RE: [PATCH 13/21]middle-end: Update loop form analysis to support early break

[Tamar Christina <Tamar.Christina@arm.com>]

ping

> -----Original Message-----
> From: Tamar Christina <Tamar.Christina@arm.com>
> Sent: Monday, November 27, 2023 10:48 PM
> To: Tamar Christina <Tamar.Christina@arm.com>; gcc-patches@gcc.gnu.org
> Cc: nd <nd@arm.com>; rguenther@suse.de; jlaw@ventanamicro.com
> Subject: RE: [PATCH 13/21]middle-end: Update loop form analysis to support early
> break
> 
> Ping
> 
> > -----Original Message-----
> > From: Tamar Christina <tamar.christina@arm.com>
> > Sent: Monday, November 6, 2023 7:41 AM
> > To: gcc-patches@gcc.gnu.org
> > Cc: nd <nd@arm.com>; rguenther@suse.de; jlaw@ventanamicro.com
> > Subject: [PATCH 13/21]middle-end: Update loop form analysis to support
> > early break
> >
> > Hi All,
> >
> > This sets LOOP_VINFO_EARLY_BREAKS and does some misc changes so the
> > other patches are self contained.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> >
> > Ok for master?
> >
> > Thanks,
> > Tamar
> >
> > gcc/ChangeLog:
> >
> > 	* tree-vect-loop.cc (vect_analyze_loop_form): Analyse all exits.
> > 	(vect_create_loop_vinfo): Set LOOP_VINFO_EARLY_BREAKS.
> > 	(vect_transform_loop): Use it.
> >
> > --- inline copy of patch --
> > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index
> > 51a054c5b035ac80dfbbf3b5ba2f6da82fda91f6..f9483eff6e9606e835906fb
> > 991f07cd6052491d0 100644
> > --- a/gcc/tree-vect-loop.cc
> > +++ b/gcc/tree-vect-loop.cc
> > @@ -1700,12 +1700,12 @@ vect_compute_single_scalar_iteration_cost
> > (loop_vec_info loop_vinfo)
> >    loop_vinfo->scalar_costs->finish_cost (nullptr);  }
> >
> > -
> >  /* Function vect_analyze_loop_form.
> >
> >     Verify that certain CFG restrictions hold, including:
> >     - the loop has a pre-header
> > -   - the loop has a single entry and exit
> > +   - the loop has a single entry
> > +   - nested loops can have only a single exit.
> >     - the loop exit condition is simple enough
> >     - the number of iterations can be analyzed, i.e, a countable loop.  The
> >       niter could be analyzed under some assumptions.  */ @@ -1841,10
> > +1841,14 @@ vect_analyze_loop_form (class loop *loop,
> > vect_loop_form_info *info)
> >  				   "not vectorized: latch block not empty.\n");
> >
> >    /* Make sure the exit is not abnormal.  */
> > -  if (exit_e->flags & EDGE_ABNORMAL)
> > -    return opt_result::failure_at (vect_location,
> > -				   "not vectorized:"
> > -				   " abnormal loop exit edge.\n");
> > +  auto_vec<edge> exits = get_loop_exit_edges (loop);
> > +  for (edge e : exits)
> > +    {
> > +      if (e->flags & EDGE_ABNORMAL)
> > +	return opt_result::failure_at (vect_location,
> > +				       "not vectorized:"
> > +				       " abnormal loop exit edge.\n");
> > +    }
> >
> >    info->conds
> >      = vect_get_loop_niters (loop, exit_e, &info->assumptions, @@ -1920,6
> > +1924,10 @@ vect_create_loop_vinfo (class loop *loop, vec_info_shared
> > *shared,
> >
> >    LOOP_VINFO_IV_EXIT (loop_vinfo) = info->loop_exit;
> >
> > +  /* Check to see if we're vectorizing multiple exits.  */
> > + LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
> > +    = !LOOP_VINFO_LOOP_CONDS (loop_vinfo).is_empty ();
> > +
> >    if (info->inner_loop_cond)
> >      {
> >        stmt_vec_info inner_loop_cond_info @@ -11577,7 +11585,7 @@
> > vect_transform_loop (loop_vec_info loop_vinfo, gimple *loop_vectorized_call)
> >    /* Make sure there exists a single-predecessor exit bb.  Do this before
> >       versioning.   */
> >    edge e = LOOP_VINFO_IV_EXIT (loop_vinfo);
> > -  if (! single_pred_p (e->dest))
> > +  if (! single_pred_p (e->dest) && !LOOP_VINFO_EARLY_BREAKS
> > + (loop_vinfo))
> >      {
> >        split_loop_exit_edge (e, true);
> >        if (dump_enabled_p ())
> >
> >
> >
> >
> > --