Fix SmiCompare on 64 bit to distinguish between comparisons where...

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
===================================================================
--- src/x64/assembler-x64.h	(revision 7153)
+++ src/x64/assembler-x64.h	(working copy)
@@ -656,11 +656,12 @@
 
   // Move sign extended immediate to memory location.
   void movq(const Operand& dst, Immediate value);
-  // New x64 instructions to load a 64-bit immediate into a register.
+  // Instructions to load a 64-bit immediate into a register.
   // All 64-bit immediates must have a relocation mode.
   void movq(Register dst, void* ptr, RelocInfo::Mode rmode);
   void movq(Register dst, int64_t value, RelocInfo::Mode rmode);
   void movq(Register dst, const char* s, RelocInfo::Mode rmode);
+  void movq(Register dst, Smi* smi);
   // Moves the address of the external reference into the register.
   void movq(Register dst, ExternalReference ext);
   void movq(Register dst, Handle<Object> handle, RelocInfo::Mode rmode);
@@ -681,7 +682,7 @@
   void repmovsl();
   void repmovsq();
 
-  // New x64 instruction to load from an immediate 64-bit pointer into RAX.
+  // Instruction to load from an immediate 64-bit pointer into RAX.
   void load_rax(void* ptr, RelocInfo::Mode rmode);
   void load_rax(ExternalReference ext);