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[Bug tree-optimization/21458] VRP does not remove a conditional in a loop
- From: "kazu at cs dot umass dot edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 10 May 2005 05:48:02 -0000
- Subject: [Bug tree-optimization/21458] VRP does not remove a conditional in a loop
- References: <20050509010537.21458.kazu@cs.umass.edu>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From kazu at cs dot umass dot edu 2005-05-10 05:47 -------
DOM leaves PHI nodes like
# i_5 = PHI <1(0)>;
Then SCEV gives a symbolic initial value like i_5 with the step being 1.
So the information from SCEV is useless here.
With a tcb-like pass ordering (running VRP after CCP, COPY-PROP, etc
but before DOM), we don't see a degenerate PHI node like above.
Then it's just a matter of making vrp_meet slightly aggressive on
meeting two VR_RANGEs.
--
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |kazu at cs dot umass dot edu
|dot org |
Status|NEW |ASSIGNED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21458