GVN fix, preventing loads hoisting above stores to the same field when HObjectAccess's representati…

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HYDROGEN_INSTRUCTIONS_H_
 #define V8_HYDROGEN_INSTRUCTIONS_H_
 
 #include "src/v8.h"
 
 #include "src/allocation.h"
@@ skipping 6184 matching lines @@
         JSArrayBufferView::kByteLengthOffset);
   }
 
   static HObjectAccess ForGlobalObjectNativeContext() {
     return HObjectAccess(kInobject, GlobalObject::kNativeContextOffset);
   }
 
   void PrintTo(StringStream* stream) const;
 
   inline bool Equals(HObjectAccess that) const {
-    return value_ == that.value_;  // portion and offset must match
+    return value_ == that.value_;
+  }
+
+  // Returns true if |this| access refers to the same field as |that|, which
+  // means that both have same |offset| and |portion| values.
+  inline bool SameField(HObjectAccess that) const {
+    uint32_t mask = PortionField::kMask | OffsetField::kMask;
+    return (value_ & mask) == (that.value_ & mask);
   }
 
  protected:
   void SetGVNFlags(HValue *instr, PropertyAccessType access_type);
 
  private:
   // internal use only; different parts of an object or array
   enum Portion {
     kMaps,             // map of an object
     kArrayLengths,     // the length of an array
@@ skipping 1586 matching lines @@
 };
 
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_