[PATCH] Update BBs in cleanup_barriers pass (PR rtl-optimization/61058)

[Jakub Jelinek]

On Tue, Jan 27, 2015 at 09:25:32AM +0100, Eric Botcazou wrote:
> > Yes, they do, that is why it crashed during final.
> 
> OK.  Why wouldn't it work to call reorder_insns instead of reorder_insns_nobb?

Because reorder_insns doesn't handle the case of moving a barrier into a
middle of basic block.

      if (!BARRIER_P (from)
          && (bb2 = BLOCK_FOR_INSN (from)))
        {
          if (BB_END (bb2) == to)
            BB_END (bb2) = prev;
          df_set_bb_dirty (bb2);
        }
    
      if (BB_END (bb) == after)
        BB_END (bb) = to;

      for (x = from; x != NEXT_INSN (to); x = NEXT_INSN (x))
        if (!BARRIER_P (x))
          df_insn_change_bb (x, bb);

from == to is a BARRIER in this case, BB_END (bb) != after (BB_END
is actually PREV_INSN (from)), so this doesn't do anything at all.

While what we need is:

1) set BB_END to after
2) clear BLOCK_FOR_INSN on the notes after AFTER (after addition of
   barrier after FROM == TO) until former PREV_INSN (FROM) (inclusive)

	Jakub