[Bug tree-optimization/50767] [4.7 Regression] ICE: in refs_may_alias_p_1, at tree-ssa-alias.c:1004 with -O2 -fno-tree-copy-prop -fno-tree-dominator-opts

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50767

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011-10-18
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
   Target Milestone|---                         |4.7.0
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-10-18 
09:39:16 UTC ---
Confirmed.  For

# VUSE <.MEM_4(D)>
ss.1_8 = 0B;

we ask

648                       if (gimple_vuse (def_stmt)
649                           && gimple_assign_single_p (def_stmt)
650                           && refs_may_alias_p (gimple_assign_lhs (stmt),
651                                                gimple_assign_rhs1
(def_stmt)))

but the stmt should not have a VUSE, calling update_stmt on it removes the
VUSE.  Probably caused by the patch for PR50389, related to PR50768.  Mine.