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[Bug tree-optimization/84737] [8 Regression] 20% degradation in CPU2000 172.mgrid starting with r256888
- From: "marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 13 Mar 2018 14:31:39 +0000
- Subject: [Bug tree-optimization/84737] [8 Regression] 20% degradation in CPU2000 172.mgrid starting with r256888
- Auto-submitted: auto-generated
- References: <bug-84737-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84737
--- Comment #8 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Martin Jambor from comment #7)
> Do I understand it correctly that you suspect that the new IPA-CP
> clone that is created from r256888 on is harmful? In that case, you
Yes.
> want to test that by trying higher values of ipa-cp-eval-threshold,
> something like --param ipa-cp-eval-threshold 610 (i.e. bigger than
> 606). Of course, if there are other clones with evaluations between
> 500 and 610, it would affect them too.
>
> You may also want to try both fast and slow revisions with
> -fno-ipa-cp-clone as the first step, actually.
Btw. I can confirm that same clones is created on x86_64, but there's no speed
impact of the clone creation.
Is it also reproducible on ppc64{,le} ?