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

src/hydrogen-instructions.cc

 // 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 3219 matching lines @@
   int32_t current_size_constant =
       HConstant::cast(current_size)->GetInteger32Constant();
   HBasicBlock* block = dominator->block();
   Zone* zone = block->zone();
   HInstruction* new_dominator_size = new(zone) HConstant(
       dominator_size_constant + current_size_constant);
   new_dominator_size->InsertBefore(dominator_allocate_instr);
   dominator_allocate_instr->UpdateSize(new_dominator_size);
 
 #ifdef VERIFY_HEAP
-  HInstruction* free_space_instr =
-      new(zone) HInnerAllocatedObject(dominator_allocate_instr,
-                                      dominator_size_constant,
-                                      type());
-  free_space_instr->InsertAfter(dominator_allocate_instr);
-  HConstant* filler_map = new(zone) HConstant(
-      isolate()->factory()->free_space_map(),
-      UniqueValueId(isolate()->heap()->free_space_map()),
-      Representation::Tagged(),
-      HType::Tagged(),
-      false,
-      true,
-      false,
-      false);
-  filler_map->InsertAfter(free_space_instr);
-
-  HInstruction* store_map = new(zone) HStoreNamedField(
-      free_space_instr, HObjectAccess::ForMap(), filler_map);
-  store_map->SetFlag(HValue::kHasNoObservableSideEffects);
-  store_map->InsertAfter(filler_map);
-
-  HInstruction* free_space_size = new(zone) HConstant(current_size_constant);
-  free_space_size->InsertAfter(store_map);
-  HObjectAccess access =
-      HObjectAccess::ForJSObjectOffset(FreeSpace::kSizeOffset);
-  HInstruction* store_size = new(zone) HStoreNamedField(
-      free_space_instr, access, free_space_size);
-  store_size->SetFlag(HValue::kHasNoObservableSideEffects);
-  store_size->InsertAfter(free_space_size);
+  if (FLAG_verify_heap) {
+    dominator_allocate_instr->SetFlags(HAllocate::PREFILL_WITH_FILLER);
+  }
 #endif
 
   // After that replace the dominated allocate instruction.
   HInstruction* dominated_allocate_instr =
       new(zone) HInnerAllocatedObject(dominator_allocate_instr,
                                       dominator_size_constant,
                                       type());
   dominated_allocate_instr->InsertBefore(this);
   DeleteAndReplaceWith(dominated_allocate_instr);
   if (FLAG_trace_allocation_folding) {
@@ skipping 715 matching lines @@
     case kBackingStore:
       if (!name_.is_null()) stream->Add(*String::cast(*name_)->ToCString());
       stream->Add("[backing-store]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal