Correctly retain argument value when deopting from Math.round on x64.

src/x64/lithium-x64.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 1115 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoMathFloor(HUnaryMathOperation* instr) {
   LOperand* input = UseRegisterAtStart(instr->value());
   LMathFloor* result = new(zone()) LMathFloor(input);
   return AssignEnvironment(DefineAsRegister(result));
 }
 
 
 LInstruction* LChunkBuilder::DoMathRound(HUnaryMathOperation* instr) {
-  LOperand* input = UseRegisterAtStart(instr->value());
-  LMathRound* result = new(zone()) LMathRound(input);
+  LOperand* input = UseRegister(instr->value());
+  LOperand* temp = FixedTemp(xmm4);
+  LMathRound* result = new(zone()) LMathRound(input, temp);
   return AssignEnvironment(DefineAsRegister(result));
 }
 
 
 LInstruction* LChunkBuilder::DoMathAbs(HUnaryMathOperation* instr) {
   LOperand* context = UseAny(instr->context());
   LOperand* input = UseRegisterAtStart(instr->value());
   LMathAbs* result = new(zone()) LMathAbs(context, input);
   return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
 }
@@ skipping 1372 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64