On Mon, Jan 26, 2009 at 12:06:49PM +0100, Dominik 'Rathann' Mierzejewski wrote: > I don't know about non-x86 arches (it's probably less of a problem), but > for x86 such change can (as you probably know) affect the overall speed > of the generated code and must be benchmarked. I would be in favour of > changing the default cflags to include -march=i586 if it gives measurable > benefits, i.e. faster binaries and/or smaller code size, but slower binaries > are not acceptable. Performance on i?86 is mostly the matter of -mtune, which should stay the same (-mtune=generic, tuning for contemporary Intel and AMD CPUs). The difference between -march=i386 -mtune=generic and -march=i486 -mtune=generic is just that xadd[bwl], bswap and cmpxchg[bwl] insns can be generated for the latter, for -march=i586 -mtune=generic also cmpxchg8b insn. Except for bswap, that's mainly for __sync_* builtins, OpenMP #pragma omp atomic, and other users of atomic insns. Jakub -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
