From 84684e0f78c20c51492722a5b95cda778ad77073 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 11 Jan 2021 12:04:32 +0100 Subject: [PATCH] tree-optimization/91403 - avoid excessive code-generation The vectorizer, for large permuted grouped loads, generates inefficient intermediate code (cleaned up only later) that runs into complexity issues in SCEV analysis and elsewhere. For the non-single-element interleaving case we already put a hard limit in place, this applies the same limit to the missing case. 2021-01-11 Richard Biener PR tree-optimization/91403 * tree-vect-data-refs.c (vect_analyze_group_access_1): Cap single-element interleaving group size at 4096 elements. * gcc.dg/vect/pr91403.c: New testcase. --- gcc/testsuite/gcc.dg/vect/pr91403.c | 11 +++++++++++ gcc/tree-vect-data-refs.c | 6 +++++- 2 files changed, 16 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/vect/pr91403.c diff --git a/gcc/testsuite/gcc.dg/vect/pr91403.c b/gcc/testsuite/gcc.dg/vect/pr91403.c new file mode 100644 index 00000000000..5b9b76060ab --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr91403.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-O3" } */ + +extern int a[][1000000]; +int b; +void c() +{ + for (int d = 2; d <= 9; d++) + for (int e = 32; e <= 41; e++) + b += a[d][5]; +} diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c index c71ff7378d2..97c8577ebe7 100644 --- a/gcc/tree-vect-data-refs.c +++ b/gcc/tree-vect-data-refs.c @@ -2538,7 +2538,11 @@ vect_analyze_group_access_1 (vec_info *vinfo, dr_vec_info *dr_info) size. */ if (DR_IS_READ (dr) && (dr_step % type_size) == 0 - && groupsize > 0) + && groupsize > 0 + /* This could be UINT_MAX but as we are generating code in a very + inefficient way we have to cap earlier. + See PR91403 for example. */ + && groupsize <= 4096) { DR_GROUP_FIRST_ELEMENT (stmt_info) = stmt_info; DR_GROUP_SIZE (stmt_info) = groupsize; -- 2.30.2