X64: Make SmiCompare use the Smi-register when possible.

src/x64/macro-assembler-x64.cc

 // Copyright 2009 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 764 matching lines @@
 void MacroAssembler::SmiCompare(Register dst, Register src) {
   cmpq(dst, src);
 }
 
 
 void MacroAssembler::SmiCompare(Register dst, Smi* src) {
   ASSERT(!dst.is(kScratchRegister));
   if (src->value() == 0) {
     testq(dst, dst);
   } else {
-    Move(kScratchRegister, src);
-    cmpq(dst, kScratchRegister);
+    Register constant_reg = GetSmiConstant(src);
+    cmpq(dst, constant_reg);
   }
 }
 
 
 void MacroAssembler::SmiCompare(Register dst, const Operand& src) {
   cmpq(dst, src);
 }
 
 
 void MacroAssembler::SmiCompare(const Operand& dst, Register src) {
@@ skipping 2150 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