[Bug tree-optimization/48290] New: FAIL: gcc.dg/vect/pr38529.c, ICE in vect_get_vec_def_for_operand, at tree-vect-stmts.c:1072

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48290

           Summary: FAIL: gcc.dg/vect/pr38529.c, ICE in
                    vect_get_vec_def_for_operand, at
                    tree-vect-stmts.c:1072
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: rguenth@gcc.gnu.org
                CC: irar@gcc.gnu.org


The vectorizer seems to mishandle PHIs for

<bb 3>:

<bb 4>:
  # j_17 = PHI <j_5(3), 0(7)>
  # ivtmp.6_14 = PHI <ivtmp.6_15(3), 17(7)>
  j_5 = j_17 + 1;
  ivtmp.6_15 = ivtmp.6_14 - 1;
  if (ivtmp.6_15 != 0)
    goto <bb 3>;
  else
    goto <bb 5>;

<bb 5>:
  # a_I_lsm.4_2 = PHI <0.0(4)>
  a[i_16] = a_I_lsm.4_2;
  i_6 = i_16 + 1;
  ivtmp.5_12 = ivtmp.5_10 - 1;
  if (ivtmp.5_12 != 0)
    goto <bb 6>;
  else
    goto <bb 8>;

<bb 6>:

<bb 7>:
  # i_16 = PHI <0(2), i_6(6)>
  # ivtmp.5_10 = PHI <4(2), ivtmp.5_12(6)>
  goto <bb 4>;


in outer loop vectorization.  Somehow this PHI isn't processed at all.

While I will fix copyprop further to propagate the zero to its single use
I think the vectorizer shouldn't ICE on this case either.

Ira, can you have a look?

Thanks,
Richard.