more robust purge_dead_edges

[Jan Hubicka]

Hi,
to make split_all_insns working, purge_dead_edges must handle conditional jumps
(I explicitly allow in the documentation) and (conditional) returns.

Bootstreapped/regtested i686

St čec 25 00:40:19 CEST 2001  Jan Hubicka  <jh@suse.cz>
	* flow.c (purge_dead_edges): Handle conditional jumps and conditional returns
	too.

*** flow.c.old	Tue Jul 24 17:13:33 2001
--- flow.c	Wed Jul 25 00:37:12 2001
*************** purge_dead_edges (bb)
*** 9783,9803 ****
      return;
    if (GET_CODE (insn) == JUMP_INSN)
      {
        for (e = bb->succ; e; e = next)
  	{
  	  next = e->succ_next;
! 	  if (e->dest == EXIT_BLOCK_PTR || e->dest->head != JUMP_LABEL (insn))
! 	    remove_edge (e);
  	}
!       if (bb->succ && bb->succ->succ_next)
! 	abort ();
!       if (!bb->succ)
  	return;
-       bb->succ->probability = REG_BR_PROB_BASE;
-       bb->succ->count = bb->count;
- 
        if (rtl_dump_file)
  	fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index);
        return;
      }
    /* If we don't see a jump insn, we don't know exactly why the block would
--- 9802,9857 ----
      return;
    if (GET_CODE (insn) == JUMP_INSN)
      {
+       int removed = 0;
+       rtx note;
+       edge b,f;
+       /* We do care only about conditional jumps and simplejumps.  */
+       if (!any_condjump_p (insn)
+ 	  && !simplejump_p (insn))
+ 	return;
        for (e = bb->succ; e; e = next)
  	{
  	  next = e->succ_next;
! 
! 	  /* Check purposes we can have edge.  */
! 	  if ((e->flags & EDGE_FALLTHRU)
! 	      && any_condjump_p (insn))
! 	    continue;
! 	  if (e->dest != EXIT_BLOCK_PTR
! 	      && e->dest->head == JUMP_LABEL (insn))
! 	    continue;
! 	  if (e->dest == EXIT_BLOCK_PTR
! 	      && returnjump_p (insn))
! 	    continue;
! 	  removed = 1;
! 	  remove_edge (e);
  	}
!       if (!bb->succ || !removed)
  	return;
        if (rtl_dump_file)
  	fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index);
+       if (!optimize)
+ 	return;
+ 
+       /* Redistribute probabilities.  */
+       if (!bb->succ->succ_next)
+ 	{
+ 	  bb->succ->probability = REG_BR_PROB_BASE;
+ 	  bb->succ->count = bb->count;
+         }
+       else
+ 	{
+ 	  note = find_reg_note (insn, REG_BR_PROB, NULL);
+ 	  /* We should have prediction on each conditional jump.  */
+ 	  if (!note)
+ 	    abort ();
+ 	  b = BRANCH_EDGE (bb);
+ 	  f = FALLTHRU_EDGE (bb);
+ 	  b->probability = INTVAL (XEXP (note, 0));
+ 	  f->probability = REG_BR_PROB_BASE - b->probability;
+ 	  b->count = bb->count * b->probability / REG_BR_PROB_BASE;
+ 	  f->count = bb->count * f->probability / REG_BR_PROB_BASE;
+ 	}
        return;
      }
    /* If we don't see a jump insn, we don't know exactly why the block would