Eliminate write barrier for global stores at compile time if value stored is a smi.

Omit smi check inside write barriers if the value is known to be a heap object.

Refine inferred types of some instructions.
Review URL: http://codereview.chromium.org/8256016

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9618 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-arm.h

@@ -1260,7 +1260,6 @@ class LStoreContextSlot: public LTemplateInstruction<0, 2, 0> {
   LOperand* context() { return InputAt(0); }
   LOperand* value() { return InputAt(1); }
   int slot_index() { return hydrogen()->slot_index(); }
-  int needs_write_barrier() { return hydrogen()->NeedsWriteBarrier(); }
 
   virtual void PrintDataTo(StringStream* stream);
 };
@@ -1561,7 +1560,6 @@ class LStoreNamedField: public LTemplateInstruction<0, 2, 0> {
   Handle<Object> name() const { return hydrogen()->name(); }
   bool is_in_object() { return hydrogen()->is_in_object(); }
   int offset() { return hydrogen()->offset(); }
-  bool needs_write_barrier() { return hydrogen()->NeedsWriteBarrier(); }
   Handle<Map> transition() const { return hydrogen()->transition(); }
 };
 

src/arm/lithium-codegen-arm.cc

@@ -2251,13 +2251,19 @@ void LCodeGen::DoStoreGlobalCell(LStoreGlobalCell* instr) {
   __ str(value, FieldMemOperand(scratch, JSGlobalPropertyCell::kValueOffset));
 
   // Cells are always in the remembered set.
-  __ RecordWriteField(scratch,
-                      JSGlobalPropertyCell::kValueOffset,
-                      value,
-                      scratch2,
-                      kLRHasBeenSaved,
-                      kSaveFPRegs,
-                      OMIT_REMEMBERED_SET);
+  if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
+    __ RecordWriteField(scratch,
+                        JSGlobalPropertyCell::kValueOffset,
+                        value,
+                        scratch2,
+                        kLRHasBeenSaved,
+                        kSaveFPRegs,
+                        OMIT_REMEMBERED_SET,
+                        check_needed);
+  }
 }
 
 
@@ -2285,13 +2291,18 @@ void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register value = ToRegister(instr->value());
   MemOperand target = ContextOperand(context, instr->slot_index());
   __ str(value, target);
-  if (instr->needs_write_barrier()) {
+  if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     __ RecordWriteContextSlot(context,
                               target.offset(),
                               value,
                               scratch0(),
                               kLRHasBeenSaved,
-                              kSaveFPRegs);
+                              kSaveFPRegs,
+                              EMIT_REMEMBERED_SET,
+                              check_needed);
   }
 }
 
@@ -3297,21 +3308,36 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
   }
 
   // Do the store.
+  HType type = instr->hydrogen()->value()->type();
+  SmiCheck check_needed =
+      type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
   if (instr->is_in_object()) {
     __ str(value, FieldMemOperand(object, offset));
-    if (instr->needs_write_barrier()) {
+    if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the object for in-object properties.
-      __ RecordWriteField(
-          object, offset, value, scratch, kLRHasBeenSaved, kSaveFPRegs);
+      __ RecordWriteField(object,
+                          offset,
+                          value,
+                          scratch,
+                          kLRHasBeenSaved,
+                          kSaveFPRegs,
+                          EMIT_REMEMBERED_SET,
+                          check_needed);
     }
   } else {
     __ ldr(scratch, FieldMemOperand(object, JSObject::kPropertiesOffset));
     __ str(value, FieldMemOperand(scratch, offset));
-    if (instr->needs_write_barrier()) {
+    if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the properties array.
       // object is used as a scratch register.
-      __ RecordWriteField(
-          scratch, offset, value, object, kLRHasBeenSaved, kSaveFPRegs);
+      __ RecordWriteField(scratch,
+                          offset,
+                          value,
+                          object,
+                          kLRHasBeenSaved,
+                          kSaveFPRegs,
+                          EMIT_REMEMBERED_SET,
+                          check_needed);
     }
   }
 }
@@ -3362,9 +3388,18 @@ void LCodeGen::DoStoreKeyedFastElement(LStoreKeyedFastElement* instr) {
   }
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     // Compute address of modified element and store it into key register.
     __ add(key, scratch, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
-    __ RecordWrite(elements, key, value, kLRHasBeenSaved, kSaveFPRegs);
+    __ RecordWrite(elements,
+                   key,
+                   value,
+                   kLRHasBeenSaved,
+                   kSaveFPRegs,
+                   EMIT_REMEMBERED_SET,
+                   check_needed);
   }
 }
 
@@ -4349,8 +4384,9 @@ void LCodeGen::DoTypeofIsAndBranch(LTypeofIsAndBranch* instr) {
                                                   false_label,
                                                   input,
                                                   instr->type_literal());
-
-  EmitBranch(true_block, false_block, final_branch_condition);
+  if (final_branch_condition != kNoCondition) {
+    EmitBranch(true_block, false_block, final_branch_condition);
+  }
 }
 
 
@@ -4420,9 +4456,7 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
     final_branch_condition = eq;
 
   } else {
-    final_branch_condition = ne;
     __ b(false_label);
-    // A dead branch instruction will be generated after this point.
   }
 
   return final_branch_condition;

src/arm/lithium-codegen-arm.h

@@ -272,8 +272,10 @@ class LCodeGen BASE_EMBEDDED {
   // Emits optimized code for typeof x == "y".  Modifies input register.
   // Returns the condition on which a final split to
   // true and false label should be made, to optimize fallthrough.
-  Condition EmitTypeofIs(Label* true_label, Label* false_label,
-                         Register input, Handle<String> type_name);
+  Condition EmitTypeofIs(Label* true_label,
+                         Label* false_label,
+                         Register input,
+                         Handle<String> type_name);
 
   // Emits optimized code for %_IsObject(x).  Preserves input register.
   // Returns the condition on which a final split to

src/hydrogen-instructions.cc

@@ -1746,6 +1746,12 @@ HType HInstanceOfKnownGlobal::CalculateInferredType() {
 }
 
 
+HType HChange::CalculateInferredType() {
+  if (from().IsDouble() && to().IsTagged()) return HType::HeapNumber();
+  return type();
+}
+
+
 HType HBitwiseBinaryOperation::CalculateInferredType() {
   return HType::TaggedNumber();
 }
@@ -1801,6 +1807,31 @@ HType HSar::CalculateInferredType() {
 }
 
 
+HType HStringCharFromCode::CalculateInferredType() {
+  return HType::String();
+}
+
+
+HType HArrayLiteral::CalculateInferredType() {
+  return HType::JSArray();
+}
+
+
+HType HObjectLiteral::CalculateInferredType() {
+  return HType::JSObject();
+}
+
+
+HType HRegExpLiteral::CalculateInferredType() {
+  return HType::JSObject();
+}
+
+
+HType HFunctionLiteral::CalculateInferredType() {
+  return HType::JSObject();
+}
+
+
 HValue* HUnaryMathOperation::EnsureAndPropagateNotMinusZero(
     BitVector* visited) {
   visited->Add(id());

src/hydrogen-instructions.h

@@ -397,6 +397,11 @@ class HType {
     return type_ == kUninitialized;
   }
 
+  bool IsHeapObject() {
+    ASSERT(type_ != kUninitialized);
+    return IsHeapNumber() || IsString() || IsNonPrimitive();
+  }
+
   static HType TypeFromValue(Handle<Object> value);
 
   const char* ToString();
@@ -1101,12 +1106,14 @@ class HChange: public HUnaryOperation {
     ASSERT(!value->representation().IsNone() && !to.IsNone());
     ASSERT(!value->representation().Equals(to));
     set_representation(to);
+    set_type(HType::TaggedNumber());
     SetFlag(kUseGVN);
     if (deoptimize_on_undefined) SetFlag(kDeoptimizeOnUndefined);
     if (is_truncating) SetFlag(kTruncatingToInt32);
   }
 
   virtual HValue* EnsureAndPropagateNotMinusZero(BitVector* visited);
+  virtual HType CalculateInferredType();
 
   Representation from() { return value()->representation(); }
   Representation to() { return representation(); }
@@ -3260,6 +3267,13 @@ class HLoadGlobalGeneric: public HTemplateInstruction<2> {
 };
 
 
+static inline bool StoringValueNeedsWriteBarrier(HValue* value) {
+  return !value->type().IsBoolean()
+      && !value->type().IsSmi()
+      && !(value->IsConstant() && HConstant::cast(value)->ImmortalImmovable());
+}
+
+
 class HStoreGlobalCell: public HUnaryOperation {
  public:
   HStoreGlobalCell(HValue* value,
@@ -3275,6 +3289,9 @@ class HStoreGlobalCell: public HUnaryOperation {
   bool RequiresHoleCheck() {
     return !details_.IsDontDelete() || details_.IsReadOnly();
   }
+  bool NeedsWriteBarrier() {
+    return StoringValueNeedsWriteBarrier(value());
+  }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
@@ -3355,13 +3372,6 @@ class HLoadContextSlot: public HUnaryOperation {
 };
 
 
-static inline bool StoringValueNeedsWriteBarrier(HValue* value) {
-  return !value->type().IsBoolean()
-      && !value->type().IsSmi()
-      && !(value->IsConstant() && HConstant::cast(value)->ImmortalImmovable());
-}
-
-
 class HStoreContextSlot: public HTemplateInstruction<2> {
  public:
   HStoreContextSlot(HValue* context, int slot_index, HValue* value)
@@ -3948,7 +3958,7 @@ class HStringCharFromCode: public HTemplateInstruction<2> {
   HStringCharFromCode(HValue* context, HValue* char_code) {
     SetOperandAt(0, context);
     SetOperandAt(1, char_code);
-     set_representation(Representation::Tagged());
+    set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
   }
 
@@ -3957,6 +3967,7 @@ class HStringCharFromCode: public HTemplateInstruction<2> {
         ? Representation::Tagged()
         : Representation::Integer32();
   }
+  virtual HType CalculateInferredType();
 
   HValue* context() { return OperandAt(0); }
   HValue* value() { return OperandAt(1); }
@@ -4034,6 +4045,7 @@ class HArrayLiteral: public HMaterializedLiteral<1> {
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(ArrayLiteral)
 
@@ -4068,6 +4080,7 @@ class HObjectLiteral: public HMaterializedLiteral<1> {
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(ObjectLiteral)
 
@@ -4097,6 +4110,7 @@ class HRegExpLiteral: public HMaterializedLiteral<1> {
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(RegExpLiteral)
 
@@ -4121,6 +4135,7 @@ class HFunctionLiteral: public HTemplateInstruction<1> {
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(FunctionLiteral)
 

src/ia32/lithium-codegen-ia32.cc

@@ -2116,12 +2116,18 @@ void LCodeGen::DoStoreGlobalCell(LStoreGlobalCell* instr) {
   __ mov(FieldOperand(object, offset), value);
 
   // Cells are always in the remembered set.
-  __ RecordWriteField(object,
-                      offset,
-                      value,
-                      address,
-                      kSaveFPRegs,
-                      OMIT_REMEMBERED_SET);
+  if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
+    __ RecordWriteField(object,
+                        offset,
+                        value,
+                        address,
+                        kSaveFPRegs,
+                        OMIT_REMEMBERED_SET,
+                        check_needed);
+  }
 }
 
 
@@ -2149,10 +2155,19 @@ void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register value = ToRegister(instr->value());
   __ mov(ContextOperand(context, instr->slot_index()), value);
-  if (instr->needs_write_barrier()) {
+  if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     Register temp = ToRegister(instr->TempAt(0));
     int offset = Context::SlotOffset(instr->slot_index());
-    __ RecordWriteContextSlot(context, offset, value, temp, kSaveFPRegs);
+    __ RecordWriteContextSlot(context,
+                              offset,
+                              value,
+                              temp,
+                              kSaveFPRegs,
+                              EMIT_REMEMBERED_SET,
+                              check_needed);
   }
 }
 
@@ -3146,21 +3161,36 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
   }
 
   // Do the store.
+  HType type = instr->hydrogen()->value()->type();
+  SmiCheck check_needed =
+      type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
   if (instr->is_in_object()) {
     __ mov(FieldOperand(object, offset), value);
-    if (instr->needs_write_barrier()) {
+    if (instr->hydrogen()->NeedsWriteBarrier()) {
       Register temp = ToRegister(instr->TempAt(0));
       // Update the write barrier for the object for in-object properties.
-      __ RecordWriteField(object, offset, value, temp, kSaveFPRegs);
+      __ RecordWriteField(object,
+                          offset,
+                          value,
+                          temp,
+                          kSaveFPRegs,
+                          EMIT_REMEMBERED_SET,
+                          check_needed);
     }
   } else {
     Register temp = ToRegister(instr->TempAt(0));
     __ mov(temp, FieldOperand(object, JSObject::kPropertiesOffset));
     __ mov(FieldOperand(temp, offset), value);
-    if (instr->needs_write_barrier()) {
+    if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the properties array.
       // object is used as a scratch register.
-      __ RecordWriteField(temp, offset, value, object, kSaveFPRegs);
+      __ RecordWriteField(temp,
+                          offset,
+                          value,
+                          object,
+                          kSaveFPRegs,
+                          EMIT_REMEMBERED_SET,
+                          check_needed);
     }
   }
 }
@@ -3259,13 +3289,21 @@ void LCodeGen::DoStoreKeyedFastElement(LStoreKeyedFastElement* instr) {
   }
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     // Compute address of modified element and store it into key register.
     __ lea(key,
            FieldOperand(elements,
                         key,
                         times_pointer_size,
                         FixedArray::kHeaderSize));
-    __ RecordWrite(elements, key, value, kSaveFPRegs);
+    __ RecordWrite(elements,
+                   key,
+                   value,
+                   kSaveFPRegs,
+                   EMIT_REMEMBERED_SET,
+                   check_needed);
   }
 }
 
@@ -4247,12 +4285,11 @@ void LCodeGen::DoTypeofIsAndBranch(LTypeofIsAndBranch* instr) {
   Label* true_label = chunk_->GetAssemblyLabel(true_block);
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
-  Condition final_branch_condition = EmitTypeofIs(true_label,
-                                                  false_label,
-                                                  input,
-                                                  instr->type_literal());
-
-  EmitBranch(true_block, false_block, final_branch_condition);
+  Condition final_branch_condition =
+      EmitTypeofIs(true_label, false_label, input, instr->type_literal());
+  if (final_branch_condition != no_condition) {
+    EmitBranch(true_block, false_block, final_branch_condition);
+  }
 }
 
 
@@ -4319,11 +4356,8 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
     final_branch_condition = zero;
 
   } else {
-    final_branch_condition = not_equal;
     __ jmp(false_label);
-    // A dead branch instruction will be generated after this point.
   }
-
   return final_branch_condition;
 }
 

src/ia32/lithium-codegen-ia32.h

@@ -270,8 +270,10 @@ class LCodeGen BASE_EMBEDDED {
   // Emits optimized code for typeof x == "y".  Modifies input register.
   // Returns the condition on which a final split to
   // true and false label should be made, to optimize fallthrough.
-  Condition EmitTypeofIs(Label* true_label, Label* false_label,
-                         Register input, Handle<String> type_name);
+  Condition EmitTypeofIs(Label* true_label,
+                         Label* false_label,
+                         Register input,
+                         Handle<String> type_name);
 
   // Emits optimized code for %_IsObject(x).  Preserves input register.
   // Returns the condition on which a final split to

src/ia32/lithium-ia32.h

@@ -1295,7 +1295,6 @@ class LStoreContextSlot: public LTemplateInstruction<0, 2, 1> {
   LOperand* context() { return InputAt(0); }
   LOperand* value() { return InputAt(1); }
   int slot_index() { return hydrogen()->slot_index(); }
-  int needs_write_barrier() { return hydrogen()->NeedsWriteBarrier(); }
 
   virtual void PrintDataTo(StringStream* stream);
 };
@@ -1617,7 +1616,6 @@ class LStoreNamedField: public LTemplateInstruction<0, 2, 1> {
   Handle<Object> name() const { return hydrogen()->name(); }
   bool is_in_object() { return hydrogen()->is_in_object(); }
   int offset() { return hydrogen()->offset(); }
-  bool needs_write_barrier() { return hydrogen()->NeedsWriteBarrier(); }
   Handle<Map> transition() const { return hydrogen()->transition(); }
 };
 

src/x64/lithium-codegen-x64.cc

@@ -2055,19 +2055,24 @@ void LCodeGen::DoStoreGlobalCell(LStoreGlobalCell* instr) {
   // Store the value.
   __ movq(Operand(address, 0), value);
 
-  Label smi_store;
-  __ JumpIfSmi(value, &smi_store, Label::kNear);
+  if (instr->hydrogen()->NeedsWriteBarrier()) {
+    Label smi_store;
+    HType type = instr->hydrogen()->value()->type();
+    if (!type.IsHeapNumber() && !type.IsString() && !type.IsNonPrimitive()) {
+      __ JumpIfSmi(value, &smi_store, Label::kNear);
+    }
 
-  int offset = JSGlobalPropertyCell::kValueOffset - kHeapObjectTag;
-  __ lea(object, Operand(address, -offset));
-  // Cells are always in the remembered set.
-  __ RecordWrite(object,
-                 address,
-                 value,
-                 kSaveFPRegs,
-                 OMIT_REMEMBERED_SET,
-                 OMIT_SMI_CHECK);
-  __ bind(&smi_store);
+    int offset = JSGlobalPropertyCell::kValueOffset - kHeapObjectTag;
+    __ lea(object, Operand(address, -offset));
+    // Cells are always in the remembered set.
+    __ RecordWrite(object,
+                   address,
+                   value,
+                   kSaveFPRegs,
+                   OMIT_REMEMBERED_SET,
+                   OMIT_SMI_CHECK);
+    __ bind(&smi_store);
+  }
 }
 
 
@@ -2094,10 +2099,19 @@ void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register value = ToRegister(instr->value());
   __ movq(ContextOperand(context, instr->slot_index()), value);
-  if (instr->needs_write_barrier()) {
+  if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     int offset = Context::SlotOffset(instr->slot_index());
     Register scratch = ToRegister(instr->TempAt(0));
-    __ RecordWriteContextSlot(context, offset, value, scratch, kSaveFPRegs);
+    __ RecordWriteContextSlot(context,
+                              offset,
+                              value,
+                              scratch,
+                              kSaveFPRegs,
+                              EMIT_REMEMBERED_SET,
+                              check_needed);
   }
 }
 
@@ -3061,21 +3075,36 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
   }
 
   // Do the store.
+  HType type = instr->hydrogen()->value()->type();
+  SmiCheck check_needed =
+      type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
   if (instr->is_in_object()) {
     __ movq(FieldOperand(object, offset), value);
-    if (instr->needs_write_barrier()) {
+    if (instr->hydrogen()->NeedsWriteBarrier()) {
       Register temp = ToRegister(instr->TempAt(0));
       // Update the write barrier for the object for in-object properties.
-      __ RecordWriteField(object, offset, value, temp, kSaveFPRegs);
+      __ RecordWriteField(object,
+                          offset,
+                          value,
+                          temp,
+                          kSaveFPRegs,
+                          EMIT_REMEMBERED_SET,
+                          check_needed);
     }
   } else {
     Register temp = ToRegister(instr->TempAt(0));
     __ movq(temp, FieldOperand(object, JSObject::kPropertiesOffset));
     __ movq(FieldOperand(temp, offset), value);
-    if (instr->needs_write_barrier()) {
+    if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the properties array.
       // object is used as a scratch register.
-      __ RecordWriteField(temp, offset, value, object, kSaveFPRegs);
+      __ RecordWriteField(temp,
+                          offset,
+                          value,
+                          object,
+                          kSaveFPRegs,
+                          EMIT_REMEMBERED_SET,
+                          check_needed);
     }
   }
 }
@@ -3182,12 +3211,20 @@ void LCodeGen::DoStoreKeyedFastElement(LStoreKeyedFastElement* instr) {
   }
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     // Compute address of modified element and store it into key register.
     __ lea(key, FieldOperand(elements,
                              key,
                              times_pointer_size,
                              FixedArray::kHeaderSize));
-    __ RecordWrite(elements, key, value, kSaveFPRegs);
+    __ RecordWrite(elements,
+                   key,
+                   value,
+                   kSaveFPRegs,
+                   EMIT_REMEMBERED_SET,
+                   check_needed);
   }
 }
 
@@ -3975,12 +4012,11 @@ void LCodeGen::DoTypeofIsAndBranch(LTypeofIsAndBranch* instr) {
   Label* true_label = chunk_->GetAssemblyLabel(true_block);
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
-  Condition final_branch_condition = EmitTypeofIs(true_label,
-                                                  false_label,
-                                                  input,
-                                                  instr->type_literal());
-
-  EmitBranch(true_block, false_block, final_branch_condition);
+  Condition final_branch_condition =
+      EmitTypeofIs(true_label, false_label, input, instr->type_literal());
+  if (final_branch_condition != no_condition) {
+    EmitBranch(true_block, false_block, final_branch_condition);
+  }
 }
 
 
@@ -4048,7 +4084,6 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
     final_branch_condition = zero;
 
   } else {
-    final_branch_condition = never;
     __ jmp(false_label);
   }
 

src/x64/lithium-codegen-x64.h

@@ -260,8 +260,10 @@ class LCodeGen BASE_EMBEDDED {
   // Emits optimized code for typeof x == "y".  Modifies input register.
   // Returns the condition on which a final split to
   // true and false label should be made, to optimize fallthrough.
-  Condition EmitTypeofIs(Label* true_label, Label* false_label,
-                         Register input, Handle<String> type_name);
+  Condition EmitTypeofIs(Label* true_label,
+                         Label* false_label,
+                         Register input,
+                         Handle<String> type_name);
 
   // Emits optimized code for %_IsObject(x).  Preserves input register.
   // Returns the condition on which a final split to

src/x64/lithium-x64.h

@@ -1260,7 +1260,6 @@ class LStoreContextSlot: public LTemplateInstruction<0, 2, 1> {
   LOperand* context() { return InputAt(0); }
   LOperand* value() { return InputAt(1); }
   int slot_index() { return hydrogen()->slot_index(); }
-  int needs_write_barrier() { return hydrogen()->NeedsWriteBarrier(); }
 
   virtual void PrintDataTo(StringStream* stream);
 };
@@ -1551,7 +1550,6 @@ class LStoreNamedField: public LTemplateInstruction<0, 2, 1> {
   Handle<Object> name() const { return hydrogen()->name(); }
   bool is_in_object() { return hydrogen()->is_in_object(); }
   int offset() { return hydrogen()->offset(); }
-  bool needs_write_barrier() { return hydrogen()->NeedsWriteBarrier(); }
   Handle<Map> transition() const { return hydrogen()->transition(); }
 };