use compare nil ic only for non-strict equality. strict-equality only has one...

use compare nil ic only for non-strict equality. strict-equality only has one check and cannot deopt. should therefore not be part of the stub.

BUG=
R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/16732002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15045 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/full-codegen-arm.cc

@@ -4765,9 +4765,7 @@ void FullCodeGenerator::EmitLiteralCompareNil(CompareOperation* expr,
 
   VisitForAccumulatorValue(sub_expr);
   PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-  EqualityKind kind = expr->op() == Token::EQ_STRICT
-      ? kStrictEquality : kNonStrictEquality;
-  if (kind == kStrictEquality) {
+  if (expr->op() == Token::EQ_STRICT) {
     Heap::RootListIndex nil_value = nil == kNullValue ?
         Heap::kNullValueRootIndex :
         Heap::kUndefinedValueRootIndex;
@@ -4775,9 +4773,7 @@ void FullCodeGenerator::EmitLiteralCompareNil(CompareOperation* expr,
     __ cmp(r0, r1);
     Split(eq, if_true, if_false, fall_through);
   } else {
-    Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(),
-                                                         kNonStrictEquality,
-                                                         nil);
+    Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(), nil);
     CallIC(ic, RelocInfo::CODE_TARGET, expr->CompareOperationFeedbackId());
     __ cmp(r0, Operand(0));
     Split(ne, if_true, if_false, fall_through);

src/code-stubs-hydrogen.cc

@@ -736,7 +736,7 @@ HValue* CodeStubGraphBuilder<CompareNilICStub>::BuildCodeInitializedStub() {
   CompareNilICStub* stub = casted_stub();
   HIfContinuation continuation;
   Handle<Map> sentinel_map(graph()->isolate()->heap()->meta_map());
-  BuildCompareNil(GetParameter(0), stub->GetKind(),
+  BuildCompareNil(GetParameter(0),
                   stub->GetTypes(), sentinel_map,
                   RelocInfo::kNoPosition, &continuation);
   IfBuilder if_nil(this, &continuation);

src/code-stubs.cc

@@ -432,25 +432,18 @@ void ICCompareStub::Generate(MacroAssembler* masm) {
 
 void CompareNilICStub::Record(Handle<Object> object) {
   ASSERT(types_ != Types::FullCompare());
-  if (equality_kind_ == kStrictEquality) {
-    // When testing for strict equality only one value will evaluate to true
-    types_.RemoveAll();
-    types_.Add((nil_value_ == kNullValue) ? NULL_TYPE:
-                                            UNDEFINED);
+  if (object->IsNull()) {
+    types_.Add(NULL_TYPE);
+  } else if (object->IsUndefined()) {
+    types_.Add(UNDEFINED);
+  } else if (object->IsUndetectableObject() ||
+             object->IsOddball() ||
+             !object->IsHeapObject()) {
+    types_ = Types::FullCompare();
+  } else if (IsMonomorphic()) {
+    types_ = Types::FullCompare();
   } else {
-    if (object->IsNull()) {
-      types_.Add(NULL_TYPE);
-    } else if (object->IsUndefined()) {
-      types_.Add(UNDEFINED);
-    } else if (object->IsUndetectableObject() ||
-               object->IsOddball() ||
-               !object->IsHeapObject()) {
-      types_ = Types::FullCompare();
-    } else if (IsMonomorphic()) {
-      types_ = Types::FullCompare();
-    } else {
-      types_.Add(MONOMORPHIC_MAP);
-    }
+    types_.Add(MONOMORPHIC_MAP);
   }
 }
 
@@ -477,8 +470,6 @@ void CompareNilICStub::PrintName(StringStream* stream) {
   types_.Print(stream);
   stream->Add((nil_value_ == kNullValue) ? "(NullValue|":
                                            "(UndefinedValue|");
-  stream->Add((equality_kind_ == kStrictEquality) ? "StrictEquality)":
-                                                    "NonStrictEquality)");
 }
 
 

src/code-stubs.h

@@ -1154,24 +1154,21 @@ class CompareNilICStub : public HydrogenCodeStub  {
   // boolean flags we need to store. :-P
   STATIC_ASSERT(NUMBER_OF_TYPES <= 6);
 
-  CompareNilICStub(EqualityKind kind, NilValue nil, Types types = Types())
+  CompareNilICStub(NilValue nil, Types types = Types())
       : types_(types) {
-    equality_kind_ = kind;
     nil_value_ = nil;
   }
 
   CompareNilICStub(Code::ExtraICState ic_state,
                    InitializationState init_state = INITIALIZED)
       : HydrogenCodeStub(init_state) {
-    equality_kind_ = EqualityKindField::decode(ic_state);
     nil_value_ = NilValueField::decode(ic_state);
     types_ = Types(ExtractTypesFromExtraICState(ic_state));
   }
 
   static Handle<Code> GetUninitialized(Isolate* isolate,
-                                       EqualityKind kind,
                                        NilValue nil) {
-    return CompareNilICStub(kind, nil, UNINITIALIZED).GetCode(isolate);
+    return CompareNilICStub(nil, UNINITIALIZED).GetCode(isolate);
   }
 
   virtual void InitializeInterfaceDescriptor(
@@ -1179,7 +1176,7 @@ class CompareNilICStub : public HydrogenCodeStub  {
       CodeStubInterfaceDescriptor* descriptor);
 
   static void InitializeForIsolate(Isolate* isolate) {
-    CompareNilICStub compare_stub(kStrictEquality, kNullValue, UNINITIALIZED);
+    CompareNilICStub compare_stub(kNullValue, UNINITIALIZED);
     compare_stub.InitializeInterfaceDescriptor(
         isolate,
         isolate->code_stub_interface_descriptor(CodeStub::CompareNilIC));
@@ -1199,10 +1196,9 @@ class CompareNilICStub : public HydrogenCodeStub  {
 
   Handle<Code> GenerateCode();
 
-  // extra ic state = nil_value | equality_kind | type_n-1 | ... | type_0
+  // extra ic state = nil_value | type_n-1 | ... | type_0
   virtual Code::ExtraICState GetExtraICState() {
     return NilValueField::encode(nil_value_)         |
-           EqualityKindField::encode(equality_kind_) |
            types_.ToIntegral();
   }
   static byte ExtractTypesFromExtraICState(
@@ -1213,32 +1209,25 @@ class CompareNilICStub : public HydrogenCodeStub  {
   void Record(Handle<Object> object);
 
   bool IsMonomorphic() const { return types_.Contains(MONOMORPHIC_MAP); }
-  EqualityKind GetKind() const { return equality_kind_; }
   NilValue GetNilValue() const { return nil_value_; }
   Types GetTypes() const { return types_; }
   void ClearTypes() { types_.RemoveAll(); }
-  void SetKind(EqualityKind kind) { equality_kind_ = kind; }
 
   virtual void PrintName(StringStream* stream);
 
  private:
   friend class CompareNilIC;
 
-  CompareNilICStub(EqualityKind kind, NilValue nil,
-                   InitializationState init_state)
+  CompareNilICStub(NilValue nil, InitializationState init_state)
       : HydrogenCodeStub(init_state) {
-    equality_kind_ = kind;
     nil_value_ = nil;
   }
 
-  class EqualityKindField : public BitField<EqualityKind, NUMBER_OF_TYPES, 1> {
-  };
-  class NilValueField : public BitField<NilValue, NUMBER_OF_TYPES+1, 1> {};
+  class NilValueField : public BitField<NilValue, NUMBER_OF_TYPES, 1> {};
 
   virtual CodeStub::Major MajorKey() { return CompareNilIC; }
   virtual int NotMissMinorKey() { return GetExtraICState(); }
 
-  EqualityKind equality_kind_;
   NilValue nil_value_;
   Types types_;
 

src/hydrogen.cc

@@ -1698,7 +1698,6 @@ HValue* HGraphBuilder::BuildCloneShallowArray(HContext* context,
 
 void HGraphBuilder::BuildCompareNil(
     HValue* value,
-    EqualityKind kind,
     CompareNilICStub::Types types,
     Handle<Map> map,
     int position,
@@ -1733,9 +1732,7 @@ void HGraphBuilder::BuildCompareNil(
       // emitted below is the actual monomorphic map.
       BuildCheckMap(value, map);
     } else {
-      if (kind == kNonStrictEquality) {
-        if_nil.Deopt();
-      }
+      if_nil.Deopt();
     }
   }
 
@@ -9921,19 +9918,22 @@ void HOptimizedGraphBuilder::HandleLiteralCompareNil(CompareOperation* expr,
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
-  EqualityKind kind =
-      expr->op() == Token::EQ_STRICT ? kStrictEquality : kNonStrictEquality;
   HIfContinuation continuation;
   CompareNilICStub::Types types;
-  if (kind == kStrictEquality) {
-    types.Add((nil == kNullValue) ? CompareNilICStub::NULL_TYPE :
-                                    CompareNilICStub::UNDEFINED);
-  } else {
-    types = CompareNilICStub::Types(expr->compare_nil_types());
-    if (types.IsEmpty()) types = CompareNilICStub::Types::FullCompare();
+  if (expr->op() == Token::EQ_STRICT) {
+    IfBuilder if_nil(this);
+    if_nil.If<HCompareObjectEqAndBranch>(
+        value, (nil == kNullValue) ? graph()->GetConstantNull()
+                                   : graph()->GetConstantUndefined());
+    if_nil.Then();
+    if_nil.Else();
+    if_nil.CaptureContinuation(&continuation);
+    return ast_context()->ReturnContinuation(&continuation, expr->id());
   }
+  types = CompareNilICStub::Types(expr->compare_nil_types());
+  if (types.IsEmpty()) types = CompareNilICStub::Types::FullCompare();
   Handle<Map> map_handle = expr->map();
-  BuildCompareNil(value, kind, types, map_handle,
+  BuildCompareNil(value, types, map_handle,
                   expr->position(), &continuation);
   return ast_context()->ReturnContinuation(&continuation, expr->id());
 }

src/hydrogen.h

@@ -1353,7 +1353,6 @@ class HGraphBuilder {
 
   void BuildCompareNil(
       HValue* value,
-      EqualityKind kind,
       CompareNilICStub::Types types,
       Handle<Map> map,
       int position,

src/ia32/full-codegen-ia32.cc

@@ -4768,18 +4768,14 @@ void FullCodeGenerator::EmitLiteralCompareNil(CompareOperation* expr,
   VisitForAccumulatorValue(sub_expr);
   PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
 
-  EqualityKind kind = expr->op() == Token::EQ_STRICT
-      ? kStrictEquality : kNonStrictEquality;
   Handle<Object> nil_value = nil == kNullValue
       ? isolate()->factory()->null_value()
       : isolate()->factory()->undefined_value();
-  if (kind == kStrictEquality) {
+  if (expr->op() == Token::EQ_STRICT) {
     __ cmp(eax, nil_value);
     Split(equal, if_true, if_false, fall_through);
   } else {
-    Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(),
-                                                         kNonStrictEquality,
-                                                         nil);
+    Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(), nil);
     CallIC(ic, RelocInfo::CODE_TARGET, expr->CompareOperationFeedbackId());
     __ test(eax, eax);
     Split(not_zero, if_true, if_false, fall_through);

src/ic.cc

@@ -2943,16 +2943,8 @@ void CompareNilIC::Clear(Address address, Code* target) {
 }
 
 
-MaybeObject* CompareNilIC::DoCompareNilSlow(EqualityKind kind,
-                                            NilValue nil,
+MaybeObject* CompareNilIC::DoCompareNilSlow(NilValue nil,
                                             Handle<Object> object) {
-  if (kind == kStrictEquality) {
-    if (nil == kNullValue) {
-      return Smi::FromInt(object->IsNull());
-    } else {
-      return Smi::FromInt(object->IsUndefined());
-    }
-  }
   if (object->IsNull() || object->IsUndefined()) {
     return Smi::FromInt(true);
   }
@@ -2973,7 +2965,6 @@ MaybeObject* CompareNilIC::CompareNil(Handle<Object> object) {
   stub.Record(object);
   old_types.TraceTransition(stub.GetTypes());
 
-  EqualityKind kind = stub.GetKind();
   NilValue nil = stub.GetNilValue();
 
   // Find or create the specialized stub to support the new set of types.
@@ -2987,7 +2978,7 @@ MaybeObject* CompareNilIC::CompareNil(Handle<Object> object) {
     code = stub.GetCode(isolate());
   }
   set_target(*code);
-  return DoCompareNilSlow(kind, nil, object);
+  return DoCompareNilSlow(nil, object);
 }
 
 

src/ic.h

@@ -789,8 +789,7 @@ class CompareNilIC: public IC {
 
   static void Clear(Address address, Code* target);
 
-  static MUST_USE_RESULT MaybeObject* DoCompareNilSlow(EqualityKind kind,
-                                                       NilValue nil,
+  static MUST_USE_RESULT MaybeObject* DoCompareNilSlow(NilValue nil,
                                                        Handle<Object> object);
 };
 

src/stub-cache.cc

@@ -909,8 +909,6 @@ Handle<Code> StubCache::ComputeCallMiss(int argc,
 
 Handle<Code> StubCache::ComputeCompareNil(Handle<Map> receiver_map,
                                           CompareNilICStub& stub) {
-  stub.SetKind(kNonStrictEquality);
-
   Handle<String> name(isolate_->heap()->empty_string());
   if (!receiver_map->is_shared()) {
     Handle<Code> cached_ic = FindIC(name, receiver_map, Code::COMPARE_NIL_IC,

src/v8.h

@@ -146,10 +146,6 @@ class V8 : public AllStatic {
 enum NilValue { kNullValue, kUndefinedValue };
 
 
-// JavaScript defines two kinds of equality.
-enum EqualityKind { kStrictEquality, kNonStrictEquality };
-
-
 } }  // namespace v8::internal
 
 namespace i = v8::internal;

src/x64/full-codegen-x64.cc

@@ -4754,18 +4754,14 @@ void FullCodeGenerator::EmitLiteralCompareNil(CompareOperation* expr,
 
   VisitForAccumulatorValue(sub_expr);
   PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-  EqualityKind kind = expr->op() == Token::EQ_STRICT
-      ? kStrictEquality : kNonStrictEquality;
-  if (kind == kStrictEquality) {
+  if (expr->op() == Token::EQ_STRICT) {
     Heap::RootListIndex nil_value = nil == kNullValue ?
         Heap::kNullValueRootIndex :
         Heap::kUndefinedValueRootIndex;
     __ CompareRoot(rax, nil_value);
     Split(equal, if_true, if_false, fall_through);
   } else {
-    Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(),
-                                                         kNonStrictEquality,
-                                                         nil);
+    Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(), nil);
     CallIC(ic, RelocInfo::CODE_TARGET, expr->CompareOperationFeedbackId());
     __ testq(rax, rax);
     Split(not_zero, if_true, if_false, fall_through);

test/cctest/test-compare-nil-ic-stub.cc

@@ -46,9 +46,8 @@ TEST(TypeConstructors) {
 TEST(ExternalICStateParsing) {
   Types types;
   types.Add(CompareNilICStub::UNDEFINED);
-  CompareNilICStub stub(kNonStrictEquality, kUndefinedValue, types);
+  CompareNilICStub stub(kUndefinedValue, types);
   CompareNilICStub stub2(stub.GetExtraICState());
-  CHECK_EQ(stub.GetKind(), stub2.GetKind());
   CHECK_EQ(stub.GetNilValue(), stub2.GetNilValue());
   CHECK_EQ(stub.GetTypes().ToIntegral(), stub2.GetTypes().ToIntegral());
 }