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Re: [PATCH v4] Repeat jump threading after combine
- From: Ilya Leoshkevich <iii at linux dot ibm dot com>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, Andreas Krebbel <krebbel at linux dot ibm dot com>, rdapp at linux dot ibm dot com
- Date: Mon, 26 Nov 2018 16:26:49 +0100
- Subject: Re: [PATCH v4] Repeat jump threading after combine
- References: <20181126121140.7176-1-iii@linux.ibm.com> <20181126150732.GF23873@gate.crashing.org>
> Am 26.11.2018 um 16:07 schrieb Segher Boessenkool <segher@kernel.crashing.org>:
>
>> # ppc64le-redhat-linux:
>> 511.povray_r -1.29%
>> 482.sphinx3 -0.65%
>> 456.hmmer -0.53%
>> 519.lbm_r -0.51%
>> # skip |dt| < 0.5%
>> 549.fotonik3d_r +1.13%
>> 403.gcc +1.76%
>> 500.perlbench_r +2.35%
>
> 2% degradation on gcc and perlbench isn't really acceptable. It is
> certainly possible this is an uarch effect of indirect jumps and we are
> just very unlucky now (and were lucky before), but this doesn't sound
> good to me :-/
>
> What did you run this on? p8?
That was p9 (gcc135).