This makes sure to detect overflow when computing DR_GROUP_GAP
and DR_GROUP_SIZE more thoroughly so artificial testcases like the
added one are not fooling the existing check.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
2022-01-05 Richard Biener <rguent...@suse.de>
PR tree-optimization/103816
* tree-vect-data-refs.c (vect_analyze_group_access_1): Also
check DR_GROUP_GAP compute for overflow and representability.
* gcc.dg/torture/pr103816.c: New testcase.
---
gcc/testsuite/gcc.dg/torture/pr103816.c | 10 ++++++++++
gcc/tree-vect-data-refs.c | 15 ++++++++++++++-
2 files changed, 24 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr103816.c
diff --git a/gcc/testsuite/gcc.dg/torture/pr103816.c
b/gcc/testsuite/gcc.dg/torture/pr103816.c
new file mode 100644
index 00000000000..769036a1af8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr103816.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-w" } */
+
+extern struct {
+ unsigned char a;
+ unsigned char b;
+ unsigned char c;
+ unsigned char d;
+} g[];
+void main() { g[0].b = (g[0].b & g[4].b) * g[2305843009213693952ULL].c; }
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index 2b3ec6289de..dd20ed974af 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -2721,7 +2721,20 @@ vect_analyze_group_access_1 (vec_info *vinfo,
dr_vec_info *dr_info)
/* Check that the distance between two accesses is equal to the type
size. Otherwise, we have gaps. */
diff = (TREE_INT_CST_LOW (DR_INIT (data_ref))
- - TREE_INT_CST_LOW (prev_init)) / type_size;
+ - TREE_INT_CST_LOW (prev_init)) / type_size;
+ if (diff < 1 || diff > UINT_MAX)
+ {
+ /* For artificial testcases with array accesses with large
+ constant indices we can run into overflow issues which
+ can end up fooling the groupsize constraint below so
+ check the individual gaps (which are represented as
+ unsigned int) as well. */
+ if (dump_enabled_p ())
+ dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+ "interleaved access with gap larger "
+ "than representable\n");
+ return false;
+ }
if (diff != 1)
{
/* FORNOW: SLP of accesses with gaps is not supported. */
--
2.31.1
