[turbofan] Implemented the optional Float32RoundTruncate operator.

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

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 
 #include "src/base/adapters.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
@@ skipping 1140 matching lines @@
 void InstructionSelector::VisitFloat32RoundUp(Node* node) {
   VisitRR(this, node, kSSEFloat32Round | MiscField::encode(kRoundUp));
 }
 
 
 void InstructionSelector::VisitFloat64RoundUp(Node* node) {
   VisitRR(this, node, kSSEFloat64Round | MiscField::encode(kRoundUp));
 }
 
 
+void InstructionSelector::VisitFloat32RoundTruncate(Node* node) {
+  VisitRR(this, node, kSSEFloat32Round | MiscField::encode(kRoundToZero));
+}
+
+
 void InstructionSelector::VisitFloat64RoundTruncate(Node* node) {
   VisitRR(this, node, kSSEFloat64Round | MiscField::encode(kRoundToZero));
 }
 
 
 void InstructionSelector::VisitFloat64RoundTiesAway(Node* node) {
   UNREACHABLE();
 }
 
 
@@ skipping 527 matching lines @@
       MachineOperatorBuilder::kWord32Ctz | MachineOperatorBuilder::kWord64Ctz;
   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::kFloat64RoundTiesEven;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8