------- Comment #26 from rguenther at suse dot de 2009-07-15 15:00 -------
Subject: Re: [4.4/4.5 Regression] internal
compiler error: in compute_antic, at tree-ssa-pre.c:2501
On Wed, 15 Jul 2009, dberlin at dberlin dot org wrote:
> Subject: Re: [4.4/4.5 Regression] internal
> compiler error: in compute_antic, at tree-ssa-pre.c:2501
>
> On Wed, Jul 15, 2009 at 9:58 AM, rguenther at suse dot
> de<gcc-bugzi...@gcc.gnu.org> wrote:
> >
> >
> > ------- Comment #24 from rguenther at suse dot de ?2009-07-15 13:58 -------
> > Subject: Re: ?[4.4/4.5 Regression] internal
> > ?compiler error: in compute_antic, at tree-ssa-pre.c:2501
> >
> > On Wed, 15 Jul 2009, dberlin at dberlin dot org wrote:
> >
> >> ------- Comment #23 from dberlin at gcc dot gnu dot org ?2009-07-15 13:46
> >> -------
> >> Subject: Re: ?[4.4/4.5 Regression] internal
> >> ? ? ? ? compiler error: in compute_antic, at tree-ssa-pre.c:2501
> >>
> >> a_1 shouldn't be in the maximal set. If it is, that's a bug.
> >
> > D.1251_5 = a_1->flag;
> >
> > so it's even in exp_gen.
>
> I expect it got in exp_gen through add_to_exp_gen.
> But the check there should have ensured it didn't get into the maximal set.
Indeed it's not in there. The maximal set is w/o the patch
maximal[0] := { a_3(D) (0003), b_4(D) (0004),
{component_ref<flag>,indirect_ref,a...@.mem_13(D) (0005),
{component_ref<pos>,indirect_ref,a...@.mem_13(D) (0006),
{component_ref<pos>,indirect_ref,b...@.mem_13(D) (0007),
{plus_expr,D.1254_10,D.1255_11} (0008) }
without them in the maximal-set we seem to get into non-monotonic
situations during ANTIC calculation because nobody cleans PHI_GEN, so
it will *add* bits. ... ?
The logic behind
"PHI nodes can't go in the maximal sets because they are not in
TMP_GEN, so it is possible to get into non-monotonic situations
during ANTIC calculation, because it will *add* bits."
sounds weird. Isn't the maximal set only used initially, so it
will at most add bits once?
The patch btw bootstrapped and tested ok.
Richard.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40321
