[turbofan] Added the RoundInt64ToFloat64 instruction to TurboFan.

src/x64/macro-assembler-x64.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 845 matching lines @@
     CpuFeatureScope scope(this, AVX);
     vxorpd(dst, dst, dst);
     vcvtqsi2sd(dst, dst, src);
   } else {
     xorpd(dst, dst);
     cvtqsi2sd(dst, src);
   }
 }
 
 
+void MacroAssembler::Cvtqsi2sd(XMMRegister dst, const Operand& src) {
+  if (CpuFeatures::IsSupported(AVX)) {
+    CpuFeatureScope scope(this, AVX);
+    vxorpd(dst, dst, dst);
+    vcvtqsi2sd(dst, dst, src);
+  } else {
+    xorpd(dst, dst);
+    cvtqsi2sd(dst, src);
+  }
+}
+
+
 void MacroAssembler::Cvtsd2si(Register dst, XMMRegister src) {
   if (CpuFeatures::IsSupported(AVX)) {
     CpuFeatureScope scope(this, AVX);
     vcvtsd2si(dst, src);
   } else {
     cvtsd2si(dst, src);
   }
 }
 
 
@@ skipping 4496 matching lines @@
   movl(rax, dividend);
   shrl(rax, Immediate(31));
   addl(rdx, rax);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64