This is the mail archive of the
mailing list for the GCC project.
Re: CFG problems on alpha
> On Thu, Oct 25, 2001 at 03:26:38PM +0200, Jan Hubicka wrote:
> > I've just checked that and it don't appear to be the case, as
> > try_optimize_cfg always cleansup and find_unrechable_blocks don't
> > use aux.
> It is the case. It's a typo. You set a bit on an edge
> instead of a block, and those don't get cleaned up.
> *** cfgcleanup.c 2001/10/23 13:34:23 1.10
> --- cfgcleanup.c 2001/10/26 07:11:53
> *************** merge_blocks (e, b, c, mode)
> *** 490,496 ****
> if (b_fallthru_edge->src == ENTRY_BLOCK_PTR)
> return false;
> - BB_SET_FLAG (b_fallthru_edge, BB_UPDATE_LIFE);
> notice_new_block (force_nonfallthru (b_fallthru_edge));
> merge_blocks_move_predecessor_nojumps (b, c);
> However, I can't figure out why this is here. You've just insertted
> a branch in a new block, and notice_new_block takes care of updating
> the new block. So what's this?
Uhm, I now remember what I was shooting for - what I need to handle is
the case that force_nonfallthru will insert the jump at the end of
basic block, instead of creating new.
The b_fallthru_edge has been supposed to be b_fallthru_edge->src of course :(
> ! BB_SET_FLAG (b_fallthru_edge->src, BB_UPDATE_LIFE);
I've found another latent bug in merge_blocks_nomove - it does not update
the global_live_at_end flag of basic block. The attached patch should solve
it, I am just bootstrapping it. OK if it passes?
Sat Oct 27 00:14:41 CEST 2001 Jan Hubicka <firstname.lastname@example.org>
* cfgrtl.c (merge_blocks_nomove): Update life info properly.
RCS file: /cvs/gcc/egcs/gcc/cfgrtl.c,v
retrieving revision 1.4
diff -c -3 -p -r1.4 cfgrtl.c
*** cfgrtl.c 2001/10/11 03:15:24 1.4
--- cfgrtl.c 2001/10/26 22:14:27
*************** merge_blocks_nomove (a, b)
*** 603,608 ****
--- 603,609 ----
/* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
b->pred = b->succ = NULL;
+ a->global_live_at_end = b->global_live_at_end;