fix bugs in flow jump pass

[Jan Hubicka <jh at suse dot cz>]

Hi
Fixes for few problems I've found in my code while experimenting with
it futher.  The forwarder_block_p didn't work for fallthru blocks,
as CODE_LABEL is not active insn. I've also changed it to return true
even for blocks falling trought to exit, so I've needed to adjust
few other places.

Also there has been some problems when updating basic block frequencies
and such.

Bootstrapped/regtested i586
Honza

Fri Jun 29 14:38:10 CEST 2001  Jan Hubicka  <jh@suse.cz>
	* flow.c (forwarder_block_p): Fix for fallthru blocks.
	(try_redirect_by_replacing_jump): Update properly the count
	and frequency information.

Index: flow.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/flow.c,v
retrieving revision 1.410
diff -c -3 -p -r1.410 flow.c
*** flow.c	2001/06/29 03:30:17	1.410
--- flow.c	2001/06/29 12:40:09
*************** static bool
*** 1597,1614 ****
  forwarder_block_p (bb)
       basic_block bb;
  {
!   rtx insn;
    if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
        || !bb->succ || bb->succ->succ_next)
      return false;
  
!   insn = next_active_insn (bb->head);
!   if (!insn)
!     return false;
!   if (GET_CODE (insn) == CODE_LABEL
!       || (GET_CODE (insn) == JUMP_INSN && onlyjump_p (insn)))
!     return true;
!   return false;
  }
  
  /* Return nonzero if we can reach target from src by falling trought.  */
--- 1600,1618 ----
  forwarder_block_p (bb)
       basic_block bb;
  {
!   rtx insn = bb->head;
    if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
        || !bb->succ || bb->succ->succ_next)
      return false;
  
!   while (insn != bb->end)
!     {
!       if (active_insn_p (insn))
! 	return false;
!       insn = NEXT_INSN (insn);
!     }
!   return (!active_insn_p (insn)
! 	  || (GET_CODE (insn) == JUMP_INSN && onlyjump_p (insn)));
  }
  
  /* Return nonzero if we can reach target from src by falling trought.  */
*************** try_redirect_by_replacing_jump (e, targe
*** 1699,1704 ****
--- 1705,1712 ----
      e->flags = EDGE_FALLTHRU;
    else
      e->flags = 0;
+   e->probability = REG_BR_PROB_BASE;
+   e->count = src->count;
  
    /* Fixup barriers.  */
    barrier = next_nonnote_insn (insn);
*************** redirect_edge_and_branch (e, target)
*** 1766,1772 ****
        for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
  	if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
  	  {
! 	    RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (VOIDmode, new_label);
  	    --LABEL_NUSES (old_label);
  	    ++LABEL_NUSES (new_label);
  	  }
--- 1788,1794 ----
        for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
  	if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
  	  {
! 	    RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
  	    --LABEL_NUSES (old_label);
  	    ++LABEL_NUSES (new_label);
  	  }
*************** redirect_edge_and_branch (e, target)
*** 1815,1820 ****
--- 1837,1844 ----
        if (s)
  	{
  	  s->flags |= e->flags;
+ 	  s->probability += e->probability;
+ 	  s->count += e->count;
  	  remove_edge (e);
  	}
        else
*************** try_simplify_condjump (src)
*** 2888,2894 ****
    redirect_edge_succ (fallthru, next_block->succ->dest);
  
    branch->flags |= EDGE_FALLTHRU;
!   fallthru->flags &= EDGE_FALLTHRU;
    
    flow_delete_block (next_block);
    return true;
--- 2923,2929 ----
    redirect_edge_succ (fallthru, next_block->succ->dest);
  
    branch->flags |= EDGE_FALLTHRU;
!   fallthru->flags &= ~EDGE_FALLTHRU;
    
    flow_delete_block (next_block);
    return true;