[turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 9952eb3b659678f11768997de16e269637575458..9d9971474659bc4f26032848068aed46cbe22fa2 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -823,6 +823,30 @@ void MacroAssembler::Cvtlsi2sd(XMMRegister dst, const Operand& src) {
 }
 
 
+void MacroAssembler::Cvtlsi2ss(XMMRegister dst, Register src) {
+  if (CpuFeatures::IsSupported(AVX)) {
+    CpuFeatureScope scope(this, AVX);
+    vxorps(dst, dst, dst);
+    vcvtlsi2ss(dst, dst, src);
+  } else {
+    xorps(dst, dst);
+    cvtlsi2ss(dst, src);
+  }
+}
+
+
+void MacroAssembler::Cvtlsi2ss(XMMRegister dst, const Operand& src) {
+  if (CpuFeatures::IsSupported(AVX)) {
+    CpuFeatureScope scope(this, AVX);
+    vxorps(dst, dst, dst);
+    vcvtlsi2ss(dst, dst, src);
+  } else {
+    xorps(dst, dst);
+    cvtlsi2ss(dst, src);
+  }
+}
+
+
 void MacroAssembler::Cvtqsi2ss(XMMRegister dst, Register src) {
   if (CpuFeatures::IsSupported(AVX)) {
     CpuFeatureScope scope(this, AVX);