[turbofan] Implemented the optional Float32RoundDown operator.

src/compiler/arm/instruction-selector-arm.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 "src/base/adapters.h"
 #include "src/base/bits.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 1097 matching lines @@
 void InstructionSelector::VisitFloat32Sqrt(Node* node) {
   VisitRR(this, kArmVsqrtF32, node);
 }
 
 
 void InstructionSelector::VisitFloat64Sqrt(Node* node) {
   VisitRR(this, kArmVsqrtF64, node);
 }
 
 
+void InstructionSelector::VisitFloat32RoundDown(Node* node) {
+  VisitRR(this, kArmVrintmF32, node);
+}
+
+
 void InstructionSelector::VisitFloat64RoundDown(Node* node) {
   VisitRR(this, kArmVrintmF64, node);
 }
 
 
 void InstructionSelector::VisitFloat64RoundUp(Node* node) {
   VisitRR(this, kArmVrintpF64, node);
 }
 
 
@@ skipping 434 matching lines @@
 MachineOperatorBuilder::Flags
 InstructionSelector::SupportedMachineOperatorFlags() {
   MachineOperatorBuilder::Flags flags =
       MachineOperatorBuilder::kInt32DivIsSafe |
       MachineOperatorBuilder::kUint32DivIsSafe;
   if (CpuFeatures::IsSupported(ARMv8)) {
     flags |= MachineOperatorBuilder::kFloat64RoundDown |
              MachineOperatorBuilder::kFloat64RoundUp |
              MachineOperatorBuilder::kFloat64RoundTruncate |
              MachineOperatorBuilder::kFloat64RoundTiesAway |
-             MachineOperatorBuilder::kFloat64RoundTiesEven;
+             MachineOperatorBuilder::kFloat64RoundTiesEven |
+             MachineOperatorBuilder::kFloat32RoundDown;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8