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v8/src/code-stubs-hydrogen.cc
danno 6236060c9c [stubs] Port LoadFieldStub to TF 
LoadFieldStub is the last Crankshaft/Hydrogen stub that stands in the way
of being able to run --ignition-staging --turbo without any Crankshaft support,
even for ICs/stubs.

Review-Url: https://codereview.chromium.org/2595343002
Cr-Commit-Position: refs/heads/master@{#41939}
2016-12-23 12:01:26 +00:00

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27 KiB
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// 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.
#include "src/code-stubs.h"
#include <memory>
#include "src/bailout-reason.h"
#include "src/code-factory.h"
#include "src/code-stub-assembler.h"
#include "src/crankshaft/hydrogen.h"
#include "src/crankshaft/lithium.h"
#include "src/field-index.h"
#include "src/ic/ic.h"
namespace v8 {
namespace internal {
static LChunk* OptimizeGraph(HGraph* graph) {
DisallowHeapAllocation no_allocation;
DisallowHandleAllocation no_handles;
DisallowHandleDereference no_deref;
DCHECK(graph != NULL);
BailoutReason bailout_reason = kNoReason;
if (!graph->Optimize(&bailout_reason)) {
FATAL(GetBailoutReason(bailout_reason));
}
LChunk* chunk = LChunk::NewChunk(graph);
if (chunk == NULL) {
FATAL(GetBailoutReason(graph->info()->bailout_reason()));
}
return chunk;
}
class CodeStubGraphBuilderBase : public HGraphBuilder {
public:
explicit CodeStubGraphBuilderBase(CompilationInfo* info, CodeStub* code_stub)
: HGraphBuilder(info, code_stub->GetCallInterfaceDescriptor(), false),
arguments_length_(NULL),
info_(info),
code_stub_(code_stub),
descriptor_(code_stub),
context_(NULL) {
int parameter_count = GetParameterCount();
parameters_.reset(new HParameter*[parameter_count]);
}
virtual bool BuildGraph();
protected:
virtual HValue* BuildCodeStub() = 0;
int GetParameterCount() const { return descriptor_.GetParameterCount(); }
int GetRegisterParameterCount() const {
return descriptor_.GetRegisterParameterCount();
}
HParameter* GetParameter(int parameter) {
DCHECK(parameter < GetParameterCount());
return parameters_[parameter];
}
Representation GetParameterRepresentation(int parameter) {
return RepresentationFromMachineType(
descriptor_.GetParameterType(parameter));
}
bool IsParameterCountRegister(int index) const {
return descriptor_.GetRegisterParameter(index)
.is(descriptor_.stack_parameter_count());
}
HValue* GetArgumentsLength() {
// This is initialized in BuildGraph()
DCHECK(arguments_length_ != NULL);
return arguments_length_;
}
CompilationInfo* info() { return info_; }
CodeStub* stub() { return code_stub_; }
HContext* context() { return context_; }
Isolate* isolate() { return info_->isolate(); }
HLoadNamedField* BuildLoadNamedField(HValue* object, FieldIndex index);
void BuildStoreNamedField(HValue* object, HValue* value, FieldIndex index,
Representation representation,
bool transition_to_field);
HValue* BuildPushElement(HValue* object, HValue* argc,
HValue* argument_elements, ElementsKind kind);
HValue* BuildToString(HValue* input, bool convert);
HValue* BuildToPrimitive(HValue* input, HValue* input_map);
private:
std::unique_ptr<HParameter* []> parameters_;
HValue* arguments_length_;
CompilationInfo* info_;
CodeStub* code_stub_;
CodeStubDescriptor descriptor_;
HContext* context_;
};
bool CodeStubGraphBuilderBase::BuildGraph() {
// Update the static counter each time a new code stub is generated.
isolate()->counters()->code_stubs()->Increment();
if (FLAG_trace_hydrogen_stubs) {
const char* name = CodeStub::MajorName(stub()->MajorKey());
PrintF("-----------------------------------------------------------\n");
PrintF("Compiling stub %s using hydrogen\n", name);
isolate()->GetHTracer()->TraceCompilation(info());
}
int param_count = GetParameterCount();
int register_param_count = GetRegisterParameterCount();
HEnvironment* start_environment = graph()->start_environment();
HBasicBlock* next_block = CreateBasicBlock(start_environment);
Goto(next_block);
next_block->SetJoinId(BailoutId::StubEntry());
set_current_block(next_block);
bool runtime_stack_params = descriptor_.stack_parameter_count().is_valid();
HInstruction* stack_parameter_count = NULL;
for (int i = 0; i < param_count; ++i) {
Representation r = GetParameterRepresentation(i);
HParameter* param;
if (i >= register_param_count) {
param = Add<HParameter>(i - register_param_count,
HParameter::STACK_PARAMETER, r);
} else {
param = Add<HParameter>(i, HParameter::REGISTER_PARAMETER, r);
}
start_environment->Bind(i, param);
parameters_[i] = param;
if (i < register_param_count && IsParameterCountRegister(i)) {
param->set_type(HType::Smi());
stack_parameter_count = param;
arguments_length_ = stack_parameter_count;
}
}
DCHECK(!runtime_stack_params || arguments_length_ != NULL);
if (!runtime_stack_params) {
stack_parameter_count =
Add<HConstant>(param_count - register_param_count - 1);
// graph()->GetConstantMinus1();
arguments_length_ = graph()->GetConstant0();
}
context_ = Add<HContext>();
start_environment->BindContext(context_);
start_environment->Bind(param_count, context_);
Add<HSimulate>(BailoutId::StubEntry());
NoObservableSideEffectsScope no_effects(this);
HValue* return_value = BuildCodeStub();
// We might have extra expressions to pop from the stack in addition to the
// arguments above.
HInstruction* stack_pop_count = stack_parameter_count;
if (descriptor_.function_mode() == JS_FUNCTION_STUB_MODE) {
if (!stack_parameter_count->IsConstant() &&
descriptor_.hint_stack_parameter_count() < 0) {
HInstruction* constant_one = graph()->GetConstant1();
stack_pop_count = AddUncasted<HAdd>(stack_parameter_count, constant_one);
stack_pop_count->ClearFlag(HValue::kCanOverflow);
// TODO(mvstanton): verify that stack_parameter_count+1 really fits in a
// smi.
} else {
int count = descriptor_.hint_stack_parameter_count();
stack_pop_count = Add<HConstant>(count);
}
}
if (current_block() != NULL) {
HReturn* hreturn_instruction = New<HReturn>(return_value,
stack_pop_count);
FinishCurrentBlock(hreturn_instruction);
}
return true;
}
template <class Stub>
class CodeStubGraphBuilder: public CodeStubGraphBuilderBase {
public:
explicit CodeStubGraphBuilder(CompilationInfo* info, CodeStub* stub)
: CodeStubGraphBuilderBase(info, stub) {}
typedef typename Stub::Descriptor Descriptor;
protected:
virtual HValue* BuildCodeStub() {
if (casted_stub()->IsUninitialized()) {
return BuildCodeUninitializedStub();
} else {
return BuildCodeInitializedStub();
}
}
virtual HValue* BuildCodeInitializedStub() {
UNIMPLEMENTED();
return NULL;
}
virtual HValue* BuildCodeUninitializedStub() {
// Force a deopt that falls back to the runtime.
HValue* undefined = graph()->GetConstantUndefined();
IfBuilder builder(this);
builder.IfNot<HCompareObjectEqAndBranch, HValue*>(undefined, undefined);
builder.Then();
builder.ElseDeopt(DeoptimizeReason::kForcedDeoptToRuntime);
return undefined;
}
Stub* casted_stub() { return static_cast<Stub*>(stub()); }
};
Handle<Code> HydrogenCodeStub::GenerateLightweightMissCode(
ExternalReference miss) {
Factory* factory = isolate()->factory();
// Generate the new code.
MacroAssembler masm(isolate(), NULL, 256, CodeObjectRequired::kYes);
{
// Update the static counter each time a new code stub is generated.
isolate()->counters()->code_stubs()->Increment();
// Generate the code for the stub.
masm.set_generating_stub(true);
// TODO(yangguo): remove this once we can serialize IC stubs.
masm.enable_serializer();
NoCurrentFrameScope scope(&masm);
GenerateLightweightMiss(&masm, miss);
}
// Create the code object.
CodeDesc desc;
masm.GetCode(&desc);
// Copy the generated code into a heap object.
Handle<Code> new_object = factory->NewCode(
desc, GetCodeFlags(), masm.CodeObject(), NeedsImmovableCode());
return new_object;
}
Handle<Code> HydrogenCodeStub::GenerateRuntimeTailCall(
CodeStubDescriptor* descriptor) {
const char* name = CodeStub::MajorName(MajorKey());
Zone zone(isolate()->allocator(), ZONE_NAME);
CallInterfaceDescriptor interface_descriptor(GetCallInterfaceDescriptor());
compiler::CodeAssemblerState state(isolate(), &zone, interface_descriptor,
GetCodeFlags(), name);
CodeStubAssembler assembler(&state);
int total_params = interface_descriptor.GetStackParameterCount() +
interface_descriptor.GetRegisterParameterCount();
switch (total_params) {
case 0:
assembler.TailCallRuntime(descriptor->miss_handler_id(),
assembler.Parameter(0));
break;
case 1:
assembler.TailCallRuntime(descriptor->miss_handler_id(),
assembler.Parameter(1), assembler.Parameter(0));
break;
case 2:
assembler.TailCallRuntime(descriptor->miss_handler_id(),
assembler.Parameter(2), assembler.Parameter(0),
assembler.Parameter(1));
break;
case 3:
assembler.TailCallRuntime(descriptor->miss_handler_id(),
assembler.Parameter(3), assembler.Parameter(0),
assembler.Parameter(1), assembler.Parameter(2));
break;
case 4:
assembler.TailCallRuntime(descriptor->miss_handler_id(),
assembler.Parameter(4), assembler.Parameter(0),
assembler.Parameter(1), assembler.Parameter(2),
assembler.Parameter(3));
break;
default:
UNIMPLEMENTED();
break;
}
return compiler::CodeAssembler::GenerateCode(&state);
}
template <class Stub>
static Handle<Code> DoGenerateCode(Stub* stub) {
Isolate* isolate = stub->isolate();
CodeStubDescriptor descriptor(stub);
if (FLAG_minimal && descriptor.has_miss_handler()) {
return stub->GenerateRuntimeTailCall(&descriptor);
}
// If we are uninitialized we can use a light-weight stub to enter
// the runtime that is significantly faster than using the standard
// stub-failure deopt mechanism.
if (stub->IsUninitialized() && descriptor.has_miss_handler()) {
DCHECK(!descriptor.stack_parameter_count().is_valid());
return stub->GenerateLightweightMissCode(descriptor.miss_handler());
}
base::ElapsedTimer timer;
if (FLAG_profile_hydrogen_code_stub_compilation) {
timer.Start();
}
Zone zone(isolate->allocator(), ZONE_NAME);
CompilationInfo info(CStrVector(CodeStub::MajorName(stub->MajorKey())),
isolate, &zone, stub->GetCodeFlags());
// Parameter count is number of stack parameters.
int parameter_count = descriptor.GetStackParameterCount();
if (descriptor.function_mode() == NOT_JS_FUNCTION_STUB_MODE) {
parameter_count--;
}
info.set_parameter_count(parameter_count);
CodeStubGraphBuilder<Stub> builder(&info, stub);
LChunk* chunk = OptimizeGraph(builder.CreateGraph());
Handle<Code> code = chunk->Codegen();
if (FLAG_profile_hydrogen_code_stub_compilation) {
OFStream os(stdout);
os << "[Lazy compilation of " << stub << " took "
<< timer.Elapsed().InMillisecondsF() << " ms]" << std::endl;
}
return code;
}
HValue* CodeStubGraphBuilderBase::BuildPushElement(HValue* object, HValue* argc,
HValue* argument_elements,
ElementsKind kind) {
// Precheck whether all elements fit into the array.
if (!IsFastObjectElementsKind(kind)) {
LoopBuilder builder(this, context(), LoopBuilder::kPostIncrement);
HValue* start = graph()->GetConstant0();
HValue* key = builder.BeginBody(start, argc, Token::LT);
{
HInstruction* argument =
Add<HAccessArgumentsAt>(argument_elements, argc, key);
IfBuilder can_store(this);
can_store.IfNot<HIsSmiAndBranch>(argument);
if (IsFastDoubleElementsKind(kind)) {
can_store.And();
can_store.IfNot<HCompareMap>(argument,
isolate()->factory()->heap_number_map());
}
can_store.ThenDeopt(DeoptimizeReason::kFastPathFailed);
can_store.End();
}
builder.EndBody();
}
HValue* length = Add<HLoadNamedField>(object, nullptr,
HObjectAccess::ForArrayLength(kind));
HValue* new_length = AddUncasted<HAdd>(length, argc);
HValue* max_key = AddUncasted<HSub>(new_length, graph()->GetConstant1());
HValue* elements = Add<HLoadNamedField>(object, nullptr,
HObjectAccess::ForElementsPointer());
elements = BuildCheckForCapacityGrow(object, elements, kind, length, max_key,
true, STORE);
LoopBuilder builder(this, context(), LoopBuilder::kPostIncrement);
HValue* start = graph()->GetConstant0();
HValue* key = builder.BeginBody(start, argc, Token::LT);
{
HValue* argument = Add<HAccessArgumentsAt>(argument_elements, argc, key);
HValue* index = AddUncasted<HAdd>(key, length);
AddElementAccess(elements, index, argument, object, nullptr, kind, STORE);
}
builder.EndBody();
return new_length;
}
HLoadNamedField* CodeStubGraphBuilderBase::BuildLoadNamedField(
HValue* object, FieldIndex index) {
Representation representation = index.is_double()
? Representation::Double()
: Representation::Tagged();
int offset = index.offset();
HObjectAccess access = index.is_inobject()
? HObjectAccess::ForObservableJSObjectOffset(offset, representation)
: HObjectAccess::ForBackingStoreOffset(offset, representation);
if (index.is_double() &&
(!FLAG_unbox_double_fields || !index.is_inobject())) {
// Load the heap number.
object = Add<HLoadNamedField>(
object, nullptr, access.WithRepresentation(Representation::Tagged()));
// Load the double value from it.
access = HObjectAccess::ForHeapNumberValue();
}
return Add<HLoadNamedField>(object, nullptr, access);
}
void CodeStubGraphBuilderBase::BuildStoreNamedField(
HValue* object, HValue* value, FieldIndex index,
Representation representation, bool transition_to_field) {
DCHECK(!index.is_double() || representation.IsDouble());
int offset = index.offset();
HObjectAccess access =
index.is_inobject()
? HObjectAccess::ForObservableJSObjectOffset(offset, representation)
: HObjectAccess::ForBackingStoreOffset(offset, representation);
if (representation.IsDouble()) {
if (!FLAG_unbox_double_fields || !index.is_inobject()) {
HObjectAccess heap_number_access =
access.WithRepresentation(Representation::Tagged());
if (transition_to_field) {
// The store requires a mutable HeapNumber to be allocated.
NoObservableSideEffectsScope no_side_effects(this);
HInstruction* heap_number_size = Add<HConstant>(HeapNumber::kSize);
// TODO(hpayer): Allocation site pretenuring support.
HInstruction* heap_number =
Add<HAllocate>(heap_number_size, HType::HeapObject(), NOT_TENURED,
MUTABLE_HEAP_NUMBER_TYPE, graph()->GetConstant0());
AddStoreMapConstant(heap_number,
isolate()->factory()->mutable_heap_number_map());
Add<HStoreNamedField>(heap_number, HObjectAccess::ForHeapNumberValue(),
value);
// Store the new mutable heap number into the object.
access = heap_number_access;
value = heap_number;
} else {
// Load the heap number.
object = Add<HLoadNamedField>(object, nullptr, heap_number_access);
// Store the double value into it.
access = HObjectAccess::ForHeapNumberValue();
}
}
} else if (representation.IsHeapObject()) {
BuildCheckHeapObject(value);
}
Add<HStoreNamedField>(object, access, value, INITIALIZING_STORE);
}
template <>
HValue* CodeStubGraphBuilder<TransitionElementsKindStub>::BuildCodeStub() {
ElementsKind const from_kind = casted_stub()->from_kind();
ElementsKind const to_kind = casted_stub()->to_kind();
HValue* const object = GetParameter(Descriptor::kObject);
HValue* const map = GetParameter(Descriptor::kMap);
// The {object} is known to be a JSObject (otherwise it wouldn't have elements
// anyways).
object->set_type(HType::JSObject());
info()->MarkAsSavesCallerDoubles();
DCHECK_IMPLIES(IsFastHoleyElementsKind(from_kind),
IsFastHoleyElementsKind(to_kind));
if (AllocationSite::GetMode(from_kind, to_kind) == TRACK_ALLOCATION_SITE) {
Add<HTrapAllocationMemento>(object);
}
if (!IsSimpleMapChangeTransition(from_kind, to_kind)) {
HInstruction* elements = AddLoadElements(object);
IfBuilder if_objecthaselements(this);
if_objecthaselements.IfNot<HCompareObjectEqAndBranch>(
elements, Add<HConstant>(isolate()->factory()->empty_fixed_array()));
if_objecthaselements.Then();
{
// Determine the elements capacity.
HInstruction* elements_length = AddLoadFixedArrayLength(elements);
// Determine the effective (array) length.
IfBuilder if_objectisarray(this);
if_objectisarray.If<HHasInstanceTypeAndBranch>(object, JS_ARRAY_TYPE);
if_objectisarray.Then();
{
// The {object} is a JSArray, load the special "length" property.
Push(Add<HLoadNamedField>(object, nullptr,
HObjectAccess::ForArrayLength(from_kind)));
}
if_objectisarray.Else();
{
// The {object} is some other JSObject.
Push(elements_length);
}
if_objectisarray.End();
HValue* length = Pop();
BuildGrowElementsCapacity(object, elements, from_kind, to_kind, length,
elements_length);
}
if_objecthaselements.End();
}
Add<HStoreNamedField>(object, HObjectAccess::ForMap(), map);
return object;
}
Handle<Code> TransitionElementsKindStub::GenerateCode() {
return DoGenerateCode(this);
}
template <>
HValue* CodeStubGraphBuilder<BinaryOpICStub>::BuildCodeInitializedStub() {
BinaryOpICState state = casted_stub()->state();
HValue* left = GetParameter(Descriptor::kLeft);
HValue* right = GetParameter(Descriptor::kRight);
AstType* left_type = state.GetLeftType();
AstType* right_type = state.GetRightType();
AstType* result_type = state.GetResultType();
DCHECK(!left_type->Is(AstType::None()) && !right_type->Is(AstType::None()) &&
(state.HasSideEffects() || !result_type->Is(AstType::None())));
HValue* result = NULL;
HAllocationMode allocation_mode(NOT_TENURED);
if (state.op() == Token::ADD && (left_type->Maybe(AstType::String()) ||
right_type->Maybe(AstType::String())) &&
!left_type->Is(AstType::String()) && !right_type->Is(AstType::String())) {
// For the generic add stub a fast case for string addition is performance
// critical.
if (left_type->Maybe(AstType::String())) {
IfBuilder if_leftisstring(this);
if_leftisstring.If<HIsStringAndBranch>(left);
if_leftisstring.Then();
{
Push(BuildBinaryOperation(state.op(), left, right, AstType::String(),
right_type, result_type,
state.fixed_right_arg(), allocation_mode));
}
if_leftisstring.Else();
{
Push(BuildBinaryOperation(state.op(), left, right, left_type,
right_type, result_type,
state.fixed_right_arg(), allocation_mode));
}
if_leftisstring.End();
result = Pop();
} else {
IfBuilder if_rightisstring(this);
if_rightisstring.If<HIsStringAndBranch>(right);
if_rightisstring.Then();
{
Push(BuildBinaryOperation(state.op(), left, right, left_type,
AstType::String(), result_type,
state.fixed_right_arg(), allocation_mode));
}
if_rightisstring.Else();
{
Push(BuildBinaryOperation(state.op(), left, right, left_type,
right_type, result_type,
state.fixed_right_arg(), allocation_mode));
}
if_rightisstring.End();
result = Pop();
}
} else {
result = BuildBinaryOperation(state.op(), left, right, left_type,
right_type, result_type,
state.fixed_right_arg(), allocation_mode);
}
// If we encounter a generic argument, the number conversion is
// observable, thus we cannot afford to bail out after the fact.
if (!state.HasSideEffects()) {
result = EnforceNumberType(result, result_type);
}
return result;
}
Handle<Code> BinaryOpICStub::GenerateCode() {
return DoGenerateCode(this);
}
template <>
HValue* CodeStubGraphBuilder<BinaryOpWithAllocationSiteStub>::BuildCodeStub() {
BinaryOpICState state = casted_stub()->state();
HValue* allocation_site = GetParameter(Descriptor::kAllocationSite);
HValue* left = GetParameter(Descriptor::kLeft);
HValue* right = GetParameter(Descriptor::kRight);
AstType* left_type = state.GetLeftType();
AstType* right_type = state.GetRightType();
AstType* result_type = state.GetResultType();
HAllocationMode allocation_mode(allocation_site);
return BuildBinaryOperation(state.op(), left, right, left_type, right_type,
result_type, state.fixed_right_arg(),
allocation_mode);
}
Handle<Code> BinaryOpWithAllocationSiteStub::GenerateCode() {
return DoGenerateCode(this);
}
HValue* CodeStubGraphBuilderBase::BuildToString(HValue* input, bool convert) {
if (!convert) return BuildCheckString(input);
IfBuilder if_inputissmi(this);
HValue* inputissmi = if_inputissmi.If<HIsSmiAndBranch>(input);
if_inputissmi.Then();
{
// Convert the input smi to a string.
Push(BuildNumberToString(input, AstType::SignedSmall()));
}
if_inputissmi.Else();
{
HValue* input_map =
Add<HLoadNamedField>(input, inputissmi, HObjectAccess::ForMap());
HValue* input_instance_type = Add<HLoadNamedField>(
input_map, inputissmi, HObjectAccess::ForMapInstanceType());
IfBuilder if_inputisstring(this);
if_inputisstring.If<HCompareNumericAndBranch>(
input_instance_type, Add<HConstant>(FIRST_NONSTRING_TYPE), Token::LT);
if_inputisstring.Then();
{
// The input is already a string.
Push(input);
}
if_inputisstring.Else();
{
// Convert to primitive first (if necessary), see
// ES6 section 12.7.3 The Addition operator.
IfBuilder if_inputisprimitive(this);
STATIC_ASSERT(FIRST_PRIMITIVE_TYPE == FIRST_TYPE);
if_inputisprimitive.If<HCompareNumericAndBranch>(
input_instance_type, Add<HConstant>(LAST_PRIMITIVE_TYPE), Token::LTE);
if_inputisprimitive.Then();
{
// The input is already a primitive.
Push(input);
}
if_inputisprimitive.Else();
{
// Convert the input to a primitive.
Push(BuildToPrimitive(input, input_map));
}
if_inputisprimitive.End();
// Convert the primitive to a string value.
HValue* values[] = {Pop()};
Callable toString = CodeFactory::ToString(isolate());
Push(AddUncasted<HCallWithDescriptor>(Add<HConstant>(toString.code()), 0,
toString.descriptor(),
ArrayVector(values)));
}
if_inputisstring.End();
}
if_inputissmi.End();
return Pop();
}
HValue* CodeStubGraphBuilderBase::BuildToPrimitive(HValue* input,
HValue* input_map) {
// Get the native context of the caller.
HValue* native_context = BuildGetNativeContext();
// Determine the initial map of the %ObjectPrototype%.
HValue* object_function_prototype_map =
Add<HLoadNamedField>(native_context, nullptr,
HObjectAccess::ForContextSlot(
Context::OBJECT_FUNCTION_PROTOTYPE_MAP_INDEX));
// Determine the initial map of the %StringPrototype%.
HValue* string_function_prototype_map =
Add<HLoadNamedField>(native_context, nullptr,
HObjectAccess::ForContextSlot(
Context::STRING_FUNCTION_PROTOTYPE_MAP_INDEX));
// Determine the initial map of the String function.
HValue* string_function = Add<HLoadNamedField>(
native_context, nullptr,
HObjectAccess::ForContextSlot(Context::STRING_FUNCTION_INDEX));
HValue* string_function_initial_map = Add<HLoadNamedField>(
string_function, nullptr, HObjectAccess::ForPrototypeOrInitialMap());
// Determine the map of the [[Prototype]] of {input}.
HValue* input_prototype =
Add<HLoadNamedField>(input_map, nullptr, HObjectAccess::ForPrototype());
HValue* input_prototype_map =
Add<HLoadNamedField>(input_prototype, nullptr, HObjectAccess::ForMap());
// For string wrappers (JSValue instances with [[StringData]] internal
// fields), we can shortcirciut the ToPrimitive if
//
// (a) the {input} map matches the initial map of the String function,
// (b) the {input} [[Prototype]] is the unmodified %StringPrototype% (i.e.
// no one monkey-patched toString, @@toPrimitive or valueOf), and
// (c) the %ObjectPrototype% (i.e. the [[Prototype]] of the
// %StringPrototype%) is also unmodified, that is no one sneaked a
// @@toPrimitive into the %ObjectPrototype%.
//
// If all these assumptions hold, we can just take the [[StringData]] value
// and return it.
// TODO(bmeurer): This just repairs a regression introduced by removing the
// weird (and broken) intrinsic %_IsStringWrapperSafeForDefaultValue, which
// was intendend to something similar to this, although less efficient and
// wrong in the presence of @@toPrimitive. Long-term we might want to move
// into the direction of having a ToPrimitiveStub that can do common cases
// while staying in JavaScript land (i.e. not going to C++).
IfBuilder if_inputisstringwrapper(this);
if_inputisstringwrapper.If<HCompareObjectEqAndBranch>(
input_map, string_function_initial_map);
if_inputisstringwrapper.And();
if_inputisstringwrapper.If<HCompareObjectEqAndBranch>(
input_prototype_map, string_function_prototype_map);
if_inputisstringwrapper.And();
if_inputisstringwrapper.If<HCompareObjectEqAndBranch>(
Add<HLoadNamedField>(Add<HLoadNamedField>(input_prototype_map, nullptr,
HObjectAccess::ForPrototype()),
nullptr, HObjectAccess::ForMap()),
object_function_prototype_map);
if_inputisstringwrapper.Then();
{
Push(BuildLoadNamedField(
input, FieldIndex::ForInObjectOffset(JSValue::kValueOffset)));
}
if_inputisstringwrapper.Else();
{
// TODO(bmeurer): Add support for fast ToPrimitive conversion using
// a dedicated ToPrimitiveStub.
Add<HPushArguments>(input);
Push(Add<HCallRuntime>(Runtime::FunctionForId(Runtime::kToPrimitive), 1));
}
if_inputisstringwrapper.End();
return Pop();
}
template <>
HValue* CodeStubGraphBuilder<ToBooleanICStub>::BuildCodeInitializedStub() {
ToBooleanICStub* stub = casted_stub();
IfBuilder if_true(this);
if_true.If<HBranch>(GetParameter(Descriptor::kArgument), stub->hints());
if_true.Then();
if_true.Return(graph()->GetConstantTrue());
if_true.Else();
if_true.End();
return graph()->GetConstantFalse();
}
Handle<Code> ToBooleanICStub::GenerateCode() { return DoGenerateCode(this); }
} // namespace internal
} // namespace v8
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