Duplicating immediate predecessor of EXIT_BLOCK

[mcrosier@ncsu.edu]

> mcrosier@ncsu.edu writes:
>
>> I'm interested in duplicating the immediate predecessor basic block of
>> the
>> EXIT_BLOCK, but this makes the EXIT_BLOCK have 2 predecessors which
>> isn't
>> allowed.  Can someone give me some guidances as to how I can insert a
>> bogus block between the two to allow the duplication?
>
> Why can't EXIT_BLOCK have two predecessors?
>
> Ian
>

>From can_duplicate_block_p():
/* Duplicating fallthru block to exit would require adding a jump and
splitting the real last BB. */
e = find_edge (bb, EXIT_BLOCK_PTR);
if ( e && (e->flags & EDGE_FALLTHRU))
  return false;