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[Bug tree-optimization/42646] Jump threading breaks canonical loop forms
- From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 8 Jan 2010 11:52:55 -0000
- Subject: [Bug tree-optimization/42646] Jump threading breaks canonical loop forms
- References: <bug-42646-15392@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #4 from rguenth at gcc dot gnu dot org 2010-01-08 11:52 -------
It just means that we shouldn't thread to the header but always to the latch
block. Note that this restriction should probably be restricted to the
threading before loop optimizations. Or the 1st jump threading should simply
avoid to thread over backedges (equivalent to removing the 1st DOM pass -
though
there is interesting fallout regarding jump-threading / loop header copying
pass ordering).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42646