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Re: [PATCH x86] Increase PARAM_MAX_COMPLETELY_PEELED_INSNS when branch is costly
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: Jan Hubicka <hubicka at ucw dot cz>
- Cc: gcc-patches at gcc dot gnu dot org, Richard Biener <richard dot guenther at gmail dot com>, Evgeny Stupachenko <evstupac at gmail dot com>, Uros Bizjak <ubizjak at gmail dot com>
- Date: Fri, 31 Oct 2014 13:14:39 +0100
- Subject: Re: [PATCH x86] Increase PARAM_MAX_COMPLETELY_PEELED_INSNS when branch is costly
- Authentication-results: sourceware.org; auth=none
- References: <CAOvf_xwBqY++PGRC_+1=rzHO18jvc+TP5mmR=PjYvGgm=63NuA at mail dot gmail dot com> <CAFiYyc1YjAYk8M8QMp=2Uo11SoQmZtcj-Eb=L-gxLyQ=6GTXmA at mail dot gmail dot com> <20141013122332 dot GA9404 at atrey dot karlin dot mff dot cuni dot cz>
> Agreed, I think the value of 100 was set decade ago by Zdenek and me
> completely artifically. I do not recall any serious tuning of this flag.
Are you talking bout PARAM_MAX_COMPLETELY_PEELED_INSNS here? If so, see:
https://gcc.gnu.org/ml/gcc-patches/2012-11/msg01193.html
We have experienced performance regressions because of this arbitrary change
and bumped it back to 200 unconditionally.
--
Eric Botcazou