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Re: [RFC] Cse reducing performance of register allocation with -O2
- From: Dominik Vogt <vogt at linux dot vnet dot ibm dot com>
- To: gcc at gcc dot gnu dot org
- Cc: vmakarov at redhat dot com
- Date: Thu, 22 Oct 2015 11:05:28 +0100
- Subject: Re: [RFC] Cse reducing performance of register allocation with -O2
- Authentication-results: sourceware.org; auth=none
- References: <20151013131230 dot GA30317 at linux dot vnet dot ibm dot com> <561D3A28 dot 9090407 at redhat dot com> <561D71A8 dot 5010300 at redhat dot com>
- Reply-to: vogt at linux dot vnet dot ibm dot com
On Tue, Oct 13, 2015 at 05:03:36PM -0400, Vladimir Makarov wrote:
[snip]
> I checked my article
>
> ftp://ftp.uvsq.fr/pub/gcc/summit/2004/Fighting%20Register%20Pressure.pdf
>
> and GVN gave mostly 0.2% on eon only. The current environment is
> quite different (IRA, LRA) so the results might be different too.
>
> Also as I remember I implemented GVN only for pseudos.
>
> LRA also checks values too but again only for reload and original pseudos.
Do you still have the branches you've tested back then? I'd
really like to try how this patch affects other targets (big
endian?). Gcc seems to do a better job optimising code for x86 in
some complicated situations, so the extra logic might pay off more
on other targets.
Ciao
Dominik ^_^ ^_^
--
Dominik Vogt
IBM Germany