[turbofan] Added the RoundInt64ToFloat64 instruction to TurboFan.

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 900 matching lines @@
         break;
       }
       default:
         break;
     }
   }
   Emit(kX64Movl, g.DefineAsRegister(node), g.Use(value));
 }
 
 
+void InstructionSelector::VisitRoundInt64ToFloat64(Node* node) {
+  X64OperandGenerator g(this);
+  Emit(kSSEInt64ToFloat64, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
+}
+
+
 void InstructionSelector::VisitBitcastFloat32ToInt32(Node* node) {
   X64OperandGenerator g(this);
   Emit(kX64BitcastFI, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
 }
 
 
 void InstructionSelector::VisitBitcastFloat64ToInt64(Node* node) {
   X64OperandGenerator g(this);
   Emit(kX64BitcastDL, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
 }
@@ skipping 670 matching lines @@
   if (CpuFeatures::IsSupported(SSE4_1)) {
     flags |= MachineOperatorBuilder::kFloat64RoundDown |
              MachineOperatorBuilder::kFloat64RoundTruncate;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8