[Bug tree-optimization/92704] [8/9/10 Regression] ICE: Segmentation fault (in process_bb)

[prathamesh3492 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92704

prathamesh3492 at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |prathamesh3492 at gcc dot 
gnu.org

--- Comment #1 from prathamesh3492 at gcc dot gnu.org ---
This seems, to happen because we end up with following phi defining .MEM_113 in
ifcvt dump:

  <bb 40> [local count: 3667364]:
  # q7_91 = PHI <q7_15(5), q7_108(50)>
  # zr_lsm.55_92 = PHI <iftmp.5_13(5), iftmp.5_105(50)>
  # .MEM_113 = PHI <(5), .MEM_106(50)>

.MEM_113 phi seems to have NULL (!) arg, which then causes segfault in
following hunk in tree-ssa-sccvn.c:process_bb()

          gphi *phi = gsi.phi ();
          use_operand_p use_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e);
          tree arg = USE_FROM_PTR (use_p);
          if (TREE_CODE (arg) != SSA_NAME
              || virtual_operand_p (arg))
            continue;

Passing -fno-tree-loop-ifconvert in addition to other options, doesn't cause
the segfault. I assume phi args cannot be NULL ?

Thanks,
Prathamesh