Thanks for your quick reply,sorry for the missing of information.
I meet this problem in risc-v test:
gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul8-8.c
I found that this SLP change will add additional instrutions in the
test, please see this link:
https://godbolt.org/z/5Tfqs9zqj
在 2024/07/18 15:05, Richard Biener 写道:
On Thu, 18 Jul 2024, Jiawei wrote:
This patch improves SLP reduction handling by ensuring proper processing
even for a single reduction statement.Vectorization instances are now built
only when there are multiple scalar statements to combine into an SLP
reduction.
An example seehttps://gcc.gnu.org/bugzilla/show_bug.cgi?id=110632,
this patch fix this problem,handling SLP reduction as expected.
That PR is lacking any information so I'm not sure what kind of problem
you are fixing.
But the patch is clearly wrong - we want to use SLP even for single
reduction statements, the non-SLP path is going away.
I located the problem from the following modifications and made some
attempts.
But it seems wrong, do you have any suggestions?
- if (scalar_stmts.length () > 1)
+ /* Save for re-processing on failure. */
+ vec<stmt_vec_info> saved_stmts = scalar_stmts.copy ();
+ vec<stmt_vec_info> roots = vNULL;
+ vec<tree> remain = vNULL;
+ if (scalar_stmts.length () <= 1
+ || !vect_build_slp_instance (loop_vinfo,
+ slp_inst_kind_reduc_group,
+ scalar_stmts, roots, remain,
+ max_tree_size, &limit, bst_map,
+ NULL))
{
- vec<stmt_vec_info> roots = vNULL;
- vec<tree> remain = vNULL;
- vect_build_slp_instance (loop_vinfo,
slp_inst_kind_reduc_group,
- scalar_stmts, roots, remain,
- max_tree_size, &limit, bst_map,
NULL);
BR,
Jiawei
Richard.
gcc/ChangeLog:
* tree-vect-slp.cc (vect_analyze_slp): Improved handling of SLP
reductions
for single reduction statements.
---
gcc/tree-vect-slp.cc | 49 +++++++++++++++++++++-----------------------
1 file changed, 23 insertions(+), 26 deletions(-)
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 55ae496cbb2..b6dfd9fd32f 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -4054,34 +4054,31 @@ vect_analyze_slp (vec_info *vinfo, unsigned
max_tree_size)
}
}
/* Save for re-processing on failure. */
- vec<stmt_vec_info> saved_stmts = scalar_stmts.copy ();
- vec<stmt_vec_info> roots = vNULL;
- vec<tree> remain = vNULL;
- if (scalar_stmts.length () <= 1
- || !vect_build_slp_instance (loop_vinfo,
- slp_inst_kind_reduc_group,
- scalar_stmts, roots, remain,
- max_tree_size, &limit, bst_map,
- NULL))
- {
- if (scalar_stmts.length () <= 1)
- scalar_stmts.release ();
- /* Do SLP discovery for single-lane reductions. */
- for (auto stmt_info : saved_stmts)
- {
- vec<stmt_vec_info> stmts;
- vec<stmt_vec_info> roots = vNULL;
- vec<tree> remain = vNULL;
- stmts.create (1);
- stmts.quick_push (vect_stmt_to_vectorize (stmt_info));
- vect_build_slp_instance (vinfo,
- slp_inst_kind_reduc_group,
- stmts, roots, remain,
- max_tree_size, &limit,
- bst_map, NULL);
+ if (loop_vinfo->reductions.length() > 0) {
+ vec<stmt_vec_info> scalar_stmts;
+ scalar_stmts.create(loop_vinfo->reductions.length());
+
+ for (auto next_info : loop_vinfo->reductions) {
+ if (STMT_VINFO_DEF_TYPE(next_info) == vect_reduction_def) {
+ gassign *g = dyn_cast<gassign*>(STMT_VINFO_STMT(next_info));
+ if (!g || !lane_reducing_op_p(gimple_assign_rhs_code(g))) {
+ scalar_stmts.quick_push(next_info);
}
- saved_stmts.release ();
+ }
}
+
+ if (scalar_stmts.length() > 1) {
+ vec<stmt_vec_info> roots = vNULL;
+ vec<tree> remain = vNULL;
+ if (!vect_build_slp_instance(loop_vinfo, slp_inst_kind_reduc_group,
scalar_stmts, roots, remain, max_tree_size, &limit, bst_map, NULL)) {
+ scalar_stmts.release();
+ }
+ }
+ else {
+ scalar_stmts.release();
+ }
+ }
+
}
}
