This is the mail archive of the
mailing list for the GCC project.
Re: patch: rs6000 specific
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: dalej at apple dot com
- Cc: Geoff Keating <geoffk at redhat dot com>, gcc-patches at gcc dot gnu dot org
- Date: Tue, 04 Dec 2001 22:16:16 -0500
- Subject: Re: patch: rs6000 specific
>>>>> Dale Johannesen writes:
> Let's see if we can agree on the goal here. Multiply-add generation
> is controlled by the -fno-fused-madd switch, as you said. IMO when
> multiply-add generation is on (as it is by default) we should recognize
> as many mathematically correct cases of it as possible, without concern
> for IEEE compliance, since it's not compliant anyway. I do not mean
> combine should behave this way, only the ppc-specific code. This implies
> that we can't rely on combine to make IEEE-unsafe transformations;
> this needs to be done in the ppc-specific patterns. Do you agree with
> this, and if not, what do you think the goal should be?
I guess that I do not agree with this goal. If GCC can generate
the transformations but only does them when -ffast-math is enabled, the
PowerPC backend should not duplicate those transformations.