On Mon, 8 Apr 2024, Richard Biener wrote:
> On Fri, 5 Apr 2024, Jan Hubicka wrote:
>
> > > + /* When there's a call that might not return the last iteration
> > > + is possibly partial. This matches what we check in invariant
> > > + motion.
> > > + ??? For the call argument evaluation it would be still OK. */
> > > + if (!may_have_exited
> > > + && is_gimple_call (stmt)
> > > + && gimple_has_side_effects (stmt))
> > > + may_have_exited = true;
> >
> > I think you are missing here non-call EH, volatile asms and traps.
> > We have stmt_may_terminate_function_p which tests there.
>
> That returns true for all variable array accesses, I think we want
> to catch traps explicitly here. I'm going to do
>
> if (!may_have_exited
> && (gimple_has_side_effects (stmt)
> || stmt_can_throw_external (cfun, stmt)))
> may_have_exited = true;
>
> that should cover all but the generic trapping and not use IPA info
> to prove no side-effects.
Hum. Maybe I'm a bit confused but we seem to "properly" take things
into account via maybe_lower_iteration_bound and are not directly using
the recorded bounds? The function does a DFS walk though, not
reliably finding exits via calls early enough (it also lacks external
EH). Oddly enough it seems to handle(?) gcc.dg/tree-ssa/cunroll-9.c
"correctly", but not gcc.dg/tree-ssa/cunroll-10.c which has the
number of iterations wrongly computed.
Maybe we should really record all the bounds properly but merge them
to a loop upper bound at one place? gcc.dg/tree-ssa/cunroll-11.c
needs to see the g_x[i] bound is enforced in all paths to the latch
for example.
I'm most definitely defering this to GCC 15 now, I wonder if you
have any preferences here (and maybe want to pick this up also
for cleanup - it's mostly your code).
Richard.
> Richard.
>
> > Honza
> > > +
> > > + infer_loop_bounds_from_array (loop, stmt,
> > > + reliable && !may_have_exited);
> > >
> > > - if (reliable)
> > > + if (reliable && !may_have_exited)
> > > {
> > > infer_loop_bounds_from_signedness (loop, stmt);
> > > infer_loop_bounds_from_pointer_arith (loop, stmt);
> > > }
> > > }
> > > -
> > > }
> > > }
> > >
> > > @@ -4832,7 +4855,7 @@ estimate_numbers_of_iterations (class loop *loop)
> > > diagnose those loops with -Waggressive-loop-optimizations. */
> > > number_of_latch_executions (loop);
> > >
> > > - basic_block *body = get_loop_body (loop);
> > > + basic_block *body = get_loop_body_in_rpo (cfun, loop);
> > > auto_vec<edge> exits = get_loop_exit_edges (loop, body);
> > > likely_exit = single_likely_exit (loop, exits);
> > > FOR_EACH_VEC_ELT (exits, i, ex)
> > > --
> > > 2.35.3
> >
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
