Add and use ElementsKind side effect

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 165 matching lines @@
   V(TypeofIsAndBranch)                         \
   V(UnaryMathOperation)                        \
   V(UnknownOSRValue)                           \
   V(UseConst)                                  \
   V(ValueOf)
 
 #define GVN_FLAG_LIST(V)                       \
   V(Calls)                                     \
   V(InobjectFields)                            \
   V(BackingStoreFields)                        \
+  V(ElementsKind)                              \
   V(ArrayElements)                             \
   V(DoubleArrayElements)                       \
   V(SpecializedArrayElements)                  \
   V(GlobalVars)                                \
   V(Maps)                                      \
   V(ArrayLengths)                              \
   V(ContextSlots)                              \
   V(OsrEntries)
 
 #define DECLARE_ABSTRACT_INSTRUCTION(type)          \
@@ skipping 418 matching lines @@
   void ClearOperands();
 
   int flags() const { return flags_; }
   void SetFlag(Flag f) { flags_ |= (1 << f); }
   void ClearFlag(Flag f) { flags_ &= ~(1 << f); }
   bool CheckFlag(Flag f) const { return (flags_ & (1 << f)) != 0; }
 
   void SetAllSideEffects() { flags_ |= AllSideEffects(); }
   void ClearAllSideEffects() { flags_ &= ~AllSideEffects(); }
   bool HasSideEffects() const { return (flags_ & AllSideEffects()) != 0; }
+  bool HasObservableSideEffects() const {
+    return (flags_ & ObservableSideEffects()) != 0;
+  }
 
   int ChangesFlags() const { return flags_ & ChangesFlagsMask(); }
+  int ObservableChangesFlags() const {
+    return flags_ & ChangesFlagsMask() & ObservableSideEffects();
+  }
 
   Range* range() const { return range_; }
   bool HasRange() const { return range_ != NULL; }
   void AddNewRange(Range* r);
   void RemoveLastAddedRange();
   void ComputeInitialRange();
 
   // Representation helpers.
   virtual Representation RequiredInputRepresentation(int index) = 0;
 
@@ skipping 59 matching lines @@
   GVN_FLAG_LIST(ADD_FLAG)
 #undef ADD_FLAG
     return result;
   }
 
   // A flag mask to mark an instruction as having arbitrary side effects.
   static int AllSideEffects() {
     return ChangesFlagsMask() & ~(1 << kChangesOsrEntries);
   }
 
+  // A flag mask of all side effects that can make observable changes in
+  // an executing program (i.e. are not safe to repeat, move or remove);
+  static int ObservableSideEffects() {
+    return ChangesFlagsMask() & ~(1 << kChangesElementsKind);
+  }
+
   // Remove the matching use from the use list if present.  Returns the
   // removed list node or NULL.
   HUseListNode* RemoveUse(HValue* value, int index);
 
   void RegisterUse(int index, HValue* new_value);
 
   HBasicBlock* block_;
 
   // The id of this instruction in the hydrogen graph, assigned when first
   // added to the graph. Reflects creation order.
@@ skipping 1017 matching lines @@
  protected:
   virtual bool DataEquals(HValue* other) { return true; }
 };
 
 
 class HElementsKind: public HUnaryOperation {
  public:
   explicit HElementsKind(HValue* value) : HUnaryOperation(value) {
     set_representation(Representation::Integer32());
     SetFlag(kUseGVN);
-    SetFlag(kDependsOnMaps);
+    SetFlag(kDependsOnElementsKind);
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
 
   DECLARE_CONCRETE_INSTRUCTION(ElementsKind)
 
  protected:
   virtual bool DataEquals(HValue* other) { return true; }
@@ skipping 106 matching lines @@
   BuiltinFunctionId op_;
 };
 
 
 class HLoadElements: public HUnaryOperation {
  public:
   explicit HLoadElements(HValue* value) : HUnaryOperation(value) {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
     SetFlag(kDependsOnMaps);
+    SetFlag(kDependsOnElementsKind);
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
 
   DECLARE_CONCRETE_INSTRUCTION(LoadElements)
 
  protected:
   virtual bool DataEquals(HValue* other) { return true; }
@@ skipping 2029 matching lines @@
 
 class HTransitionElementsKind: public HTemplateInstruction<1> {
  public:
   HTransitionElementsKind(HValue* object,
                           Handle<Map> original_map,
                           Handle<Map> transitioned_map)
       : original_map_(original_map),
         transitioned_map_(transitioned_map) {
     SetOperandAt(0, object);
     SetFlag(kUseGVN);
-    SetFlag(kDependsOnMaps);
+    SetFlag(kChangesElementsKind);
     set_representation(Representation::Tagged());
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
 
   HValue* object() { return OperandAt(0); }
   Handle<Map> original_map() { return original_map_; }
   Handle<Map> transitioned_map() { return transitioned_map_; }
@@ skipping 368 matching lines @@
 
   DECLARE_CONCRETE_INSTRUCTION(In)
 };
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_