src/code-stubs-hydrogen.cc

// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "v8.h"

#include "code-stubs.h"
#include "hydrogen.h"
#include "lithium.h"

namespace v8 {
namespace internal {


static LChunk* OptimizeGraph(HGraph* graph) {
  DisallowHeapAllocation no_allocation;
  DisallowHandleAllocation no_handles;
  DisallowHandleDereference no_deref;

  ASSERT(graph != NULL);
  SmartArrayPointer<char> bailout_reason;
  if (!graph->Optimize(&bailout_reason)) {
    FATAL(bailout_reason.is_empty() ? "unknown" : *bailout_reason);
  }
  LChunk* chunk = LChunk::NewChunk(graph);
  if (chunk == NULL) {
    FATAL(graph->info()->bailout_reason());
  }
  return chunk;
}


class CodeStubGraphBuilderBase : public HGraphBuilder {
 public:
  CodeStubGraphBuilderBase(Isolate* isolate, HydrogenCodeStub* stub)
      : HGraphBuilder(&info_),
        arguments_length_(NULL),
        info_(stub, isolate),
        context_(NULL) {
    descriptor_ = stub->GetInterfaceDescriptor(isolate);
    parameters_.Reset(new HParameter*[descriptor_->register_param_count_]);
  }
  virtual bool BuildGraph();

 protected:
  virtual HValue* BuildCodeStub() = 0;
  HParameter* GetParameter(int parameter) {
    ASSERT(parameter < descriptor_->register_param_count_);
    return parameters_[parameter];
  }
  HValue* GetArgumentsLength() {
    // This is initialized in BuildGraph()
    ASSERT(arguments_length_ != NULL);
    return arguments_length_;
  }
  CompilationInfo* info() { return &info_; }
  HydrogenCodeStub* stub() { return info_.code_stub(); }
  HContext* context() { return context_; }
  Isolate* isolate() { return info_.isolate(); }

  class ArrayContextChecker {
   public:
    ArrayContextChecker(HGraphBuilder* builder, HValue* constructor,
                        HValue* array_function)
        : checker_(builder) {
      checker_.If<HCompareObjectEqAndBranch, HValue*>(constructor,
                                                      array_function);
      checker_.Then();
    }

    ~ArrayContextChecker() {
      checker_.ElseDeopt();
      checker_.End();
    }
   private:
    IfBuilder checker_;
  };

  enum ArgumentClass {
    NONE,
    SINGLE,
    MULTIPLE
  };

  HValue* BuildArrayConstructor(ElementsKind kind,
                                ContextCheckMode context_mode,
                                AllocationSiteOverrideMode override_mode,
                                ArgumentClass argument_class);
  HValue* BuildInternalArrayConstructor(ElementsKind kind,
                                        ArgumentClass argument_class);

 private:
  HValue* BuildArraySingleArgumentConstructor(JSArrayBuilder* builder);
  HValue* BuildArrayNArgumentsConstructor(JSArrayBuilder* builder,
                                          ElementsKind kind);

  SmartArrayPointer<HParameter*> parameters_;
  HValue* arguments_length_;
  CompilationInfoWithZone info_;
  CodeStubInterfaceDescriptor* 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) {
    const char* name = CodeStub::MajorName(stub()->MajorKey(), false);
    PrintF("-----------------------------------------------------------\n");
    PrintF("Compiling stub %s using hydrogen\n", name);
    isolate()->GetHTracer()->TraceCompilation(&info_);
  }

  Zone* zone = this->zone();
  int param_count = descriptor_->register_param_count_;
  HEnvironment* start_environment = graph()->start_environment();
  HBasicBlock* next_block = CreateBasicBlock(start_environment);
  current_block()->Goto(next_block);
  next_block->SetJoinId(BailoutId::StubEntry());
  set_current_block(next_block);

  HConstant* undefined_constant = new(zone) HConstant(
      isolate()->factory()->undefined_value());
  AddInstruction(undefined_constant);
  graph()->set_undefined_constant(undefined_constant);

  for (int i = 0; i < param_count; ++i) {
    HParameter* param =
        new(zone) HParameter(i, HParameter::REGISTER_PARAMETER);
    AddInstruction(param);
    start_environment->Bind(i, param);
    parameters_[i] = param;
  }

  HInstruction* stack_parameter_count;
  if (descriptor_->stack_parameter_count_ != NULL) {
    ASSERT(descriptor_->environment_length() == (param_count + 1));
    stack_parameter_count = new(zone) HParameter(param_count,
                                                 HParameter::REGISTER_PARAMETER,
                                                 Representation::Integer32());
    stack_parameter_count->set_type(HType::Smi());
    // It's essential to bind this value to the environment in case of deopt.
    AddInstruction(stack_parameter_count);
    start_environment->Bind(param_count, stack_parameter_count);
    arguments_length_ = stack_parameter_count;
  } else {
    ASSERT(descriptor_->environment_length() == param_count);
    stack_parameter_count = graph()->GetConstantMinus1();
    arguments_length_ = graph()->GetConstant0();
  }

  context_ = new(zone) HContext();
  AddInstruction(context_);
  start_environment->BindContext(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* amount = graph()->GetConstant1();
      stack_pop_count = AddInstruction(
          HAdd::New(zone, context_, stack_parameter_count, amount));
      stack_pop_count->ChangeRepresentation(Representation::Integer32());
      stack_pop_count->ClearFlag(HValue::kCanOverflow);
    } else {
      int count = descriptor_->hint_stack_parameter_count_;
      stack_pop_count = AddInstruction(new(zone) HConstant(count));
    }
  }

  if (current_block() != NULL) {
    HReturn* hreturn_instruction = new(zone) HReturn(return_value,
                                                     context_,
                                                     stack_pop_count);
    current_block()->Finish(hreturn_instruction);
    set_current_block(NULL);
  }
  return true;
}


template <class Stub>
class CodeStubGraphBuilder: public CodeStubGraphBuilderBase {
 public:
  explicit CodeStubGraphBuilder(Stub* stub)
      : CodeStubGraphBuilderBase(Isolate::Current(), stub) {}

 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();
    return undefined;
  }

  Stub* casted_stub() { return static_cast<Stub*>(stub()); }
};


Handle<Code> HydrogenCodeStub::GenerateLightweightMissCode(Isolate* isolate) {
  Factory* factory = isolate->factory();

  // Generate the new code.
  MacroAssembler masm(isolate, NULL, 256);

  {
    // Update the static counter each time a new code stub is generated.
    isolate->counters()->code_stubs()->Increment();

    // Nested stubs are not allowed for leaves.
    AllowStubCallsScope allow_scope(&masm, false);

    // Generate the code for the stub.
    masm.set_generating_stub(true);
    NoCurrentFrameScope scope(&masm);
    GenerateLightweightMiss(&masm);
  }

  // Create the code object.
  CodeDesc desc;
  masm.GetCode(&desc);

  // Copy the generated code into a heap object.
  Code::Flags flags = Code::ComputeFlags(
      GetCodeKind(),
      GetICState(),
      GetExtraICState(),
      GetStubType(),
      GetStubFlags());
  Handle<Code> new_object = factory->NewCode(
      desc, flags, masm.CodeObject(), NeedsImmovableCode());
  return new_object;
}


template <class Stub>
static Handle<Code> DoGenerateCode(Stub* stub) {
  Isolate* isolate = Isolate::Current();
  CodeStub::Major  major_key =
      static_cast<HydrogenCodeStub*>(stub)->MajorKey();
  CodeStubInterfaceDescriptor* descriptor =
      isolate->code_stub_interface_descriptor(major_key);
  if (descriptor->register_param_count_ < 0) {
    stub->InitializeInterfaceDescriptor(isolate, 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()) {
    ASSERT(descriptor->stack_parameter_count_ == NULL);
    return stub->GenerateLightweightMissCode(isolate);
  }
  CodeStubGraphBuilder<Stub> builder(stub);
  LChunk* chunk = OptimizeGraph(builder.CreateGraph());
  return chunk->Codegen();
}


template <>
HValue* CodeStubGraphBuilder<ToNumberStub>::BuildCodeStub() {
  HValue* value = GetParameter(0);

  // Check if the parameter is already a SMI or heap number.
  IfBuilder if_number(this);
  if_number.If<HIsSmiAndBranch>(value);
  if_number.OrIf<HCompareMap>(value, isolate()->factory()->heap_number_map());
  if_number.Then();

  // Return the number.
  Push(value);

  if_number.Else();

  // Convert the parameter to number using the builtin.
  HValue* function = AddLoadJSBuiltin(Builtins::TO_NUMBER, context());
  Add<HPushArgument>(value);
  Push(Add<HInvokeFunction>(context(), function, 1));

  if_number.End();

  return Pop();
}


Handle<Code> ToNumberStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<FastCloneShallowArrayStub>::BuildCodeStub() {
  Zone* zone = this->zone();
  Factory* factory = isolate()->factory();
  HValue* undefined = graph()->GetConstantUndefined();
  AllocationSiteMode alloc_site_mode = casted_stub()->allocation_site_mode();
  FastCloneShallowArrayStub::Mode mode = casted_stub()->mode();
  int length = casted_stub()->length();

  HInstruction* allocation_site =
      AddInstruction(new(zone) HLoadKeyed(GetParameter(0),
                                          GetParameter(1),
                                          NULL,
                                          FAST_ELEMENTS));
  IfBuilder checker(this);
  checker.IfNot<HCompareObjectEqAndBranch, HValue*>(allocation_site, undefined);
  checker.Then();

  HObjectAccess access = HObjectAccess::ForAllocationSiteTransitionInfo();
  HInstruction* boilerplate = AddLoad(allocation_site, access);
  if (mode == FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS) {
    HValue* elements = AddLoadElements(boilerplate);

    IfBuilder if_fixed_cow(this);
    if_fixed_cow.If<HCompareMap>(elements, factory->fixed_cow_array_map());
    if_fixed_cow.Then();
    environment()->Push(BuildCloneShallowArray(context(),
                                               boilerplate,
                                               allocation_site,
                                               alloc_site_mode,
                                               FAST_ELEMENTS,
                                               0/*copy-on-write*/));
    if_fixed_cow.Else();

    IfBuilder if_fixed(this);
    if_fixed.If<HCompareMap>(elements, factory->fixed_array_map());
    if_fixed.Then();
    environment()->Push(BuildCloneShallowArray(context(),
                                               boilerplate,
                                               allocation_site,
                                               alloc_site_mode,
                                               FAST_ELEMENTS,
                                               length));
    if_fixed.Else();
    environment()->Push(BuildCloneShallowArray(context(),
                                               boilerplate,
                                               allocation_site,
                                               alloc_site_mode,
                                               FAST_DOUBLE_ELEMENTS,
                                               length));
  } else {
    ElementsKind elements_kind = casted_stub()->ComputeElementsKind();
    environment()->Push(BuildCloneShallowArray(context(),
                                               boilerplate,
                                               allocation_site,
                                               alloc_site_mode,
                                               elements_kind,
                                               length));
  }

  checker.ElseDeopt();
  checker.End();

  return environment()->Pop();
}


Handle<Code> FastCloneShallowArrayStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<FastCloneShallowObjectStub>::BuildCodeStub() {
  Zone* zone = this->zone();
  HValue* undefined = graph()->GetConstantUndefined();

  HInstruction* boilerplate =
      AddInstruction(new(zone) HLoadKeyed(GetParameter(0),
                                          GetParameter(1),
                                          NULL,
                                          FAST_ELEMENTS));

  IfBuilder checker(this);
  checker.IfNot<HCompareObjectEqAndBranch, HValue*>(boilerplate, undefined);
  checker.And();

  int size = JSObject::kHeaderSize + casted_stub()->length() * kPointerSize;
  HValue* boilerplate_size =
      AddInstruction(new(zone) HInstanceSize(boilerplate));
  HValue* size_in_words =
      AddInstruction(new(zone) HConstant(size >> kPointerSizeLog2));
  checker.If<HCompareNumericAndBranch>(boilerplate_size,
                                       size_in_words, Token::EQ);
  checker.Then();

  HValue* size_in_bytes = AddInstruction(new(zone) HConstant(size));
  HAllocate::Flags flags = HAllocate::CAN_ALLOCATE_IN_NEW_SPACE;
  if (isolate()->heap()->ShouldGloballyPretenure()) {
    flags = static_cast<HAllocate::Flags>(
       flags | HAllocate::CAN_ALLOCATE_IN_OLD_POINTER_SPACE);
  }

  HInstruction* object = AddInstruction(new(zone)
      HAllocate(context(), size_in_bytes, HType::JSObject(), flags));

  for (int i = 0; i < size; i += kPointerSize) {
    HObjectAccess access = HObjectAccess::ForJSObjectOffset(i);
    AddStore(object, access, AddLoad(boilerplate, access));
  }

  environment()->Push(object);
  checker.ElseDeopt();
  checker.End();

  return environment()->Pop();
}


Handle<Code> FastCloneShallowObjectStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<CreateAllocationSiteStub>::BuildCodeStub() {
  Zone* zone = this->zone();

  HValue* size = AddInstruction(new(zone) HConstant(AllocationSite::kSize));
  HAllocate::Flags flags = HAllocate::DefaultFlags();
  flags = static_cast<HAllocate::Flags>(
      flags | HAllocate::CAN_ALLOCATE_IN_OLD_POINTER_SPACE);
  HInstruction* object = AddInstruction(new(zone)
      HAllocate(context(), size, HType::JSObject(), flags));

  // Store the map
  Handle<Map> allocation_site_map(isolate()->heap()->allocation_site_map(),
                                  isolate());
  AddStoreMapConstant(object, allocation_site_map);

  // Store the payload (smi elements kind)
  HValue* initial_elements_kind = AddInstruction(new(zone) HConstant(
      GetInitialFastElementsKind()));
  Add<HStoreNamedField>(object,
                        HObjectAccess::ForAllocationSiteTransitionInfo(),
                        initial_elements_kind);

  Add<HLinkObjectInList>(object, HObjectAccess::ForAllocationSiteWeakNext(),
                         HLinkObjectInList::ALLOCATION_SITE_LIST);

  // We use a hammer (SkipWriteBarrier()) to indicate that we know the input
  // cell is really a Cell, and so no write barrier is needed.
  // TODO(mvstanton): Add a debug_code check to verify the input cell is really
  // a cell. (perhaps with a new instruction, HAssert).
  HInstruction* cell = GetParameter(0);
  HObjectAccess access = HObjectAccess::ForCellValue();
  HStoreNamedField* store = AddStore(cell, access, object);
  store->SkipWriteBarrier();
  return cell;
}


Handle<Code> CreateAllocationSiteStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<KeyedLoadFastElementStub>::BuildCodeStub() {
  HInstruction* load = BuildUncheckedMonomorphicElementAccess(
      GetParameter(0), GetParameter(1), NULL, NULL,
      casted_stub()->is_js_array(), casted_stub()->elements_kind(),
      false, NEVER_RETURN_HOLE, STANDARD_STORE);
  return load;
}


Handle<Code> KeyedLoadFastElementStub::GenerateCode() {
  return DoGenerateCode(this);
}


template<>
HValue* CodeStubGraphBuilder<LoadFieldStub>::BuildCodeStub() {
  HObjectAccess access = casted_stub()->is_inobject() ?
      HObjectAccess::ForJSObjectOffset(casted_stub()->offset()) :
      HObjectAccess::ForBackingStoreOffset(casted_stub()->offset());
  return AddInstruction(BuildLoadNamedField(GetParameter(0), access,
      casted_stub()->representation()));
}


Handle<Code> LoadFieldStub::GenerateCode() {
  return DoGenerateCode(this);
}


template<>
HValue* CodeStubGraphBuilder<KeyedLoadFieldStub>::BuildCodeStub() {
  HObjectAccess access = casted_stub()->is_inobject() ?
      HObjectAccess::ForJSObjectOffset(casted_stub()->offset()) :
      HObjectAccess::ForBackingStoreOffset(casted_stub()->offset());
  return AddInstruction(BuildLoadNamedField(GetParameter(0), access,
      casted_stub()->representation()));
}


Handle<Code> KeyedLoadFieldStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<KeyedStoreFastElementStub>::BuildCodeStub() {
  BuildUncheckedMonomorphicElementAccess(
      GetParameter(0), GetParameter(1), GetParameter(2), NULL,
      casted_stub()->is_js_array(), casted_stub()->elements_kind(),
      true, NEVER_RETURN_HOLE, casted_stub()->store_mode());

  return GetParameter(2);
}


Handle<Code> KeyedStoreFastElementStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<TransitionElementsKindStub>::BuildCodeStub() {
  info()->MarkAsSavesCallerDoubles();

  BuildTransitionElementsKind(GetParameter(0),
                              GetParameter(1),
                              casted_stub()->from_kind(),
                              casted_stub()->to_kind(),
                              true);

  return GetParameter(0);
}


Handle<Code> TransitionElementsKindStub::GenerateCode() {
  return DoGenerateCode(this);
}

HValue* CodeStubGraphBuilderBase::BuildArrayConstructor(
    ElementsKind kind,
    ContextCheckMode context_mode,
    AllocationSiteOverrideMode override_mode,
    ArgumentClass argument_class) {
  HValue* constructor = GetParameter(ArrayConstructorStubBase::kConstructor);
  if (context_mode == CONTEXT_CHECK_REQUIRED) {
    HInstruction* array_function = BuildGetArrayFunction(context());
    ArrayContextChecker checker(this, constructor, array_function);
  }

  HValue* property_cell = GetParameter(ArrayConstructorStubBase::kPropertyCell);
  // Walk through the property cell to the AllocationSite
  HValue* alloc_site = AddInstruction(new(zone()) HLoadNamedField(property_cell,
      HObjectAccess::ForCellValue()));
  JSArrayBuilder array_builder(this, kind, alloc_site, constructor,
                               override_mode);
  HValue* result = NULL;
  switch (argument_class) {
    case NONE:
      result = array_builder.AllocateEmptyArray();
      break;
    case SINGLE:
      result = BuildArraySingleArgumentConstructor(&array_builder);
      break;
    case MULTIPLE:
      result = BuildArrayNArgumentsConstructor(&array_builder, kind);
      break;
  }

  return result;
}


HValue* CodeStubGraphBuilderBase::BuildInternalArrayConstructor(
    ElementsKind kind, ArgumentClass argument_class) {
  HValue* constructor = GetParameter(
      InternalArrayConstructorStubBase::kConstructor);
  JSArrayBuilder array_builder(this, kind, constructor);

  HValue* result = NULL;
  switch (argument_class) {
    case NONE:
      result = array_builder.AllocateEmptyArray();
      break;
    case SINGLE:
      result = BuildArraySingleArgumentConstructor(&array_builder);
      break;
    case MULTIPLE:
      result = BuildArrayNArgumentsConstructor(&array_builder, kind);
      break;
  }
  return result;
}


HValue* CodeStubGraphBuilderBase::BuildArraySingleArgumentConstructor(
    JSArrayBuilder* array_builder) {
  // Smi check and range check on the input arg.
  HValue* constant_one = graph()->GetConstant1();
  HValue* constant_zero = graph()->GetConstant0();

  HInstruction* elements = AddInstruction(
      new(zone()) HArgumentsElements(false));
  HInstruction* argument = AddInstruction(
      new(zone()) HAccessArgumentsAt(elements, constant_one, constant_zero));

  HConstant* max_alloc_length =
      new(zone()) HConstant(JSObject::kInitialMaxFastElementArray);
  AddInstruction(max_alloc_length);
  const int initial_capacity = JSArray::kPreallocatedArrayElements;
  HConstant* initial_capacity_node = new(zone()) HConstant(initial_capacity);
  AddInstruction(initial_capacity_node);

  HBoundsCheck* checked_arg = Add<HBoundsCheck>(argument, max_alloc_length);
  IfBuilder if_builder(this);
  if_builder.If<HCompareNumericAndBranch>(checked_arg, constant_zero,
                                          Token::EQ);
  if_builder.Then();
  Push(initial_capacity_node);  // capacity
  Push(constant_zero);  // length
  if_builder.Else();
  Push(checked_arg);  // capacity
  Push(checked_arg);  // length
  if_builder.End();

  // Figure out total size
  HValue* length = Pop();
  HValue* capacity = Pop();
  return array_builder->AllocateArray(capacity, length, true);
}


HValue* CodeStubGraphBuilderBase::BuildArrayNArgumentsConstructor(
    JSArrayBuilder* array_builder, ElementsKind kind) {
  // We need to fill with the hole if it's a smi array in the multi-argument
  // case because we might have to bail out while copying arguments into
  // the array because they aren't compatible with a smi array.
  // If it's a double array, no problem, and if it's fast then no
  // problem either because doubles are boxed.
  HValue* length = GetArgumentsLength();
  bool fill_with_hole = IsFastSmiElementsKind(kind);
  HValue* new_object = array_builder->AllocateArray(length,
                                                    length,
                                                    fill_with_hole);
  HValue* elements = array_builder->GetElementsLocation();
  ASSERT(elements != NULL);

  // Now populate the elements correctly.
  LoopBuilder builder(this,
                      context(),
                      LoopBuilder::kPostIncrement);
  HValue* start = graph()->GetConstant0();
  HValue* key = builder.BeginBody(start, length, Token::LT);
  HInstruction* argument_elements = AddInstruction(
      new(zone()) HArgumentsElements(false));
  HInstruction* argument = AddInstruction(new(zone()) HAccessArgumentsAt(
      argument_elements, length, key));

  AddInstruction(new(zone()) HStoreKeyed(elements, key, argument, kind));
  builder.EndBody();
  return new_object;
}


template <>
HValue* CodeStubGraphBuilder<ArrayNoArgumentConstructorStub>::BuildCodeStub() {
  ElementsKind kind = casted_stub()->elements_kind();
  ContextCheckMode context_mode = casted_stub()->context_mode();
  AllocationSiteOverrideMode override_mode = casted_stub()->override_mode();
  return BuildArrayConstructor(kind, context_mode, override_mode, NONE);
}


Handle<Code> ArrayNoArgumentConstructorStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<ArraySingleArgumentConstructorStub>::
    BuildCodeStub() {
  ElementsKind kind = casted_stub()->elements_kind();
  ContextCheckMode context_mode = casted_stub()->context_mode();
  AllocationSiteOverrideMode override_mode = casted_stub()->override_mode();
  return BuildArrayConstructor(kind, context_mode, override_mode, SINGLE);
}


Handle<Code> ArraySingleArgumentConstructorStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<ArrayNArgumentsConstructorStub>::BuildCodeStub() {
  ElementsKind kind = casted_stub()->elements_kind();
  ContextCheckMode context_mode = casted_stub()->context_mode();
  AllocationSiteOverrideMode override_mode = casted_stub()->override_mode();
  return BuildArrayConstructor(kind, context_mode, override_mode, MULTIPLE);
}


Handle<Code> ArrayNArgumentsConstructorStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<InternalArrayNoArgumentConstructorStub>::
    BuildCodeStub() {
  ElementsKind kind = casted_stub()->elements_kind();
  return BuildInternalArrayConstructor(kind, NONE);
}


Handle<Code> InternalArrayNoArgumentConstructorStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<InternalArraySingleArgumentConstructorStub>::
    BuildCodeStub() {
  ElementsKind kind = casted_stub()->elements_kind();
  return BuildInternalArrayConstructor(kind, SINGLE);
}


Handle<Code> InternalArraySingleArgumentConstructorStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<InternalArrayNArgumentsConstructorStub>::
    BuildCodeStub() {
  ElementsKind kind = casted_stub()->elements_kind();
  return BuildInternalArrayConstructor(kind, MULTIPLE);
}


Handle<Code> InternalArrayNArgumentsConstructorStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<CompareNilICStub>::BuildCodeInitializedStub() {
  Isolate* isolate = graph()->isolate();
  CompareNilICStub* stub = casted_stub();
  HIfContinuation continuation;
  Handle<Map> sentinel_map(isolate->heap()->meta_map());
  Handle<Type> type = stub->GetType(isolate, sentinel_map);
  BuildCompareNil(GetParameter(0), type, RelocInfo::kNoPosition, &continuation);
  IfBuilder if_nil(this, &continuation);
  if_nil.Then();
  if (continuation.IsFalseReachable()) {
    if_nil.Else();
    if_nil.Return(graph()->GetConstant0());
  }
  if_nil.End();
  return continuation.IsTrueReachable()
      ? graph()->GetConstant1()
      : graph()->GetConstantUndefined();
}


Handle<Code> CompareNilICStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<UnaryOpStub>::BuildCodeInitializedStub() {
  UnaryOpStub* stub = casted_stub();
  Handle<Type> type = stub->GetType(graph()->isolate());
  HValue* input = GetParameter(0);

  // Prevent unwanted HChange being inserted to ensure that the stub
  // deopts on newly encountered types.
  if (!type->Maybe(Type::Double())) {
    input = AddInstruction(new(zone())
        HForceRepresentation(input, Representation::Smi()));
  }

  if (!type->Is(Type::Number())) {
    // If we expect to see other things than Numbers, we will create a generic
    // stub, which handles all numbers and calls into the runtime for the rest.
    IfBuilder if_number(this);
    if_number.If<HIsNumberAndBranch>(input);
    if_number.Then();
    HInstruction* res = BuildUnaryMathOp(input, type, stub->operation());
    if_number.Return(AddInstruction(res));
    if_number.Else();
    HValue* function = AddLoadJSBuiltin(stub->ToJSBuiltin(), context());
    Add<HPushArgument>(GetParameter(0));
    HValue* result = Add<HInvokeFunction>(context(), function, 1);
    if_number.Return(result);
    if_number.End();
    return graph()->GetConstantUndefined();
  }

  return AddInstruction(BuildUnaryMathOp(input, type, stub->operation()));
}


Handle<Code> UnaryOpStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<ToBooleanStub>::BuildCodeInitializedStub() {
  ToBooleanStub* stub = casted_stub();

  IfBuilder if_true(this);
  if_true.If<HBranch>(GetParameter(0), stub->GetTypes());
  if_true.Then();
  if_true.Return(graph()->GetConstant1());
  if_true.Else();
  if_true.End();
  return graph()->GetConstant0();
}


Handle<Code> ToBooleanStub::GenerateCode() {
  return DoGenerateCode(this);
}


template <>
HValue* CodeStubGraphBuilder<StoreGlobalStub>::BuildCodeInitializedStub() {
  StoreGlobalStub* stub = casted_stub();
  Handle<Object> hole(isolate()->heap()->the_hole_value(), isolate());
  Handle<Object> placeholer_value(Smi::FromInt(0), isolate());
  Handle<PropertyCell> placeholder_cell =
      isolate()->factory()->NewPropertyCell(placeholer_value);

  HParameter* receiver = GetParameter(0);
  HParameter* value = GetParameter(2);

  // Check that the map of the global has not changed: use a placeholder map
  // that will be replaced later with the global object's map.
  Handle<Map> placeholder_map = isolate()->factory()->meta_map();
  AddInstruction(HCheckMaps::New(
      receiver, placeholder_map, zone(), top_info()));

  HValue* cell = Add<HConstant>(placeholder_cell, Representation::Tagged());
  HObjectAccess access(HObjectAccess::ForCellPayload(isolate()));
  HValue* cell_contents = Add<HLoadNamedField>(cell, access);

  if (stub->is_constant()) {
    IfBuilder builder(this);
    builder.If<HCompareObjectEqAndBranch>(cell_contents, value);
    builder.Then();
    builder.ElseDeopt();
    builder.End();
  } else {
    // Load the payload of the global parameter cell. A hole indicates that the
    // property has been deleted and that the store must be handled by the
    // runtime.
    IfBuilder builder(this);
    HValue* hole_value = Add<HConstant>(hole, Representation::Tagged());
    builder.If<HCompareObjectEqAndBranch>(cell_contents, hole_value);
    builder.Then();
    builder.Deopt();
    builder.Else();
    Add<HStoreNamedField>(cell, access, value);
    builder.End();
  }

  return value;
}


Handle<Code> StoreGlobalStub::GenerateCode() {
  return DoGenerateCode(this);
}


template<>
HValue* CodeStubGraphBuilder<ElementsTransitionAndStoreStub>::BuildCodeStub() {
  HValue* value = GetParameter(0);
  HValue* map = GetParameter(1);
  HValue* key = GetParameter(2);
  HValue* object = GetParameter(3);

  if (FLAG_trace_elements_transitions) {
    // Tracing elements transitions is the job of the runtime.
    Add<HDeoptimize>(Deoptimizer::EAGER);
  } else {
    info()->MarkAsSavesCallerDoubles();

    BuildTransitionElementsKind(object, map,
                                casted_stub()->from_kind(),
                                casted_stub()->to_kind(),
                                casted_stub()->is_jsarray());

    BuildUncheckedMonomorphicElementAccess(object, key, value, NULL,
                                          casted_stub()->is_jsarray(),
                                          casted_stub()->to_kind(),
                                          true, ALLOW_RETURN_HOLE,
                                          casted_stub()->store_mode());
  }

  return value;
}


Handle<Code> ElementsTransitionAndStoreStub::GenerateCode() {
  return DoGenerateCode(this);
}


} }  // namespace v8::internal