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Re: Loop unrolling-related SPEC regressions?
- From: Jan Hubicka <jh at suse dot cz>
- To: Joe Buck <jbuck at synopsys dot COM>
- Cc: Paolo Carlini <pcarlini at unitus dot it>, gcc at gcc dot gnu dot org, rth at redhat dot com
- Date: Mon, 4 Feb 2002 19:54:06 +0100
- Subject: Re: Loop unrolling-related SPEC regressions?
- References: <3C5ADF19.6A6865D9@unitus.it> <200202011914.LAA03458@atrus.synopsys.com>
>
> > browsing the latest results from Andreas, it looks like a few of them (e.g.,
> > 164.gzip, 186.crafty, 200.sixtrack) are showing a definite regression in the
> > PEAK case, characterized by -funroll-all-loops.
>
> It's not clear to me that -funroll-all-loops is the correct setting for
> PEAK, as bloating out the code may make the cache perform worse.
We do use them in the testing runs for exactly these purposes.
It tends to show the "bugs" that causes unnecesary code growth in some
areas unnoticed by other benchmarks.
THe base/peak flags are not supposed to bring best performance,
but be good for testing majority of gcc features.
Honza