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

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 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 5062 matching lines @@
 
   if (instr->size()->IsConstantOperand()) {
     int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
     __ Allocate(size, result, temp, no_reg, deferred->entry(), flags);
   } else {
     Register size = ToRegister(instr->size());
     __ Allocate(size, result, temp, no_reg, deferred->entry(), flags);
   }
 
   __ bind(deferred->exit());
+
+  if (instr->hydrogen()->MustPrefillWithFiller()) {
+    if (instr->size()->IsConstantOperand()) {
+      int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
+      __ movl(temp, Immediate((size / kPointerSize) - 1));
+    } else {
+      temp = ToRegister(instr->size());
+      __ sar(temp, Immediate(kPointerSizeLog2));
+      __ decl(temp);
+    }
+    Label loop;
+    __ bind(&loop);
+    __ Move(FieldOperand(result, temp, times_pointer_size, 0),
+        isolate()->factory()->one_pointer_filler_map());
+    __ decl(temp);
+    __ j(not_zero, &loop);
+  }
 }
 
 
 void LCodeGen::DoDeferredAllocate(LAllocate* instr) {
   Register result = ToRegister(instr->result());
 
   // TODO(3095996): Get rid of this. For now, we need to make the
   // result register contain a valid pointer because it is already
   // contained in the register pointer map.
   __ Move(result, Smi::FromInt(0));
@@ skipping 433 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64