[Bug tree-optimization/32540] [4.3 Regression] Exponential time behavior in PRE

[dberlin at dberlin dot org]

------- Comment #12 from dberlin at gcc dot gnu dot org  2007-11-01 21:24 -------
Subject: Re:  [4.3 Regression] Exponential time behavior in PRE

Yes, the heuristics can sometimes generate a very large number of
copies to eliminate a single redundancy.
This is jsut the way the standard PRE heuristics work.
If you want to try to come up with a better one, you are welcome to :)


On 1 Nov 2007 21:16:45 -0000, jakub at gcc dot gnu dot org
<gcc-bugzilla@gcc.gnu.org> wrote:
>
>
> ------- Comment #11 from jakub at gcc dot gnu dot org  2007-11-01 21:16 -------
> This isn't just a compile time hog, but sometimes (see PR33922) it creates many
> times bigger and far slower code as well.
>
>
> --
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32540
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32540