[turbofan] Implemented the TruncateFloat32ToInt64 TurboFan operator.

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 8affaafd2bee53fbc0d6386533f13093f99bcbf9..5b95591f1702f642c50196ccf68cdf09aa664b44 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -967,6 +967,26 @@ void MacroAssembler::Cvttsd2si(Register dst, const Operand& src) {
 }
 
 
+void MacroAssembler::Cvttss2siq(Register dst, XMMRegister src) {
+  if (CpuFeatures::IsSupported(AVX)) {
+    CpuFeatureScope scope(this, AVX);
+    vcvttss2siq(dst, src);
+  } else {
+    cvttss2siq(dst, src);
+  }
+}
+
+
+void MacroAssembler::Cvttss2siq(Register dst, const Operand& src) {
+  if (CpuFeatures::IsSupported(AVX)) {
+    CpuFeatureScope scope(this, AVX);
+    vcvttss2siq(dst, src);
+  } else {
+    cvttss2siq(dst, src);
+  }
+}
+
+
 void MacroAssembler::Cvttsd2siq(Register dst, XMMRegister src) {
   if (CpuFeatures::IsSupported(AVX)) {
     CpuFeatureScope scope(this, AVX);