Use xorps to break the cvtsi2sd unnecessary dependence due to its partially written

src/ia32/macro-assembler-ia32.h

Index: src/ia32/macro-assembler-ia32.h
diff --git a/src/ia32/macro-assembler-ia32.h b/src/ia32/macro-assembler-ia32.h
index e4e4533bf5f8e2f4b2b66360ba166666353ad130..d8136924463574bc154996a252085aa5f67bf94b 100644
--- a/src/ia32/macro-assembler-ia32.h
+++ b/src/ia32/macro-assembler-ia32.h
@@ -366,6 +366,12 @@ class MacroAssembler: public Assembler {
   void Set(Register dst, const Immediate& x);
   void Set(const Operand& dst, const Immediate& x);
 
+  // cvtsi2sd instruction only writes to the low 64-bit of dst register, which
+  // hinders register renaming and makes dependence chains longer. So we use
+  // xorps to clear the dst register before cvtsi2sd to solve this issue.
+  void Cvtsi2sd(XMMRegister dst, Register src) { Cvtsi2sd(dst, Operand(src)); }
+  void Cvtsi2sd(XMMRegister dst, const Operand& src);
+
   // Support for constant splitting.
   bool IsUnsafeImmediate(const Immediate& x);
   void SafeSet(Register dst, const Immediate& x);