https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84217
--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
Tentative patch:
...
diff --git a/gcc/omp-expand.c b/gcc/omp-expand.c
index 90e0631..bb20490 100644
--- a/gcc/omp-expand.c
+++ b/gcc/omp-expand.c
@@ -1433,6 +1433,8 @@ expand_oacc_collapse_init (const struct omp_for_data *fd,
plus_type = sizetype;
if (POINTER_TYPE_P (diff_type) || TYPE_UNSIGNED (diff_type))
diff_type = signed_type_for (diff_type);
+ if (TYPE_PRECISION (diff_type) < TYPE_PRECISION (integer_type_node))
+ diff_type = integer_type_node;
if (tiling)
{
...
