[Bug tree-optimization/37242] missed FRE opportunity because of signedness of addition

[rguenther at suse dot de]

------- 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.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37242