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[Bug tree-optimization/64853] [5 Regression] wrong code at -Os and above on x86_64-linux-gnu
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 29 Jan 2015 09:18:20 +0000
- Subject: [Bug tree-optimization/64853] [5 Regression] wrong code at -Os and above on x86_64-linux-gnu
- Auto-submitted: auto-generated
- References: <bug-64853-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64853
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I think the problem is that:
Visiting statement:
_15 = _56 & 1;
Applying pattern match.pd:312, gimple-match.c:13772
Applying pattern match.pd:235, gimple-match.c:13525
Match-and-simplified _56 & 1 to 0
Intersecting
[0, 0]
and
[0, 1]
to
[0, 0]
Found new range for _15: [0, 0]
might be reasonable during iteration, when not yet considering the backedge as
executable, but we actually never visit this statement again, perhaps due to
match-and-simplify looking at earlier statements. Richard, can you please have
a look?