https://gcc.gnu.org/g:1990e6544b9f0db39c470b999c32d2ecdd419f46
commit r13-10355-g1990e6544b9f0db39c470b999c32d2ecdd419f46 Author: Richard Biener <[email protected]> Date: Wed Sep 13 11:04:31 2023 +0200 tree-optimization/111387 - BB SLP and irreducible regions When we split an irreducible region for BB vectorization analysis the defensive handling of external backedge defs in vect_get_and_check_slp_defs doesn't work since that relies on dominance info to identify a backedge. The testcase also shows we are iterating over the function in a sub-optimal way which is why we split the irreducible region in the first place. The fix is to mark backedges and use EDGE_DFS_BACK to identify them. PR tree-optimization/111387 * tree-vect-slp.cc (vect_get_and_check_slp_defs): Check EDGE_DFS_BACK when doing BB vectorization. (vect_slp_function): Mark backedges. * gcc.dg/torture/pr111387.c: New testcase. Diff: --- gcc/testsuite/gcc.dg/torture/pr111387.c | 34 +++++++++++++++++++++++++++++++++ gcc/tree-vect-slp.cc | 11 ++++++++--- 2 files changed, 42 insertions(+), 3 deletions(-) diff --git a/gcc/testsuite/gcc.dg/torture/pr111387.c b/gcc/testsuite/gcc.dg/torture/pr111387.c new file mode 100644 index 000000000000..e14eeef6e4ad --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr111387.c @@ -0,0 +1,34 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-ftree-vectorize -fno-vect-cost-model" } */ + +struct { + unsigned a; + unsigned b; +} c; +int d, e, f, g, h; +int main() +{ + if (c.b && g && g > 7) + goto i; + j: + if (c.a) { + int k = 0; + unsigned l = c.b; + if (0) { + m: + k = l = c.b; + } + c.a = k; + c.b = l; + } + if (0) { + i: + goto m; + } + if (d) + goto j; + for (f = 5; f; f--) + if (h) + e = 0; + return 0; +} diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc index d5b114dbcc9c..19050c2c164a 100644 --- a/gcc/tree-vect-slp.cc +++ b/gcc/tree-vect-slp.cc @@ -594,9 +594,13 @@ vect_get_and_check_slp_defs (vec_info *vinfo, unsigned char swap, { oprnd = gimple_arg (stmt_info->stmt, opno); if (gphi *stmt = dyn_cast <gphi *> (stmt_info->stmt)) - backedge = dominated_by_p (CDI_DOMINATORS, - gimple_phi_arg_edge (stmt, opno)->src, - gimple_bb (stmt_info->stmt)); + { + edge e = gimple_phi_arg_edge (stmt, opno); + backedge = (is_a <bb_vec_info> (vinfo) + ? e->flags & EDGE_DFS_BACK + : dominated_by_p (CDI_DOMINATORS, e->src, + gimple_bb (stmt_info->stmt))); + } } if (TREE_CODE (oprnd) == VIEW_CONVERT_EXPR) oprnd = TREE_OPERAND (oprnd, 0); @@ -7678,6 +7682,7 @@ vect_slp_function (function *fun) bool r = false; int *rpo = XNEWVEC (int, n_basic_blocks_for_fn (fun)); unsigned n = pre_and_rev_post_order_compute_fn (fun, NULL, rpo, false); + mark_dfs_back_edges (fun); /* For the moment split the function into pieces to avoid making the iteration on the vector mode moot. Split at points we know
