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| author | Olivier Hainque <hainque@adacore.com> | 2008-03-21 13:18:35 +0000 |
|---|---|---|
| committer | Olivier Hainque <hainque@gcc.gnu.org> | 2008-03-21 13:18:35 +0000 |
| commit | f4351641f0c9a8d7d0962da084bb9127ce41bef8 (patch) | |
| tree | 7dd9334039fab5a07642c27136c90dcf452b6bc4 /gcc/ada | |
| parent | 10c5d1a0a8cf531acc940ca357894e807f1b90d8 (diff) | |
| download | gcc-f4351641f0c9a8d7d0962da084bb9127ce41bef8.zip gcc-f4351641f0c9a8d7d0962da084bb9127ce41bef8.tar.gz gcc-f4351641f0c9a8d7d0962da084bb9127ce41bef8.tar.bz2 | |
trans.c (Attribute_to_gnu): Compute as (hb < lb) ? 0 : hb - lb + 1 instead of max (hb - lb + 1, 0).
2008-03-21 Olivier Hainque <hainque@adacore.com>
ada/
* trans.c (Attribute_to_gnu) <'length>: Compute as (hb < lb)
? 0 : hb - lb + 1 instead of max (hb - lb + 1, 0).
testsuite/
* gnat.dg/empty_vector_length.adb: New testcase.
From-SVN: r133423
Diffstat (limited to 'gcc/ada')
| -rw-r--r-- | gcc/ada/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/ada/trans.c | 51 |
2 files changed, 35 insertions, 21 deletions
diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog index a108d89..461cbd1 100644 --- a/gcc/ada/ChangeLog +++ b/gcc/ada/ChangeLog @@ -1,3 +1,8 @@ +2008-03-21 Olivier Hainque <hainque@adacore.com> + + * trans.c (Attribute_to_gnu) <'length>: Compute as (hb < lb) + ? 0 : hb - lb + 1 instead of max (hb - lb + 1, 0). + 2008-03-21 Eric Botcazou <ebotcazou@adacore.com> * trans.c (addressable_p): Add notes on addressability issues. diff --git a/gcc/ada/trans.c b/gcc/ada/trans.c index 9e59373..8bec775 100644 --- a/gcc/ada/trans.c +++ b/gcc/ada/trans.c @@ -1181,33 +1181,42 @@ Attribute_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, int attribute) else /* attribute == Attr_Range_Length || attribute == Attr_Length */ { - tree gnu_compute_type; - if (pa && pa->length) { gnu_result = pa->length; break; } + else + { + tree gnu_compute_type + = signed_or_unsigned_type_for + (0, get_base_type (gnu_result_type)); + + tree index_type + = TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type)); + tree lb + = convert (gnu_compute_type, TYPE_MIN_VALUE (index_type)); + 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_compute_type - = signed_or_unsigned_type_for (0, - get_base_type (gnu_result_type)); - - gnu_result - = build_binary_op - (MAX_EXPR, gnu_compute_type, - build_binary_op - (PLUS_EXPR, gnu_compute_type, - build_binary_op - (MINUS_EXPR, gnu_compute_type, - convert (gnu_compute_type, - TYPE_MAX_VALUE - (TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type)))), - convert (gnu_compute_type, - TYPE_MIN_VALUE - (TYPE_INDEX_TYPE (TYPE_DOMAIN (gnu_type))))), - convert (gnu_compute_type, integer_one_node)), - convert (gnu_compute_type, integer_zero_node)); + gnu_result + = build3 + (COND_EXPR, gnu_compute_type, + build_binary_op (LT_EXPR, gnu_compute_type, hb, lb), + convert (gnu_compute_type, integer_zero_node), + build_binary_op + (PLUS_EXPR, gnu_compute_type, + build_binary_op (MINUS_EXPR, gnu_compute_type, hb, lb), + convert (gnu_compute_type, integer_one_node))); + } } /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are |