[turbofan] Implemented the TruncateFloat32ToInt64 TurboFan operator.

src/x64/assembler-x64.cc

Index: src/x64/assembler-x64.cc
diff --git a/src/x64/assembler-x64.cc b/src/x64/assembler-x64.cc
index a1d2d3b0265641fc2b9ff610313af829ee981118..36187558770dcd4ddd2171eccfce51b300f2b99e 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -3112,6 +3112,28 @@ void Assembler::cvttsd2si(Register dst, XMMRegister src) {
 }
 
 
+void Assembler::cvttss2siq(Register dst, XMMRegister src) {
+  DCHECK(!IsEnabled(AVX));
+  EnsureSpace ensure_space(this);
+  emit(0xF3);
+  emit_rex_64(dst, src);
+  emit(0x0F);
+  emit(0x2C);
+  emit_sse_operand(dst, src);
+}
+
+
+void Assembler::cvttss2siq(Register dst, const Operand& src) {
+  DCHECK(!IsEnabled(AVX));
+  EnsureSpace ensure_space(this);
+  emit(0xF3);
+  emit_rex_64(dst, src);
+  emit(0x0F);
+  emit(0x2C);
+  emit_sse_operand(dst, src);
+}
+
+
 void Assembler::cvttsd2siq(Register dst, XMMRegister src) {
   DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);