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

src/arm/lithium-codegen-arm.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 5351 matching lines @@
     Register size = ToRegister(instr->size());
     __ Allocate(size,
                 result,
                 scratch,
                 scratch2,
                 deferred->entry(),
                 flags);
   }
 
   __ bind(deferred->exit());
+
+  if (instr->hydrogen()->MustPrefillWithFiller()) {
+    if (instr->size()->IsConstantOperand()) {
+      int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
+      __ mov(scratch, Operand(size));
+    } else {
+      scratch = ToRegister(instr->size());
+    }
+    __ sub(scratch, scratch, Operand(kPointerSize));
+    __ sub(result, result, Operand(kHeapObjectTag));
+    Label loop;
+    __ bind(&loop);
+    __ mov(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
+    __ str(scratch2, MemOperand(result, scratch));
+    __ sub(scratch, scratch, Operand(kPointerSize));
+    __ cmp(scratch, Operand(0));
+    __ b(ge, &loop);
+    __ add(result, result, Operand(kHeapObjectTag));
+  }
 }
 
 
 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.
   __ mov(result, Operand(Smi::FromInt(0)));
@@ skipping 425 matching lines @@
   __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal