Intrinsify Double.toInt.

runtime/vm/assembler_x64_test.cc

Index: runtime/vm/assembler_x64_test.cc
===================================================================
--- runtime/vm/assembler_x64_test.cc	(revision 12015)
+++ runtime/vm/assembler_x64_test.cc	(working copy)
@@ -1386,12 +1386,30 @@
 
 
 ASSEMBLER_TEST_RUN(Int64ToDoubleConversion, entry) {
-  typedef double (*IntToDoubleConversionCode)();
-  double res = reinterpret_cast<IntToDoubleConversionCode>(entry)();
+  typedef double (*Int64ToDoubleConversionCode)();
+  double res = reinterpret_cast<Int64ToDoubleConversionCode>(entry)();
   EXPECT_FLOAT_EQ(static_cast<double>(12LL << 32), res, 0.001);
 }
 
 
+ASSEMBLER_TEST_GENERATE(DoubleToInt64Conversion, assembler) {
+  __ movq(RAX, Immediate(bit_cast<int64_t, double>(12.3)));
+  __ pushq(RAX);
+  __ movsd(XMM6, Address(RSP, 0));
+  __ popq(RAX);
+  __ cvttsd2siq(RDX, XMM6);
+  __ movq(RAX, RDX);
+  __ ret();
+}
+
+
+ASSEMBLER_TEST_RUN(DoubleToInt64Conversion, entry) {
+  typedef int64_t (*DoubleToInt64ConversionCode)();
+  int64_t res = reinterpret_cast<DoubleToInt64ConversionCode>(entry)();
+  EXPECT_EQ(12, res);
+}
+
+
 ASSEMBLER_TEST_GENERATE(TestObjectCompare, assembler) {
   ObjectStore* object_store = Isolate::Current()->object_store();
   const Object& obj = Object::ZoneHandle(object_store->smi_class());