https://gcc.gnu.org/g:b443d7122ee8013c5af127d3d183a03962967f57
commit r15-1728-gb443d7122ee8013c5af127d3d183a03962967f57
Author: Richard Biener <rguent...@suse.de>
Date: Thu Jun 27 11:36:07 2024 +0200
Harden SLP reduction support wrt STMT_VINFO_REDUC_IDX
The following makes sure that for a SLP reductions all lanes have
the same STMT_VINFO_REDUC_IDX. Once we move that info and can adjust
it we can implement swapping. It also makes the existing protection
against operand swapping trigger for all stmts participating in a
reduction, not just the final one marked as reduction-def.
* tree-vect-slp.cc (vect_build_slp_tree_1): Compare
STMT_VINFO_REDUC_IDX.
(vect_build_slp_tree_2): Prevent operand swapping for
all stmts participating in a reduction.
Diff:
---
gcc/tree-vect-slp.cc | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index dd9017e5b3a..48e0f9d2705 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -1072,6 +1072,7 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char
*swap,
stmt_vec_info first_load = NULL, prev_first_load = NULL;
bool first_stmt_ldst_p = false, ldst_p = false;
bool first_stmt_phi_p = false, phi_p = false;
+ int first_reduc_idx = -1;
bool maybe_soft_fail = false;
tree soft_fail_nunits_vectype = NULL_TREE;
@@ -1204,6 +1205,7 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char
*swap,
first_stmt_code = rhs_code;
first_stmt_ldst_p = ldst_p;
first_stmt_phi_p = phi_p;
+ first_reduc_idx = STMT_VINFO_REDUC_IDX (stmt_info);
/* Shift arguments should be equal in all the packed stmts for a
vector shift with scalar shift operand. */
@@ -1267,6 +1269,24 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char
*swap,
}
else
{
+ if (first_reduc_idx != STMT_VINFO_REDUC_IDX (stmt_info)
+ /* For SLP reduction groups the index isn't necessarily
+ uniform but only that of the first stmt matters. */
+ && !(first_reduc_idx != -1
+ && STMT_VINFO_REDUC_IDX (stmt_info) != -1
+ && REDUC_GROUP_FIRST_ELEMENT (stmt_info)))
+ {
+ if (dump_enabled_p ())
+ {
+ dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+ "Build SLP failed: different reduc_idx "
+ "%d instead of %d in %G",
+ STMT_VINFO_REDUC_IDX (stmt_info),
+ first_reduc_idx, stmt);
+ }
+ /* Mismatch. */
+ continue;
+ }
if (first_stmt_code != rhs_code
&& alt_stmt_code == ERROR_MARK)
alt_stmt_code = rhs_code;
@@ -2530,8 +2550,7 @@ out:
&& oprnds_info[1]->first_dt == vect_internal_def
&& is_gimple_assign (stmt_info->stmt)
/* Swapping operands for reductions breaks assumptions later on. */
- && STMT_VINFO_DEF_TYPE (stmt_info) != vect_reduction_def
- && STMT_VINFO_DEF_TYPE (stmt_info) != vect_double_reduction_def)
+ && STMT_VINFO_REDUC_IDX (stmt_info) == -1)
{
/* See whether we can swap the matching or the non-matching
stmt operands. */
