[turbofan] Added the RoundInt64ToFloat64 instruction to TurboFan.

src/x64/assembler-x64.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 1345 matching lines @@
     XMMRegister isrc2 = {src2.code()};
     vsd(0x2a, dst, src1, isrc2, kF2, k0F, kW0);
   }
   void vcvtlsi2sd(XMMRegister dst, XMMRegister src1, const Operand& src2) {
     vsd(0x2a, dst, src1, src2, kF2, k0F, kW0);
   }
   void vcvtqsi2sd(XMMRegister dst, XMMRegister src1, Register src2) {
     XMMRegister isrc2 = {src2.code()};
     vsd(0x2a, dst, src1, isrc2, kF2, k0F, kW1);
   }
+  void vcvtqsi2sd(XMMRegister dst, XMMRegister src1, const Operand& src2) {

[titzer, 2015/11/02 19:14:01]

Do you need to add disassembler support for this?

[ahaas, 2015/11/03 09:28:18]

Disassembler support already exists for this one.

+    vsd(0x2a, dst, src1, src2, kF2, k0F, kW1);
+  }
   void vcvttsd2si(Register dst, XMMRegister src) {
     XMMRegister idst = {dst.code()};
     vsd(0x2c, idst, xmm0, src, kF2, k0F, kW0);
   }
   void vcvttsd2si(Register dst, const Operand& src) {
     XMMRegister idst = {dst.code()};
     vsd(0x2c, idst, xmm0, src, kF2, k0F, kW0);
   }
   void vcvttsd2siq(Register dst, XMMRegister src) {
     XMMRegister idst = {dst.code()};
@@ skipping 782 matching lines @@
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_X64_ASSEMBLER_X64_H_