Change the register allocator so that it no longer tracks references...

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 43 matching lines @@
 // order.
 //
 // 3) By not using an enum, we are possibly preventing the compiler from
 // doing certain constant folds, which may significantly reduce the
 // code generated for some assembly instructions (because they boil down
 // to a few constants). If this is a problem, we could change the code
 // such that we use an enum in optimized mode, and the struct in debug
 // mode. This way we get the compile-time error checking in debug mode
 // and best performance in optimized code.
 //
-const int kNumRegisters = 16;
 
 struct Register {
-  bool is_valid() const  { return 0 <= code_ && code_ < kNumRegisters; }
+  bool is_valid() const  { return 0 <= code_ && code_ < 16; }
   bool is(Register reg) const  { return code_ == reg.code_; }
   // The byte-register distinction of ai32 has dissapeared.
   bool is_byte_register() const  { return false; }
   int code() const  {
     ASSERT(is_valid());
     return code_;
   }
   int bit() const  {
     UNIMPLEMENTED();
     return 0;
@@ skipping 831 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_H_