On Mon, 6 Jul 2026, Tamar Christina wrote:
> Continuing the work started in GCC 12 with g:a0dae768c6f78eba
> this patch replaces uses of SLP_TREE_SCALAR_STMTS with SLP_TREE_LANES when
> used
> to determine the number of lanes in the SLP tree. This de-couples the need to
> have the same number of scalar statements as lanes in the SLP tree.
>
> Bootstrapped Regtested on aarch64-none-linux-gnu,
> arm-none-linux-gnueabihf, x86_64-pc-linux-gnu
> -m32, -m64 and no issues.
>
> Any feedback?
>
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
> * tree-vect-slp-patterns.cc (compatible_complex_nodes_p): Support
> mismatched group sizes and use group size to iterate.
> * tree-vect-slp.cc (vect_build_slp_instance,
> vect_analyze_slp_reduc_chain, vect_analyze_slp_reduction,
> vect_analyze_slp_reduction_group, vect_analyze_slp_instance,
> vect_analyze_slp): Compare against lanes instead of .length ().
> (vect_optimize_slp_pass::get_result_with_layout): replace .length ()
> with .exist ().
> (vect_transform_slp_perm_load_1): Use lanes instead of .length ().
> (vect_remove_slp_scalar_calls): Replace iterators.
> * tree-vect-stmts.cc (vectorizable_shift): Use group size over ops
> length.
>
> ---
> diff --git a/gcc/tree-vect-slp-patterns.cc b/gcc/tree-vect-slp-patterns.cc
> index
> 181281c2154bedfc8e8c6b1bde1226e194ba99e5..3194642ef88e20b60eadc44b1d69c0d4f5a59a96
> 100644
> --- a/gcc/tree-vect-slp-patterns.cc
> +++ b/gcc/tree-vect-slp-patterns.cc
> @@ -762,7 +762,10 @@ compatible_complex_nodes_p (slp_compat_nodes_map_t
> *compat_cache,
> are externals. */
> if (SLP_TREE_DEF_TYPE (a) != vect_internal_def)
> {
> - for (unsigned i = 0; i < SLP_TREE_SCALAR_OPS (a).length (); i++)
> + unsigned group_size = SLP_TREE_LANES (a);
> + gcc_assert (SLP_TREE_SCALAR_OPS (a).length () == group_size
> + && SLP_TREE_SCALAR_OPS (b).length () == group_size);
> + for (unsigned i = 0; i < group_size; i++)
OK.
> {
> tree op1 = SLP_TREE_SCALAR_OPS (a)[pa[i % 2]];
> tree op2 = SLP_TREE_SCALAR_OPS (b)[pb[i % 2]];
> diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
> index
> 514bc0c5c654cc392ab5a47ea6b08b65fe7786fe..e74556b7dc558f931482b9dc1300d90c84b008fd
> 100644
> --- a/gcc/tree-vect-slp.cc
> +++ b/gcc/tree-vect-slp.cc
> @@ -4285,8 +4285,8 @@ vect_build_slp_instance (vec_info *vinfo,
> /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> the number of scalar stmts in the root in a few places.
> Verify that assumption holds. */
The comment and the copies need adjustment with the change. I wonder
whether at the point this was added SLP_TREE_LANES existed?
That said, group_size in this function is the number of "scalar"
stmts. I think we want to elide 'group_size' from the
vect_build_slp_tree API since this is not a "global" invariant
but the number of lanes could change throughout the SLP graph.
The assertions are still somewhat relevant in that the root nodes
number of lanes should match the number of lanes from the scalar
stmt seeds.
> - gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE (new_instance))
> - .length () == group_size);
> + gcc_assert (SLP_TREE_LANES (SLP_INSTANCE_TREE (new_instance))
> + == group_size);
>
> if (dump_enabled_p ())
> {
> @@ -4720,8 +4720,8 @@ vect_analyze_slp_reduc_chain (loop_vec_info vinfo,
> /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> the number of scalar stmts in the root in a few places.
> Verify that assumption holds. */
> - gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE (new_instance))
> - .length () == group_size);
> + gcc_assert (SLP_TREE_LANES (SLP_INSTANCE_TREE (new_instance))
> + == group_size);
>
> if (dump_enabled_p ())
> {
> @@ -4809,8 +4809,8 @@ vect_analyze_slp_reduction (loop_vec_info vinfo,
> /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> the number of scalar stmts in the root in a few places.
> Verify that assumption holds. */
> - gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE (new_instance))
> - .length () == group_size);
> + gcc_assert (SLP_TREE_LANES (SLP_INSTANCE_TREE (new_instance))
> + == group_size);
>
> if (dump_enabled_p ())
> {
> @@ -4882,8 +4882,8 @@ vect_analyze_slp_reduction_group (loop_vec_info
> loop_vinfo,
> /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> the number of scalar stmts in the root in a few places.
> Verify that assumption holds. */
> - gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE (new_instance))
> - .length () == group_size);
> + gcc_assert (SLP_TREE_LANES (SLP_INSTANCE_TREE (new_instance))
> + == group_size);
>
> if (dump_enabled_p ())
> {
> @@ -5138,8 +5138,8 @@ vect_analyze_slp_instance (vec_info *vinfo,
> /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> the number of scalar stmts in the root in a few places.
> Verify that assumption holds. */
> - gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE (new_instance))
> - .length () == group_size);
> + gcc_assert (SLP_TREE_LANES (SLP_INSTANCE_TREE (new_instance))
> + == group_size);
>
> if (dump_enabled_p ())
> {
> @@ -5385,8 +5385,8 @@ vect_analyze_slp_instance (vec_info *vinfo,
> /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> the number of scalar stmts in the root in a few places.
> Verify that assumption holds. */
> - gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE (new_instance))
> - .length () == group_size);
> + gcc_assert (SLP_TREE_LANES (SLP_INSTANCE_TREE (new_instance))
> + == group_size);
>
> if (dump_enabled_p ())
> {
> @@ -7906,7 +7906,7 @@ vect_optimize_slp_pass::get_result_with_layout
> (slp_tree node,
>
> unsigned int num_lanes = SLP_TREE_LANES (node);
> result = vect_create_new_slp_node (num_inputs, VEC_PERM_EXPR);
> - if (SLP_TREE_SCALAR_STMTS (node).length ())
> + if (SLP_TREE_SCALAR_STMTS (node).exists ())
OK.
> {
> auto &stmts = SLP_TREE_SCALAR_STMTS (result);
> stmts.safe_splice (SLP_TREE_SCALAR_STMTS (node));
> @@ -8819,7 +8819,7 @@ vect_prologue_cost_for_slp (vec_info *vinfo, slp_tree
> node,
> constants can be implemented as load from the constant pool.
> When all elements are the same we can use a splat. */
> tree vectype = SLP_TREE_VECTYPE (node);
> - unsigned group_size = SLP_TREE_SCALAR_OPS (node).length ();
> + unsigned group_size = SLP_TREE_LANES (node);
OK.
> unsigned HOST_WIDE_INT const_nunits;
> unsigned nelt_limit;
> unsigned nvectors = vect_get_num_copies (vinfo, node);
> @@ -10987,7 +10987,7 @@ vect_transform_slp_perm_load_1 (vec_info *vinfo,
> slp_tree node,
> stmt_vec_info stmt_info = SLP_TREE_SCALAR_STMTS (node)[0];
> int vec_index = 0;
> tree vectype = SLP_TREE_VECTYPE (node);
> - unsigned int group_size = SLP_TREE_SCALAR_STMTS (node).length ();
> + unsigned int group_size = SLP_TREE_LANES (node);
OK.
> unsigned int mask_element;
> unsigned dr_group_size;
> machine_mode mode;
> diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
> index
> 76e24b2c1699b022e4480fc4aac87ff0b6ddf650..f41d49541d570b656eec10227f7f030051acd0bb
> 100644
> --- a/gcc/tree-vect-stmts.cc
> +++ b/gcc/tree-vect-stmts.cc
> @@ -6388,15 +6388,18 @@ vectorizable_shift (vec_info *vinfo,
> /* Now adjust the constant shift amount in place. */
> if (incompatible_op1_vectype_p
> && dt[1] == vect_constant_def)
> - for (unsigned i = 0;
> - i < SLP_TREE_SCALAR_OPS (slp_op1).length (); ++i)
> - {
> - SLP_TREE_SCALAR_OPS (slp_op1)[i]
> - = fold_convert (TREE_TYPE (vectype),
> - SLP_TREE_SCALAR_OPS (slp_op1)[i]);
> - gcc_assert ((TREE_CODE (SLP_TREE_SCALAR_OPS (slp_op1)[i])
> - == INTEGER_CST));
> - }
> + {
> + unsigned group_size = SLP_TREE_LANES (slp_op1);
> + gcc_assert (SLP_TREE_SCALAR_OPS (slp_op1).length () == group_size);
This is OK in principle, but how do we handle this when re-vectorizing
vector by scalar shifts? Have scalar stmts of the vector operand
{ v0, v0, v0, v0 } and the scalar shift { s, s, s, s }, so both
expanded to be TYPE_VECTOR_SUBPARTS times?
> + for (unsigned i = 0; i < group_size; ++i)
> + {
> + SLP_TREE_SCALAR_OPS (slp_op1)[i]
> + = fold_convert (TREE_TYPE (vectype),
> + SLP_TREE_SCALAR_OPS (slp_op1)[i]);
> + gcc_assert ((TREE_CODE (SLP_TREE_SCALAR_OPS (slp_op1)[i])
> + == INTEGER_CST));
> + }
> + }
> SLP_TREE_TYPE (slp_node) = shift_vec_info_type;
> DUMP_VECT_SCOPE ("vectorizable_shift");
> vect_model_simple_cost (vinfo, 1, slp_node, cost_vec);
>
>
>
--
Richard Biener <[email protected]>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Jochen Jaser, Andrew McDonald; (HRB 36809, AG Nuernberg)
