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[Bug tree-optimization/32540] [4.3 Regression] Exponential time behavior in PRE
- From: "rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 20 Oct 2007 20:52:01 -0000
- Subject: [Bug tree-optimization/32540] [4.3 Regression] Exponential time behavior in PRE
- References: <bug-32540-2744@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #9 from rguenther at suse dot de 2007-10-20 20:52 -------
Subject: Re: [4.3 Regression] Exponential time
behavior in PRE
On Sat, 20 Oct 2007, dberlin at dberlin dot org wrote:
> ------- Comment #8 from dberlin at gcc dot gnu dot org 2007-10-20 20:49 -------
> Subject: Re: [4.3 Regression] Exponential time behavior in PRE
>
> We may just want to disable PPRE of constants entirely :)
If you don't initialize the variable to zero we or in all the bits then
the value will be not constant, but still 'var | constant' with 2**24
different constants...
Richard.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32540