------- Comment #1 from rguenth at gcc dot gnu dot org 2008-01-11 15:57 -------
It's doing the correct thing. We have
p_1, name memory tag: NMT.14, is dereferenced, points-to vars: { SFT.3 SFT.7 }
(SFT.3 is x.x, SFT.7 is z.x)
Now, NMT.14 is marked call clobbered:
NMT.14, UID D.1582, struct A, is addressable, score: 40, direct reads: 2,
direct writes: 1, indirect reads: 0, indirect writes: 2, call clobbered (passed
to call), may aliases: { SFT.3 SFT.7 }
because one of its pointed-to vars is call clobbered (SFT.7, aka z, which is
passed to the call). Here:
static void
compute_tag_properties (void)
{
...
EXECUTE_IF_SET_IN_BITMAP (ma, 0, i, bi)
{
entry = referenced_var (i);
/* Call clobbered entries cause the tag to be marked
call clobbered. */
if (!tagcc && is_call_clobbered (entry))
{
mark_call_clobbered (tag, var_ann (entry)->escape_mask);
tagcc = true;
changed = true;
}
I don't know if we can disable this if var_ann (entry)->escape_mask ==
ESCAPE_TO_CALL.
I don't know if we need to propagate tags from NMT aliases to the NMT
this way at all - after all we add all subvars of an escaped var to
call clobbered vars already.
So, confirmed - there's a missing optimization.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu dot
| |org
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |alias, missed-optimization
Last reconfirmed|0000-00-00 00:00:00 |2008-01-11 15:57:57
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34743
