Unify and simplify the FastCloneShallowArrayStub

- Don't bake in length/capacity into full codegen calls of stubs,
  allowing boilerplates to increase their capacity without regenerating
  code.
- Unify all variants of the clone stub into a single,
  length-independent version.
- Various tweaks to make sure that the clone stub doesn't spill and
  therefore need an eager stack frame.
- Handle all lengths of array literals in the fast case.

R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/257563004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20974 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/code-stubs-arm.cc

@@ -81,6 +81,11 @@ void FastCloneShallowArrayStub::InitializeInterfaceDescriptor(
   static Register registers[] = { r3, r2, r1 };
   descriptor->register_param_count_ = 3;
   descriptor->register_params_ = registers;
+  static Representation representations[] = {
+    Representation::Tagged(),
+    Representation::Smi(),
+    Representation::Tagged() };
+  descriptor->register_param_representations_ = representations;
   descriptor->deoptimization_handler_ =
       Runtime::FunctionForId(
           Runtime::kHiddenCreateArrayLiteralStubBailout)->entry;
@@ -224,6 +229,11 @@ static void InitializeArrayConstructorDescriptor(
     descriptor->stack_parameter_count_ = r0;
     descriptor->register_param_count_ = 3;
     descriptor->register_params_ = registers_variable_args;
+    static Representation representations[] = {
+        Representation::Tagged(),
+        Representation::Tagged(),
+        Representation::Integer32() };
+    descriptor->register_param_representations_ = representations;
   }
 
   descriptor->hint_stack_parameter_count_ = constant_stack_parameter_count;
@@ -251,6 +261,10 @@ static void InitializeInternalArrayConstructorDescriptor(
     descriptor->stack_parameter_count_ = r0;
     descriptor->register_param_count_ = 2;
     descriptor->register_params_ = registers_variable_args;
+    static Representation representations[] = {
+        Representation::Tagged(),
+        Representation::Integer32() };
+    descriptor->register_param_representations_ = representations;
   }
 
   descriptor->hint_stack_parameter_count_ = constant_stack_parameter_count;

src/arm/full-codegen-arm.cc

@@ -1821,33 +1821,12 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
   __ ldr(r3, FieldMemOperand(r3, JSFunction::kLiteralsOffset));
   __ mov(r2, Operand(Smi::FromInt(expr->literal_index())));
   __ mov(r1, Operand(constant_elements));
-  if (has_fast_elements && constant_elements_values->map() ==
-      isolate()->heap()->fixed_cow_array_map()) {
-    FastCloneShallowArrayStub stub(
-        isolate(),
-        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS,
-        allocation_site_mode,
-        length);
-    __ CallStub(&stub);
-    __ IncrementCounter(
-        isolate()->counters()->cow_arrays_created_stub(), 1, r1, r2);
-  } else if (expr->depth() > 1 || Serializer::enabled() ||
-             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
+  if (expr->depth() > 1) {
     __ mov(r0, Operand(Smi::FromInt(flags)));
     __ Push(r3, r2, r1, r0);
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);
   } else {
-    ASSERT(IsFastSmiOrObjectElementsKind(constant_elements_kind) ||
-           FLAG_smi_only_arrays);
-    FastCloneShallowArrayStub::Mode mode =
-        FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS;
-
-    if (has_fast_elements) {
-      mode = FastCloneShallowArrayStub::CLONE_ELEMENTS;
-    }
-
-    FastCloneShallowArrayStub stub(isolate(), mode, allocation_site_mode,
-                                   length);
+    FastCloneShallowArrayStub stub(isolate(), allocation_site_mode);
     __ CallStub(&stub);
   }
 

src/arm64/code-stubs-arm64.cc

@@ -88,6 +88,11 @@ void FastCloneShallowArrayStub::InitializeInterfaceDescriptor(
   static Register registers[] = { x3, x2, x1 };
   descriptor->register_param_count_ = sizeof(registers) / sizeof(registers[0]);
   descriptor->register_params_ = registers;
+  static Representation representations[] = {
+    Representation::Tagged(),
+    Representation::Smi(),
+    Representation::Tagged() };
+  descriptor->register_param_representations_ = representations;
   descriptor->deoptimization_handler_ =
       Runtime::FunctionForId(
           Runtime::kHiddenCreateArrayLiteralStubBailout)->entry;
@@ -253,6 +258,11 @@ static void InitializeArrayConstructorDescriptor(
     descriptor->register_param_count_ =
         sizeof(registers_variable_args) / sizeof(registers_variable_args[0]);
     descriptor->register_params_ = registers_variable_args;
+    static Representation representations[] = {
+        Representation::Tagged(),
+        Representation::Tagged(),
+        Representation::Integer32() };
+    descriptor->register_param_representations_ = representations;
   }
 
   descriptor->hint_stack_parameter_count_ = constant_stack_parameter_count;
@@ -299,6 +309,10 @@ static void InitializeInternalArrayConstructorDescriptor(
     descriptor->register_param_count_ =
         sizeof(registers_variable_args) / sizeof(registers_variable_args[0]);
     descriptor->register_params_ = registers_variable_args;
+    static Representation representations[] = {
+        Representation::Tagged(),
+        Representation::Integer32() };
+    descriptor->register_param_representations_ = representations;
   }
 
   descriptor->hint_stack_parameter_count_ = constant_stack_parameter_count;

src/arm64/full-codegen-arm64.cc

@@ -1824,35 +1824,12 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
   __ Ldr(x3, FieldMemOperand(x3, JSFunction::kLiteralsOffset));
   __ Mov(x2, Smi::FromInt(expr->literal_index()));
   __ Mov(x1, Operand(constant_elements));
-  if (has_fast_elements && constant_elements_values->map() ==
-      isolate()->heap()->fixed_cow_array_map()) {
-    FastCloneShallowArrayStub stub(
-        isolate(),
-        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS,
-        allocation_site_mode,
-        length);
-    __ CallStub(&stub);
-    __ IncrementCounter(
-        isolate()->counters()->cow_arrays_created_stub(), 1, x10, x11);
-  } else if ((expr->depth() > 1) || Serializer::enabled() ||
-             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
+  if (expr->depth() > 1) {
     __ Mov(x0, Smi::FromInt(flags));
     __ Push(x3, x2, x1, x0);
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);
   } else {
-    ASSERT(IsFastSmiOrObjectElementsKind(constant_elements_kind) ||
-           FLAG_smi_only_arrays);
-    FastCloneShallowArrayStub::Mode mode =
-        FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS;
-
-    if (has_fast_elements) {
-      mode = FastCloneShallowArrayStub::CLONE_ELEMENTS;
-    }
-
-    FastCloneShallowArrayStub stub(isolate(),
-                                   mode,
-                                   allocation_site_mode,
-                                   length);
+    FastCloneShallowArrayStub stub(isolate(), allocation_site_mode);
     __ CallStub(&stub);
   }
 

src/code-stubs-hydrogen.cc

@@ -150,9 +150,9 @@ bool CodeStubGraphBuilderBase::BuildGraph() {
   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 = descriptor_->IsParameterCountRegister(i)
-        ? Representation::Integer32()
-        : Representation::Tagged();
+    Representation r = descriptor_->register_param_representations_ == NULL
+        ? Representation::Tagged()
+        : descriptor_->register_param_representations_[i];
     HParameter* param = Add<HParameter>(i, HParameter::REGISTER_PARAMETER, r);
     start_environment->Bind(i, param);
     parameters_[i] = param;
@@ -353,8 +353,6 @@ HValue* CodeStubGraphBuilder<FastCloneShallowArrayStub>::BuildCodeStub() {
   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 = Add<HLoadKeyed>(GetParameter(0),
                                                   GetParameter(1),
@@ -369,46 +367,40 @@ HValue* CodeStubGraphBuilder<FastCloneShallowArrayStub>::BuildCodeStub() {
       AllocationSite::kTransitionInfoOffset);
   HInstruction* boilerplate = Add<HLoadNamedField>(
       allocation_site, static_cast<HValue*>(NULL), access);
-  HValue* push_value;
-  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();
-    push_value = BuildCloneShallowArray(boilerplate,
-                                        allocation_site,
-                                        alloc_site_mode,
-                                        FAST_ELEMENTS,
-                                        0/*copy-on-write*/);
-    environment()->Push(push_value);
-    if_fixed_cow.Else();
-
-    IfBuilder if_fixed(this);
-    if_fixed.If<HCompareMap>(elements, factory->fixed_array_map());
-    if_fixed.Then();
-    push_value = BuildCloneShallowArray(boilerplate,
-                                        allocation_site,
-                                        alloc_site_mode,
-                                        FAST_ELEMENTS,
-                                        length);
-    environment()->Push(push_value);
-    if_fixed.Else();
-    push_value = BuildCloneShallowArray(boilerplate,
-                                        allocation_site,
-                                        alloc_site_mode,
-                                        FAST_DOUBLE_ELEMENTS,
-                                        length);
-    environment()->Push(push_value);
-  } else {
-    ElementsKind elements_kind = casted_stub()->ComputeElementsKind();
-    push_value = BuildCloneShallowArray(boilerplate,
-                                        allocation_site,
-                                        alloc_site_mode,
-                                        elements_kind,
-                                        length);
-    environment()->Push(push_value);
-  }
+  HValue* elements = AddLoadElements(boilerplate);
+  HValue* capacity = AddLoadFixedArrayLength(elements);
+  IfBuilder zero_capacity(this);
+  zero_capacity.If<HCompareNumericAndBranch>(capacity, graph()->GetConstant0(),
+                                           Token::EQ);
+  zero_capacity.Then();
+  Push(BuildCloneShallowArrayEmpty(boilerplate,
+                                   allocation_site,
+                                   alloc_site_mode));
+  zero_capacity.Else();
+  IfBuilder if_fixed_cow(this);
+  if_fixed_cow.If<HCompareMap>(elements, factory->fixed_cow_array_map());
+  if_fixed_cow.Then();
+  Push(BuildCloneShallowArrayCow(boilerplate,
+                                 allocation_site,
+                                 alloc_site_mode,
+                                 FAST_ELEMENTS));
+  if_fixed_cow.Else();
+  IfBuilder if_fixed(this);
+  if_fixed.If<HCompareMap>(elements, factory->fixed_array_map());
+  if_fixed.Then();
+  Push(BuildCloneShallowArrayNonEmpty(boilerplate,
+                                      allocation_site,
+                                      alloc_site_mode,
+                                      FAST_ELEMENTS));
+
+  if_fixed.Else();
+  Push(BuildCloneShallowArrayNonEmpty(boilerplate,
+                                      allocation_site,
+                                      alloc_site_mode,
+                                      FAST_DOUBLE_ELEMENTS));
+  if_fixed.End();
+  if_fixed_cow.End();
+  zero_capacity.End();
 
   checker.ElseDeopt("Uninitialized boilerplate literals");
   checker.End();

src/code-stubs.cc

@@ -45,6 +45,7 @@ CodeStubInterfaceDescriptor::CodeStubInterfaceDescriptor()
       hint_stack_parameter_count_(-1),
       function_mode_(NOT_JS_FUNCTION_STUB_MODE),
       register_params_(NULL),
+      register_param_representations_(NULL),
       deoptimization_handler_(NULL),
       handler_arguments_mode_(DONT_PASS_ARGUMENTS),
       miss_handler_(),
@@ -752,9 +753,7 @@ void FastNewContextStub::InstallDescriptors(Isolate* isolate) {
 
 // static
 void FastCloneShallowArrayStub::InstallDescriptors(Isolate* isolate) {
-  FastCloneShallowArrayStub stub(isolate,
-                                 FastCloneShallowArrayStub::CLONE_ELEMENTS,
-                                 DONT_TRACK_ALLOCATION_SITE, 0);
+  FastCloneShallowArrayStub stub(isolate, DONT_TRACK_ALLOCATION_SITE);
   InstallDescriptor(isolate, &stub);
 }
 

src/code-stubs.h

@@ -300,6 +300,7 @@ struct CodeStubInterfaceDescriptor {
   int hint_stack_parameter_count_;
   StubFunctionMode function_mode_;
   Register* register_params_;
+  Representation* register_param_representations_;
 
   Address deoptimization_handler_;
   HandlerArgumentsMode handler_arguments_mode_;
@@ -604,50 +605,18 @@ class FastNewContextStub V8_FINAL : public HydrogenCodeStub {
 class FastCloneShallowArrayStub : public HydrogenCodeStub {
  public:
   // Maximum length of copied elements array.
-  static const int kMaximumClonedLength = 8;
-  enum Mode {
-    CLONE_ELEMENTS,
-    CLONE_DOUBLE_ELEMENTS,
-    COPY_ON_WRITE_ELEMENTS,
-    CLONE_ANY_ELEMENTS,
-    LAST_CLONE_MODE = CLONE_ANY_ELEMENTS
-  };
-
-  static const int kFastCloneModeCount = LAST_CLONE_MODE + 1;
+  static const int kMaximumInlinedCloneLength = 8;
 
   FastCloneShallowArrayStub(Isolate* isolate,
-                            Mode mode,
-                            AllocationSiteMode allocation_site_mode,
-                            int length)
+                            AllocationSiteMode allocation_site_mode)
       : HydrogenCodeStub(isolate),
-        mode_(mode),
-        allocation_site_mode_(allocation_site_mode),
-        length_((mode == COPY_ON_WRITE_ELEMENTS) ? 0 : length) {
-    ASSERT_GE(length_, 0);
-    ASSERT_LE(length_, kMaximumClonedLength);
-  }
+      allocation_site_mode_(allocation_site_mode) {}
 
-  Mode mode() const { return mode_; }
-  int length() const { return length_; }
   AllocationSiteMode allocation_site_mode() const {
     return allocation_site_mode_;
   }
 
-  ElementsKind ComputeElementsKind() const {
-    switch (mode()) {
-      case CLONE_ELEMENTS:
-      case COPY_ON_WRITE_ELEMENTS:
-        return FAST_ELEMENTS;
-      case CLONE_DOUBLE_ELEMENTS:
-        return FAST_DOUBLE_ELEMENTS;
-      case CLONE_ANY_ELEMENTS:
-        /*fall-through*/;
-    }
-    UNREACHABLE();
-    return LAST_ELEMENTS_KIND;
-  }
-
-  virtual Handle<Code> GenerateCode() V8_OVERRIDE;
+  virtual Handle<Code> GenerateCode();
 
   virtual void InitializeInterfaceDescriptor(
       CodeStubInterfaceDescriptor* descriptor) V8_OVERRIDE;
@@ -655,22 +624,13 @@ class FastCloneShallowArrayStub : public HydrogenCodeStub {
   static void InstallDescriptors(Isolate* isolate);
 
  private:
-  Mode mode_;
   AllocationSiteMode allocation_site_mode_;
-  int length_;
 
   class AllocationSiteModeBits: public BitField<AllocationSiteMode, 0, 1> {};
-  class ModeBits: public BitField<Mode, 1, 4> {};
-  class LengthBits: public BitField<int, 5, 4> {};
   // Ensure data fits within available bits.
-  STATIC_ASSERT(LAST_ALLOCATION_SITE_MODE == 1);
-  STATIC_ASSERT(kFastCloneModeCount < 16);
-  STATIC_ASSERT(kMaximumClonedLength < 16);
   Major MajorKey() { return FastCloneShallowArray; }
   int NotMissMinorKey() {
-    return AllocationSiteModeBits::encode(allocation_site_mode_)
-        | ModeBits::encode(mode_)
-        | LengthBits::encode(length_);
+    return AllocationSiteModeBits::encode(allocation_site_mode_);
   }
 };
 

src/hydrogen.h

@@ -1421,7 +1421,8 @@ class HGraphBuilder {
     store_map->SkipWriteBarrier();
     return store_map;
   }
-  HLoadNamedField* AddLoadElements(HValue* object);
+  HLoadNamedField* AddLoadElements(HValue* object,
+                                   HValue* dependency = NULL);
 
   bool MatchRotateRight(HValue* left,
                         HValue* right,
@@ -1437,7 +1438,12 @@ class HGraphBuilder {
                                Maybe<int> fixed_right_arg,
                                HAllocationMode allocation_mode);
 
-  HLoadNamedField* AddLoadFixedArrayLength(HValue *object);
+  HLoadNamedField* AddLoadFixedArrayLength(HValue *object,
+                                           HValue *dependency = NULL);
+
+  HLoadNamedField* AddLoadArrayLength(HValue *object,
+                                      ElementsKind kind,
+                                      HValue *dependency = NULL);
 
   HValue* AddLoadJSBuiltin(Builtins::JavaScript builtin);
 
@@ -1780,18 +1786,33 @@ class HGraphBuilder {
                                  HValue* from,
                                  HValue* to);
 
-  void BuildCopyElements(HValue* from_elements,
+  void BuildCopyElements(HValue* array,
+                         HValue* from_elements,
                          ElementsKind from_elements_kind,
                          HValue* to_elements,
                          ElementsKind to_elements_kind,
                          HValue* length,
                          HValue* capacity);
 
-  HValue* BuildCloneShallowArray(HValue* boilerplate,
-                                 HValue* allocation_site,
-                                 AllocationSiteMode mode,
-                                 ElementsKind kind,
-                                 int length);
+  HValue* BuildCloneShallowArrayCommon(HValue* boilerplate,
+                                       HValue* allocation_site,
+                                       HValue* extra_size,
+                                       HValue** return_elements,
+                                       AllocationSiteMode mode);
+
+  HValue* BuildCloneShallowArrayCow(HValue* boilerplate,
+                                    HValue* allocation_site,
+                                    AllocationSiteMode mode,
+                                    ElementsKind kind);
+
+  HValue* BuildCloneShallowArrayEmpty(HValue* boilerplate,
+                                      HValue* allocation_site,
+                                      AllocationSiteMode mode);
+
+  HValue* BuildCloneShallowArrayNonEmpty(HValue* boilerplate,
+                                         HValue* allocation_site,
+                                         AllocationSiteMode mode,
+                                         ElementsKind kind);
 
   HValue* BuildElementIndexHash(HValue* index);
 

src/ia32/code-stubs-ia32.cc

@@ -86,6 +86,11 @@ void FastCloneShallowArrayStub::InitializeInterfaceDescriptor(
   static Register registers[] = { eax, ebx, ecx };
   descriptor->register_param_count_ = 3;
   descriptor->register_params_ = registers;
+  static Representation representations[] = {
+    Representation::Tagged(),
+    Representation::Smi(),
+    Representation::Tagged() };
+  descriptor->register_param_representations_ = representations;
   descriptor->deoptimization_handler_ =
       Runtime::FunctionForId(
           Runtime::kHiddenCreateArrayLiteralStubBailout)->entry;
@@ -217,6 +222,11 @@ static void InitializeArrayConstructorDescriptor(
     descriptor->stack_parameter_count_ = eax;
     descriptor->register_param_count_ = 3;
     descriptor->register_params_ = registers_variable_args;
+    static Representation representations[] = {
+        Representation::Tagged(),
+        Representation::Tagged(),
+        Representation::Integer32() };
+    descriptor->register_param_representations_ = representations;
   }
 
   descriptor->hint_stack_parameter_count_ = constant_stack_parameter_count;
@@ -244,6 +254,10 @@ static void InitializeInternalArrayConstructorDescriptor(
     descriptor->stack_parameter_count_ = eax;
     descriptor->register_param_count_ = 2;
     descriptor->register_params_ = registers_variable_args;
+    static Representation representations[] = {
+        Representation::Tagged(),
+        Representation::Integer32() };
+    descriptor->register_param_representations_ = representations;
   }
 
   descriptor->hint_stack_parameter_count_ = constant_stack_parameter_count;

src/ia32/full-codegen-ia32.cc

@@ -1758,24 +1758,7 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     allocation_site_mode = DONT_TRACK_ALLOCATION_SITE;
   }
 
-  Heap* heap = isolate()->heap();
-  if (has_constant_fast_elements &&
-      constant_elements_values->map() == heap->fixed_cow_array_map()) {
-    // If the elements are already FAST_*_ELEMENTS, the boilerplate cannot
-    // change, so it's possible to specialize the stub in advance.
-    __ IncrementCounter(isolate()->counters()->cow_arrays_created_stub(), 1);
-    __ mov(ebx, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
-    __ mov(eax, FieldOperand(ebx, JSFunction::kLiteralsOffset));
-    __ mov(ebx, Immediate(Smi::FromInt(expr->literal_index())));
-    __ mov(ecx, Immediate(constant_elements));
-    FastCloneShallowArrayStub stub(
-        isolate(),
-        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS,
-        allocation_site_mode,
-        length);
-    __ CallStub(&stub);
-  } else if (expr->depth() > 1 || Serializer::enabled() ||
-             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
+  if (expr->depth() > 1) {
     __ mov(ebx, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
     __ push(FieldOperand(ebx, JSFunction::kLiteralsOffset));
     __ push(Immediate(Smi::FromInt(expr->literal_index())));
@@ -1783,25 +1766,11 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     __ push(Immediate(Smi::FromInt(flags)));
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);
   } else {
-    ASSERT(IsFastSmiOrObjectElementsKind(constant_elements_kind) ||
-           FLAG_smi_only_arrays);
-    FastCloneShallowArrayStub::Mode mode =
-        FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS;
-
-    // If the elements are already FAST_*_ELEMENTS, the boilerplate cannot
-    // change, so it's possible to specialize the stub in advance.
-    if (has_constant_fast_elements) {
-      mode = FastCloneShallowArrayStub::CLONE_ELEMENTS;
-    }
-
     __ mov(ebx, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
     __ mov(eax, FieldOperand(ebx, JSFunction::kLiteralsOffset));
     __ mov(ebx, Immediate(Smi::FromInt(expr->literal_index())));
     __ mov(ecx, Immediate(constant_elements));
-    FastCloneShallowArrayStub stub(isolate(),
-                                   mode,
-                                   allocation_site_mode,
-                                   length);
+    FastCloneShallowArrayStub stub(isolate(), allocation_site_mode);
     __ CallStub(&stub);
   }
 

src/mips/full-codegen-mips.cc

@@ -1845,7 +1845,7 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     __ IncrementCounter(isolate()->counters()->cow_arrays_created_stub(),
         1, a1, a2);
   } else if (expr->depth() > 1 || Serializer::enabled() ||
-             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
+             length > FastCloneShallowArrayStub::kMaximumInlinedCloneLength) {
     __ li(a0, Operand(Smi::FromInt(flags)));
     __ Push(a3, a2, a1, a0);
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);

src/v8-counters.h

@@ -128,6 +128,7 @@ namespace internal {
   SC(call_premonomorphic_stubs, V8.CallPreMonomorphicStubs)           \
   SC(call_normal_stubs, V8.CallNormalStubs)                           \
   SC(call_megamorphic_stubs, V8.CallMegamorphicStubs)                 \
+  SC(inlined_copyied_elements, V8.InlinedCopiedElements)              \
   SC(arguments_adaptors, V8.ArgumentsAdaptors)                        \
   SC(compilation_cache_hits, V8.CompilationCacheHits)                 \
   SC(compilation_cache_misses, V8.CompilationCacheMisses)             \

src/x64/code-stubs-x64.cc

@@ -82,6 +82,11 @@ void FastCloneShallowArrayStub::InitializeInterfaceDescriptor(
   static Register registers[] = { rax, rbx, rcx };
   descriptor->register_param_count_ = 3;
   descriptor->register_params_ = registers;
+  static Representation representations[] = {
+    Representation::Tagged(),
+    Representation::Smi(),
+    Representation::Tagged() };
+  descriptor->register_param_representations_ = representations;
   descriptor->deoptimization_handler_ =
       Runtime::FunctionForId(
           Runtime::kHiddenCreateArrayLiteralStubBailout)->entry;
@@ -211,6 +216,11 @@ static void InitializeArrayConstructorDescriptor(
     descriptor->handler_arguments_mode_ = PASS_ARGUMENTS;
     descriptor->stack_parameter_count_ = rax;
     descriptor->register_param_count_ = 3;
+    static Representation representations[] = {
+        Representation::Tagged(),
+        Representation::Tagged(),
+        Representation::Integer32() };
+    descriptor->register_param_representations_ = representations;
     descriptor->register_params_ = registers_variable_args;
   }
 
@@ -239,6 +249,10 @@ static void InitializeInternalArrayConstructorDescriptor(
     descriptor->stack_parameter_count_ = rax;
     descriptor->register_param_count_ = 2;
     descriptor->register_params_ = registers_variable_args;
+    static Representation representations[] = {
+        Representation::Tagged(),
+        Representation::Integer32() };
+    descriptor->register_param_representations_ = representations;
   }
 
   descriptor->hint_stack_parameter_count_ = constant_stack_parameter_count;

src/x64/full-codegen-x64.cc

@@ -1796,24 +1796,7 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     allocation_site_mode = DONT_TRACK_ALLOCATION_SITE;
   }
 
-  Heap* heap = isolate()->heap();
-  if (has_constant_fast_elements &&
-      constant_elements_values->map() == heap->fixed_cow_array_map()) {
-    // If the elements are already FAST_*_ELEMENTS, the boilerplate cannot
-    // change, so it's possible to specialize the stub in advance.
-    __ IncrementCounter(isolate()->counters()->cow_arrays_created_stub(), 1);
-    __ movp(rbx, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
-    __ movp(rax, FieldOperand(rbx, JSFunction::kLiteralsOffset));
-    __ Move(rbx, Smi::FromInt(expr->literal_index()));
-    __ Move(rcx, constant_elements);
-    FastCloneShallowArrayStub stub(
-        isolate(),
-        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS,
-        allocation_site_mode,
-        length);
-    __ CallStub(&stub);
-  } else if (expr->depth() > 1 || Serializer::enabled() ||
-             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
+  if (expr->depth() > 1) {
     __ movp(rbx, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
     __ Push(FieldOperand(rbx, JSFunction::kLiteralsOffset));
     __ Push(Smi::FromInt(expr->literal_index()));
@@ -1821,24 +1804,11 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     __ Push(Smi::FromInt(flags));
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);
   } else {
-    ASSERT(IsFastSmiOrObjectElementsKind(constant_elements_kind) ||
-           FLAG_smi_only_arrays);
-    FastCloneShallowArrayStub::Mode mode =
-        FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS;
-
-    // If the elements are already FAST_*_ELEMENTS, the boilerplate cannot
-    // change, so it's possible to specialize the stub in advance.
-    if (has_constant_fast_elements) {
-      mode = FastCloneShallowArrayStub::CLONE_ELEMENTS;
-    }
-
     __ movp(rbx, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
     __ movp(rax, FieldOperand(rbx, JSFunction::kLiteralsOffset));
     __ Move(rbx, Smi::FromInt(expr->literal_index()));
     __ Move(rcx, constant_elements);
-    FastCloneShallowArrayStub stub(isolate(),
-                                   mode,
-                                   allocation_site_mode, length);
+    FastCloneShallowArrayStub stub(isolate(), allocation_site_mode);
     __ CallStub(&stub);
   }