[Bug c/12650] New: [tree-ssa] ICE in tree-flow-inline.h with "-O -fssa" but not with "-O"

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

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12650

           Summary: [tree-ssa] ICE in tree-flow-inline.h with "-O -fssa" but
                    not with "-O"
           Product: gcc
           Version: tree-ssa
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: steven at gcc dot gnu dot org
                CC: dnovillo at redhat dot com,gcc-bugs at gcc dot gnu dot
                    org

The following:

void
foo (void)
{
  goto loop_entry;
loop_start:
loop_entry:
  goto loop_start;
loop_exit:
}

compiles with just "-O" but segfaults with "-O -fssa"

Normally I wouldn't give a s... about -fssa, but:
a) this test case was deduced from gcc.dg/20020304-1.c which
   also ICEs on the tree-ssa branch on a sanity check after
   -fssa-ccp.  This new ICE might be related, perhaps we just
   compute broken dominance information for RTL???
b) this ICE happens in tree-flow-inline.h according to gdb:

Program received signal SIGSEGV, Segmentation fault.
compute_dominance_frontiers_1 (frontiers=0x8627520, idom=0x8627610, bb=0,
    done=0x86275f8) at tree-flow-inline.h:270
270     tree-flow-inline.h: No such file or directory.
        in tree-flow-inline.h

    Weird to have a tree-ssa failure with RTL SSA, but in tree-ssa code!