Fix potential overwriting of debug jumps of following code.

src/x64/macro-assembler-x64.cc

 // Copyright 2010 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 50 matching lines @@
 void MacroAssembler::PushRoot(Heap::RootListIndex index) {
   push(Operand(kRootRegister, index << kPointerSizeLog2));
 }
 
 
 void MacroAssembler::CompareRoot(Register with, Heap::RootListIndex index) {
   cmpq(with, Operand(kRootRegister, index << kPointerSizeLog2));
 }
 
 
-void MacroAssembler::CompareRoot(Operand with, Heap::RootListIndex index) {
+void MacroAssembler::CompareRoot(const Operand& with,
+                                 Heap::RootListIndex index) {
+  ASSERT(!with.AddressUsesRegister(kScratchRegister));
   LoadRoot(kScratchRegister, index);
   cmpq(with, kScratchRegister);
 }
 
 
 void MacroAssembler::RecordWriteHelper(Register object,
                                        Register addr,
                                        Register scratch) {
   if (FLAG_debug_code) {
     // Check that the object is not in new space.
@@ skipping 2388 matching lines @@
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64