https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111017
Bug ID: 111017
Summary: [OpenMP] Wrong code with non-rectangular loop nest
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: openmp, wrong-code
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: burnus at gcc dot gnu.org
CC: jakub at gcc dot gnu.org
Target Milestone: ---
At a glance, the following looks fine to me - but it fails with UBSAN as
follows:
test.c:10:15: runtime error: index -42 out of bounds for type 'int [1024]'
test.c:10:8: runtime error: index -42 out of bounds for type 'int [1024]'
=================================================================
==619433==ERROR: AddressSanitizer: stack-buffer-overflow on address
0x7f2942e01060 at pc 0x000000401856 bp 0x7f29415fecb0 sp 0x7f29415feca8
READ of size 4 at 0x7f2942e01060 thread T1
test.c:10:22: runtime error: index -4210096 out of bounds for type 'int [1024]'
#define DIM 32
#define N (DIM*DIM)
int
main() {
int a[N] = {}, b[N] = {}, c[N];
#pragma omp parallel for collapse(2)
for (int i = 0; i < DIM; i++) {
for (int j = (i*DIM); j < (i*DIM + DIM); j++) {
c[j] = a[j] + b[j];
}
}
}
Longer version using 'target teams loop', which segfault here (w/o offloading
configured + w/o UBSAN):
https://github.com/SOLLVE/sollve_vv/blob/master/tests/5.0/teams_loop/test_target_teams_loop_collapse.c
