HStoreKeyed for Smis optimized for x64 + related redundant moves of elements removed

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 6675 matching lines @@
                            : Representation::Tagged();
     } else if (index == 1) {
       return ArrayInstructionInterface::KeyedAccessIndexRequirement(
           OperandAt(1)->representation());
     }
 
     ASSERT_EQ(index, 2);
     if (IsDoubleOrFloatElementsKind(elements_kind())) {
       return Representation::Double();
     }
-
+    if (SmiValuesAre32Bits() && IsFastPackedSmiElementsKind(elements_kind())) {
+      return Representation::Integer32();
+    }
     if (IsFastSmiElementsKind(elements_kind())) {
       return Representation::Smi();
     }
 
     return is_external() ? Representation::Integer32()
                          : Representation::Tagged();
   }
 
   bool is_external() const {
     return IsExternalArrayElementsKind(elements_kind());
   }
 
   virtual Representation observed_input_representation(int index) V8_OVERRIDE {
     if (index < 2) return RequiredInputRepresentation(index);
     if (IsUninitialized()) {
       return Representation::None();
     }
+    if (IsDoubleOrFloatElementsKind(elements_kind())) {
+      return Representation::Double();
+    }
+    if (SmiValuesAre32Bits() && IsFastPackedSmiElementsKind(elements_kind())) {
+      return Representation::Integer32();
+    }
     if (IsFastSmiElementsKind(elements_kind())) {
       return Representation::Smi();
     }
-    if (IsDoubleOrFloatElementsKind(elements_kind())) {
-      return Representation::Double();
-    }
     if (is_external()) {
       return Representation::Integer32();
     }
     // For fast object elements kinds, don't assume anything.
     return Representation::None();
   }
 
   HValue* elements() { return OperandAt(0); }
   HValue* key() { return OperandAt(1); }
   HValue* value() { return OperandAt(2); }
   bool value_is_smi() const {
     return IsFastSmiElementsKind(elements_kind_);
   }
+  // Indicates whether this is a store to a item that was previously
+  // initialized.
+  bool store_to_initialized_element() const {
+    return store_to_initialized_element_;
+  }
+  void set_store_to_initialized_element(bool v) {
+    store_to_initialized_element_ = v;
+  }
   ElementsKind elements_kind() const { return elements_kind_; }
   uint32_t index_offset() { return index_offset_; }
   void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
   virtual int MaxIndexOffsetBits() {
     return 31 - ElementsKindToShiftSize(elements_kind_);
   }
   HValue* GetKey() { return key(); }
   void SetKey(HValue* key) { SetOperandAt(1, key); }
   bool IsDehoisted() { return is_dehoisted_; }
   void SetDehoisted(bool is_dehoisted) { is_dehoisted_ = is_dehoisted; }
@@ skipping 30 matching lines @@
 
   DECLARE_CONCRETE_INSTRUCTION(StoreKeyed)
 
  private:
   HStoreKeyed(HValue* obj, HValue* key, HValue* val,
               ElementsKind elements_kind)
       : elements_kind_(elements_kind),
       index_offset_(0),
       is_dehoisted_(false),
       is_uninitialized_(false),
+      store_to_initialized_element_(false),
       new_space_dominator_(NULL) {
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
     SetOperandAt(2, val);
 
     if (IsFastObjectElementsKind(elements_kind)) {
       SetFlag(kTrackSideEffectDominators);
       SetGVNFlag(kDependsOnNewSpacePromotion);
     }
     if (is_external()) {
@@ skipping 11 matching lines @@
     if (elements_kind >= EXTERNAL_BYTE_ELEMENTS &&
         elements_kind <= EXTERNAL_UNSIGNED_INT_ELEMENTS) {
       SetFlag(kTruncatingToInt32);
     }
   }
 
   ElementsKind elements_kind_;
   uint32_t index_offset_;
   bool is_dehoisted_ : 1;
   bool is_uninitialized_ : 1;
+  bool store_to_initialized_element_: 1;
   HValue* new_space_dominator_;
 };
 
 
 class HStoreKeyedGeneric V8_FINAL : public HTemplateInstruction<4> {
  public:
   DECLARE_INSTRUCTION_WITH_CONTEXT_FACTORY_P4(HStoreKeyedGeneric, HValue*,
                                               HValue*, HValue*, StrictModeFlag);
 
   HValue* object() { return OperandAt(0); }
@@ skipping 669 matching lines @@
   virtual bool IsDeletable() const V8_OVERRIDE { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_