[Bug tree-optimization/31191] [4.3 Regression] 1000% Runtime regression for FreeFEM navier-stokes example

["hubicka at ucw dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #2 from hubicka at ucw dot cz  2007-03-15 22:01 -------
Subject: Re:   New: [4.3 Regression] 1000% Runtime regression for FreeFEM
navier-stokes example

> The regression was introduced between r120825 (10s runtime) and r120846 (110s
> runtime).  The obvious candidate is:
> 
> +2007-01-16  Jan Hubicka  <jh@suse.cz>
> +
> +       * cgraph.h (cgraph_decide_inlining_incrementally): Kill.
> +       * tree-pass.h: Reorder to make IPA passes appear toegher.
> +       (pass_early_inline, pass_inline_parameters, pass_apply_inline):
> Declare.+       * cgraphunit.c (cgraph_finalize_function): Do not compute
> inling
> +       parameters, do not call early inliner.

This patch enabled more inlining on many of C++ testcases with overall
win on C++ benchmark suite. I know this regression goes away with
http://gcc.gnu.org/ml/gcc-patches/2007-02/msg00318.html
(see Feb 4 results)

>From brief analysis I did some time ago, there are number of functions
in freefem hitting aliasing grouping limits that didn't hit it before
the patch in January,

I believe the way it gets solved by simple DSE is the just fact
that we never build function with so many memory references to lose
track with at first place by elliminating these references early.
This seems to be quite common on other C++ testcases too, so I hope we
will find way to do this in 4.3.

Hopefully Diego will get time to implement the AA before IPA so we can
get this without the extra pass.

Honza


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31191