| > You assume that modern high performance processors execute instructions. Yeah, stop making stuff up about me. > they analyze, optimize and emit their an internal instruction stream and then execute that. I know how an out-of-order, superscalar processor works. I also know that they can't do magic, because their optimizations are severely limited by time and scope constraints (although they do have access to some information that isn't available at compile time). > That extra step is what makes fiddly UB type 'optimizations' worthless. I'm not arguing for optimizations based on UB. This subthread is about compiler optimizations in general, which bokglobule claimed to be nearly always unnecessary. > Dan Bernstein says you're wrong. Do you have a study you can cite? Do you think just dropping a name will convince anyone? > Performance is everything with encryption. I never claimed it wasn't. I claimed that performance isn't the reason why cryptography kernels are rewritten in assembly, and that's because C + optimizing compiler is already fast enough and the small performance gain alone doesn't justify the switch to assembly. |