Use mutable heapnumbers to store doubles in fields.

src/hydrogen-instructions.h

 // 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
@@ skipping 188 matching lines @@
   V(WrapReceiver)
 
 #define GVN_TRACKED_FLAG_LIST(V)               \
   V(Maps)                                      \
   V(NewSpacePromotion)
 
 #define GVN_UNTRACKED_FLAG_LIST(V)             \
   V(Calls)                                     \
   V(InobjectFields)                            \
   V(BackingStoreFields)                        \
+  V(DoubleFields)                              \
   V(ElementsKind)                              \
   V(ElementsPointer)                           \
   V(ArrayElements)                             \
   V(DoubleArrayElements)                       \
   V(SpecializedArrayElements)                  \
   V(GlobalVars)                                \
   V(ArrayLengths)                              \
   V(ContextSlots)                              \
   V(OsrEntries)
 
@@ skipping 4981 matching lines @@
 
     if (FLAG_track_fields && field_representation.IsSmi()) {
       set_type(HType::Smi());
       set_representation(Representation::Tagged());
     } else if (FLAG_track_double_fields && field_representation.IsDouble()) {
       set_representation(field_representation);
     } else {
       set_representation(Representation::Tagged());
     }
     SetFlag(kUseGVN);
-    SetGVNFlag(kDependsOnMaps);
-    if (is_in_object) {
+    if (FLAG_track_double_fields && representation().IsDouble()) {
+      ASSERT(is_in_object);
+      ASSERT(offset == HeapNumber::kValueOffset);
+      SetGVNFlag(kDependsOnDoubleFields);
+    } else if (is_in_object) {
       SetGVNFlag(kDependsOnInobjectFields);
+      SetGVNFlag(kDependsOnMaps);
     } else {
       SetGVNFlag(kDependsOnBackingStoreFields);
+      SetGVNFlag(kDependsOnMaps);
     }
   }
 
   static HLoadNamedField* NewArrayLength(Zone* zone, HValue* object,
                                          HValue* typecheck,
                                          HType type = HType::Tagged()) {
     Representation representation =
         type.IsSmi() ? Representation::Smi() : Representation::Tagged();
     HLoadNamedField* result = new(zone) HLoadNamedField(
         object, true, representation, JSArray::kLengthOffset, typecheck);
@@ skipping 319 matching lines @@
 
   virtual HValue* Canonicalize();
 
   DECLARE_CONCRETE_INSTRUCTION(LoadKeyedGeneric)
 };
 
 
 class HStoreNamedField: public HTemplateInstruction<2> {
  public:
   HStoreNamedField(HValue* obj,
-                   Handle<String> name,
+                   Handle<Name> name,
                    HValue* val,
                    bool in_object,
                    Representation field_representation,
                    int offset)
       : name_(name),
         is_in_object_(in_object),
         field_representation_(field_representation),
         offset_(offset),
         transition_unique_id_(),
         new_space_dominator_(NULL) {
     SetOperandAt(0, obj);
     SetOperandAt(1, val);
     SetFlag(kTrackSideEffectDominators);
-    SetGVNFlag(kDependsOnNewSpacePromotion);
-    if (is_in_object_) {
+    if (FLAG_track_double_fields && field_representation.IsDouble()) {
+      SetGVNFlag(kChangesDoubleFields);
+    } else if (is_in_object_) {
       SetGVNFlag(kChangesInobjectFields);
+      SetGVNFlag(kDependsOnNewSpacePromotion);
     } else {
       SetGVNFlag(kChangesBackingStoreFields);
+      SetGVNFlag(kDependsOnNewSpacePromotion);
     }
   }
 
   DECLARE_CONCRETE_INSTRUCTION(StoreNamedField)
 
   virtual Representation RequiredInputRepresentation(int index) {
-    if (FLAG_track_fields && index == 1 && field_representation_.IsSmi()) {
+    if (FLAG_track_double_fields &&
+        index == 1 && field_representation_.IsDouble()) {
+      return field_representation_;
+    } else if (FLAG_track_fields &&
+               index == 1 && field_representation_.IsSmi()) {
       return Representation::Integer32();
     }
     return Representation::Tagged();
   }
   virtual void SetSideEffectDominator(GVNFlag side_effect, HValue* dominator) {
     ASSERT(side_effect == kChangesNewSpacePromotion);
     new_space_dominator_ = dominator;
   }
   virtual void PrintDataTo(StringStream* stream);
 
   HValue* object() { return OperandAt(0); }
   HValue* value() { return OperandAt(1); }
 
-  Handle<String> name() const { return name_; }
+  Handle<Name> name() const { return name_; }
   bool is_in_object() const { return is_in_object_; }
   int offset() const { return offset_; }
   Handle<Map> transition() const { return transition_; }
   UniqueValueId transition_unique_id() const { return transition_unique_id_; }
   void set_transition(Handle<Map> map) { transition_ = map; }
   HValue* new_space_dominator() const { return new_space_dominator_; }
 
   bool NeedsWriteBarrier() {
+    ASSERT(!(FLAG_track_double_fields && field_representation_.IsDouble()) ||
+           transition_.is_null());
     return (!FLAG_track_fields || !field_representation_.IsSmi()) &&
+        // If there is a transition, a new storage object needs to be allocated.
+        !(FLAG_track_double_fields && field_representation_.IsDouble()) &&
         StoringValueNeedsWriteBarrier(value()) &&
         ReceiverObjectNeedsWriteBarrier(object(), new_space_dominator());
   }
 
   bool NeedsWriteBarrierForMap() {
     return ReceiverObjectNeedsWriteBarrier(object(), new_space_dominator());
   }
 
   virtual void FinalizeUniqueValueId() {
     transition_unique_id_ = UniqueValueId(transition_);
   }
 
   Representation field_representation() const {
     return field_representation_;
   }
 
  private:
-  Handle<String> name_;
+  Handle<Name> name_;
   bool is_in_object_;
   Representation field_representation_;
   int offset_;
   Handle<Map> transition_;
   UniqueValueId transition_unique_id_;
   HValue* new_space_dominator_;
 };
 
 
 class HStoreNamedGeneric: public HTemplateInstruction<3> {
@@ skipping 891 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_