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[Bug tree-optimization/49419] [4.6/4.7 regression] gcc -O2 miscompiles gp2c
- 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, 16 Jun 2011 08:18:57 +0000
- Subject: [Bug tree-optimization/49419] [4.6/4.7 regression] gcc -O2 miscompiles gp2c
- Auto-submitted: auto-generated
- References: <bug-49419-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49419
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-06-16 08:17:46 UTC ---
The bug should be fixed now, though VRP should be cerrtainly improved in
various ways, including choosing better vr during extract_range_from_assert,
trying to derive numeric ranges from symbolic ranges x - 1 maximums or x + 1
minimums,
and IMHO adjust_range_for_scev could use number_of_latch_executions to see if
the number is simple enough and a smaller iteration count can be derived from
its value ranges or, e.g. if it is the init SSA_NAME itself or that plus/minus
a constant, it could determine it doesn't decrease until -INF but only until 0
+- constant.