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Re: Enabling -frename-registers?
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Bernd Schmidt <bschmidt at redhat dot com>,GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 29 Jan 2016 19:50:13 +0100
- Subject: Re: Enabling -frename-registers?
- Authentication-results: sourceware.org; auth=none
- References: <56AB9759 dot 407 at t-online dot de> <56ABA2BA dot 3030705 at redhat dot com>
On January 29, 2016 6:34:50 PM GMT+01:00, Bernd Schmidt <bschmidt@redhat.com> wrote:
>So PR57193 has an example of sub-optimal code generation, with some
>unnecessary register moves left after LRA. These seem to be difficult
>to
>prevent, but last year Robert Suchanek made some modifications to
>regrename that allow it to clean up such cases. Enabling
>-frename-registers removes one of the two unnecessary copies, and I'm
>pretty sure I could make it eliminate the other one as well with a bit
>more work.
>
>Hence, this patch. The renamer has seen a lot of fixes over the years
>and should be in pretty good shape IMO. Still, I won't deny that this
>is
>a bit riskier than the usual bugfix patch at this stage.
>
>Bootstrapped and tested on x86_64-linux, with my earlier patch to fix
>some i386 tests. Thoughts? Should we do this for gcc-7 at least?
I don't think it's appropriate at this stage.
Richard.
>
>Bernd