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# [RFC] Use simpler math functions when user selects -ffast-math

*From*: OndÅej BÃlka <neleai at seznam dot cz>
*To*: andrew dot n dot senkevich at gmail dot com
*Cc*: libc-alpha at sourceware dot org
*Date*: Wed, 12 Aug 2015 00:30:07 +0200
*Subject*: [RFC] Use simpler math functions when user selects -ffast-math
*Authentication-results*: sourceware.org; auth=none

Hi Andrew,
When I checked isfinite performance I noticed that for most math
functions wrapper is unnecessary when -ffinite-math-only is set from
-ffast-math as they evaluate to constant.
So if you are still interested at improving math library you could in
similar way as vector math add calls to say fast_sin, fast_cos... I don't
know how to make vectorizer also recognize these so I ask you.
Adding new symbols would allow to fix bug that due accuracy math
functions need to be very slow on some inputs. As with -ffast-math you
don't have to worry much about accuracy we could finally fix these bugs.
So what do you say?