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Re: What is acceptable for -ffast-math? A numerical viewpoint
- To: dewar at gnat dot com, wolfgang dot bangerth at iwr dot uni-heidelberg dot de
- Subject: Re: What is acceptable for -ffast-math? A numerical viewpoint
- From: dewar at gnat dot com
- Date: Wed, 1 Aug 2001 09:28:36 -0400 (EDT)
- Cc: gcc at gcc dot gnu dot org
<<An n% increase in speed makes n hours on a 4-day run. But then you're
right that it is probably not worth the effort to implement optimizations
that get you 1 or 2 per cent. If it's 10%, it starts getting interesting.
warning: 10% is a VERY heavy burden, very few individual optimizations
can make this much effect, so I would actually accept a much smaller
threshhold. For example, if the a/b/c transformation made a 2% imrpovement
to established programs, quake or SPEC :-) then it is on the radar as