diff options
Diffstat (limited to 'gcc/ada/trans.c')
| -rw-r--r-- | gcc/ada/trans.c | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/gcc/ada/trans.c b/gcc/ada/trans.c index cb0e8c6..07bdc69 100644 --- a/gcc/ada/trans.c +++ b/gcc/ada/trans.c @@ -1234,9 +1234,16 @@ Attribute_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, int attribute) } else { - tree gnu_compute_type - = signed_or_unsigned_type_for - (0, get_base_type (gnu_result_type)); + /* We used to compute the length as max (hb - lb + 1, 0), + which could overflow for some cases of empty arrays, e.g. + when lb == index_type'first. We now compute the length as + (hb < lb) ? 0 : hb - lb + 1, which would only overflow in + much rarer cases, for extremely large arrays we expect + never to encounter in practice. In addition, the former + computation required the use of potentially constraining + signed arithmetic while the latter doesn't. */ + + tree gnu_compute_type = get_base_type (gnu_result_type); tree index_type = TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type)); @@ -1245,14 +1252,6 @@ Attribute_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, int attribute) tree hb = convert (gnu_compute_type, TYPE_MAX_VALUE (index_type)); - /* We used to compute the length as max (hb - lb + 1, 0), - which could overflow for some cases of empty arrays, e.g. - when lb == index_type'first. - - We now compute it as (hb < lb) ? 0 : hb - lb + 1, which - could overflow as well, but only for extremely large arrays - which we expect never to encounter in practice. */ - gnu_result = build3 (COND_EXPR, gnu_compute_type, |