Ping
> -----Original Message-----
> From: Tamar Christina <tamar.christ...@arm.com>
> Sent: Monday, November 6, 2023 7:41 AM
> To: gcc-patches@gcc.gnu.org
> Cc: nd <n...@arm.com>; rguent...@suse.de; j...@ventanamicro.com
> Subject: [PATCH 12/21]middle-end: Add remaining changes to peeling and
> vectorizer to support early breaks
>
> Hi All,
>
> This finishes wiring that didn't fit in any of the other patches.
> Essentially just adding related changes so peeling for early break works.
>
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
>
> Ok for master?
>
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
> * tree-vect-loop-manip.cc (vect_set_loop_condition_normal,
> vect_do_peeling): Support early breaks.
> * tree-vect-loop.cc (vect_need_peeling_or_partial_vectors_p):
> Likewise.
> * tree-vectorizer.cc (pass_vectorize::execute): Check all exits.
>
> --- inline copy of patch --
> diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc index
> eef2bb50c1505f5cf802d5d80300affc2cbe69f6..9c1405d79fd8fe8689007df
> 3b7605b7a3d3ecdd7 100644
> --- a/gcc/tree-vect-loop-manip.cc
> +++ b/gcc/tree-vect-loop-manip.cc
> @@ -1187,7 +1187,7 @@ vect_set_loop_condition_partial_vectors_avx512
> (class loop *loop,
> loop handles exactly VF scalars per iteration. */
>
> static gcond *
> -vect_set_loop_condition_normal (loop_vec_info /* loop_vinfo */, edge
> exit_edge,
> +vect_set_loop_condition_normal (loop_vec_info loop_vinfo, edge
> +exit_edge,
> class loop *loop, tree niters, tree step,
> tree final_iv, bool niters_maybe_zero,
> gimple_stmt_iterator loop_cond_gsi) @@ -
> 1296,7 +1296,8 @@ vect_set_loop_condition_normal (loop_vec_info /*
> loop_vinfo */, edge exit_edge,
> gsi_insert_before (&loop_cond_gsi, cond_stmt, GSI_SAME_STMT);
>
> /* Record the number of latch iterations. */
> - if (limit == niters)
> + if (limit == niters
> + || LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
> /* Case A: the loop iterates NITERS times. Subtract one to get the
> latch count. */
> loop->nb_iterations = fold_build2 (MINUS_EXPR, niters_type, niters, @@ -
> 3242,6 +3243,16 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree niters,
> tree nitersm1,
> bound_epilog += vf - 1;
> if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo))
> bound_epilog += 1;
> +
> + /* For early breaks the scalar loop needs to execute at most VF times
> + to find the element that caused the break. */ if
> + (LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
> + {
> + bound_epilog = vf;
> + /* Force a scalar epilogue as we can't vectorize the index finding. */
> + vect_epilogues = false;
> + }
> +
> bool epilog_peeling = maybe_ne (bound_epilog, 0U);
> poly_uint64 bound_scalar = bound_epilog;
>
> @@ -3376,14 +3387,23 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree
> niters, tree nitersm1,
> bound_prolog + bound_epilog)
> : (!LOOP_REQUIRES_VERSIONING (loop_vinfo)
> || vect_epilogues));
> +
> + /* We only support early break vectorization on known bounds at this time.
> + This means that if the vector loop can't be entered then we won't
> generate
> + it at all. So for now force skip_vector off because the additional
> control
> + flow messes with the BB exits and we've already analyzed them. */
> + skip_vector = skip_vector && !LOOP_VINFO_EARLY_BREAKS (loop_vinfo);
> +
> /* Epilog loop must be executed if the number of iterations for epilog
> loop is known at compile time, otherwise we need to add a check at
> the end of vector loop and skip to the end of epilog loop. */
> bool skip_epilog = (prolog_peeling < 0
> || !LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
> || !vf.is_constant ());
> - /* PEELING_FOR_GAPS is special because epilog loop must be executed. */
> - if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo))
> + /* PEELING_FOR_GAPS and peeling for early breaks are special because
> epilog
> + loop must be executed. */
> + if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo)
> + || LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
> skip_epilog = false;
>
> class loop *scalar_loop = LOOP_VINFO_SCALAR_LOOP (loop_vinfo); diff --git
> a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index
> 55d6aee3d29151e6b528f6fdde15c693e5bdd847..51a054c5b035ac80dfbbf
> 3b5ba2f6da82fda91f6 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -1236,6 +1236,14 @@ vect_need_peeling_or_partial_vectors_p
> (loop_vec_info loop_vinfo)
> th = LOOP_VINFO_COST_MODEL_THRESHOLD
> (LOOP_VINFO_ORIG_LOOP_INFO
> (loop_vinfo));
>
> + /* When we have multiple exits and VF is unknown, we must require partial
> + vectors because the loop bounds is not a minimum but a maximum. That
> is to
> + say we cannot unpredicate the main loop unless we peel or use partial
> + vectors in the epilogue. */
> + if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
> + && !LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant ())
> + return true;
> +
> if (LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
> && LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) >= 0)
> {
> @@ -3149,7 +3157,8 @@ start_over:
>
> /* If an epilogue loop is required make sure we can create one. */
> if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo)
> - || LOOP_VINFO_PEELING_FOR_NITER (loop_vinfo))
> + || LOOP_VINFO_PEELING_FOR_NITER (loop_vinfo)
> + || LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
> {
> if (dump_enabled_p ())
> dump_printf_loc (MSG_NOTE, vect_location, "epilog loop required\n");
> diff --git a/gcc/tree-vectorizer.cc b/gcc/tree-vectorizer.cc index
> d97e2b54c25ac60378935392aa7b73476efed74b..8b495fc7ca137109fc009
> 7c77837233c660e032a 100644
> --- a/gcc/tree-vectorizer.cc
> +++ b/gcc/tree-vectorizer.cc
> @@ -1381,7 +1381,9 @@ pass_vectorize::execute (function *fun)
> predicates that need to be shared for optimal predicate usage.
> However reassoc will re-order them and prevent CSE from working
> as it should. CSE only the loop body, not the entry. */
> - bitmap_set_bit (exit_bbs, single_exit (loop)->dest->index);
> + auto_vec<edge> exits = get_loop_exit_edges (loop);
> + for (edge exit : exits)
> + bitmap_set_bit (exit_bbs, exit->dest->index);
>
> edge entry = EDGE_PRED (loop_preheader_edge (loop)->src, 0);
> do_rpo_vn (fun, entry, exit_bbs);
>
>
>
>
> --
