The following fixes how during reduction epilogue generation we gather conditional compares for condition reductions, thereby following the reduction chain via STMT_VINFO_REDUC_IDX. The issue is that SLP nodes for COND_EXPRs can have either three or four children dependent on whether we have legacy GENERIC expressions in the transitional pattern GIMPLE for the COND_EXPR condition.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed. PR tree-optimization/115959 * tree-vect-loop.cc (vect_create_epilog_for_reduction): Get at the REDUC_IDX child in a safer way for COND_EXPR nodes. * gcc.dg/vect/pr115959.c: New testcase. --- gcc/testsuite/gcc.dg/vect/pr115959.c | 14 ++++++++++++++ gcc/tree-vect-loop.cc | 10 +++++++--- 2 files changed, 21 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/vect/pr115959.c diff --git a/gcc/testsuite/gcc.dg/vect/pr115959.c b/gcc/testsuite/gcc.dg/vect/pr115959.c new file mode 100644 index 00000000000..181d5522018 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr115959.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ + +int a; +_Bool *b; +void f() +{ + int t = a; + for (int e = 0; e < 2048; e++) + { + if (!b[e]) + t = 0; + } + a = t; +} diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index 2d68db613f8..191a37a1e1a 100644 --- a/gcc/tree-vect-loop.cc +++ b/gcc/tree-vect-loop.cc @@ -6107,9 +6107,13 @@ vect_create_epilog_for_reduction (loop_vec_info loop_vinfo, (std::make_pair (gimple_assign_rhs1 (vec_stmt), STMT_VINFO_REDUC_IDX (cond_info) == 2)); } - /* ??? We probably want to have REDUC_IDX on the SLP node? */ - cond_node = SLP_TREE_CHILDREN - (cond_node)[STMT_VINFO_REDUC_IDX (cond_info)]; + /* ??? We probably want to have REDUC_IDX on the SLP node? + We have both three and four children COND_EXPR nodes + dependent on whether the comparison is still embedded + as GENERIC. So work backwards. */ + int slp_reduc_idx = (SLP_TREE_CHILDREN (cond_node).length () - 3 + + STMT_VINFO_REDUC_IDX (cond_info)); + cond_node = SLP_TREE_CHILDREN (cond_node)[slp_reduc_idx]; } } else -- 2.35.3