On 05/25/2011 08:21 AM, Andrey Belevantsev wrote:
> Vlad, Bernd, I wonder if we can avoid having recog_memoized >=0 insns
> that do not have proper DFA reservations (that is, they do not change
> the DFA state). I see that existing practice allows this as shown by
> Bernd's patch to 48403, i.e. such insns do not count against
> issue_rate. I would be happy to fix sel-sched in the same way.
> However, both sel-sched ICEs as shown by PRs 48143 and 49014 really
> uncover the latent bugs in the backend. So, is it possible to stop
> having such insns if scheduling is desired, or otherwise distinguish the
> insns that wrongly miss the proper DFA reservation?
Add a bool target podhook, targetm.sched.all_insns_have_reservations,
and add an assert in the scheduler if it is true.
I'm not sure what a good default value would be. Defining it to true
would almost certainly break a few ports initially (even assuming we
override it in sh where it's known not to be true), but I guess it such
an assertion failure would be useful information for the target maintainers.
Or, if we want to enable extra checking on ports where not all insns
have a reservation, a new insn attribute ("has_reservation") could be
defined, defined to evaluate to true by default in genattrtab, and
(set_attr "has_reservation" "0") added in the machine descriptions where
necessary.
Bernd
