X87: [turbofan] Implemented the optional Float32RoundTruncate operator.

src/compiler/x87/instruction-selector-x87.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/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
 namespace v8 {
@@ skipping 853 matching lines @@
 
 
 void InstructionSelector::VisitFloat64RoundUp(Node* node) {
   X87OperandGenerator g(this);
   Emit(kX87Float64Round | MiscField::encode(kRoundUp), g.UseFixed(node, stX_0),
        g.Use(node->InputAt(0)));
 }
 
 
 void InstructionSelector::VisitFloat32RoundTruncate(Node* node) {
-  UNREACHABLE();
+  X87OperandGenerator g(this);
+  Emit(kX87Float32Round | MiscField::encode(kRoundToZero),
+       g.UseFixed(node, stX_0), g.Use(node->InputAt(0)));
 }
 
 
 void InstructionSelector::VisitFloat64RoundTruncate(Node* node) {
   X87OperandGenerator g(this);
   Emit(kX87Float64Round | MiscField::encode(kRoundToZero),
        g.UseFixed(node, stX_0), g.Use(node->InputAt(0)));
 }
 
 
@@ skipping 427 matching lines @@
       MachineOperatorBuilder::kFloat64Min |
       MachineOperatorBuilder::kWord32ShiftIsSafe;
   if (CpuFeatures::IsSupported(POPCNT)) {
     flags |= MachineOperatorBuilder::kWord32Popcnt;
   }
 
   flags |= MachineOperatorBuilder::kFloat32RoundDown |
            MachineOperatorBuilder::kFloat64RoundDown |
            MachineOperatorBuilder::kFloat32RoundUp |
            MachineOperatorBuilder::kFloat64RoundUp |
+           MachineOperatorBuilder::kFloat32RoundTruncate |
            MachineOperatorBuilder::kFloat64RoundTruncate |
            MachineOperatorBuilder::kFloat64RoundTiesEven;
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8