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Re: [PATCH] New fdo summary-based icache sensitive unrolling (issue6351086)
- From: Markus Trippelsdorf <markus at trippelsdorf dot de>
- To: Teresa Johnson <tejohnson at google dot com>
- Cc: reply at codereview dot appspotmail dot com, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, David Li <davidxl at google dot com>, Jan Hubicka <hubicka at ucw dot cz>
- Date: Tue, 11 Dec 2012 19:03:00 +0100
- Subject: Re: [PATCH] New fdo summary-based icache sensitive unrolling (issue6351086)
- References: <20120727044750.0B77E61471@tjsboxrox.mtv.corp.google.com> <CAAe5K+XH+HJJzFTFjdV9eb0shyTB5Vk_foKEh+Pgas5LJ5PGDw@mail.gmail.com> <CAAe5K+X2T0E4z+LaQdXG+w2eXtt4K1VPDwkbor5AbvNUAP_+jQ@mail.gmail.com>
On 2012.12.11 at 09:13 -0800, Teresa Johnson wrote:
> Ping.
> Teresa
>
> On Mon, Nov 19, 2012 at 4:58 PM, Teresa Johnson <tejohnson@google.com> wrote:
> > This patch was proposed awhile back, and the new working set program
> > summary was split out and committed separately. I would like to
> > see if the loop unroller part of the patch can now go in. For the
> > previous versions of the patch and related discussion, see:
> >
> > http://gcc.gnu.org/ml/gcc-patches/2012-06/msg00437.html
> > and
> > http://gcc.gnu.org/ml/gcc-patches/2012-07/msg01373.html
> >
> > Use the new working set information in the FDO program summary for
> > codesize based unroll and peel decisions, to prevent those
> > optimizations from increasing code size too much when the
> > program may be sensitive to icache effects.
> >
> > As part of this, cache additional loop analysis results in the niter_desc
> > auxiliary information hanging off the loop structure to reduce
> > redundant analyses during unrolling.
> >
> > Bootstrapped and tested on x86_64-unknown-linux-gnu. Ok for trunk?
I guess this is the missing piece that would fix the Firefox lto/pgo
code-size issue:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45375#c144
--
Markus