Port code to load an integer directly from a heap number from ia32 to x64....

src/x64/assembler-x64.cc

 // Copyright 2009 the V8 project authors. 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2095 matching lines @@
 void Assembler::fisttp_s(const Operand& adr) {
   ASSERT(CpuFeatures::IsEnabled(SSE3));
   EnsureSpace ensure_space(this);
   last_pc_ = pc_;
   emit_optional_rex_32(adr);
   emit(0xDB);
   emit_operand(1, adr);
 }
 
 
+void Assembler::fisttp_d(const Operand& adr) {
+  ASSERT(CpuFeatures::IsEnabled(SSE3));
+  EnsureSpace ensure_space(this);
+  last_pc_ = pc_;
+  emit_optional_rex_32(adr);
+  emit(0xDD);
+  emit_operand(1, adr);
+}
+
+
 void Assembler::fist_s(const Operand& adr) {
   EnsureSpace ensure_space(this);
   last_pc_ = pc_;
   emit_optional_rex_32(adr);
   emit(0xDB);
   emit_operand(2, adr);
 }
 
 
 void Assembler::fistp_d(const Operand& adr) {
@@ skipping 452 matching lines @@
     written_position_ = current_position_;
   }
 }
 
 
 const int RelocInfo::kApplyMask = RelocInfo::kCodeTargetMask |
                                   1 << RelocInfo::INTERNAL_REFERENCE |
                                   1 << RelocInfo::JS_RETURN;
 
 } }  // namespace v8::internal