We can at least mimic single def-use cycle optimization when doing single-lane SLP reductions and that's required to avoid regressing compared to non-SLP.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress. I've noticed this when looking at PR115438 but the fix doesn't help there. * tree-vect-loop.cc (vectorizable_reduction): Allow single-def-use cycles with SLP. (vect_transform_reduction): Handle SLP single def-use cycles. (vect_transform_cycle_phi): Likewise. * gcc.dg/vect/slp-reduc-12.c: New testcase. --- gcc/testsuite/gcc.dg/vect/slp-reduc-12.c | 18 +++++++++ gcc/tree-vect-loop.cc | 48 +++++++++++++++--------- 2 files changed, 48 insertions(+), 18 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/vect/slp-reduc-12.c diff --git a/gcc/testsuite/gcc.dg/vect/slp-reduc-12.c b/gcc/testsuite/gcc.dg/vect/slp-reduc-12.c new file mode 100644 index 00000000000..625f8097c54 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/slp-reduc-12.c @@ -0,0 +1,18 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target vect_double } */ +/* { dg-require-effective-target vect_int } */ +/* { dg-require-effective-target vect_hw_misalign } */ +/* { dg-additional-options "-Ofast" } */ + +double foo (double *x, int * __restrict a, int n) +{ + double r = 0.; + for (int i = 0; i < n; ++i) + { + a[i] = a[i] + i; + r += x[i]; + } + return r; +} + +/* { dg-final { scan-tree-dump "using single def-use cycle for reduction" "vect" } } */ diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index 8f5ac426790..b0a3f77c1ca 100644 --- a/gcc/tree-vect-loop.cc +++ b/gcc/tree-vect-loop.cc @@ -8337,7 +8337,11 @@ vectorizable_reduction (loop_vec_info loop_vinfo, participating. When unrolling we want each unrolled iteration to have its own reduction accumulator since one of the main goals of unrolling a reduction is to reduce the aggregate loop-carried latency. */ - if (ncopies > 1 + if ((ncopies > 1 + || (slp_node + && !REDUC_GROUP_FIRST_ELEMENT (stmt_info) + && SLP_TREE_LANES (slp_node) == 1 + && vect_get_num_copies (loop_vinfo, vectype_in) > 1)) && (STMT_VINFO_RELEVANT (stmt_info) <= vect_used_only_live) && reduc_chain_length == 1 && loop_vinfo->suggested_unroll_factor == 1) @@ -8390,6 +8394,10 @@ vectorizable_reduction (loop_vec_info loop_vinfo, single_defuse_cycle = false; } } + if (dump_enabled_p () && single_defuse_cycle) + dump_printf_loc (MSG_NOTE, vect_location, + "using single def-use cycle for reduction by reducing " + "multiple vectors to one in the loop body\n"); STMT_VINFO_FORCE_SINGLE_CYCLE (reduc_info) = single_defuse_cycle; /* If the reduction stmt is one of the patterns that have lane @@ -8545,9 +8553,8 @@ vect_transform_reduction (loop_vec_info loop_vinfo, { tree vectype_out = STMT_VINFO_VECTYPE (stmt_info); class loop *loop = LOOP_VINFO_LOOP (loop_vinfo); - int i; - int ncopies; - int vec_num; + unsigned ncopies; + unsigned vec_num; stmt_vec_info reduc_info = info_for_reduction (loop_vinfo, stmt_info); gcc_assert (reduc_info->is_reduc_info); @@ -8594,7 +8601,6 @@ vect_transform_reduction (loop_vec_info loop_vinfo, auto_vec<tree> vec_oprnds0; auto_vec<tree> vec_oprnds1; auto_vec<tree> vec_oprnds2; - tree def0; if (dump_enabled_p ()) dump_printf_loc (MSG_NOTE, vect_location, "transform reduction.\n"); @@ -8669,20 +8675,24 @@ vect_transform_reduction (loop_vec_info loop_vinfo, definition. */ if (single_defuse_cycle) { - gcc_assert (!slp_node); - vect_get_vec_defs_for_operand (loop_vinfo, stmt_info, 1, - op.ops[reduc_index], - reduc_index == 0 ? &vec_oprnds0 - : (reduc_index == 1 ? &vec_oprnds1 - : &vec_oprnds2)); + vect_get_vec_defs (loop_vinfo, stmt_info, slp_node, 1, + !(single_defuse_cycle && reduc_index == 0) + ? NULL_TREE : op.ops[0], &vec_oprnds0, + !(single_defuse_cycle && reduc_index == 1) + ? NULL_TREE : op.ops[1], &vec_oprnds1, + op.num_ops == 3 + && (single_defuse_cycle && reduc_index == 2) + ? op.ops[2] : NULL_TREE, &vec_oprnds2); } bool emulated_mixed_dot_prod = vect_is_emulated_mixed_dot_prod (stmt_info); - FOR_EACH_VEC_ELT (vec_oprnds0, i, def0) + unsigned num = (reduc_index == 0 + ? vec_oprnds1.length () : vec_oprnds0.length ()); + for (unsigned i = 0; i < num; ++i) { gimple *new_stmt; - tree vop[3] = { def0, vec_oprnds1[i], NULL_TREE }; + tree vop[3] = { vec_oprnds0[i], vec_oprnds1[i], NULL_TREE }; if (masked_loop_p && !mask_by_cond_expr) { /* No conditional ifns have been defined for dot-product yet. */ @@ -8737,10 +8747,7 @@ vect_transform_reduction (loop_vec_info loop_vinfo, vect_finish_stmt_generation (loop_vinfo, stmt_info, new_stmt, gsi); } - if (slp_node) - slp_node->push_vec_def (new_stmt); - else if (single_defuse_cycle - && i < ncopies - 1) + if (single_defuse_cycle && i < num - 1) { if (reduc_index == 0) vec_oprnds0.safe_push (gimple_get_lhs (new_stmt)); @@ -8749,6 +8756,8 @@ vect_transform_reduction (loop_vec_info loop_vinfo, else if (reduc_index == 2) vec_oprnds2.safe_push (gimple_get_lhs (new_stmt)); } + else if (slp_node) + slp_node->push_vec_def (new_stmt); else STMT_VINFO_VEC_STMTS (stmt_info).safe_push (new_stmt); } @@ -8812,7 +8821,10 @@ vect_transform_cycle_phi (loop_vec_info loop_vinfo, /* Check whether we should use a single PHI node and accumulate vectors to one before the backedge. */ if (STMT_VINFO_FORCE_SINGLE_CYCLE (reduc_info)) - ncopies = 1; + { + ncopies = 1; + vec_num = 1; + } /* Create the destination vector */ gphi *phi = as_a <gphi *> (stmt_info->stmt); -- 2.35.3