------- Comment #26 from rguenth at gcc dot gnu dot org 2007-04-25 14:22
-------
We fail to add the SFTs to the may_alias set of SMT.11, so add_virtual_operand
sees NULL may_aliases and doesn't add SFTs as clobbered.
I believe compute_flow_insensitive_aliasing is the culprit here as one can
easily
see that if we enter the
for (i = 0; i < ai->num_pointers; i++)
{
size_t j;
struct alias_map_d *p_map1 = ai->pointers[i];
tree tag1 = var_ann (p_map1->var)->symbol_mem_tag;
bitmap may_aliases1 = p_map1->may_aliases;
if (PTR_IS_REF_ALL (p_map1->var))
continue;
for (j = i + 1; j < ai->num_pointers; j++)
{
struct alias_map_d *p_map2 = ai->pointers[j];
tree tag2 = var_ann (p_map2->var)->symbol_mem_tag;
bitmap may_aliases2 = p_map2->may_aliases;
loop with may_aliases2 empty it will stay so. So as a fix I suggest to
add may aliases symmetrically like with
Index: tree-ssa-alias.c
===================================================================
*** tree-ssa-alias.c (revision 124151)
--- tree-ssa-alias.c (working copy)
*************** compute_flow_insensitive_aliasing (struc
*** 1287,1292 ****
--- 1287,1294 ----
struct alias_map_d *p_map2 = ai->pointers[j];
tree tag2 = var_ann (p_map2->var)->symbol_mem_tag;
bitmap may_aliases2 = p_map2->may_aliases;
+ unsigned int k;
+ bitmap_iterator bi;
if (PTR_IS_REF_ALL (p_map2->var))
continue;
*************** compute_flow_insensitive_aliasing (struc
*** 1301,1323 ****
continue;
if (!bitmap_empty_p (may_aliases2))
! {
! unsigned int k;
! bitmap_iterator bi;
!
! /* Add all the aliases for TAG2 into TAG1's alias set.
! FIXME, update grouping heuristic counters. */
! EXECUTE_IF_SET_IN_BITMAP (may_aliases2, 0, k, bi)
! add_may_alias (tag1, referenced_var (k));
! bitmap_ior_into (may_aliases1, may_aliases2);
! }
else
! {
! /* Since TAG2 does not have any aliases of its own, add
! TAG2 itself to the alias set of TAG1. */
! add_may_alias (tag1, tag2);
! bitmap_set_bit (may_aliases1, DECL_UID (tag2));
! }
}
}
--- 1303,1325 ----
continue;
if (!bitmap_empty_p (may_aliases2))
! /* Add all the aliases for TAG2 into TAG1's alias set.
! FIXME, update grouping heuristic counters. */
! EXECUTE_IF_SET_IN_BITMAP (may_aliases2, 0, k, bi)
! add_may_alias (tag1, referenced_var (k));
! else
! add_may_alias (tag1, tag2);
!
! if (!bitmap_empty_p (may_aliases1))
! /* Add all the aliases for TAG2 into TAG1's alias set.
! FIXME, update grouping heuristic counters. */
! EXECUTE_IF_SET_IN_BITMAP (may_aliases1, 0, k, bi)
! add_may_alias (tag2, referenced_var (k));
else
! add_may_alias (tag2, tag1);
!
! bitmap_ior_into (may_aliases2, may_aliases1);
! bitmap_ior_into (may_aliases1, may_aliases2);
}
}
but I have no clue what I am doing here. 't looks like big mess.
I prepare the workaround as alternative ;)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30567
