On Thu, 8 Feb 2024, Tamar Christina wrote:
> Hi All,
>
> This adds two new debug counter to aid in debugging early break code.
>
> - vect_force_last_exit: when reached will always force the final loop exit.
> - vect_skip_exit: when reached will skip selecting the current candidate exit
> as the loop exit.
>
> The first counter essentially allows you to turn off the PEELED case and the
> second counter to pick a different exit, which may mean you pick no exit at
> all.
>
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
>
> Ok for master?
>
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
> * dbgcnt.def (vect_force_last_exit, vect_skip_exit): New.
> * tree-vect-loop.cc (vec_init_loop_exit_info): Use them.
>
> --- inline copy of patch --
> diff --git a/gcc/dbgcnt.def b/gcc/dbgcnt.def
> index
> ed9f062eac2c28c52df76b39d4312dd9fde1c800..8f7bebf93fceabdf6ae86c2df591eae4848b8a5c
> 100644
> --- a/gcc/dbgcnt.def
> +++ b/gcc/dbgcnt.def
> @@ -213,5 +213,7 @@ DEBUG_COUNTER (stv_conversion)
> DEBUG_COUNTER (tail_call)
> DEBUG_COUNTER (tree_sra)
> DEBUG_COUNTER (treepre_insert)
> +DEBUG_COUNTER (vect_force_last_exit)
> DEBUG_COUNTER (vect_loop)
> +DEBUG_COUNTER (vect_skip_exit)
> DEBUG_COUNTER (vect_slp)
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index
> eed2268e9bae7e7ad36d13da03e0b54eab26ef6f..854e9d78bc71721e6559a6bc5dff78c813603a78
> 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -58,6 +58,7 @@ along with GCC; see the file COPYING3. If not see
> #include "tree-eh.h"
> #include "case-cfn-macros.h"
> #include "langhooks.h"
> +#include "dbgcnt.h"
>
> /* Loop Vectorization Pass.
>
> @@ -977,6 +978,20 @@ vec_init_loop_exit_info (class loop *loop)
> if (exits.length () == 1)
> return exits[0];
>
> + /* Check to see if we've been asked to force the last exit. */
> + if (!dbg_cnt (vect_force_last_exit))
> + {
> + basic_block bb = ip_normal_pos (loop);
> + if (!bb)
> + return NULL;
> +
> + edge exit = EDGE_SUCC (bb, 0);
> + if (exit->dest == loop->latch)
> + return EDGE_SUCC (bb, 1);
> +
> + return exit;
Err, that's quite odd. Why not just below do
> + }
> +
> /* If we have multiple exits we only support counting IV at the moment.
> Analyze all exits and return the last one we can analyze. */
> class tree_niter_desc niter_desc;
> @@ -998,6 +1013,7 @@ vec_init_loop_exit_info (class loop *loop)
> && exit->src == single_pred (loop->latch)
> && (integer_nonzerop (may_be_zero)
> || COMPARISON_CLASS_P (may_be_zero))))
> + && dbg_cnt (vect_skip_exit)
&& (dbg_cnt (vect_force_last_exit)
|| exit->src == single_pred (loop->latch))
(also computed above already)? It's also oddly named, it's more like
vect_allow_peeled_exit or so.
It's also seemingly redundant with vect_skip_exit, no?
Note the counter gets incremented even if we'd not consider the exit
because we have a later candidate already.
I fear it's going to be quite random even with the debug counter.
Can you see whether it really helps you?
> && (!candidate
> || dominated_by_p (CDI_DOMINATORS, exit->src,
> candidate->src)))
>
>
>
>
>
--
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)
