From: Jeff Law <law@redhat.com>
To: Tom de Vries <vries@codesourcery.com>
Cc: Richard Guenther <richard.guenther@gmail.com>,
Steven Bosscher <stevenb.gcc@gmail.com>,
gcc-patches@gcc.gnu.org
Subject: Re: [PATCH, PR43864] Gimple level duplicate block cleanup.
Date: Fri, 10 Jun 2011 18:43:00 -0000 [thread overview]
Message-ID: <4DF264EC.7090305@redhat.com> (raw)
In-Reply-To: <4DEF4408.4040001@codesourcery.com>
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On 06/08/11 03:42, Tom de Vries wrote:
> Hi Richard,
>
> I have a patch for PR43864. The patch adds a gimple level duplicate block
> cleanup. The patch has been bootstrapped and reg-tested on x86_64, and
> reg-tested on ARM. The size impact on ARM for spec2000 is shown in the following
> table (%, lower is better).
>
> none pic
> thumb1 thumb2 thumb1 thumb2
> spec2000 99.9 99.9 99.8 99.8
>
> PR43864 is currently marked as a duplicate of PR20070, but I'm not sure that the
> optimizations proposed in PR20070 would fix this PR.
>
> The problem in this PR is that when compiling with -O2, the example below should
> only have one call to free. The original problem is formulated in terms of -Os,
> but currently we generate one call to free with -Os, although still not the
> smallest code possible. I'll show here the -O2 case, since that's similar to the
> original PR.
[ ... ]
FWIW, I've seen at least one paper which claims that extending value
numbering redundancy elimination to handle blocks is effective at
eliminating duplicates. Redundancy elimination for blocks turns into
CFG manipulations.
We want to do this early in the pipeline so that register numbering
doesn't get in the way.
I'm going to let you and Richi iterate, but wanted to chime in with my
general support for detecting and eliminating blocks early in the
pipeline (gimple).
jeff
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prev parent reply other threads:[~2011-06-10 18:40 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-08 9:49 Tom de Vries
2011-06-08 9:55 ` [PATCH, PR43864] Gimple level duplicate block cleanup - test cases Tom de Vries
2011-07-18 2:54 ` Tom de Vries
2011-08-19 18:38 ` Tom de Vries
2011-08-25 10:09 ` Richard Guenther
2011-06-08 10:09 ` [PATCH, PR43864] Gimple level duplicate block cleanup Richard Guenther
2011-06-08 10:40 ` Steven Bosscher
2011-06-10 17:16 ` Tom de Vries
2011-06-14 15:12 ` Richard Guenther
2011-07-12 12:21 ` Tom de Vries
2011-07-12 14:37 ` Richard Guenther
2011-07-18 0:41 ` Tom de Vries
2011-07-22 15:54 ` Richard Guenther
2011-08-19 18:33 ` Tom de Vries
2011-08-24 9:00 ` Tom de Vries
2011-08-25 1:07 ` Ian Lance Taylor
2011-08-25 9:30 ` Richard Guenther
2011-06-10 18:43 ` Jeff Law [this message]
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