https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109154
--- Comment #17 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to rguent...@suse.de from comment #15) > I think flushing denormals makes sense for "forward" propagation, Well, it still hurts quite a lot exactly for the ranges around zero. Given that most CPU honor it most of the time, I think asking users to use -funsafe-math-optimizations/-ffast-math/-Ofast if they instruct the CPU not to do that is fine (different situation is Alpha where it is the default behavior). > Given -ffast-math on x86 enables FTZ we'd have to be conservative there > as well. But OTOH we don't have any HONOR_DENORMALS or so? We don't but that is roughly what my patch adds... > Note the testcase in this PR was about -Ofast ... Indeed, for ranges from comparisons we could ignore the flush_denormals_to_zero calls always; guess we'd need to add some defaulted new flag to set, pass true to it from the comparisons and don't call it if the flag is set. In addition or instead of the above patch. Aldy?
