From e34495985e49545c468e664ee10bd0e66c7395bf Mon Sep 17 00:00:00 2001 From: Eric Botcazou Date: Fri, 8 May 2020 17:18:20 +0200 Subject: Fix uniqueness of address for aliased objects Two aliased objects must have distinct addresses, even if they have size zero, so we make sure to allocate at least one byte for them. * gcc-interface/decl.c (gnat_to_gnu_entity) : Force at least the unit size for an aliased object of a constrained nominal subtype whose size is variable. --- gcc/ada/gcc-interface/decl.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'gcc/ada/gcc-interface') diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c index a4053ee..9c1acd9 100644 --- a/gcc/ada/gcc-interface/decl.c +++ b/gcc/ada/gcc-interface/decl.c @@ -969,10 +969,19 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, bool definition) align = MINIMUM_ATOMIC_ALIGNMENT; #endif - /* Make a new type with the desired size and alignment, if needed. - But do not take into account alignment promotions to compute the - size of the object. */ + /* Do not take into account aliased adjustments or alignment promotions + to compute the size of the object. */ tree gnu_object_size = gnu_size ? gnu_size : TYPE_SIZE (gnu_type); + + /* If the object is aliased, of a constrained nominal subtype and its + size might be zero at run time, we force at least the unit size. */ + if (Is_Aliased (gnat_entity) + && !Is_Constr_Subt_For_UN_Aliased (gnat_type) + && Is_Array_Type (Underlying_Type (gnat_type)) + && !TREE_CONSTANT (gnu_object_size)) + gnu_size = size_binop (MAX_EXPR, gnu_object_size, bitsize_unit_node); + + /* Make a new type with the desired size and alignment, if needed. */ if (gnu_size || align > 0) { tree orig_type = gnu_type; -- cgit v1.1