[ranman]

are you sure the compiler is smart enough to do that? I think we frequently assume compilers are smarter than they really are because we don't fully understand them anymore... but in practice I find they often do very dumb things.

[lmm]

No, but I am sure that my automated performance testing procedures will detect if I've introduced a significant performance problem, and it would be an inefficient use of my time to worry about insignificant performance effects.

[Dylan16807]

Register renaming is one of the most very basic levels of optimization. I challenge you to find me a single optimizing compiler that slows down when you give names to temporary results. Hell, I can show you non-optimizing compilers that suffer no slowdown from code like this.