[turbofan] Implemented the ChangeFloat64ToInt64 TurboFan operator.

test/cctest/compiler/test-run-machops.cc

Index: test/cctest/compiler/test-run-machops.cc
diff --git a/test/cctest/compiler/test-run-machops.cc b/test/cctest/compiler/test-run-machops.cc
index 08f8f3f4c31da4fb474c7dc3fb056af7c0cfaa53..c6ed018a3a8705e17f92f3b501b6322fc5a1de66 100644
--- a/test/cctest/compiler/test-run-machops.cc
+++ b/test/cctest/compiler/test-run-machops.cc
@@ -5346,18 +5346,20 @@ TEST(RunBitcastInt64ToFloat64) {
 
 
 TEST(RunBitcastFloat64ToInt64) {
-  double input = 0;
-  int64_t output = 0;
-  RawMachineAssemblerTester<int32_t> m;
-  m.StoreToPointer(
-      &output, kMachInt64,
-      m.BitcastFloat64ToInt64(m.LoadFromPointer(&input, kMachFloat64)));
-  m.Return(m.Int32Constant(11));
-  FOR_FLOAT64_INPUTS(i) {
-    input = *i;
-    CHECK_EQ(11, m.Call());
-    double expected = bit_cast<int64_t>(input);
-    CHECK_EQ(expected, output);
+  BufferedRawMachineAssemblerTester<int64_t> m(kMachFloat64);
+
+  m.Return(m.BitcastFloat64ToInt64(m.Parameter(0)));
+  FOR_FLOAT64_INPUTS(i) { CHECK_EQ(bit_cast<int64_t>(*i), m.Call(*i)); }
+}
+
+
+TEST(RunChangeFloat64ToInt64) {
+  BufferedRawMachineAssemblerTester<int64_t> m(kMachFloat64);
+  m.Return(m.ChangeFloat64ToInt64(m.Parameter(0)));
+
+  FOR_INT64_INPUTS(i) {
+    double input = static_cast<double>(*i);
+    CHECK_EQ(static_cast<int64_t>(input), m.Call(input));
   }
 }