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Re: [PATCH PR79663]Only reversely combine refs for ZERO length chains in predcom
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Bin Cheng <Bin dot Cheng at arm dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, nd <nd at arm dot com>
- Date: Thu, 23 Feb 2017 16:02:59 +0100
- Subject: Re: [PATCH PR79663]Only reversely combine refs for ZERO length chains in predcom
- Authentication-results: sourceware.org; auth=none
- References: <VI1PR0802MB21767BE3572DFBC65CC99BBFE7530@VI1PR0802MB2176.eurprd08.prod.outlook.com>
On Thu, Feb 23, 2017 at 12:24 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
> Hi,
> This patch resolves spec2k/mgrid regression as reported by PR79663. Root cause has been
> described thoroughly in comment #1/#2 of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79663
> This patch handles ZERO/non-ZERO length chains differently and only reversely combines refs
> for ZERO length chains. It also does small improvement with in place list swap.
> Bootstrap and test on x86_64 and AArch64, is it OK?
Ok.
Thanks,
Richard.
> Thanks,
> bin
>
> 2017-01-21 Bin Cheng <bin.cheng@arm.com>
>
> PR tree-optimization/79663
> * tree-predcom.c (combine_chains): Process refs in reverse order
> only for ZERO length chains, and add explaining comment.