[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 757 matching lines @@
   Emit(kSSEFloat32ToFloat64, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
 }
 
 
 void InstructionSelector::VisitChangeInt32ToFloat64(Node* node) {
   X64OperandGenerator g(this);
   Emit(kSSEInt32ToFloat64, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
 }
 
 
+void InstructionSelector::VisitRoundInt64ToFloat64(Node* node) {
+  X64OperandGenerator g(this);
+  Emit(kSSEInt64ToFloat64, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
+}
+
+
 void InstructionSelector::VisitChangeUint32ToFloat64(Node* node) {
   X64OperandGenerator g(this);
   Emit(kSSEUint32ToFloat64, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
 }
 
 
 void InstructionSelector::VisitChangeFloat64ToInt32(Node* node) {
   X64OperandGenerator g(this);
   Emit(kSSEFloat64ToInt32, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
 }
@@ skipping 813 matching lines @@
   if (CpuFeatures::IsSupported(SSE4_1)) {
     flags |= MachineOperatorBuilder::kFloat64RoundDown |
              MachineOperatorBuilder::kFloat64RoundTruncate;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8