[turbofan] Implement rounding of floats on x64 and ia32 without sse4.1.

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index c47a42eefe3da6684257f8cbfa9bdc6f3c2a661d..5fe031f6463c953b1a4a09315d4ca2740fdbba67 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -1787,21 +1787,19 @@ InstructionSelector::SupportedMachineOperatorFlags() {
       MachineOperatorBuilder::kFloat64Max |
       MachineOperatorBuilder::kFloat64Min |
       MachineOperatorBuilder::kWord32ShiftIsSafe |
-      MachineOperatorBuilder::kWord32Ctz | MachineOperatorBuilder::kWord64Ctz;
+      MachineOperatorBuilder::kWord32Ctz | MachineOperatorBuilder::kWord64Ctz |
+      MachineOperatorBuilder::kFloat32RoundDown |
+      MachineOperatorBuilder::kFloat32RoundUp |
+      MachineOperatorBuilder::kFloat32RoundTruncate |
+      MachineOperatorBuilder::kFloat32RoundTiesEven |
+      MachineOperatorBuilder::kFloat64RoundDown |
+      MachineOperatorBuilder::kFloat64RoundUp |
+      MachineOperatorBuilder::kFloat64RoundTruncate |
+      MachineOperatorBuilder::kFloat64RoundTiesEven;
   if (CpuFeatures::IsSupported(POPCNT)) {
     flags |= MachineOperatorBuilder::kWord32Popcnt |
              MachineOperatorBuilder::kWord64Popcnt;
   }
-  if (CpuFeatures::IsSupported(SSE4_1)) {
-    flags |= MachineOperatorBuilder::kFloat32RoundDown |
-             MachineOperatorBuilder::kFloat64RoundDown |
-             MachineOperatorBuilder::kFloat32RoundUp |
-             MachineOperatorBuilder::kFloat64RoundUp |
-             MachineOperatorBuilder::kFloat32RoundTruncate |
-             MachineOperatorBuilder::kFloat64RoundTruncate |
-             MachineOperatorBuilder::kFloat32RoundTiesEven |
-             MachineOperatorBuilder::kFloat64RoundTiesEven;
-  }
   return flags;
 }