[Bug middle-end/110832] [14 Regression] 14% capacita -O2 regression between g:9fdbd7d6fa5e0a76 (2023-07-26 01:45) and g:ca912a39cccdd990 (2023-07-27 03:44) on zen3 and core

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110832

--- Comment #7 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Richard Biener from comment #6)
> Do we know whether we could in theory improve the sanitizing by optimization
> without -funsafe-math-optimizations (I think -fno-trapping-math,
> -ffinite-math-only -fno-signalling-nans should be a better guard?)?

I was looking at -funsafe-math-optimizations because the compiler links in
crtfastmath.c which sets DAZ and FTZ flags, so eventual denormals won't bother
us. -fu-m-o also enables -fno-trapping-math, which assumes masked FP
exceptions, so we can still allow V2SF infinities and NaNs. FYI, clang enables
this optimization by default, since it defaults to -fno-trapping-math. It seems
to me that they don't care about denormals.