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[Bug tree-optimization/37242] missed FRE opportunity because of signedness of addition
- From: "rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 28 Aug 2008 08:45:46 -0000
- Subject: [Bug tree-optimization/37242] missed FRE opportunity because of signedness of addition
- References: <bug-37242-7849@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #16 from rguenther at suse dot de 2008-08-28 08:45 -------
Subject: Re: missed FRE opportunity because of
signedness of addition
On Thu, 28 Aug 2008, bonzini at gnu dot org wrote:
> ------- Comment #15 from bonzini at gnu dot org 2008-08-28 08:42 -------
> I think that PRE does not try to simplify expressions that it inserts.
Correct. PRE does minimal expression simplification during PHI
translation, but that's it. Note that gimple expressions itself
never simplify apart from constant folding, the simplify_*_expression
routines in SCCVN instead combine multiple expressions.
Is the optimization the second PRE run does a full redundancy removal
or a new partial redundancy?
Richard.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37242