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[Bug tree-optimization/37102] [4.3/4.4 Regression] out-of-SSA is broken
- From: "amacleod at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 17 Sep 2008 14:34:04 -0000
- Subject: [Bug tree-optimization/37102] [4.3/4.4 Regression] out-of-SSA is broken
- References: <bug-37102-12544@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #13 from amacleod at redhat dot com 2008-09-17 14:34 -------
I was in the middle of updating this PR and taking possesion :-)
Upon further reflection, I don't think it is acceptable for out-of-ssa to
generate incorrect code simply because an optimization wasn't run before it.
So, there are 2 basic choices. ONnis as you state, only there is an additional
bit required during the rewrite verification.
The other option is a very mini dead phi removal done at the same time as
virtual phis are eliminated. its only a few lines of code and simple removes
PHIs with no uses, and takes care of the ripple effect as well. I have a patch
for it as well, its just not completely tested yet.
I'll attach both in a minute, I just wanted you to know I was looking at it :-)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37102