[Bug tree-optimization/46036] New: [4.6 Regression] verify_ssa failed: definition in block 3 follows the use

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46036

           Summary: [4.6 Regression] verify_ssa failed: definition in
                    block 3 follows the use
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: rguenth@gcc.gnu.org


function no_of_edges(self) result(res)
      integer(kind=kind(1)) :: edge_bit_string
      integer(kind=kind(1)) :: res
      integer(kind=kind(1)) :: e
      do e = 0, 11
        if (.not. btest(edge_bit_string,e)) cycle
        res = res + 1
      end do
   end function

> ./f951 -quiet -O -ftree-vectorize -flto t.f90 
t.f90: In function 'no_of_edges_':
t.f90:1:0: error: definition in block 3 follows the use
for SSA_NAME: D.1536_19 in statement:
res_3 = [cond_expr] D.1536_19 ? res_12 : res_2;
t.f90:1:0: internal compiler error: verify_ssa failed
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

for some reason needs -flto to trigger.  if-conversion produces:

<bb 3>:
  # e_1 = PHI <0(2), e_14(4)>
  # res_2 = PHI <res_6(D)(2), res_3(4)>
  # ivtmp.2_17 = PHI <12(2), ivtmp.2_18(4)>
  D.1524_8 = edge_bit_string_7(D) >> e_1;
  D.1525_9 = D.1524_8 & 1;
  D.1526_10 = (logical(kind=4)) D.1525_9;
  res_12 = res_2 + 1;
  res_3 = [cond_expr] D.1536_19 ? res_12 : res_2;
  e_14 = e_1 + 1;
  ivtmp.2_18 = ivtmp.2_17 - 1;
  D.1536_19 = (<unnamed type>) D.1526_10;
  D.1537_20 = !D.1536_19;
  D.1538_21 = D.1536_19 || D.1537_20;
  if (ivtmp.2_18 == 0)
    goto <bb 5>;
  else
    goto <bb 4>;