Make snapshots reproducible.

src/x64/assembler-x64-inl.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 352 matching lines @@
   if (mode == UPDATE_WRITE_BARRIER &&
       host() != NULL) {
     // TODO(1550) We are passing NULL as a slot because cell can never be on
     // evacuation candidate.
     host()->GetHeap()->incremental_marking()->RecordWrite(
         host(), NULL, cell);
   }
 }
 
 
+void RelocInfo::WipeOut() {
+  if (IsEmbeddedObject(rmode_) || IsExternalReference(rmode_)) {
+    Memory::Address_at(pc_) = NULL;
+  } else if (IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_)) {
+    // Effectively write zero into the relocation.
+    Assembler::set_target_address_at(pc_, pc_ + sizeof(int32_t));
+  } else {
+    UNREACHABLE();
+  }
+}
+
+
 bool RelocInfo::IsPatchedReturnSequence() {
   // The recognized call sequence is:
   //  movq(kScratchRegister, address); call(kScratchRegister);
   // It only needs to be distinguished from a return sequence
   //  movq(rsp, rbp); pop(rbp); ret(n); int3 *6
   // The 11th byte is int3 (0xCC) in the return sequence and
   // REX.WB (0x48+register bit) for the call sequence.
 #ifdef ENABLE_DEBUGGER_SUPPORT
   return pc_[Assembler::kMoveAddressIntoScratchRegisterInstructionLength] !=
          0xCC;
@@ skipping 162 matching lines @@
   ASSERT(len_ == 1 || len_ == 2);
   int32_t* p = reinterpret_cast<int32_t*>(&buf_[len_]);
   *p = disp;
   len_ += sizeof(int32_t);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_INL_H_