------- Comment #18 from dberlin at gcc dot gnu dot org 2009-02-05 17:43
-------
Subject: Re: [4.3/4.4 Regression]
-fprofile-generate = huge SCCs for PRE
My hacking will seriously improve this, since it doesn't iterate over
pieces of the SCC that aren't changing (which often is most of it).
On large SCC's, most of the time is actually being spent revisiting
things that can't possibly have changed.
(IE out of 5000 members of the SCC, 200 could have changed but we
visit all 5000 anyway).
On Thu, Feb 5, 2009 at 4:14 AM, rguenth at gcc dot gnu dot org
<gcc-bugzi...@gcc.gnu.org> wrote:
>
>
> ------- Comment #11 from rguenth at gcc dot gnu dot org 2009-02-05 09:14
> -------
> I get
>
> tree PRE : 1.57 (50%) usr 0.09 (29%) sys 1.68 (29%) wall
> 295 kB ( 3%) ggc
>
> on current trunk (w/o checking). While 50% is quite high the absolute time
> is low. Though I wonder why FRE is so much better.
>
> tree FRE : 0.03 ( 1%) usr 0.01 ( 3%) sys 0.05 ( 1%) wall
> 85 kB ( 1%) ggc
>
>
> Danny, does your recent hacking around SCCVN improve this testcase?
>
>
> --
>
> rguenth at gcc dot gnu dot org changed:
>
> What |Removed |Added
> ----------------------------------------------------------------------------
> CC| |dberlin at gcc dot gnu dot
> | |org
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35639
>
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35639
