From 5cbaf84c191b9a3e3cb26545c808d208bdbf2ab5 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Thu, 13 Oct 2022 14:24:05 +0200 Subject: [PATCH] tree-optimization/107160 - avoid reusing multiple accumulators Epilogue vectorization is not set up to re-use a vectorized accumulator consisting of more than one vector. For non-SLP we always reduce to a single but for SLP that isn't happening. In such case we currenlty miscompile the epilog so avoid this. PR tree-optimization/107160 * tree-vect-loop.cc (vect_create_epilog_for_reduction): Do not register accumulator if we failed to reduce it to a single vector. * gcc.dg/vect/pr107160.c: New testcase. --- gcc/testsuite/gcc.dg/vect/pr107160.c | 41 ++++++++++++++++++++++++++++ gcc/tree-vect-loop.cc | 3 +- 2 files changed, 43 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/vect/pr107160.c diff --git a/gcc/testsuite/gcc.dg/vect/pr107160.c b/gcc/testsuite/gcc.dg/vect/pr107160.c new file mode 100644 index 000000000000..4f9f853cafb7 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr107160.c @@ -0,0 +1,41 @@ +/* { dg-do run } */ + +#include + +#define N 128 +float fl[N]; + +__attribute__ ((noipa)) void +init () +{ + for (int i = 0; i < N; i++) + fl[i] = i; +} + +__attribute__ ((noipa)) float +foo (int n1) +{ + float sum0, sum1, sum2, sum3; + sum0 = sum1 = sum2 = sum3 = 0.0f; + + int n = (n1 / 4) * 4; + for (int i = 0; i < n; i += 4) + { + sum0 += fabs (fl[i]); + sum1 += fabs (fl[i + 1]); + sum2 += fabs (fl[i + 2]); + sum3 += fabs (fl[i + 3]); + } + + return sum0 + sum1 + sum2 + sum3; +} + +int +main () +{ + init (); + float res = foo (80); + if (res != 3160) + __builtin_abort (); + return 0; +} diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index 1996ecfee7aa..b1442a935819 100644 --- a/gcc/tree-vect-loop.cc +++ b/gcc/tree-vect-loop.cc @@ -6232,7 +6232,8 @@ vect_create_epilog_for_reduction (loop_vec_info loop_vinfo, } /* Record this operation if it could be reused by the epilogue loop. */ - if (STMT_VINFO_REDUC_TYPE (reduc_info) == TREE_CODE_REDUCTION) + if (STMT_VINFO_REDUC_TYPE (reduc_info) == TREE_CODE_REDUCTION + && vec_num == 1) loop_vinfo->reusable_accumulators.put (scalar_results[0], { orig_reduc_input, reduc_info }); -- 2.43.5