Push safepoint registers in deferred number-to-i/u only on-demand.

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 1727 matching lines @@
       LOperand* value = UseRegister(instr->value());
       return AssignEnvironment(
           DefineAsRegister(new(zone()) LDoubleToI(value)));
     }
   } else if (from.IsInteger32()) {
     info()->MarkAsDeferredCalling();
     if (to.IsTagged()) {
       HValue* val = instr->value();
       LOperand* value = UseRegister(val);
       if (val->CheckFlag(HInstruction::kUint32)) {
-        LOperand* temp = FixedTemp(xmm1);
-        LNumberTagU* result = new(zone()) LNumberTagU(value, temp);
+        LOperand* temp1 = TempRegister();
+        LOperand* temp2 = FixedTemp(xmm1);
+        LNumberTagU* result = new(zone()) LNumberTagU(value, temp1, temp2);
         return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
       } else if (val->HasRange() && val->range()->IsInSmiRange()) {
         return DefineSameAsFirst(new(zone()) LSmiTag(value));
       } else {
         LNumberTagI* result = new(zone()) LNumberTagI(value);
         return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
       }
     } else if (to.IsSmi()) {
       HValue* val = instr->value();
       LOperand* value = UseRegister(val);
@@ skipping 676 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