>>81
When performance matters on that level, you should be doing straight machine-code instead of trying to tweak the compiler guesses. And obviously after a decent profiling session. No amount of keywords will ever evaluate to any sensible, objective measurement of performance gain.
That's a reason why no one uses individual '-foptimize-whatever-fuck-trees' flags and instead use '-O3' flags, without ever profiling anything. People just say they care, but they don't really care; they're satisfied in _believing_ the compiler will get things any better in terms of performance. Keywords give them an extra self-delusional power.
For what is worth, the only keyword that matters in C is 'restrict'. 'restrict' is a C99 keyword; the vast majority of the programs are still written in C89, thus not getting 'restrict' or getting them as an extension. And often getting them wrong.