https://gcc.gnu.org/g:2cb9925f4001b931f43ea64b64adf9dbc1089bfa
commit r16-4465-g2cb9925f4001b931f43ea64b64adf9dbc1089bfa Author: Richard Biener <[email protected]> Date: Fri Oct 17 09:26:25 2025 +0200 tree-optimization/122301 - fix ICE and improve vectorization of min/max reduction The following fixes another issue with updating of reduc_idx in pattern sequences. But the testcase also shows the pattern in question is harmful for vectorization since a reduction path may not contain promotions/demotions. So the already existing but ineffective check to guard the pattern is fixed. PR tree-optimization/122301 * tree-vect-patterns.cc (vect_recog_over_widening_pattern): Fix reduction guard. (vect_mark_pattern_stmts): Fix reduction def check. * gcc.dg/vect/vect-pr122301.c: New testcase. Diff: --- gcc/testsuite/gcc.dg/vect/vect-pr122301.c | 16 ++++++++++++++++ gcc/tree-vect-patterns.cc | 9 ++++++--- 2 files changed, 22 insertions(+), 3 deletions(-) diff --git a/gcc/testsuite/gcc.dg/vect/vect-pr122301.c b/gcc/testsuite/gcc.dg/vect/vect-pr122301.c new file mode 100644 index 000000000000..acc7aedf1902 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/vect-pr122301.c @@ -0,0 +1,16 @@ +/* { dg-do compile } */ + +int get_prev_frame_segid(unsigned char *p, int n) +{ + int tem; + unsigned seg_id = 8; + for (int x = 0; x < n; x++) + { + int a = seg_id; + tem = a < p[x] ? a : p[x]; + seg_id = tem; + } + return tem; +} + +/* { dg-final { scan-tree-dump "optimized: loop vectorized" "vect" { target { vect_int && { ! vect_no_int_min_max } } } } } */ diff --git a/gcc/tree-vect-patterns.cc b/gcc/tree-vect-patterns.cc index db30db7b8a5c..a5c721e61535 100644 --- a/gcc/tree-vect-patterns.cc +++ b/gcc/tree-vect-patterns.cc @@ -3001,7 +3001,7 @@ vect_recog_over_widening_pattern (vec_info *vinfo, tree_code code = gimple_assign_rhs_code (last_stmt); /* Punt for reductions where we don't handle the type conversions. */ - if (STMT_VINFO_DEF_TYPE (last_stmt_info) == vect_reduction_def) + if (vect_is_reduction (last_stmt_info)) return NULL; /* Keep the first operand of a COND_EXPR as-is: only the other two @@ -7517,14 +7517,17 @@ vect_mark_pattern_stmts (vec_info *vinfo, break; } /* Try harder to find a mid-entry into an earlier pattern - sequence. This means that the initial 'lookfor' was + sequence. Likewise an entry to a stmt skipping a conversion + on an input. This means that the initial 'lookfor' was bogus. */ if (!found) { for (unsigned i = 0; i < op.num_ops; ++i) if (TREE_CODE (op.ops[i]) == SSA_NAME) if (auto def = vinfo->lookup_def (op.ops[i])) - if (vect_is_reduction (def)) + if (vect_is_reduction (def) + || (is_a <gphi *> (def->stmt) + && STMT_VINFO_REDUC_DEF (def) != NULL)) { STMT_VINFO_REDUC_IDX (vinfo->lookup_stmt (s)) = i; lookfor = gimple_get_lhs (s);
