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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/46590] [4.6/4.7/4.8 Regression] long compile time with -O2 and many loops
Date: Thu, 23 Aug 2012 07:14:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46590

--- Comment #30 from rguenther at suse dot de <rguenther at suse dot de> 2012-08-23 07:13:13 UTC ---
On Wed, 22 Aug 2012, stevenb.gcc at gmail dot com wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46590
> 
> --- Comment #29 from stevenb.gcc at gmail dot com <stevenb.gcc at gmail dot com> 2012-08-22 17:33:00 UTC ---
> > I thought that loop header copying wouldn't need to insert new PHI nodes
> > and thus can do with TODO_update_ssa_no_phi if we are in loop-closed SSA form,
> > but appearantly that is not the case (I didn't inverstigate further here,
> > but possibly that's just because virtual operands are not in loop-closed
> > SSA form).
> 
> I'll experiment with VOPs in LC-SSA.

You might have seen the patch I posted - it passed testing and I will
install it today.