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

src/hydrogen-instructions.h

 // Copyright 2011 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
@@ skipping 379 matching lines @@
 
   bool IsJSObject() {
     ASSERT(type_ != kUninitialized);
     return ((type_ & kJSObject) == kJSObject);
   }
 
   bool IsUninitialized() {
     return type_ == kUninitialized;
   }
 
+  bool IsHeapObject() {
+    ASSERT(type_ != kUninitialized);
+    return IsHeapNumber() || IsString() || IsNonPrimitive();
+  }
+
   static HType TypeFromValue(Handle<Object> value);
 
   const char* ToString();
   const char* ToShortString();
 
  private:
   enum Type {
     kTagged = 0x1,           // 0000 0000 0000 0001
     kTaggedPrimitive = 0x5,  // 0000 0000 0000 0101
     kTaggedNumber = 0xd,     // 0000 0000 0000 1101
@@ skipping 684 matching lines @@
 class HChange: public HUnaryOperation {
  public:
   HChange(HValue* value,
           Representation to,
           bool is_truncating,
           bool deoptimize_on_undefined)
       : HUnaryOperation(value) {
     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(); }
   bool deoptimize_on_undefined() const {
     return CheckFlag(kDeoptimizeOnUndefined);
   }
   virtual Representation RequiredInputRepresentation(int index) {
     return from();
   }
 
@@ skipping 2133 matching lines @@
   }
 
   DECLARE_CONCRETE_INSTRUCTION(LoadGlobalGeneric)
 
  private:
   Handle<Object> name_;
   bool for_typeof_;
 };
 
 
+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,
                    Handle<JSGlobalPropertyCell> cell,
                    PropertyDetails details)
       : HUnaryOperation(value),
         cell_(cell),
         details_(details) {
     SetFlag(kChangesGlobalVars);
   }
 
   Handle<JSGlobalPropertyCell> cell() const { return cell_; }
   bool RequiresHoleCheck() {
     return !details_.IsDontDelete() || details_.IsReadOnly();
   }
+  bool NeedsWriteBarrier() {
+    return StoringValueNeedsWriteBarrier(value());
+  }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
   virtual void PrintDataTo(StringStream* stream);
 
   DECLARE_CONCRETE_INSTRUCTION(StoreGlobalCell)
 
  private:
   Handle<JSGlobalPropertyCell> cell_;
@@ skipping 60 matching lines @@
   virtual bool DataEquals(HValue* other) {
     HLoadContextSlot* b = HLoadContextSlot::cast(other);
     return (slot_index() == b->slot_index());
   }
 
  private:
   int slot_index_;
 };
 
 
-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)
       : slot_index_(slot_index) {
     SetOperandAt(0, context);
     SetOperandAt(1, value);
     SetFlag(kChangesContextSlots);
   }
 
   HValue* context() { return OperandAt(0); }
@@ skipping 566 matching lines @@
     return new Range(0, String::kMaxUC16CharCode);
   }
 };
 
 
 class HStringCharFromCode: public HTemplateInstruction<2> {
  public:
   HStringCharFromCode(HValue* context, HValue* char_code) {
     SetOperandAt(0, context);
     SetOperandAt(1, char_code);
-     set_representation(Representation::Tagged());
+    set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return index == 0
         ? Representation::Tagged()
         : Representation::Integer32();
   }
+  virtual HType CalculateInferredType();
 
   HValue* context() { return OperandAt(0); }
   HValue* value() { return OperandAt(1); }
 
   virtual bool DataEquals(HValue* other) { return true; }
 
   DECLARE_CONCRETE_INSTRUCTION(StringCharFromCode)
 };
 
 
@@ skipping 57 matching lines @@
 
   HValue* context() { return OperandAt(0); }
   Handle<FixedArray> constant_elements() const { return constant_elements_; }
   int length() const { return length_; }
 
   bool IsCopyOnWrite() const;
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(ArrayLiteral)
 
  private:
   int length_;
   Handle<FixedArray> constant_elements_;
 };
 
 
 class HObjectLiteral: public HMaterializedLiteral<1> {
@@ skipping 14 matching lines @@
   HValue* context() { return OperandAt(0); }
   Handle<FixedArray> constant_properties() const {
     return constant_properties_;
   }
   bool fast_elements() const { return fast_elements_; }
   bool has_function() const { return has_function_; }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(ObjectLiteral)
 
  private:
   Handle<FixedArray> constant_properties_;
   bool fast_elements_;
   bool has_function_;
 };
 
 
 class HRegExpLiteral: public HMaterializedLiteral<1> {
  public:
   HRegExpLiteral(HValue* context,
                  Handle<String> pattern,
                  Handle<String> flags,
                  int literal_index)
       : HMaterializedLiteral<1>(literal_index, 0),
         pattern_(pattern),
         flags_(flags) {
     SetOperandAt(0, context);
   }
 
   HValue* context() { return OperandAt(0); }
   Handle<String> pattern() { return pattern_; }
   Handle<String> flags() { return flags_; }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(RegExpLiteral)
 
  private:
   Handle<String> pattern_;
   Handle<String> flags_;
 };
 
 
 class HFunctionLiteral: public HTemplateInstruction<1> {
  public:
   HFunctionLiteral(HValue* context,
                    Handle<SharedFunctionInfo> shared,
                    bool pretenure)
       : shared_info_(shared), pretenure_(pretenure) {
     SetOperandAt(0, context);
     set_representation(Representation::Tagged());
   }
 
   HValue* context() { return OperandAt(0); }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(FunctionLiteral)
 
   Handle<SharedFunctionInfo> shared_info() const { return shared_info_; }
   bool pretenure() const { return pretenure_; }
 
  private:
   Handle<SharedFunctionInfo> shared_info_;
   bool pretenure_;
 };
@@ skipping 99 matching lines @@
 
   DECLARE_CONCRETE_INSTRUCTION(In)
 };
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_