
  #if V8_TARGET_ARCH_IA32
  
  #include "src/base/bits.h"
  #include "src/base/division-by-constant.h"
  #include "src/base/utils/random-number-generator.h"
  #include "src/bootstrapper.h"
  #include "src/callable.h"
  #include "src/code-factory.h"
  #include "src/code-stubs.h"
  #include "src/debug/debug.h"
  #include "src/external-reference-table.h"
  #include "src/frame-constants.h"
  #include "src/frames-inl.h"
  #include "src/instruction-stream.h"
  #include "src/runtime/runtime.h"
  #include "src/snapshot/snapshot.h"
  
  #include "src/ia32/assembler-ia32-inl.h"
  #include "src/ia32/macro-assembler-ia32.h"
  
  namespace v8 {
  namespace internal {
  
  // -------------------------------------------------------------------------
  // MacroAssembler implementation.
  
  MacroAssembler::MacroAssembler(Isolate* isolate,
                                 const AssemblerOptions& options, void* buffer,
                                 int size, CodeObjectRequired create_code_object)
      : TurboAssembler(isolate, options, buffer, size, create_code_object) {
    if (create_code_object == CodeObjectRequired::kYes) {
      // Unlike TurboAssembler, which can be used off the main thread and may not
      // allocate, macro assembler creates its own copy of the self-reference
      // marker in order to disambiguate between self-references during nested
      // code generation (e.g.: codegen of the current object triggers stub
      // compilation through CodeStub::GetCode()).
      code_object_ = Handle<HeapObject>::New(
          *isolate->factory()->NewSelfReferenceMarker(), isolate);
    }
  
  #ifdef V8_EMBEDDED_BUILTINS
    // Fake it as long as we use indirections through an embedded external
    // reference. This will let us implement indirections without a real
    // root register.
    // TODO(jgruber, v8:6666): Remove once a real root register exists.
    if (FLAG_embedded_builtins) set_root_array_available(true);
  #endif  // V8_EMBEDDED_BUILTINS
  }
  
  void TurboAssembler::LoadRoot(Register destination, RootIndex index) {
    // TODO(jgruber, v8:6666): Support loads through the root register once it
    // exists.
    if (isolate()->heap()->RootCanBeTreatedAsConstant(index)) {
      Handle<Object> object = isolate()->heap()->root_handle(index);
      if (object->IsSmi()) {
        mov(destination, Immediate(Smi::cast(*object)));
        return;
      } else if (!options().isolate_independent_code) {
        DCHECK(object->IsHeapObject());
        mov(destination, Handle<HeapObject>::cast(object));
        return;
      }
    }
    ExternalReference roots_array_start =
        ExternalReference::roots_array_start(isolate());
    mov(destination, Immediate(static_cast<int>(index)));
    mov(destination,
        StaticArray(destination, times_pointer_size, roots_array_start));
  }
  
  void MacroAssembler::CompareRoot(Register with, Register scratch,
                                   RootIndex index) {
    ExternalReference roots_array_start =
        ExternalReference::roots_array_start(isolate());
    mov(scratch, Immediate(static_cast<int>(index)));
    cmp(with, StaticArray(scratch, times_pointer_size, roots_array_start));
  }
  
  void MacroAssembler::CompareRoot(Register with, RootIndex index) {
    DCHECK(isolate()->heap()->RootCanBeTreatedAsConstant(index));
    Handle<Object> object = isolate()->heap()->root_handle(index);
    if (object->IsHeapObject()) {
      cmp(with, Handle<HeapObject>::cast(object));
    } else {
      cmp(with, Immediate(Smi::cast(*object)));
    }
  }
  
  void MacroAssembler::CompareRoot(Operand with, RootIndex index) {
    DCHECK(isolate()->heap()->RootCanBeTreatedAsConstant(index));
    Handle<Object> object = isolate()->heap()->root_handle(index);
    if (object->IsHeapObject()) {
      cmp(with, Handle<HeapObject>::cast(object));
    } else {
      cmp(with, Immediate(Smi::cast(*object)));
    }
  }
  
  void MacroAssembler::PushRoot(RootIndex index) {
    DCHECK(isolate()->heap()->RootCanBeTreatedAsConstant(index));
    Handle<Object> object = isolate()->heap()->root_handle(index);
    if (object->IsHeapObject()) {
      Push(Handle<HeapObject>::cast(object));
    } else {
      Push(Smi::cast(*object));
    }
  }
  
  void TurboAssembler::LoadFromConstantsTable(Register destination,
                                              int constant_index) {
    DCHECK(!is_ebx_addressable_);
    DCHECK(isolate()->heap()->RootCanBeTreatedAsConstant(
        RootIndex::kBuiltinsConstantsTable));
    // TODO(jgruber): LoadRoot should be a register-relative load once we have
    // the kRootRegister.
    LoadRoot(destination, RootIndex::kBuiltinsConstantsTable);
    mov(destination,
        FieldOperand(destination,
                     FixedArray::kHeaderSize + constant_index * kPointerSize));
  }
  
  void TurboAssembler::LoadRootRegisterOffset(Register destination,
                                              intptr_t offset) {
    DCHECK(!is_ebx_addressable_);
    DCHECK(is_int32(offset));
    // TODO(jgruber): Register-relative load once kRootRegister exists.
    mov(destination, Immediate(ExternalReference::roots_array_start(isolate())));
    if (offset != 0) {
      add(destination, Immediate(offset));
    }
  }
  
  void TurboAssembler::LoadRootRelative(Register destination, int32_t offset) {
    DCHECK(!is_ebx_addressable_);
    // TODO(jgruber): Register-relative load once kRootRegister exists.
    LoadRootRegisterOffset(destination, offset);
    mov(destination, Operand(destination, 0));
  }
  
  void TurboAssembler::LoadAddress(Register destination,
                                   ExternalReference source) {
    if (FLAG_embedded_builtins) {
      if (root_array_available_ && options().isolate_independent_code) {
        IndirectLoadExternalReference(destination, source);
        return;
      }
    }
    mov(destination, Immediate(source));
  }
  
  Operand TurboAssembler::StaticVariable(const ExternalReference& ext) {
    // TODO(jgruber,v8:6666): Root-relative operand once kRootRegister exists.
    return Operand(ext.address(), RelocInfo::EXTERNAL_REFERENCE);
  }
  
  Operand TurboAssembler::StaticArray(Register index, ScaleFactor scale,
                                      const ExternalReference& ext) {
    // TODO(jgruber,v8:6666): Root-relative operand once kRootRegister exists.
    return Operand(index, scale, ext.address(), RelocInfo::EXTERNAL_REFERENCE);
  }
  
  static constexpr Register saved_regs[] = {eax, ecx, edx};
  
  static constexpr int kNumberOfSavedRegs = sizeof(saved_regs) / sizeof(Register);
  
  int TurboAssembler::RequiredStackSizeForCallerSaved(SaveFPRegsMode fp_mode,
                                                      Register exclusion1,
                                                      Register exclusion2,
                                                      Register exclusion3) const {
    int bytes = 0;
    for (int i = 0; i < kNumberOfSavedRegs; i++) {
      Register reg = saved_regs[i];
      if (reg != exclusion1 && reg != exclusion2 && reg != exclusion3) {
        bytes += kPointerSize;
      }
    }
  
    if (fp_mode == kSaveFPRegs) {
      // Count all XMM registers except XMM0.
      bytes += kDoubleSize * (XMMRegister::kNumRegisters - 1);
    }
  
    return bytes;
  }
  
  int TurboAssembler::PushCallerSaved(SaveFPRegsMode fp_mode, Register exclusion1,
                                      Register exclusion2, Register exclusion3) {
    // We don't allow a GC during a store buffer overflow so there is no need to
    // store the registers in any particular way, but we do have to store and
    // restore them.
    int bytes = 0;
    for (int i = 0; i < kNumberOfSavedRegs; i++) {
      Register reg = saved_regs[i];
      if (reg != exclusion1 && reg != exclusion2 && reg != exclusion3) {
        push(reg);
        bytes += kPointerSize;
      }
    }
  
    if (fp_mode == kSaveFPRegs) {
      // Save all XMM registers except XMM0.
      int delta = kDoubleSize * (XMMRegister::kNumRegisters - 1);
      sub(esp, Immediate(delta));
      for (int i = XMMRegister::kNumRegisters - 1; i > 0; i--) {
        XMMRegister reg = XMMRegister::from_code(i);
        movsd(Operand(esp, (i - 1) * kDoubleSize), reg);
      }
      bytes += delta;
    }
  
    return bytes;
  }
  
  int TurboAssembler::PopCallerSaved(SaveFPRegsMode fp_mode, Register exclusion1,
                                     Register exclusion2, Register exclusion3) {
    int bytes = 0;
    if (fp_mode == kSaveFPRegs) {
      // Restore all XMM registers except XMM0.
      int delta = kDoubleSize * (XMMRegister::kNumRegisters - 1);
      for (int i = XMMRegister::kNumRegisters - 1; i > 0; i--) {
        XMMRegister reg = XMMRegister::from_code(i);
        movsd(reg, Operand(esp, (i - 1) * kDoubleSize));
      }
      add(esp, Immediate(delta));
      bytes += delta;
    }
  
    for (int i = kNumberOfSavedRegs - 1; i >= 0; i--) {
      Register reg = saved_regs[i];
      if (reg != exclusion1 && reg != exclusion2 && reg != exclusion3) {
        pop(reg);
        bytes += kPointerSize;
      }
    }
  
    return bytes;
  }
  
  void MacroAssembler::DoubleToI(Register result_reg, XMMRegister input_reg,
                                 XMMRegister scratch, Label* lost_precision,
                                 Label* is_nan, Label::Distance dst) {
    DCHECK(input_reg != scratch);
    cvttsd2si(result_reg, Operand(input_reg));
    Cvtsi2sd(scratch, Operand(result_reg));
    ucomisd(scratch, input_reg);
    j(not_equal, lost_precision, dst);
    j(parity_even, is_nan, dst);
  }
  
  void MacroAssembler::RecordWriteField(Register object, int offset,
                                        Register value, Register dst,
                                        SaveFPRegsMode save_fp,
                                        RememberedSetAction remembered_set_action,
                                        SmiCheck smi_check) {
    // First, check if a write barrier is even needed. The tests below
    // catch stores of Smis.
    Label done;
  
    // Skip barrier if writing a smi.
    if (smi_check == INLINE_SMI_CHECK) {
      JumpIfSmi(value, &done);
    }
  
    // Although the object register is tagged, the offset is relative to the start
    // of the object, so so offset must be a multiple of kPointerSize.
    DCHECK(IsAligned(offset, kPointerSize));
  
    lea(dst, FieldOperand(object, offset));
    if (emit_debug_code()) {
      Label ok;
      test_b(dst, Immediate(kPointerSize - 1));
      j(zero, &ok, Label::kNear);
      int3();
      bind(&ok);
    }
  
    RecordWrite(object, dst, value, save_fp, remembered_set_action,
                OMIT_SMI_CHECK);
  
    bind(&done);
  
    // Clobber clobbered input registers when running with the debug-code flag
    // turned on to provoke errors.
    if (emit_debug_code()) {
      mov(value, Immediate(bit_cast<int32_t>(kZapValue)));
      mov(dst, Immediate(bit_cast<int32_t>(kZapValue)));
    }
  }
  
  void TurboAssembler::SaveRegisters(RegList registers) {
    DCHECK_GT(NumRegs(registers), 0);
    for (int i = 0; i < Register::kNumRegisters; ++i) {
      if ((registers >> i) & 1u) {
        push(Register::from_code(i));
      }
    }
  }
  
  void TurboAssembler::RestoreRegisters(RegList registers) {
    DCHECK_GT(NumRegs(registers), 0);
    for (int i = Register::kNumRegisters - 1; i >= 0; --i) {
      if ((registers >> i) & 1u) {
        pop(Register::from_code(i));
      }
    }
  }
  
  void TurboAssembler::CallRecordWriteStub(
      Register object, Register address,
      RememberedSetAction remembered_set_action, SaveFPRegsMode fp_mode) {
    // TODO(albertnetymk): For now we ignore remembered_set_action and fp_mode,
    // i.e. always emit remember set and save FP registers in RecordWriteStub. If
    // large performance regression is observed, we should use these values to
    // avoid unnecessary work.
  
    Callable const callable =
        Builtins::CallableFor(isolate(), Builtins::kRecordWrite);
    RegList registers = callable.descriptor().allocatable_registers();
  
    SaveRegisters(registers);
  
    Register object_parameter(callable.descriptor().GetRegisterParameter(
        RecordWriteDescriptor::kObject));
    Register slot_parameter(
        callable.descriptor().GetRegisterParameter(RecordWriteDescriptor::kSlot));
    Register remembered_set_parameter(callable.descriptor().GetRegisterParameter(
        RecordWriteDescriptor::kRememberedSet));
    Register fp_mode_parameter(callable.descriptor().GetRegisterParameter(
        RecordWriteDescriptor::kFPMode));
  
    push(object);
    push(address);
  
    pop(slot_parameter);
    pop(object_parameter);
  
    Move(remembered_set_parameter, Smi::FromEnum(remembered_set_action));
    Move(fp_mode_parameter, Smi::FromEnum(fp_mode));
    Call(callable.code(), RelocInfo::CODE_TARGET);
  
    RestoreRegisters(registers);
  }
  
  void MacroAssembler::RecordWrite(Register object, Register address,
                                   Register value, SaveFPRegsMode fp_mode,
                                   RememberedSetAction remembered_set_action,
                                   SmiCheck smi_check) {
    DCHECK(object != value);
    DCHECK(object != address);
    DCHECK(value != address);
    AssertNotSmi(object);
  
    if (remembered_set_action == OMIT_REMEMBERED_SET &&
        !FLAG_incremental_marking) {
      return;
    }
  
    if (emit_debug_code()) {
      Label ok;
      cmp(value, Operand(address, 0));
      j(equal, &ok, Label::kNear);
      int3();
      bind(&ok);
    }
  
    // First, check if a write barrier is even needed. The tests below
    // catch stores of Smis and stores into young gen.
    Label done;
  
    if (smi_check == INLINE_SMI_CHECK) {
      // Skip barrier if writing a smi.
      JumpIfSmi(value, &done, Label::kNear);
    }
  
    CheckPageFlag(value,
                  value,  // Used as scratch.
                  MemoryChunk::kPointersToHereAreInterestingMask, zero, &done,
                  Label::kNear);
    CheckPageFlag(object,
                  value,  // Used as scratch.
                  MemoryChunk::kPointersFromHereAreInterestingMask,
                  zero,
                  &done,
                  Label::kNear);
  
    CallRecordWriteStub(object, address, remembered_set_action, fp_mode);
  
    bind(&done);
  
    // Count number of write barriers in generated code.
    isolate()->counters()->write_barriers_static()->Increment();
    IncrementCounter(isolate()->counters()->write_barriers_dynamic(), 1);
  
    // Clobber clobbered registers when running with the debug-code flag
    // turned on to provoke errors.
    if (emit_debug_code()) {
      mov(address, Immediate(bit_cast<int32_t>(kZapValue)));
      mov(value, Immediate(bit_cast<int32_t>(kZapValue)));
    }
  }
  
  void MacroAssembler::MaybeDropFrames() {
    // Check whether we need to drop frames to restart a function on the stack.
    ExternalReference restart_fp =
        ExternalReference::debug_restart_fp_address(isolate());
    mov(eax, StaticVariable(restart_fp));
    test(eax, eax);
    j(not_zero, BUILTIN_CODE(isolate(), FrameDropperTrampoline),
      RelocInfo::CODE_TARGET);
  }
  
  void TurboAssembler::Cvtsi2ss(XMMRegister dst, Operand src) {
    xorps(dst, dst);
    cvtsi2ss(dst, src);
  }
  
  void TurboAssembler::Cvtsi2sd(XMMRegister dst, Operand src) {
    xorpd(dst, dst);
    cvtsi2sd(dst, src);
  }
  
  void TurboAssembler::Cvtui2ss(XMMRegister dst, Operand src, Register tmp) {
    Label done;
    Register src_reg = src.is_reg_only() ? src.reg() : tmp;
    if (src_reg == tmp) mov(tmp, src);
    cvtsi2ss(dst, src_reg);
    test(src_reg, src_reg);
    j(positive, &done, Label::kNear);
  
    // Compute {src/2 | (src&1)} (retain the LSB to avoid rounding errors).
    if (src_reg != tmp) mov(tmp, src_reg);
    shr(tmp, 1);
    // The LSB is shifted into CF. If it is set, set the LSB in {tmp}.
    Label msb_not_set;
    j(not_carry, &msb_not_set, Label::kNear);
    or_(tmp, Immediate(1));
    bind(&msb_not_set);
    cvtsi2ss(dst, tmp);
    addss(dst, dst);
    bind(&done);
  }
  
  void TurboAssembler::Cvttss2ui(Register dst, Operand src, XMMRegister tmp) {
    Label done;
    cvttss2si(dst, src);
    test(dst, dst);
    j(positive, &done);
    Move(tmp, static_cast<float>(INT32_MIN));
    addss(tmp, src);
    cvttss2si(dst, tmp);
    or_(dst, Immediate(0x80000000));
    bind(&done);
  }
  
  void TurboAssembler::Cvtui2sd(XMMRegister dst, Operand src) {
    Label done;
    cmp(src, Immediate(0));
    ExternalReference uint32_bias = ExternalReference::address_of_uint32_bias();
    Cvtsi2sd(dst, src);
    j(not_sign, &done, Label::kNear);
    addsd(dst, StaticVariable(uint32_bias));
    bind(&done);
  }
  
  void TurboAssembler::Cvttsd2ui(Register dst, Operand src, XMMRegister tmp) {
    Move(tmp, -2147483648.0);
    addsd(tmp, src);
    cvttsd2si(dst, tmp);
    add(dst, Immediate(0x80000000));
  }
  
  void TurboAssembler::ShlPair(Register high, Register low, uint8_t shift) {
    if (shift >= 32) {
      mov(high, low);
      shl(high, shift - 32);
      xor_(low, low);
    } else {
      shld(high, low, shift);
      shl(low, shift);
    }
  }
  
  void TurboAssembler::ShlPair_cl(Register high, Register low) {
    shld_cl(high, low);
    shl_cl(low);
    Label done;
    test(ecx, Immediate(0x20));
    j(equal, &done, Label::kNear);
    mov(high, low);
    xor_(low, low);
    bind(&done);
  }
  
  void TurboAssembler::ShrPair(Register high, Register low, uint8_t shift) {
    if (shift >= 32) {
      mov(low, high);
      shr(low, shift - 32);
      xor_(high, high);
    } else {
      shrd(high, low, shift);
      shr(high, shift);
    }
  }
  
  void TurboAssembler::ShrPair_cl(Register high, Register low) {
    shrd_cl(low, high);
    shr_cl(high);
    Label done;
    test(ecx, Immediate(0x20));
    j(equal, &done, Label::kNear);
    mov(low, high);
    xor_(high, high);
    bind(&done);
  }
  
  void TurboAssembler::SarPair(Register high, Register low, uint8_t shift) {
    if (shift >= 32) {
      mov(low, high);
      sar(low, shift - 32);
      sar(high, 31);
    } else {
      shrd(high, low, shift);
      sar(high, shift);
    }
  }
  
  void TurboAssembler::SarPair_cl(Register high, Register low) {
    shrd_cl(low, high);
    sar_cl(high);
    Label done;
    test(ecx, Immediate(0x20));
    j(equal, &done, Label::kNear);
    mov(low, high);
    sar(high, 31);
    bind(&done);
  }
  
  void MacroAssembler::CmpObjectType(Register heap_object,
                                     InstanceType type,
                                     Register map) {
    mov(map, FieldOperand(heap_object, HeapObject::kMapOffset));
    CmpInstanceType(map, type);
  }
  
  
  void MacroAssembler::CmpInstanceType(Register map, InstanceType type) {
    cmpw(FieldOperand(map, Map::kInstanceTypeOffset), Immediate(type));
  }
  
  void MacroAssembler::AssertSmi(Register object) {
    if (emit_debug_code()) {
      test(object, Immediate(kSmiTagMask));
      Check(equal, AbortReason::kOperandIsNotASmi);
    }
  }
  
  void MacroAssembler::AssertConstructor(Register object) {
    if (emit_debug_code()) {
      test(object, Immediate(kSmiTagMask));
      Check(not_equal, AbortReason::kOperandIsASmiAndNotAConstructor);
      Push(object);
      mov(object, FieldOperand(object, HeapObject::kMapOffset));
      test_b(FieldOperand(object, Map::kBitFieldOffset),
             Immediate(Map::IsConstructorBit::kMask));
      Pop(object);
      Check(not_zero, AbortReason::kOperandIsNotAConstructor);
    }
  }
  
  void MacroAssembler::AssertFunction(Register object) {
    if (emit_debug_code()) {
      test(object, Immediate(kSmiTagMask));
      Check(not_equal, AbortReason::kOperandIsASmiAndNotAFunction);
      Push(object);
      CmpObjectType(object, JS_FUNCTION_TYPE, object);
      Pop(object);
      Check(equal, AbortReason::kOperandIsNotAFunction);
    }
  }
  
  
  void MacroAssembler::AssertBoundFunction(Register object) {
    if (emit_debug_code()) {
      test(object, Immediate(kSmiTagMask));
      Check(not_equal, AbortReason::kOperandIsASmiAndNotABoundFunction);
      Push(object);
      CmpObjectType(object, JS_BOUND_FUNCTION_TYPE, object);
      Pop(object);
      Check(equal, AbortReason::kOperandIsNotABoundFunction);
    }
  }
  
  void MacroAssembler::AssertGeneratorObject(Register object) {
    if (!emit_debug_code()) return;
  
    test(object, Immediate(kSmiTagMask));
    Check(not_equal, AbortReason::kOperandIsASmiAndNotAGeneratorObject);
  
    {
      Push(object);
      Register map = object;
  
      // Load map
      mov(map, FieldOperand(object, HeapObject::kMapOffset));
  
      Label do_check;
      // Check if JSGeneratorObject
      CmpInstanceType(map, JS_GENERATOR_OBJECT_TYPE);
      j(equal, &do_check, Label::kNear);
  
      // Check if JSAsyncGeneratorObject
      CmpInstanceType(map, JS_ASYNC_GENERATOR_OBJECT_TYPE);
  
      bind(&do_check);
      Pop(object);
    }
  
    Check(equal, AbortReason::kOperandIsNotAGeneratorObject);
  }
  
  void MacroAssembler::AssertUndefinedOrAllocationSite(Register object) {
    if (emit_debug_code()) {
      Label done_checking;
      AssertNotSmi(object);
      cmp(object, isolate()->factory()->undefined_value());
      j(equal, &done_checking);
      cmp(FieldOperand(object, 0),
          Immediate(isolate()->factory()->allocation_site_map()));
      Assert(equal, AbortReason::kExpectedUndefinedOrCell);
      bind(&done_checking);
    }
  }
  
  
  void MacroAssembler::AssertNotSmi(Register object) {
    if (emit_debug_code()) {
      test(object, Immediate(kSmiTagMask));
      Check(not_equal, AbortReason::kOperandIsASmi);
    }
  }
  
  void TurboAssembler::StubPrologue(StackFrame::Type type) {
    push(ebp);  // Caller's frame pointer.
    mov(ebp, esp);
    push(Immediate(StackFrame::TypeToMarker(type)));
  }
  
  void TurboAssembler::Prologue() {
    push(ebp);  // Caller's frame pointer.
    mov(ebp, esp);
    push(esi);  // Callee's context.
    push(edi);  // Callee's JS function.
  }
  
  void TurboAssembler::EnterFrame(StackFrame::Type type) {
    push(ebp);
    mov(ebp, esp);
    push(Immediate(StackFrame::TypeToMarker(type)));
  }
  
  void TurboAssembler::LeaveFrame(StackFrame::Type type) {
    if (emit_debug_code()) {
      cmp(Operand(ebp, CommonFrameConstants::kContextOrFrameTypeOffset),
          Immediate(StackFrame::TypeToMarker(type)));
      Check(equal, AbortReason::kStackFrameTypesMustMatch);
    }
    leave();
  }
  
  #ifdef V8_OS_WIN
  void TurboAssembler::AllocateStackFrame(Register bytes_scratch) {
    // In windows, we cannot increment the stack size by more than one page
    // (minimum page size is 4KB) without accessing at least one byte on the
    // page. Check this:
    // https://msdn.microsoft.com/en-us/library/aa227153(v=vs.60).aspx.
    constexpr int kPageSize = 4 * 1024;
    Label check_offset;
    Label touch_next_page;
    jmp(&check_offset);
    bind(&touch_next_page);
    sub(esp, Immediate(kPageSize));
    // Just to touch the page, before we increment further.
    mov(Operand(esp, 0), Immediate(0));
    sub(bytes_scratch, Immediate(kPageSize));
  
    bind(&check_offset);
    cmp(bytes_scratch, kPageSize);
    j(greater, &touch_next_page);
  
    sub(esp, bytes_scratch);
  }
  #endif
  
  void MacroAssembler::EnterBuiltinFrame(Register context, Register target,
                                         Register argc) {
    Push(ebp);
    Move(ebp, esp);
    Push(context);
    Push(target);
    Push(argc);
  }
  
  void MacroAssembler::LeaveBuiltinFrame(Register context, Register target,
                                         Register argc) {
    Pop(argc);
    Pop(target);
    Pop(context);
    leave();
  }
  
  void MacroAssembler::EnterExitFramePrologue(StackFrame::Type frame_type) {
    DCHECK(frame_type == StackFrame::EXIT ||
           frame_type == StackFrame::BUILTIN_EXIT);
  
    // Set up the frame structure on the stack.
    DCHECK_EQ(+2 * kPointerSize, ExitFrameConstants::kCallerSPDisplacement);
    DCHECK_EQ(+1 * kPointerSize, ExitFrameConstants::kCallerPCOffset);
    DCHECK_EQ(0 * kPointerSize, ExitFrameConstants::kCallerFPOffset);
    push(ebp);
    mov(ebp, esp);
  
    // Reserve room for entry stack pointer and push the code object.
    push(Immediate(StackFrame::TypeToMarker(frame_type)));
    DCHECK_EQ(-2 * kPointerSize, ExitFrameConstants::kSPOffset);
    push(Immediate(0));  // Saved entry sp, patched before call.
    DCHECK_EQ(-3 * kPointerSize, ExitFrameConstants::kCodeOffset);
    push(Immediate(CodeObject()));  // Accessed from ExitFrame::code_slot.
  
    STATIC_ASSERT(edx == kRuntimeCallFunctionRegister);
    STATIC_ASSERT(esi == kContextRegister);
  
    // Save the frame pointer and the context in top.
    ExternalReference c_entry_fp_address =
        ExternalReference::Create(IsolateAddressId::kCEntryFPAddress, isolate());
    ExternalReference context_address =
        ExternalReference::Create(IsolateAddressId::kContextAddress, isolate());
    ExternalReference c_function_address =
        ExternalReference::Create(IsolateAddressId::kCFunctionAddress, isolate());
    mov(StaticVariable(c_entry_fp_address), ebp);
    mov(StaticVariable(context_address), esi);
    mov(StaticVariable(c_function_address), edx);
  }
  
  
  void MacroAssembler::EnterExitFrameEpilogue(int argc, bool save_doubles) {
    // Optionally save all XMM registers.
    if (save_doubles) {
      int space = XMMRegister::kNumRegisters * kDoubleSize + argc * kPointerSize;
      sub(esp, Immediate(space));
      const int offset = -ExitFrameConstants::kFixedFrameSizeFromFp;
      for (int i = 0; i < XMMRegister::kNumRegisters; i++) {
        XMMRegister reg = XMMRegister::from_code(i);
        movsd(Operand(ebp, offset - ((i + 1) * kDoubleSize)), reg);
      }
    } else {
      sub(esp, Immediate(argc * kPointerSize));
    }
  
    // Get the required frame alignment for the OS.
    const int kFrameAlignment = base::OS::ActivationFrameAlignment();
    if (kFrameAlignment > 0) {
      DCHECK(base::bits::IsPowerOfTwo(kFrameAlignment));
      and_(esp, -kFrameAlignment);
    }
  
    // Patch the saved entry sp.
    mov(Operand(ebp, ExitFrameConstants::kSPOffset), esp);
  }
  
  void MacroAssembler::EnterExitFrame(int argc, bool save_doubles,
                                      StackFrame::Type frame_type) {
    EnterExitFramePrologue(frame_type);
  
    // Set up argc and argv in callee-saved registers.
    int offset = StandardFrameConstants::kCallerSPOffset - kPointerSize;
    mov(edi, eax);
    lea(esi, Operand(ebp, eax, times_4, offset));
  
    // Reserve space for argc, argv and isolate.
    EnterExitFrameEpilogue(argc, save_doubles);
  }
  
  
  void MacroAssembler::EnterApiExitFrame(int argc) {
    EnterExitFramePrologue(StackFrame::EXIT);
    EnterExitFrameEpilogue(argc, false);
  }
  
  
  void MacroAssembler::LeaveExitFrame(bool save_doubles, bool pop_arguments) {
    // Optionally restore all XMM registers.
    if (save_doubles) {
      const int offset = -ExitFrameConstants::kFixedFrameSizeFromFp;
      for (int i = 0; i < XMMRegister::kNumRegisters; i++) {
        XMMRegister reg = XMMRegister::from_code(i);
        movsd(reg, Operand(ebp, offset - ((i + 1) * kDoubleSize)));
      }
    }
  
    if (pop_arguments) {
      // Get the return address from the stack and restore the frame pointer.
      mov(ecx, Operand(ebp, 1 * kPointerSize));
      mov(ebp, Operand(ebp, 0 * kPointerSize));
  
      // Pop the arguments and the receiver from the caller stack.
      lea(esp, Operand(esi, 1 * kPointerSize));
  
      // Push the return address to get ready to return.
      push(ecx);
    } else {
      // Otherwise just leave the exit frame.
      leave();
    }
  
    LeaveExitFrameEpilogue();
  }
  
  void MacroAssembler::LeaveExitFrameEpilogue() {
    // Restore current context from top and clear it in debug mode.
    ExternalReference context_address =
        ExternalReference::Create(IsolateAddressId::kContextAddress, isolate());
    mov(esi, StaticVariable(context_address));
  #ifdef DEBUG
    mov(StaticVariable(context_address), Immediate(Context::kInvalidContext));
  #endif
  
    // Clear the top frame.
    ExternalReference c_entry_fp_address =
        ExternalReference::Create(IsolateAddressId::kCEntryFPAddress, isolate());
    mov(StaticVariable(c_entry_fp_address), Immediate(0));
  }
  
  void MacroAssembler::LeaveApiExitFrame() {
    mov(esp, ebp);
    pop(ebp);
  
    LeaveExitFrameEpilogue();
  }
  
  
  void MacroAssembler::PushStackHandler() {
    // Adjust this code if not the case.
    STATIC_ASSERT(StackHandlerConstants::kSize == 2 * kPointerSize);
    STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0);
  
    push(Immediate(0));  // Padding.
  
    // Link the current handler as the next handler.
    ExternalReference handler_address =
        ExternalReference::Create(IsolateAddressId::kHandlerAddress, isolate());
    push(StaticVariable(handler_address));
  
    // Set this new handler as the current one.
    mov(StaticVariable(handler_address), esp);
  }
  
  
  void MacroAssembler::PopStackHandler() {
    STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0);
    ExternalReference handler_address =
        ExternalReference::Create(IsolateAddressId::kHandlerAddress, isolate());
    pop(StaticVariable(handler_address));
    add(esp, Immediate(StackHandlerConstants::kSize - kPointerSize));
  }
  
  
  void MacroAssembler::CallStub(CodeStub* stub) {
    DCHECK(AllowThisStubCall(stub));  // Calls are not allowed in some stubs.
    Call(stub->GetCode(), RelocInfo::CODE_TARGET);
  }
  
  void TurboAssembler::CallStubDelayed(CodeStub* stub) {
    DCHECK(AllowThisStubCall(stub));  // Calls are not allowed in some stubs.
    call(stub);
  }
  
  void MacroAssembler::TailCallStub(CodeStub* stub) {
    Jump(stub->GetCode(), RelocInfo::CODE_TARGET);
  }
  
  bool TurboAssembler::AllowThisStubCall(CodeStub* stub) {
    return has_frame() || !stub->SometimesSetsUpAFrame();
  }
  
  void MacroAssembler::CallRuntime(const Runtime::Function* f,
                                   int num_arguments,
                                   SaveFPRegsMode save_doubles) {
    // If the expected number of arguments of the runtime function is
    // constant, we check that the actual number of arguments match the
    // expectation.
    CHECK(f->nargs < 0 || f->nargs == num_arguments);
  
    // TODO(1236192): Most runtime routines don't need the number of
    // arguments passed in because it is constant. At some point we
    // should remove this need and make the runtime routine entry code
    // smarter.
    Move(kRuntimeCallArgCountRegister, Immediate(num_arguments));
    Move(kRuntimeCallFunctionRegister, Immediate(ExternalReference::Create(f)));
    Handle<Code> code =
        CodeFactory::CEntry(isolate(), f->result_size, save_doubles);
    Call(code, RelocInfo::CODE_TARGET);
  }
  
  void TurboAssembler::CallRuntimeWithCEntry(Runtime::FunctionId fid,
                                             Register centry) {
    const Runtime::Function* f = Runtime::FunctionForId(fid);
    // TODO(1236192): Most runtime routines don't need the number of
    // arguments passed in because it is constant. At some point we
    // should remove this need and make the runtime routine entry code
    // smarter.
    Move(kRuntimeCallArgCountRegister, Immediate(f->nargs));
    Move(kRuntimeCallFunctionRegister, Immediate(ExternalReference::Create(f)));
    DCHECK(!AreAliased(centry, kRuntimeCallArgCountRegister,
                       kRuntimeCallFunctionRegister));
    add(centry, Immediate(Code::kHeaderSize - kHeapObjectTag));
    Call(centry);
  }
  
  void MacroAssembler::TailCallRuntime(Runtime::FunctionId fid) {
    // ----------- S t a t e -------------
    //  -- esp[0]                 : return address
    //  -- esp[8]                 : argument num_arguments - 1
    //  ...
    //  -- esp[8 * num_arguments] : argument 0 (receiver)
    //
    //  For runtime functions with variable arguments:
    //  -- eax                    : number of  arguments
    // -----------------------------------
  
    const Runtime::Function* function = Runtime::FunctionForId(fid);
    DCHECK_EQ(1, function->result_size);
    if (function->nargs >= 0) {
      // TODO(1236192): Most runtime routines don't need the number of
      // arguments passed in because it is constant. At some point we
      // should remove this need and make the runtime routine entry code
      // smarter.
      Move(kRuntimeCallArgCountRegister, Immediate(function->nargs));
    }
    JumpToExternalReference(ExternalReference::Create(fid));
  }
  
  void MacroAssembler::JumpToExternalReference(const ExternalReference& ext,
                                               bool builtin_exit_frame) {
    // Set the entry point and jump to the C entry runtime stub.
    Move(kRuntimeCallFunctionRegister, Immediate(ext));
    Handle<Code> code = CodeFactory::CEntry(isolate(), 1, kDontSaveFPRegs,
                                            kArgvOnStack, builtin_exit_frame);
    Jump(code, RelocInfo::CODE_TARGET);
  }
  
  void MacroAssembler::JumpToInstructionStream(Address entry) {
    jmp(entry, RelocInfo::OFF_HEAP_TARGET);
  }
  
  void TurboAssembler::PrepareForTailCall(
      const ParameterCount& callee_args_count, Register caller_args_count_reg,
      Register scratch0, Register scratch1,
      int number_of_temp_values_after_return_address) {
  #if DEBUG
    if (callee_args_count.is_reg()) {
      DCHECK(!AreAliased(callee_args_count.reg(), caller_args_count_reg, scratch0,
                         scratch1));
    } else {
      DCHECK(!AreAliased(caller_args_count_reg, scratch0, scratch1));
    }
  #endif
  
    // Calculate the destination address where we will put the return address
    // after we drop current frame.
    Register new_sp_reg = scratch0;
    if (callee_args_count.is_reg()) {
      sub(caller_args_count_reg, callee_args_count.reg());
      lea(new_sp_reg,
          Operand(ebp, caller_args_count_reg, times_pointer_size,
                  StandardFrameConstants::kCallerPCOffset -
                      number_of_temp_values_after_return_address * kPointerSize));
    } else {
      lea(new_sp_reg, Operand(ebp, caller_args_count_reg, times_pointer_size,
                              StandardFrameConstants::kCallerPCOffset -
                                  (callee_args_count.immediate() +
                                   number_of_temp_values_after_return_address) *
                                      kPointerSize));
    }
  
    if (FLAG_debug_code) {
      cmp(esp, new_sp_reg);
      Check(below, AbortReason::kStackAccessBelowStackPointer);
    }
  
    // Copy return address from caller's frame to current frame's return address
    // to avoid its trashing and let the following loop copy it to the right
    // place.
    Register tmp_reg = scratch1;
    mov(tmp_reg, Operand(ebp, StandardFrameConstants::kCallerPCOffset));
    mov(Operand(esp, number_of_temp_values_after_return_address * kPointerSize),
        tmp_reg);
  
    // Restore caller's frame pointer now as it could be overwritten by
    // the copying loop.
    mov(ebp, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
  
    // +2 here is to copy both receiver and return address.
    Register count_reg = caller_args_count_reg;
    if (callee_args_count.is_reg()) {
      lea(count_reg, Operand(callee_args_count.reg(),
                             2 + number_of_temp_values_after_return_address));
    } else {
      mov(count_reg, Immediate(callee_args_count.immediate() + 2 +
                               number_of_temp_values_after_return_address));
      // TODO(ishell): Unroll copying loop for small immediate values.
    }
  
    // Now copy callee arguments to the caller frame going backwards to avoid
    // callee arguments corruption (source and destination areas could overlap).
    Label loop, entry;
    jmp(&entry, Label::kNear);
    bind(&loop);
    dec(count_reg);
    mov(tmp_reg, Operand(esp, count_reg, times_pointer_size, 0));
    mov(Operand(new_sp_reg, count_reg, times_pointer_size, 0), tmp_reg);
    bind(&entry);
    cmp(count_reg, Immediate(0));
    j(not_equal, &loop, Label::kNear);
  
    // Leave current frame.
    mov(esp, new_sp_reg);
  }
  
  void MacroAssembler::InvokePrologue(const ParameterCount& expected,
                                      const ParameterCount& actual, Label* done,
                                      bool* definitely_mismatches,
                                      InvokeFlag flag,
                                      Label::Distance done_near) {
    DCHECK_IMPLIES(expected.is_reg(), expected.reg() == ecx);
    DCHECK_IMPLIES(actual.is_reg(), actual.reg() == eax);
  
    bool definitely_matches = false;
    *definitely_mismatches = false;
    Label invoke;
    if (expected.is_immediate()) {
      DCHECK(actual.is_immediate());
      mov(eax, actual.immediate());
      if (expected.immediate() == actual.immediate()) {
        definitely_matches = true;
      } else {
        const int sentinel = SharedFunctionInfo::kDontAdaptArgumentsSentinel;
        if (expected.immediate() == sentinel) {
          // Don't worry about adapting arguments for builtins that
          // don't want that done. Skip adaption code by making it look
          // like we have a match between expected and actual number of
          // arguments.
          definitely_matches = true;
        } else {
          *definitely_mismatches = true;
          mov(ecx, expected.immediate());
        }
      }
    } else {
      if (actual.is_immediate()) {
        // Expected is in register, actual is immediate. This is the
        // case when we invoke function values without going through the
        // IC mechanism.
        mov(eax, actual.immediate());
        cmp(expected.reg(), actual.immediate());
        j(equal, &invoke);
        DCHECK(expected.reg() == ecx);
      } else if (expected.reg() != actual.reg()) {
        // Both expected and actual are in (different) registers. This
        // is the case when we invoke functions using call and apply.
        cmp(expected.reg(), actual.reg());
        j(equal, &invoke);
        DCHECK(actual.reg() == eax);
        DCHECK(expected.reg() == ecx);
      } else {
        definitely_matches = true;
        Move(eax, actual.reg());
      }
    }
  
    if (!definitely_matches) {
      Handle<Code> adaptor = BUILTIN_CODE(isolate(), ArgumentsAdaptorTrampoline);
      if (flag == CALL_FUNCTION) {
        Call(adaptor, RelocInfo::CODE_TARGET);
        if (!*definitely_mismatches) {
          jmp(done, done_near);
        }
      } else {
        Jump(adaptor, RelocInfo::CODE_TARGET);
      }
      bind(&invoke);
    }
  }
  
  void MacroAssembler::CheckDebugHook(Register fun, Register new_target,
                                      const ParameterCount& expected,
                                      const ParameterCount& actual) {
    Label skip_hook;
  
    ExternalReference debug_hook_active =
        ExternalReference::debug_hook_on_function_call_address(isolate());
    cmpb(StaticVariable(debug_hook_active), Immediate(0));
    j(equal, &skip_hook);
  
    {
      FrameScope frame(this,
                       has_frame() ? StackFrame::NONE : StackFrame::INTERNAL);
      if (expected.is_reg()) {
        SmiTag(expected.reg());
        Push(expected.reg());
      }
      if (actual.is_reg()) {
        SmiTag(actual.reg());
        Push(actual.reg());
        SmiUntag(actual.reg());
      }
      if (new_target.is_valid()) {
        Push(new_target);
      }
      Push(fun);
      Push(fun);
      Operand receiver_op =
          actual.is_reg()
              ? Operand(ebp, actual.reg(), times_pointer_size, kPointerSize * 2)
              : Operand(ebp, actual.immediate() * times_pointer_size +
                                 kPointerSize * 2);
      Push(receiver_op);
      CallRuntime(Runtime::kDebugOnFunctionCall);
      Pop(fun);
      if (new_target.is_valid()) {
        Pop(new_target);
      }
      if (actual.is_reg()) {
        Pop(actual.reg());
        SmiUntag(actual.reg());
      }
      if (expected.is_reg()) {
        Pop(expected.reg());
        SmiUntag(expected.reg());
      }
    }
    bind(&skip_hook);
  }
  
  void MacroAssembler::InvokeFunctionCode(Register function, Register new_target,
                                          const ParameterCount& expected,
                                          const ParameterCount& actual,
                                          InvokeFlag flag) {
    // You can't call a function without a valid frame.
    DCHECK(flag == JUMP_FUNCTION || has_frame());
    DCHECK(function == edi);
    DCHECK_IMPLIES(new_target.is_valid(), new_target == edx);
    DCHECK_IMPLIES(expected.is_reg(), expected.reg() == ecx);
    DCHECK_IMPLIES(actual.is_reg(), actual.reg() == eax);
  
    // On function call, call into the debugger if necessary.
    CheckDebugHook(function, new_target, expected, actual);
  
    // Clear the new.target register if not given.
    if (!new_target.is_valid()) {
      mov(edx, isolate()->factory()->undefined_value());
    }
  
    Label done;
    bool definitely_mismatches = false;
    InvokePrologue(expected, actual, &done, &definitely_mismatches, flag,
                   Label::kNear);
    if (!definitely_mismatches) {
      // We call indirectly through the code field in the function to
      // allow recompilation to take effect without changing any of the
      // call sites.
      static_assert(kJavaScriptCallCodeStartRegister == ecx, "ABI mismatch");
      mov(ecx, FieldOperand(function, JSFunction::kCodeOffset));
      add(ecx, Immediate(Code::kHeaderSize - kHeapObjectTag));
      if (flag == CALL_FUNCTION) {
        call(ecx);
      } else {
        DCHECK(flag == JUMP_FUNCTION);
        jmp(ecx);
      }
      bind(&done);
    }
  }
  
  void MacroAssembler::InvokeFunction(Register fun, Register new_target,
                                      const ParameterCount& actual,
                                      InvokeFlag flag) {
    // You can't call a function without a valid frame.
    DCHECK(flag == JUMP_FUNCTION || has_frame());
  
    DCHECK(fun == edi);
    mov(ecx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
    mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
    movzx_w(ecx,
            FieldOperand(ecx, SharedFunctionInfo::kFormalParameterCountOffset));
  
    ParameterCount expected(ecx);
    InvokeFunctionCode(edi, new_target, expected, actual, flag);
  }
  
  void MacroAssembler::LoadGlobalProxy(Register dst) {
    mov(dst, NativeContextOperand());
    mov(dst, ContextOperand(dst, Context::GLOBAL_PROXY_INDEX));
  }
  
  void MacroAssembler::LoadGlobalFunction(int index, Register function) {
    // Load the native context from the current context.
    mov(function, NativeContextOperand());
    // Load the function from the native context.
    mov(function, ContextOperand(function, index));
  }
  
  int MacroAssembler::SafepointRegisterStackIndex(int reg_code) {
    // The registers are pushed starting with the lowest encoding,
    // which means that lowest encodings are furthest away from
    // the stack pointer.
    DCHECK(reg_code >= 0 && reg_code < kNumSafepointRegisters);
    return kNumSafepointRegisters - reg_code - 1;
  }
  
  void TurboAssembler::Ret() { ret(0); }
  
  void TurboAssembler::Ret(int bytes_dropped, Register scratch) {
    if (is_uint16(bytes_dropped)) {
      ret(bytes_dropped);
    } else {
      pop(scratch);
      add(esp, Immediate(bytes_dropped));
      push(scratch);
      ret(0);
    }
  }
  
  
  void MacroAssembler::Drop(int stack_elements) {
    if (stack_elements > 0) {
      add(esp, Immediate(stack_elements * kPointerSize));
    }
  }
  
  void TurboAssembler::Move(Register dst, Register src) {
    if (dst != src) {
      mov(dst, src);
    }
  }
  
  void TurboAssembler::Move(Register dst, const Immediate& src) {
    if (!src.is_heap_object_request() && src.is_zero()) {
      xor_(dst, dst);  // Shorter than mov of 32-bit immediate 0.
    } else if (src.is_external_reference()) {
      LoadAddress(dst, src.external_reference());
    } else {
      mov(dst, src);
    }
  }
  
  void TurboAssembler::Move(Operand dst, const Immediate& src) { mov(dst, src); }
  
  void TurboAssembler::Move(Register dst, Handle<HeapObject> src) {
    if (root_array_available_ && options().isolate_independent_code) {
      IndirectLoadConstant(dst, src);
      return;
    }
    mov(dst, src);
  }
  
  void TurboAssembler::Move(XMMRegister dst, uint32_t src) {
    if (src == 0) {
      pxor(dst, dst);
    } else {
      unsigned cnt = base::bits::CountPopulation(src);
      unsigned nlz = base::bits::CountLeadingZeros32(src);
      unsigned ntz = base::bits::CountTrailingZeros32(src);
      if (nlz + cnt + ntz == 32) {
        pcmpeqd(dst, dst);
        if (ntz == 0) {
          psrld(dst, 32 - cnt);
        } else {
          pslld(dst, 32 - cnt);
          if (nlz != 0) psrld(dst, nlz);
        }
      } else {
        push(eax);
        mov(eax, Immediate(src));
        movd(dst, Operand(eax));
        pop(eax);
      }
    }
  }
  
  void TurboAssembler::Move(XMMRegister dst, uint64_t src) {
    if (src == 0) {
      pxor(dst, dst);
    } else {
      uint32_t lower = static_cast<uint32_t>(src);
      uint32_t upper = static_cast<uint32_t>(src >> 32);
      unsigned cnt = base::bits::CountPopulation(src);
      unsigned nlz = base::bits::CountLeadingZeros64(src);
      unsigned ntz = base::bits::CountTrailingZeros64(src);
      if (nlz + cnt + ntz == 64) {
        pcmpeqd(dst, dst);
        if (ntz == 0) {
          psrlq(dst, 64 - cnt);
        } else {
          psllq(dst, 64 - cnt);
          if (nlz != 0) psrlq(dst, nlz);
        }
      } else if (lower == 0) {
        Move(dst, upper);
        psllq(dst, 32);
      } else if (CpuFeatures::IsSupported(SSE4_1)) {
        CpuFeatureScope scope(this, SSE4_1);
        push(eax);
        Move(eax, Immediate(lower));
        movd(dst, Operand(eax));
        if (upper != lower) {
          Move(eax, Immediate(upper));
        }
        pinsrd(dst, Operand(eax), 1);
        pop(eax);
      } else {
        push(Immediate(upper));
        push(Immediate(lower));
        movsd(dst, Operand(esp, 0));
        add(esp, Immediate(kDoubleSize));
      }
    }
  }
  
  void TurboAssembler::Pshufhw(XMMRegister dst, Operand src, uint8_t shuffle) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpshufhw(dst, src, shuffle);
    } else {
      pshufhw(dst, src, shuffle);
    }
  }
  
  void TurboAssembler::Pshuflw(XMMRegister dst, Operand src, uint8_t shuffle) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpshuflw(dst, src, shuffle);
    } else {
      pshuflw(dst, src, shuffle);
    }
  }
  
  void TurboAssembler::Pshufd(XMMRegister dst, Operand src, uint8_t shuffle) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpshufd(dst, src, shuffle);
    } else {
      pshufd(dst, src, shuffle);
    }
  }
  
  void TurboAssembler::Psraw(XMMRegister dst, uint8_t shift) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpsraw(dst, dst, shift);
    } else {
      psraw(dst, shift);
    }
  }
  
  void TurboAssembler::Psrlw(XMMRegister dst, uint8_t shift) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpsrlw(dst, dst, shift);
    } else {
      psrlw(dst, shift);
    }
  }
  
  void TurboAssembler::Psignb(XMMRegister dst, Operand src) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpsignb(dst, dst, src);
      return;
    }
    if (CpuFeatures::IsSupported(SSSE3)) {
      CpuFeatureScope sse_scope(this, SSSE3);
      psignb(dst, src);
      return;
    }
    FATAL("no AVX or SSE3 support");
  }
  
  void TurboAssembler::Psignw(XMMRegister dst, Operand src) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpsignw(dst, dst, src);
      return;
    }
    if (CpuFeatures::IsSupported(SSSE3)) {
      CpuFeatureScope sse_scope(this, SSSE3);
      psignw(dst, src);
      return;
    }
    FATAL("no AVX or SSE3 support");
  }
  
  void TurboAssembler::Psignd(XMMRegister dst, Operand src) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpsignd(dst, dst, src);
      return;
    }
    if (CpuFeatures::IsSupported(SSSE3)) {
      CpuFeatureScope sse_scope(this, SSSE3);
      psignd(dst, src);
      return;
    }
    FATAL("no AVX or SSE3 support");
  }
  
  void TurboAssembler::Pshufb(XMMRegister dst, Operand src) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpshufb(dst, dst, src);
      return;
    }
    if (CpuFeatures::IsSupported(SSSE3)) {
      CpuFeatureScope sse_scope(this, SSSE3);
      pshufb(dst, src);
      return;
    }
    FATAL("no AVX or SSE3 support");
  }
  
  void TurboAssembler::Pblendw(XMMRegister dst, Operand src, uint8_t imm8) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpblendw(dst, dst, src, imm8);
      return;
    }
    if (CpuFeatures::IsSupported(SSE4_1)) {
      CpuFeatureScope sse_scope(this, SSE4_1);
      pblendw(dst, src, imm8);
      return;
    }
    FATAL("no AVX or SSE4.1 support");
  }
  
  void TurboAssembler::Palignr(XMMRegister dst, Operand src, uint8_t imm8) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpalignr(dst, dst, src, imm8);
      return;
    }
    if (CpuFeatures::IsSupported(SSSE3)) {
      CpuFeatureScope sse_scope(this, SSSE3);
      palignr(dst, src, imm8);
      return;
    }
    FATAL("no AVX or SSE3 support");
  }
  
  void TurboAssembler::Pextrb(Register dst, XMMRegister src, uint8_t imm8) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpextrb(dst, src, imm8);
      return;
    }
    if (CpuFeatures::IsSupported(SSE4_1)) {
      CpuFeatureScope sse_scope(this, SSE4_1);
      pextrb(dst, src, imm8);
      return;
    }
    FATAL("no AVX or SSE4.1 support");
  }
  
  void TurboAssembler::Pextrw(Register dst, XMMRegister src, uint8_t imm8) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpextrw(dst, src, imm8);
      return;
    }
    if (CpuFeatures::IsSupported(SSE4_1)) {
      CpuFeatureScope sse_scope(this, SSE4_1);
      pextrw(dst, src, imm8);
      return;
    }
    FATAL("no AVX or SSE4.1 support");
  }
  
  void TurboAssembler::Pextrd(Register dst, XMMRegister src, uint8_t imm8) {
    if (imm8 == 0) {
      Movd(dst, src);
      return;
    }
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpextrd(dst, src, imm8);
      return;
    }
    if (CpuFeatures::IsSupported(SSE4_1)) {
      CpuFeatureScope sse_scope(this, SSE4_1);
      pextrd(dst, src, imm8);
      return;
    }
    // Without AVX or SSE, we can only have 64-bit values in xmm registers.
    // We don't have an xmm scratch register, so move the data via the stack. This
    // path is rarely required, so it's acceptable to be slow.
    DCHECK_LT(imm8, 2);
    sub(esp, Immediate(kDoubleSize));
    movsd(Operand(esp, 0), src);
    mov(dst, Operand(esp, imm8 * kUInt32Size));
    add(esp, Immediate(kDoubleSize));
  }
  
  void TurboAssembler::Pinsrd(XMMRegister dst, Operand src, uint8_t imm8) {
    if (CpuFeatures::IsSupported(AVX)) {
      CpuFeatureScope scope(this, AVX);
      vpinsrd(dst, dst, src, imm8);
      return;
    }
    if (CpuFeatures::IsSupported(SSE4_1)) {
      CpuFeatureScope sse_scope(this, SSE4_1);
      pinsrd(dst, src, imm8);
      return;
    }
    // Without AVX or SSE, we can only have 64-bit values in xmm registers.
    // We don't have an xmm scratch register, so move the data via the stack. This
    // path is rarely required, so it's acceptable to be slow.
    DCHECK_LT(imm8, 2);
    sub(esp, Immediate(kDoubleSize));
    // Write original content of {dst} to the stack.
    movsd(Operand(esp, 0), dst);
    // Overwrite the portion specified in {imm8}.
    if (src.is_reg_only()) {
      mov(Operand(esp, imm8 * kUInt32Size), src.reg());
    } else {
      movss(dst, src);
      movss(Operand(esp, imm8 * kUInt32Size), dst);
    }
    // Load back the full value into {dst}.
    movsd(dst, Operand(esp, 0));
    add(esp, Immediate(kDoubleSize));
  }
  
  void TurboAssembler::Lzcnt(Register dst, Operand src) {
    if (CpuFeatures::IsSupported(LZCNT)) {
      CpuFeatureScope scope(this, LZCNT);
      lzcnt(dst, src);
      return;
    }
    Label not_zero_src;
    bsr(dst, src);
    j(not_zero, &not_zero_src, Label::kNear);
    Move(dst, Immediate(63));  // 63^31 == 32
    bind(&not_zero_src);
    xor_(dst, Immediate(31));  // for x in [0..31], 31^x == 31-x.
  }
  
  void TurboAssembler::Tzcnt(Register dst, Operand src) {
    if (CpuFeatures::IsSupported(BMI1)) {
      CpuFeatureScope scope(this, BMI1);
      tzcnt(dst, src);
      return;
    }
    Label not_zero_src;
    bsf(dst, src);
    j(not_zero, &not_zero_src, Label::kNear);
    Move(dst, Immediate(32));  // The result of tzcnt is 32 if src = 0.
    bind(&not_zero_src);
  }
  
  void TurboAssembler::Popcnt(Register dst, Operand src) {
    if (CpuFeatures::IsSupported(POPCNT)) {
      CpuFeatureScope scope(this, POPCNT);
      popcnt(dst, src);
      return;
    }
    FATAL("no POPCNT support");
  }
  
  void MacroAssembler::LoadWeakValue(Register in_out, Label* target_if_cleared) {
    cmp(in_out, Immediate(kClearedWeakHeapObject));
    j(equal, target_if_cleared);
  
    and_(in_out, Immediate(~kWeakHeapObjectMask));
  }
  
  void MacroAssembler::IncrementCounter(StatsCounter* counter, int value) {
    DCHECK_GT(value, 0);
    if (FLAG_native_code_counters && counter->Enabled()) {
      Operand operand = StaticVariable(ExternalReference::Create(counter));
      if (value == 1) {
        inc(operand);
      } else {
        add(operand, Immediate(value));
      }
    }
  }
  
  
  void MacroAssembler::DecrementCounter(StatsCounter* counter, int value) {
    DCHECK_GT(value, 0);
    if (FLAG_native_code_counters && counter->Enabled()) {
      Operand operand = StaticVariable(ExternalReference::Create(counter));
      if (value == 1) {
        dec(operand);
      } else {
        sub(operand, Immediate(value));
      }
    }
  }
  
  void TurboAssembler::Assert(Condition cc, AbortReason reason) {
    if (emit_debug_code()) Check(cc, reason);
  }
  
  void TurboAssembler::AssertUnreachable(AbortReason reason) {
    if (emit_debug_code()) Abort(reason);
  }
  
  void TurboAssembler::Check(Condition cc, AbortReason reason) {
    Label L;
    j(cc, &L);
    Abort(reason);
    // will not return here
    bind(&L);
  }
  
  void TurboAssembler::CheckStackAlignment() {
    int frame_alignment = base::OS::ActivationFrameAlignment();
    int frame_alignment_mask = frame_alignment - 1;
    if (frame_alignment > kPointerSize) {
      DCHECK(base::bits::IsPowerOfTwo(frame_alignment));
      Label alignment_as_expected;
      test(esp, Immediate(frame_alignment_mask));
      j(zero, &alignment_as_expected);
      // Abort if stack is not aligned.
      int3();
      bind(&alignment_as_expected);
    }
  }
  
  void TurboAssembler::Abort(AbortReason reason) {
  #ifdef DEBUG
    const char* msg = GetAbortReason(reason);
    RecordComment("Abort message: ");
    RecordComment(msg);
  #endif
  
    // Avoid emitting call to builtin if requested.
    if (trap_on_abort()) {
      int3();
      return;
    }
  
    if (should_abort_hard()) {
      // We don't care if we constructed a frame. Just pretend we did.
      FrameScope assume_frame(this, StackFrame::NONE);
      PrepareCallCFunction(1, eax);
      mov(Operand(esp, 0), Immediate(static_cast<int>(reason)));
      CallCFunction(ExternalReference::abort_with_reason(), 1);
      return;
    }
  
    Move(edx, Smi::FromInt(static_cast<int>(reason)));
  
    // Disable stub call restrictions to always allow calls to abort.
    if (!has_frame()) {
      // We don't actually want to generate a pile of code for this, so just
      // claim there is a stack frame, without generating one.
      FrameScope scope(this, StackFrame::NONE);
      Call(BUILTIN_CODE(isolate(), Abort), RelocInfo::CODE_TARGET);
    } else {
      Call(BUILTIN_CODE(isolate(), Abort), RelocInfo::CODE_TARGET);
    }
    // will not return here
    int3();
  }
  
  
  void TurboAssembler::PrepareCallCFunction(int num_arguments, Register scratch) {
    int frame_alignment = base::OS::ActivationFrameAlignment();
    if (frame_alignment != 0) {
      // Make stack end at alignment and make room for num_arguments words
      // and the original value of esp.
      mov(scratch, esp);
      sub(esp, Immediate((num_arguments + 1) * kPointerSize));
      DCHECK(base::bits::IsPowerOfTwo(frame_alignment));
      and_(esp, -frame_alignment);
      mov(Operand(esp, num_arguments * kPointerSize), scratch);
    } else {
      sub(esp, Immediate(num_arguments * kPointerSize));
    }
  }
  
  void TurboAssembler::CallCFunction(ExternalReference function,
                                     int num_arguments) {
    // Trashing eax is ok as it will be the return value.
    mov(eax, Immediate(function));
    CallCFunction(eax, num_arguments);
  }
  
  void TurboAssembler::CallCFunction(Register function, int num_arguments) {
    DCHECK_LE(num_arguments, kMaxCParameters);
    DCHECK(has_frame());
    // Check stack alignment.
    if (emit_debug_code()) {
      CheckStackAlignment();
    }
  
    call(function);
    if (base::OS::ActivationFrameAlignment() != 0) {
      mov(esp, Operand(esp, num_arguments * kPointerSize));
    } else {
      add(esp, Immediate(num_arguments * kPointerSize));
    }
  }
  
  void TurboAssembler::Call(Handle<Code> code_object, RelocInfo::Mode rmode) {
    if (FLAG_embedded_builtins) {
      // TODO(jgruber): Pc-relative builtin-to-builtin calls.
      if (root_array_available_ && options().isolate_independent_code) {
        // TODO(jgruber): There's no scratch register on ia32. Any call that
        // requires loading a code object from the builtins constant table must:
        // 1) spill two scratch registers, 2) load the target into scratch1, 3)
        // store the target into a virtual register on the isolate using scratch2,
        // 4) restore both scratch registers, and finally 5) call through the
        // virtual register. All affected call sites should vanish once all
        // builtins are embedded on ia32.
        UNREACHABLE();
      } else if (options().inline_offheap_trampolines) {
        int builtin_index = Builtins::kNoBuiltinId;
        if (isolate()->builtins()->IsBuiltinHandle(code_object, &builtin_index) &&
            Builtins::IsIsolateIndependent(builtin_index)) {
          // Inline the trampoline.
          RecordCommentForOffHeapTrampoline(builtin_index);
          CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
          EmbeddedData d = EmbeddedData::FromBlob();
          Address entry = d.InstructionStartOfBuiltin(builtin_index);
          call(entry, RelocInfo::OFF_HEAP_TARGET);
          return;
        }
      }
    }
    DCHECK(RelocInfo::IsCodeTarget(rmode));
    call(code_object, rmode);
  }
  
  void TurboAssembler::Jump(Handle<Code> code_object, RelocInfo::Mode rmode) {
    if (FLAG_embedded_builtins) {
      // TODO(jgruber): Pc-relative builtin-to-builtin calls.
      if (root_array_available_ && options().isolate_independent_code) {
        // TODO(jgruber): There's no scratch register on ia32. Any call that
        // requires loading a code object from the builtins constant table must:
        // 1) spill two scratch registers, 2) load the target into scratch1, 3)
        // store the target into a virtual register on the isolate using scratch2,
        // 4) restore both scratch registers, and finally 5) call through the
        // virtual register. All affected call sites should vanish once all
        // builtins are embedded on ia32.
        UNREACHABLE();
      } else if (options().inline_offheap_trampolines) {
        int builtin_index = Builtins::kNoBuiltinId;
        if (isolate()->builtins()->IsBuiltinHandle(code_object, &builtin_index) &&
            Builtins::IsIsolateIndependent(builtin_index)) {
          // Inline the trampoline.
          RecordCommentForOffHeapTrampoline(builtin_index);
          CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
          EmbeddedData d = EmbeddedData::FromBlob();
          Address entry = d.InstructionStartOfBuiltin(builtin_index);
          jmp(entry, RelocInfo::OFF_HEAP_TARGET);
          return;
        }
      }
    }
    DCHECK(RelocInfo::IsCodeTarget(rmode));
    jmp(code_object, rmode);
  }
  
  void TurboAssembler::RetpolineCall(Register reg) {
    Label setup_return, setup_target, inner_indirect_branch, capture_spec;
  
    jmp(&setup_return);  // Jump past the entire retpoline below.
  
    bind(&inner_indirect_branch);
    call(&setup_target);
  
    bind(&capture_spec);
    pause();
    jmp(&capture_spec);
  
    bind(&setup_target);
    mov(Operand(esp, 0), reg);
    ret(0);
  
    bind(&setup_return);
    call(&inner_indirect_branch);  // Callee will return after this instruction.
  }
  
  void TurboAssembler::RetpolineCall(Address destination, RelocInfo::Mode rmode) {
    Label setup_return, setup_target, inner_indirect_branch, capture_spec;
  
    jmp(&setup_return);  // Jump past the entire retpoline below.
  
    bind(&inner_indirect_branch);
    call(&setup_target);
  
    bind(&capture_spec);
    pause();
    jmp(&capture_spec);
  
    bind(&setup_target);
    mov(Operand(esp, 0), destination, rmode);
    ret(0);
  
    bind(&setup_return);
    call(&inner_indirect_branch);  // Callee will return after this instruction.
  }
  
  void TurboAssembler::RetpolineJump(Register reg) {
    Label setup_target, capture_spec;
  
    call(&setup_target);
  
    bind(&capture_spec);
    pause();
    jmp(&capture_spec);
  
    bind(&setup_target);
    mov(Operand(esp, 0), reg);
    ret(0);
  }
  
  void TurboAssembler::CheckPageFlag(Register object, Register scratch, int mask,
                                     Condition cc, Label* condition_met,
                                     Label::Distance condition_met_distance) {
    DCHECK(cc == zero || cc == not_zero);
    if (scratch == object) {
      and_(scratch, Immediate(~kPageAlignmentMask));
    } else {
      mov(scratch, Immediate(~kPageAlignmentMask));
      and_(scratch, object);
    }
    if (mask < (1 << kBitsPerByte)) {
      test_b(Operand(scratch, MemoryChunk::kFlagsOffset), Immediate(mask));
    } else {
      test(Operand(scratch, MemoryChunk::kFlagsOffset), Immediate(mask));
    }
    j(cc, condition_met, condition_met_distance);
  }
  
  void TurboAssembler::ComputeCodeStartAddress(Register dst) {
    // In order to get the address of the current instruction, we first need
    // to use a call and then use a pop, thus pushing the return address to
    // the stack and then popping it into the register.
    Label current;
    call(&current);
    int pc = pc_offset();
    bind(&current);
    pop(dst);
    if (pc != 0) {
      sub(dst, Immediate(pc));
    }
  }
  
  void TurboAssembler::ResetSpeculationPoisonRegister() {
    mov(kSpeculationPoisonRegister, Immediate(-1));
  }
  
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_TARGET_ARCH_IA32
  