// 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_X64

#include "src/codegen.h"
#include "src/ic/ic.h"
#include "src/ic/ic-compiler.h"
#include "src/ic/stub-cache.h"

namespace v8 {
namespace internal {

// ----------------------------------------------------------------------------
// Static IC stub generators.
//

#define __ ACCESS_MASM(masm)

// Helper function used to load a property from a dictionary backing storage.
// This function may return false negatives, so miss_label
// must always call a backup property load that is complete.
// This function is safe to call if name is not an internalized string,
// and will jump to the miss_label in that case.
// The generated code assumes that the receiver has slow properties,
// is not a global object and does not have interceptors.
static void GenerateDictionaryLoad(MacroAssembler* masm, Label* miss_label,
                                   Register elements, Register name,
                                   Register r0, Register r1, Register result) {
  // Register use:
  //
  // elements - holds the property dictionary on entry and is unchanged.
  //
  // name - holds the name of the property on entry and is unchanged.
  //
  // r0   - used to hold the capacity of the property dictionary.
  //
  // r1   - used to hold the index into the property dictionary.
  //
  // result - holds the result on exit if the load succeeded.

  Label done;

  // Probe the dictionary.
  NameDictionaryLookupStub::GeneratePositiveLookup(masm, miss_label, &done,
                                                   elements, name, r0, r1);

  // If probing finds an entry in the dictionary, r1 contains the
  // index into the dictionary. Check that the value is a normal
  // property.
  __ bind(&done);
  const int kElementsStartOffset =
      NameDictionary::kHeaderSize +
      NameDictionary::kElementsStartIndex * kPointerSize;
  const int kDetailsOffset = kElementsStartOffset + 2 * kPointerSize;
  __ Test(Operand(elements, r1, times_pointer_size,
                  kDetailsOffset - kHeapObjectTag),
          Smi::FromInt(PropertyDetails::TypeField::kMask));
  __ j(not_zero, miss_label);

  // Get the value at the masked, scaled index.
  const int kValueOffset = kElementsStartOffset + kPointerSize;
  __ movp(result, Operand(elements, r1, times_pointer_size,
                          kValueOffset - kHeapObjectTag));
}


// Helper function used to store a property to a dictionary backing
// storage. This function may fail to store a property even though it
// is in the dictionary, so code at miss_label must always call a
// backup property store that is complete. This function is safe to
// call if name is not an internalized string, and will jump to the miss_label
// in that case. The generated code assumes that the receiver has slow
// properties, is not a global object and does not have interceptors.
static void GenerateDictionaryStore(MacroAssembler* masm, Label* miss_label,
                                    Register elements, Register name,
                                    Register value, Register scratch0,
                                    Register scratch1) {
  // Register use:
  //
  // elements - holds the property dictionary on entry and is clobbered.
  //
  // name - holds the name of the property on entry and is unchanged.
  //
  // value - holds the value to store and is unchanged.
  //
  // scratch0 - used during the positive dictionary lookup and is clobbered.
  //
  // scratch1 - used for index into the property dictionary and is clobbered.
  Label done;

  // Probe the dictionary.
  NameDictionaryLookupStub::GeneratePositiveLookup(
      masm, miss_label, &done, elements, name, scratch0, scratch1);

  // If probing finds an entry in the dictionary, scratch0 contains the
  // index into the dictionary. Check that the value is a normal
  // property that is not read only.
  __ bind(&done);
  const int kElementsStartOffset =
      NameDictionary::kHeaderSize +
      NameDictionary::kElementsStartIndex * kPointerSize;
  const int kDetailsOffset = kElementsStartOffset + 2 * kPointerSize;
  const int kTypeAndReadOnlyMask =
      PropertyDetails::TypeField::kMask |
      PropertyDetails::AttributesField::encode(READ_ONLY);
  __ Test(Operand(elements, scratch1, times_pointer_size,
                  kDetailsOffset - kHeapObjectTag),
          Smi::FromInt(kTypeAndReadOnlyMask));
  __ j(not_zero, miss_label);

  // Store the value at the masked, scaled index.
  const int kValueOffset = kElementsStartOffset + kPointerSize;
  __ leap(scratch1, Operand(elements, scratch1, times_pointer_size,
                            kValueOffset - kHeapObjectTag));
  __ movp(Operand(scratch1, 0), value);

  // Update write barrier. Make sure not to clobber the value.
  __ movp(scratch0, value);
  __ RecordWrite(elements, scratch1, scratch0, kDontSaveFPRegs);
}

static void KeyedStoreGenerateMegamorphicHelper(
    MacroAssembler* masm, Label* fast_object, Label* fast_double, Label* slow,
    KeyedStoreCheckMap check_map, KeyedStoreIncrementLength increment_length) {
  Label transition_smi_elements;
  Label finish_object_store, non_double_value, transition_double_elements;
  Label fast_double_without_map_check;
  Register receiver = StoreDescriptor::ReceiverRegister();
  Register key = StoreDescriptor::NameRegister();
  Register value = StoreDescriptor::ValueRegister();
  DCHECK(receiver.is(rdx));
  DCHECK(key.is(rcx));
  DCHECK(value.is(rax));
  // Fast case: Do the store, could be either Object or double.
  __ bind(fast_object);
  // rbx: receiver's elements array (a FixedArray)
  // receiver is a JSArray.
  // r9: map of receiver
  if (check_map == kCheckMap) {
    __ movp(rdi, FieldOperand(rbx, HeapObject::kMapOffset));
    __ CompareRoot(rdi, Heap::kFixedArrayMapRootIndex);
    __ j(not_equal, fast_double);
  }

  // HOLECHECK: guards "A[i] = V"
  // We have to go to the runtime if the current value is the hole because
  // there may be a callback on the element
  Label holecheck_passed1;
  __ movp(kScratchRegister,
          FieldOperand(rbx, key, times_pointer_size, FixedArray::kHeaderSize));
  __ CompareRoot(kScratchRegister, Heap::kTheHoleValueRootIndex);
  __ j(not_equal, &holecheck_passed1);
  __ JumpIfDictionaryInPrototypeChain(receiver, rdi, kScratchRegister, slow);

  __ bind(&holecheck_passed1);

  // Smi stores don't require further checks.
  Label non_smi_value;
  __ JumpIfNotSmi(value, &non_smi_value);
  if (increment_length == kIncrementLength) {
    // Add 1 to receiver->length.
    __ leal(rdi, Operand(key, 1));
    __ Integer32ToSmiField(FieldOperand(receiver, JSArray::kLengthOffset), rdi);
  }
  // It's irrelevant whether array is smi-only or not when writing a smi.
  __ movp(FieldOperand(rbx, key, times_pointer_size, FixedArray::kHeaderSize),
          value);
  __ ret(0);

  __ bind(&non_smi_value);
  // Writing a non-smi, check whether array allows non-smi elements.
  // r9: receiver's map
  __ CheckFastObjectElements(r9, &transition_smi_elements);

  __ bind(&finish_object_store);
  if (increment_length == kIncrementLength) {
    // Add 1 to receiver->length.
    __ leal(rdi, Operand(key, 1));
    __ Integer32ToSmiField(FieldOperand(receiver, JSArray::kLengthOffset), rdi);
  }
  __ movp(FieldOperand(rbx, key, times_pointer_size, FixedArray::kHeaderSize),
          value);
  __ movp(rdx, value);  // Preserve the value which is returned.
  __ RecordWriteArray(rbx, rdx, key, kDontSaveFPRegs, EMIT_REMEMBERED_SET,
                      OMIT_SMI_CHECK);
  __ ret(0);

  __ bind(fast_double);
  if (check_map == kCheckMap) {
    // Check for fast double array case. If this fails, call through to the
    // runtime.
    // rdi: elements array's map
    __ CompareRoot(rdi, Heap::kFixedDoubleArrayMapRootIndex);
    __ j(not_equal, slow);
  }

  // HOLECHECK: guards "A[i] double hole?"
  // We have to see if the double version of the hole is present. If so
  // go to the runtime.
  uint32_t offset = FixedDoubleArray::kHeaderSize + sizeof(kHoleNanLower32);
  __ cmpl(FieldOperand(rbx, key, times_8, offset), Immediate(kHoleNanUpper32));
  __ j(not_equal, &fast_double_without_map_check);
  __ JumpIfDictionaryInPrototypeChain(receiver, rdi, kScratchRegister, slow);

  __ bind(&fast_double_without_map_check);
  __ StoreNumberToDoubleElements(value, rbx, key, kScratchDoubleReg,
                                 &transition_double_elements);
  if (increment_length == kIncrementLength) {
    // Add 1 to receiver->length.
    __ leal(rdi, Operand(key, 1));
    __ Integer32ToSmiField(FieldOperand(receiver, JSArray::kLengthOffset), rdi);
  }
  __ ret(0);

  __ bind(&transition_smi_elements);
  __ movp(rbx, FieldOperand(receiver, HeapObject::kMapOffset));

  // Transition the array appropriately depending on the value type.
  __ movp(r9, FieldOperand(value, HeapObject::kMapOffset));
  __ CompareRoot(r9, Heap::kHeapNumberMapRootIndex);
  __ j(not_equal, &non_double_value);

  // Value is a double. Transition FAST_SMI_ELEMENTS ->
  // FAST_DOUBLE_ELEMENTS and complete the store.
  __ LoadTransitionedArrayMapConditional(FAST_SMI_ELEMENTS,
                                         FAST_DOUBLE_ELEMENTS, rbx, rdi, slow);
  AllocationSiteMode mode =
      AllocationSite::GetMode(FAST_SMI_ELEMENTS, FAST_DOUBLE_ELEMENTS);
  ElementsTransitionGenerator::GenerateSmiToDouble(masm, receiver, key, value,
                                                   rbx, mode, slow);
  __ movp(rbx, FieldOperand(receiver, JSObject::kElementsOffset));
  __ jmp(&fast_double_without_map_check);

  __ bind(&non_double_value);
  // Value is not a double, FAST_SMI_ELEMENTS -> FAST_ELEMENTS
  __ LoadTransitionedArrayMapConditional(FAST_SMI_ELEMENTS, FAST_ELEMENTS, rbx,
                                         rdi, slow);
  mode = AllocationSite::GetMode(FAST_SMI_ELEMENTS, FAST_ELEMENTS);
  ElementsTransitionGenerator::GenerateMapChangeElementsTransition(
      masm, receiver, key, value, rbx, mode, slow);
  __ movp(rbx, FieldOperand(receiver, JSObject::kElementsOffset));
  __ jmp(&finish_object_store);

  __ bind(&transition_double_elements);
  // Elements are FAST_DOUBLE_ELEMENTS, but value is an Object that's not a
  // HeapNumber. Make sure that the receiver is a Array with FAST_ELEMENTS and
  // transition array from FAST_DOUBLE_ELEMENTS to FAST_ELEMENTS
  __ movp(rbx, FieldOperand(receiver, HeapObject::kMapOffset));
  __ LoadTransitionedArrayMapConditional(FAST_DOUBLE_ELEMENTS, FAST_ELEMENTS,
                                         rbx, rdi, slow);
  mode = AllocationSite::GetMode(FAST_DOUBLE_ELEMENTS, FAST_ELEMENTS);
  ElementsTransitionGenerator::GenerateDoubleToObject(masm, receiver, key,
                                                      value, rbx, mode, slow);
  __ movp(rbx, FieldOperand(receiver, JSObject::kElementsOffset));
  __ jmp(&finish_object_store);
}


void KeyedStoreIC::GenerateMegamorphic(MacroAssembler* masm,
                                       LanguageMode language_mode) {
  // Return address is on the stack.
  Label slow, slow_with_tagged_index, fast_object, fast_object_grow;
  Label fast_double, fast_double_grow;
  Label array, extra, check_if_double_array, maybe_name_key, miss;
  Register receiver = StoreDescriptor::ReceiverRegister();
  Register key = StoreDescriptor::NameRegister();
  DCHECK(receiver.is(rdx));
  DCHECK(key.is(rcx));

  // Check that the object isn't a smi.
  __ JumpIfSmi(receiver, &slow_with_tagged_index);
  // Get the map from the receiver.
  __ movp(r9, FieldOperand(receiver, HeapObject::kMapOffset));
  // Check that the receiver does not require access checks.
  // The generic stub does not perform map checks.
  __ testb(FieldOperand(r9, Map::kBitFieldOffset),
           Immediate(1 << Map::kIsAccessCheckNeeded));
  __ j(not_zero, &slow_with_tagged_index);
  // Check that the key is a smi.
  __ JumpIfNotSmi(key, &maybe_name_key);
  __ SmiToInteger32(key, key);

  __ CmpInstanceType(r9, JS_ARRAY_TYPE);
  __ j(equal, &array);
  // Check that the object is some kind of JS object EXCEPT JS Value type. In
  // the case that the object is a value-wrapper object, we enter the runtime
  // system to make sure that indexing into string objects works as intended.
  STATIC_ASSERT(JS_VALUE_TYPE < JS_OBJECT_TYPE);
  __ CmpInstanceType(r9, JS_OBJECT_TYPE);
  __ j(below, &slow);

  // Object case: Check key against length in the elements array.
  __ movp(rbx, FieldOperand(receiver, JSObject::kElementsOffset));
  // Check array bounds.
  __ SmiCompareInteger32(FieldOperand(rbx, FixedArray::kLengthOffset), key);
  // rbx: FixedArray
  __ j(above, &fast_object);

  // Slow case: call runtime.
  __ bind(&slow);
  __ Integer32ToSmi(key, key);
  __ bind(&slow_with_tagged_index);
  PropertyICCompiler::GenerateRuntimeSetProperty(masm, language_mode);
  // Never returns to here.

  __ bind(&maybe_name_key);
  __ movp(r9, FieldOperand(key, HeapObject::kMapOffset));
  __ movzxbp(r9, FieldOperand(r9, Map::kInstanceTypeOffset));
  __ JumpIfNotUniqueNameInstanceType(r9, &slow_with_tagged_index);

  Register vector = StoreWithVectorDescriptor::VectorRegister();
  Register slot = StoreWithVectorDescriptor::SlotRegister();
  // The handlers in the stub cache expect a vector and slot. Since we won't
  // change the IC from any downstream misses, a dummy vector can be used.
  Handle<TypeFeedbackVector> dummy_vector =
      TypeFeedbackVector::DummyVector(masm->isolate());
  int slot_index = dummy_vector->GetIndex(
      FeedbackVectorSlot(TypeFeedbackVector::kDummyKeyedStoreICSlot));
  __ Move(vector, dummy_vector);
  __ Move(slot, Smi::FromInt(slot_index));

  masm->isolate()->store_stub_cache()->GenerateProbe(masm, receiver, key, r9,
                                                     no_reg);
  // Cache miss.
  __ jmp(&miss);

  // Extra capacity case: Check if there is extra capacity to
  // perform the store and update the length. Used for adding one
  // element to the array by writing to array[array.length].
  __ bind(&extra);
  // receiver is a JSArray.
  // rbx: receiver's elements array (a FixedArray)
  // flags: smicompare (receiver.length(), rbx)
  __ j(not_equal, &slow);  // do not leave holes in the array
  __ SmiCompareInteger32(FieldOperand(rbx, FixedArray::kLengthOffset), key);
  __ j(below_equal, &slow);
  // Increment index to get new length.
  __ movp(rdi, FieldOperand(rbx, HeapObject::kMapOffset));
  __ CompareRoot(rdi, Heap::kFixedArrayMapRootIndex);
  __ j(not_equal, &check_if_double_array);
  __ jmp(&fast_object_grow);

  __ bind(&check_if_double_array);
  // rdi: elements array's map
  __ CompareRoot(rdi, Heap::kFixedDoubleArrayMapRootIndex);
  __ j(not_equal, &slow);
  __ jmp(&fast_double_grow);

  // Array case: Get the length and the elements array from the JS
  // array. Check that the array is in fast mode (and writable); if it
  // is the length is always a smi.
  __ bind(&array);
  // receiver is a JSArray.
  __ movp(rbx, FieldOperand(receiver, JSObject::kElementsOffset));

  // Check the key against the length in the array, compute the
  // address to store into and fall through to fast case.
  __ SmiCompareInteger32(FieldOperand(receiver, JSArray::kLengthOffset), key);
  __ j(below_equal, &extra);

  KeyedStoreGenerateMegamorphicHelper(masm, &fast_object, &fast_double, &slow,
                                      kCheckMap, kDontIncrementLength);
  KeyedStoreGenerateMegamorphicHelper(masm, &fast_object_grow,
                                      &fast_double_grow, &slow, kDontCheckMap,
                                      kIncrementLength);

  __ bind(&miss);
  GenerateMiss(masm);
}

void LoadIC::GenerateNormal(MacroAssembler* masm) {
  Register dictionary = rax;
  DCHECK(!dictionary.is(LoadDescriptor::ReceiverRegister()));
  DCHECK(!dictionary.is(LoadDescriptor::NameRegister()));

  Label slow;

  __ movp(dictionary, FieldOperand(LoadDescriptor::ReceiverRegister(),
                                   JSObject::kPropertiesOffset));
  GenerateDictionaryLoad(masm, &slow, dictionary,
                         LoadDescriptor::NameRegister(), rbx, rdi, rax);
  __ ret(0);

  // Dictionary load failed, go slow (but don't miss).
  __ bind(&slow);
  LoadIC::GenerateRuntimeGetProperty(masm);
}


static void LoadIC_PushArgs(MacroAssembler* masm) {
  Register receiver = LoadDescriptor::ReceiverRegister();
  Register name = LoadDescriptor::NameRegister();
  Register slot = LoadDescriptor::SlotRegister();
  Register vector = LoadWithVectorDescriptor::VectorRegister();
  DCHECK(!rdi.is(receiver) && !rdi.is(name) && !rdi.is(slot) &&
         !rdi.is(vector));

  __ PopReturnAddressTo(rdi);
  __ Push(receiver);
  __ Push(name);
  __ Push(slot);
  __ Push(vector);
  __ PushReturnAddressFrom(rdi);
}


void LoadIC::GenerateMiss(MacroAssembler* masm) {
  // The return address is on the stack.

  Counters* counters = masm->isolate()->counters();
  __ IncrementCounter(counters->ic_load_miss(), 1);

  LoadIC_PushArgs(masm);

  // Perform tail call to the entry.
  __ TailCallRuntime(Runtime::kLoadIC_Miss);
}

void LoadIC::GenerateRuntimeGetProperty(MacroAssembler* masm) {
  // The return address is on the stack.
  Register receiver = LoadDescriptor::ReceiverRegister();
  Register name = LoadDescriptor::NameRegister();

  DCHECK(!rbx.is(receiver) && !rbx.is(name));

  __ PopReturnAddressTo(rbx);
  __ Push(receiver);
  __ Push(name);
  __ PushReturnAddressFrom(rbx);

  // Do tail-call to runtime routine.
  __ TailCallRuntime(Runtime::kGetProperty);
}


void KeyedLoadIC::GenerateMiss(MacroAssembler* masm) {
  // The return address is on the stack.
  Counters* counters = masm->isolate()->counters();
  __ IncrementCounter(counters->ic_keyed_load_miss(), 1);

  LoadIC_PushArgs(masm);

  // Perform tail call to the entry.
  __ TailCallRuntime(Runtime::kKeyedLoadIC_Miss);
}

void KeyedLoadIC::GenerateRuntimeGetProperty(MacroAssembler* masm) {
  // The return address is on the stack.
  Register receiver = LoadDescriptor::ReceiverRegister();
  Register name = LoadDescriptor::NameRegister();

  DCHECK(!rbx.is(receiver) && !rbx.is(name));

  __ PopReturnAddressTo(rbx);
  __ Push(receiver);
  __ Push(name);
  __ PushReturnAddressFrom(rbx);

  // Do tail-call to runtime routine.
  __ TailCallRuntime(Runtime::kKeyedGetProperty);
}

static void StoreIC_PushArgs(MacroAssembler* masm) {
  Register receiver = StoreWithVectorDescriptor::ReceiverRegister();
  Register name = StoreWithVectorDescriptor::NameRegister();
  Register value = StoreWithVectorDescriptor::ValueRegister();
  Register slot = StoreWithVectorDescriptor::SlotRegister();
  Register vector = StoreWithVectorDescriptor::VectorRegister();
  Register temp = r11;
  DCHECK(!AreAliased(receiver, name, value, slot, vector, temp));

  __ PopReturnAddressTo(temp);
  __ Push(value);
  __ Push(slot);
  __ Push(vector);
  __ Push(receiver);
  __ Push(name);
  __ PushReturnAddressFrom(temp);
}


void StoreIC::GenerateMiss(MacroAssembler* masm) {
  // Return address is on the stack.
  StoreIC_PushArgs(masm);

  // Perform tail call to the entry.
  __ TailCallRuntime(Runtime::kStoreIC_Miss);
}


void StoreIC::GenerateNormal(MacroAssembler* masm) {
  Register receiver = StoreDescriptor::ReceiverRegister();
  Register name = StoreDescriptor::NameRegister();
  Register value = StoreDescriptor::ValueRegister();
  Register dictionary = r11;
  DCHECK(!AreAliased(dictionary, StoreWithVectorDescriptor::VectorRegister(),
                     StoreWithVectorDescriptor::SlotRegister()));

  Label miss;

  __ movp(dictionary, FieldOperand(receiver, JSObject::kPropertiesOffset));
  GenerateDictionaryStore(masm, &miss, dictionary, name, value, r8, r9);
  Counters* counters = masm->isolate()->counters();
  __ IncrementCounter(counters->ic_store_normal_hit(), 1);
  __ ret(0);

  __ bind(&miss);
  __ IncrementCounter(counters->ic_store_normal_miss(), 1);
  GenerateMiss(masm);
}


void KeyedStoreIC::GenerateMiss(MacroAssembler* masm) {
  // Return address is on the stack.
  StoreIC_PushArgs(masm);

  // Do tail-call to runtime routine.
  __ TailCallRuntime(Runtime::kKeyedStoreIC_Miss);
}

void KeyedStoreIC::GenerateSlow(MacroAssembler* masm) {
  // Return address is on the stack.
  StoreIC_PushArgs(masm);

  // Do tail-call to runtime routine.
  __ TailCallRuntime(Runtime::kKeyedStoreIC_Slow);
}

#undef __


Condition CompareIC::ComputeCondition(Token::Value op) {
  switch (op) {
    case Token::EQ_STRICT:
    case Token::EQ:
      return equal;
    case Token::LT:
      return less;
    case Token::GT:
      return greater;
    case Token::LTE:
      return less_equal;
    case Token::GTE:
      return greater_equal;
    default:
      UNREACHABLE();
      return no_condition;
  }
}


bool CompareIC::HasInlinedSmiCode(Address address) {
  // The address of the instruction following the call.
  Address test_instruction_address =
      address + Assembler::kCallTargetAddressOffset;

  // If the instruction following the call is not a test al, nothing
  // was inlined.
  return *test_instruction_address == Assembler::kTestAlByte;
}


void PatchInlinedSmiCode(Isolate* isolate, Address address,
                         InlinedSmiCheck check) {
  // The address of the instruction following the call.
  Address test_instruction_address =
      address + Assembler::kCallTargetAddressOffset;

  // If the instruction following the call is not a test al, nothing
  // was inlined.
  if (*test_instruction_address != Assembler::kTestAlByte) {
    DCHECK(*test_instruction_address == Assembler::kNopByte);
    return;
  }

  Address delta_address = test_instruction_address + 1;
  // The delta to the start of the map check instruction and the
  // condition code uses at the patched jump.
  uint8_t delta = *reinterpret_cast<uint8_t*>(delta_address);
  if (FLAG_trace_ic) {
    PrintF("[  patching ic at %p, test=%p, delta=%d\n",
           static_cast<void*>(address),
           static_cast<void*>(test_instruction_address), delta);
  }

  // Patch with a short conditional jump. Enabling means switching from a short
  // jump-if-carry/not-carry to jump-if-zero/not-zero, whereas disabling is the
  // reverse operation of that.
  Address jmp_address = test_instruction_address - delta;
  DCHECK((check == ENABLE_INLINED_SMI_CHECK)
             ? (*jmp_address == Assembler::kJncShortOpcode ||
                *jmp_address == Assembler::kJcShortOpcode)
             : (*jmp_address == Assembler::kJnzShortOpcode ||
                *jmp_address == Assembler::kJzShortOpcode));
  Condition cc =
      (check == ENABLE_INLINED_SMI_CHECK)
          ? (*jmp_address == Assembler::kJncShortOpcode ? not_zero : zero)
          : (*jmp_address == Assembler::kJnzShortOpcode ? not_carry : carry);
  *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
}
}  // namespace internal
}  // namespace v8

#endif  // V8_TARGET_ARCH_X64