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Re: Serious SPEC CPU 2006 FP performance regressions on IA32
- From: "H. J. Lu" <hjl at lucon dot org>
- To: Daniel Berlin <dberlin at dberlin dot org>
- Cc: Grigory Zagorodnev <grigory_zagorodnev at linux dot intel dot com>, "Menezes, Evandro" <evandro dot menezes at amd dot com>, gcc at gcc dot gnu dot org, ubizjak at gmail dot com, Dwarak Rajagopal <dwarak dot rajagopal at txexmtae dot amd dot com>, "Meissner, Michael" <michael dot meissner at amd dot com>
- Date: Fri, 12 Jan 2007 09:32:03 -0800
- Subject: Re: Serious SPEC CPU 2006 FP performance regressions on IA32
- References: <1449F58C868D8D4E9C72945771150BDFDF537C@SAUSEXMB1.amd.com> <45A65775.70301@linux.intel.com> <4aca3dc20701111706k15e654efy7dff5d62da3692a4@mail.gmail.com>
On Thu, Jan 11, 2007 at 08:06:31PM -0500, Daniel Berlin wrote:
> On 1/11/07, Grigory Zagorodnev <grigory_zagorodnev@linux.intel.com> wrote:
> >Menezes, Evandro wrote:
> >> Though not as pronounced, definitely significant.
> >>
> >
> >Using binary search I've detected that 30% performance regression of
> >cpu2006/437.leslie3d benchmark is caused by revision 117891.
> >
> >http://gcc.gnu.org/viewcvs?view=rev&revision=117891
> >
> >I assume same commit causes regression of all other benchmarks from
> >cpu2k6 suite (running others to confirm).
>
> This only affects 4.2, and the only solution would be to try to
> backport some of the 4.3 aliasing stuff to 4.2, which i'm not sure is
> a great idea.
>
If this serious performance in gcc 4.2 isn't addressed, it may
make gcc 4.2 less attractive since it may generate much slower
executables.
H.J.