Make X64 double-to-int32 conversion use the 64-bit version of cvttsd2si.

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 1074 matching lines @@
   void movq(XMMRegister dst, Register src);
   void movq(Register dst, XMMRegister src);
   void extractps(Register dst, XMMRegister src, byte imm8);
 
   void movsd(const Operand& dst, XMMRegister src);
   void movsd(XMMRegister dst, XMMRegister src);
   void movsd(XMMRegister dst, const Operand& src);
 
   void cvttss2si(Register dst, const Operand& src);
   void cvttsd2si(Register dst, const Operand& src);
+  void cvttsd2siq(Register dst, XMMRegister src);
 
   void cvtlsi2sd(XMMRegister dst, const Operand& src);
   void cvtlsi2sd(XMMRegister dst, Register src);
   void cvtqsi2sd(XMMRegister dst, const Operand& src);
   void cvtqsi2sd(XMMRegister dst, Register src);
 
   void cvtss2sd(XMMRegister dst, XMMRegister src);
 
   void addsd(XMMRegister dst, XMMRegister src);
   void subsd(XMMRegister dst, XMMRegister src);
@@ skipping 288 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_H_