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Re: Performance of Integer Multiplication on PIII (Results forgcc-2.95 & Athlon)
- To: Jan Hubicka <jh at suse dot cz>
- Subject: Re: Performance of Integer Multiplication on PIII (Results forgcc-2.95 & Athlon)
- From: pete at ltoi dot iap dot physik dot tu-darmstadt dot de
- Date: Mon, 5 Nov 2001 17:35:58 +0200 (MEST)
- Cc: Kevin Atkinson <kevin at atkinson dot dhs dot org>, Tim Prince <tprince at computer dot org>, <gcc at gcc dot gnu dot org>
Hi,
> Note that with -march=i686 new gcc often perofrms worse on Athlon, but it is
> mainly because it do more Athlon specific stuff.
well, actually i compare gcc-3.0.x with gcc-2.95.x (doesn't matter much
which, since both scheduler are switched off for i686) for my floating-point
heavy stuff. And gcc-3.0.x performs worse compared with gcc-2.95.x (with
-march=i686) regardles of -march=athlon or -march=i686. Other "oddities"
may render any improvements of this flag to nearly invisibility ...
How did you check your -march=athlon improvements? Integer blended
C-code only, or fp-blended code too &, that matters, which source?
Since i found indeed some fp code, for which gcc-3.0.x performs better
then gcc-2.95.x ... but it's more the exeception, than the regula.
{Had to peek at home for examples}
Peter