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Re: Optimization Question
- To: ronis at onsager dot chem dot mcgill dot ca
- Subject: Re: Optimization Question
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Wed, 28 Jul 1999 12:11:04 -0600
- cc: jquinn at nortelnetworks dot com, gcc at gcc dot gnu dot org
- Reply-To: law at cygnus dot com
In message <199907281712.NAA00732@ronispc.chem.mcgill.ca>you write:
> I think Jerry has made a good point. As far as I know, -ffast-math
> (not to mention -mno-ieee-fp) can alter the results of calculations,
> albeit often in cases where the results are likely to be wrong in any
> case.
-ffast-math is allowed to alter results, particularly around boundary
conditions (ie stuff like allowing X + 0 -> X).
Allowing some reassociations with -ffast-math is (IMHO) reasonable. But we
want to be careful that we do not go overboard as that would make -ffast-math
useless.
I actually have an implementation of this in Cygnus's tree as a side effect
of implementing some integer reassociations, but I haven't had the time to
clean up the changes and submit them.
jeff