On Wed, 15 Nov 2023, Kewen.Lin wrote:
> >> And I suppose it would be OK to do that. Empty BBs are usually removed by
> >> CFG cleanup so the situation should only happen in rare corner cases where
> >> the fix would be to actually run CFG cleanup ...
> >
> > Yeah, sel-sched invokes 'cfg_cleanup (0)' up front, and I suppose that
> > may be a preferable compromise for sched-rgn as well.
>
> Inspired by this discussion, I tested the attached patch 1 which is to run
> cleanup_cfg (0) first in haifa_sched_init, it's bootstrapped and
> regress-tested on x86_64-redhat-linux and powerpc64{,le}-linux-gnu.
I don't think you can run cleanup_cfg after sched_init. I would suggest
to put it early in schedule_insns.
> Then I assumed some of the current uses of no_real_insns_p won't encounter
> empty blocks any more, so made a patch 2 with some explicit assertions, but
> unfortunately I got ICEs during bootstrapping happens in function
> compute_priorities. I'm going to investigate it further and post more
> findings, but just heads-up to ensure if this is on the right track.
I suspect this may be caused by invoking cleanup_cfg too late.
Alexander
