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Re: RFC: Patch for gcc-5/changes.html
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Vladimir Makarov <vmakarov at redhat dot com>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 26 Mar 2015 20:54:27 +0100
- Subject: Re: RFC: Patch for gcc-5/changes.html
- Authentication-results: sourceware.org; auth=none
- References: <55145D22 dot 9050208 at redhat dot com>
> + <li>In GCC-4.9 and earlier releases PIC hard register was fixed
> + and was not used for other purposes when PIC code was
> + generated. Reuse of PIC hard register was implemented in RA
> + for GCC-5.0. It improves generated PIC code performance as
> + more hard registers can be used. As an example, shared
> + libraries and OS Android would significantly benefit from
> + such optimization. Currently it is switched on only for
> + x86/x86-64 targets. As RA infrastructure is already
> + implemented for PIC register reuse, other targets might
> + follow this in the future.</li>
PIC was always huge performance disaster on x86, I suppose with this patch in,
-fPIC benchmarks should improve quite noticeably ;)
Thanks!
Honza