https://gcc.gnu.org/g:8fe64e4d9cd22f7638fc590353c34c79b07f428f
commit r16-1959-g8fe64e4d9cd22f7638fc590353c34c79b07f428f
Author: Eric Botcazou <ebotca...@adacore.com>
Date: Thu Jun 12 22:31:06 2025 +0200
ada: Enforce alignment constraint for large Object_Size clauses
The constraint is that the Object_Size must be a multiple of the alignment
in bits. But it's enforced only when the value of the clause is lower than
the Value_Size rounded up to the alignment in bits, not for larger values.
gcc/ada/ChangeLog:
* gcc-interface/decl.cc (gnat_to_gnu_entity): Use default messages
for errors reported for Object_Size clauses.
(validate_size): Give an error for stand-alone objects of composite
types if the specified size is not a multiple of the alignment.
Diff:
---
gcc/ada/gcc-interface/decl.cc | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/gcc/ada/gcc-interface/decl.cc b/gcc/ada/gcc-interface/decl.cc
index 1d9832d69ad4..27d2cea1f3d2 100644
--- a/gcc/ada/gcc-interface/decl.cc
+++ b/gcc/ada/gcc-interface/decl.cc
@@ -4502,7 +4502,7 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr,
bool definition)
if (Known_Esize (gnat_entity))
gnu_size
= validate_size (Esize (gnat_entity), gnu_type, gnat_entity,
- VAR_DECL, false, false, size_s, type_s);
+ VAR_DECL, false, false, NULL, NULL);
/* ??? The test on Has_Size_Clause must be removed when "unknown" is
no longer represented as Uint_0 (i.e. Use_New_Unknown_Rep). */
@@ -9696,6 +9696,20 @@ validate_size (Uint uint_size, tree gnu_type, Entity_Id
gnat_object,
return NULL_TREE;
}
+ /* The size of stand-alone objects is always a multiple of the alignment,
+ but that's already enforced for elementary types by the front-end. */
+ if (kind == VAR_DECL
+ && !component_p
+ && RECORD_OR_UNION_TYPE_P (gnu_type)
+ && !TYPE_FAT_POINTER_P (gnu_type)
+ && !integer_zerop (size_binop (TRUNC_MOD_EXPR, size,
+ bitsize_int (TYPE_ALIGN (gnu_type)))))
+ {
+ post_error_ne_num ("size for& must be multiple of alignment ^",
+ gnat_error_node, gnat_object, TYPE_ALIGN (gnu_type));
+ return NULL_TREE;
+ }
+
return size;
}
