https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100471
--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:49bfa539e240cd769179751f18c472f9a4ea2248 commit r10-10608-g49bfa539e240cd769179751f18c472f9a4ea2248 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue May 11 09:07:47 2021 +0200 openmp: Fix up taskloop reduction ICE if taskloop has no iterations [PR100471] When a taskloop doesn't have any iterations, GOMP_taskloop* takes an early return, doesn't create any tasks and more importantly, doesn't create a taskgroup and doesn't register task reductions. But, the code emitted in the callers assumes task reductions have been registered and performs the reduction handling and task reduction unregistration. The pointer to the task reduction private variables is reused, on input it is the alignment and only on output it is the pointer, so in the case taskloop with no iterations the caller attempts to dereference the alignment value as if it was a pointer and crashes. We could in the early returns register the task reductions only to have them looped over and unregistered in the caller, but I think it is better to tell the caller there is nothing to task reduce and bypass all that. 2021-05-11 Jakub Jelinek <ja...@redhat.com> PR middle-end/100471 * omp-low.c (lower_omp_task_reductions): For OMP_TASKLOOP, if data is 0, bypass the reduction loop including GOMP_taskgroup_reduction_unregister call. * taskloop.c (GOMP_taskloop): If GOMP_TASK_FLAG_REDUCTION and not GOMP_TASK_FLAG_NOGROUP, when doing early return clear the task reduction pointer. * testsuite/libgomp.c/task-reduction-4.c: New test. (cherry picked from commit 98acbb3111fcb5e57d5e63d46c0d92f4e53e3c2a)
