[Turbofan] Allow compiler to elide complex aliasing code.

src/x87/assembler-x87.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 130 matching lines @@
   // Unfortunately we can't make this private in a struct.
   int reg_code;
 };
 
 
 #define DECLARE_REGISTER(R) const Register R = {Register::kCode_##R};
 GENERAL_REGISTERS(DECLARE_REGISTER)
 #undef DECLARE_REGISTER
 const Register no_reg = {Register::kCode_no_reg};
 
+static const bool kSimpleFPAliasing = true;
+
 struct X87Register {
   enum Code {
 #define REGISTER_CODE(R) kCode_##R,
     DOUBLE_REGISTERS(REGISTER_CODE)
 #undef REGISTER_CODE
         kAfterLast,
     kCode_no_reg = -1
   };
 
   static const int kMaxNumRegisters = Code::kAfterLast;
@@ skipping 953 matching lines @@
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_X87_ASSEMBLER_X87_H_