Prefill pre-allocated memory of folded allocation with one pointer fillers when heap verifier is on.

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 4946 matching lines @@
   bool for_typeof_;
 };
 
 
 class HAllocate: public HTemplateInstruction<2> {
  public:
   enum Flags {
     CAN_ALLOCATE_IN_NEW_SPACE = 1 << 0,
     CAN_ALLOCATE_IN_OLD_DATA_SPACE = 1 << 1,
     CAN_ALLOCATE_IN_OLD_POINTER_SPACE = 1 << 2,
-    ALLOCATE_DOUBLE_ALIGNED = 1 << 3
+    ALLOCATE_DOUBLE_ALIGNED = 1 << 3,
+    PREFILL_WITH_FILLER = 1 << 4
   };
 
   HAllocate(HValue* context, HValue* size, HType type, Flags flags)
       : type_(type),
         flags_(flags) {
     SetOperandAt(0, context);
     SetOperandAt(1, size);
     set_representation(Representation::Tagged());
     SetFlag(kTrackSideEffectDominators);
     SetGVNFlag(kChangesNewSpacePromotion);
@@ skipping 56 matching lines @@
   }
 
   bool GuaranteedInNewSpace() const {
     return CanAllocateInNewSpace() && !CanAllocateInOldSpace();
   }
 
   bool MustAllocateDoubleAligned() const {
     return (flags_ & ALLOCATE_DOUBLE_ALIGNED) != 0;
   }
 
+  bool MustPrefillWithFiller() const {
+    return (flags_ & PREFILL_WITH_FILLER) != 0;
+  }
+
+  void SetFlags(Flags flags) {
+    flags_ = static_cast<HAllocate::Flags>(flags_ | flags);
+  }
+
   void UpdateSize(HValue* size) {
     SetOperandAt(1, size);
   }
 
   virtual void HandleSideEffectDominator(GVNFlag side_effect,
                                          HValue* dominator);
 
   virtual void PrintDataTo(StringStream* stream);
 
   DECLARE_CONCRETE_INSTRUCTION(Allocate)
@@ skipping 1627 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_