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Re: Ada and TBAA and arrays vs. VIEW_CONVERT_EXPRs
> Right, the patch is small though, I'll install it later today.
Tested on i586-suse-linux, applied on the mainline.
2009-02-09 Eric Botcazou <ebotcazou@adacore.com>
* gcc-interface/decl.c (gnat_to_gnu_entity) <E_String_Literal_Subtype>:
Set TYPE_NONALIASED_COMPONENT on the array type only if appropriate.
(copy_alias_set): Assert that arrays have the same aliasing settings.
(substitute_in_type) <ARRAY_TYPE>: Copy TYPE_NONALIASED_COMPONENT.
--
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c (revision 144029)
+++ gcc-interface/decl.c (working copy)
@@ -2615,8 +2615,9 @@ gnat_to_gnu_entity (Entity_Id gnat_entit
gnu_type
= build_array_type (gnat_to_gnu_type (Component_Type (gnat_entity)),
gnu_index_type);
- TYPE_NONALIASED_COMPONENT (gnu_type) = 1;
- copy_alias_set (gnu_type, gnu_string_type);
+ if (array_type_has_nonaliased_component (gnat_entity, gnu_type))
+ TYPE_NONALIASED_COMPONENT (gnu_type) = 1;
+ copy_alias_set (gnu_type, gnu_string_type);
}
break;
@@ -5184,6 +5185,17 @@ copy_alias_set (tree gnu_new_type, tree
&& TYPE_MULTI_ARRAY_P (TREE_TYPE (gnu_new_type)))
copy_alias_set (TREE_TYPE (gnu_new_type), TREE_TYPE (gnu_old_type));
+ /* The alias set shouldn't be copied between array types with different
+ aliasing settings because this can break the aliasing relationship
+ between the array type and its element type. */
+#ifndef ENABLE_CHECKING
+ if (flag_strict_aliasing)
+#endif
+ gcc_assert (!(TREE_CODE (gnu_new_type) == ARRAY_TYPE
+ && TREE_CODE (gnu_old_type) == ARRAY_TYPE
+ && TYPE_NONALIASED_COMPONENT (gnu_new_type)
+ != TYPE_NONALIASED_COMPONENT (gnu_old_type)));
+
TYPE_ALIAS_SET (gnu_new_type) = get_alias_set (gnu_old_type);
record_component_aliases (gnu_new_type);
}
@@ -7510,6 +7522,7 @@ substitute_in_type (tree t, tree f, tree
new = build_array_type (component, domain);
TYPE_SIZE (new) = 0;
+ TYPE_NONALIASED_COMPONENT (new) = TYPE_NONALIASED_COMPONENT (t);
TYPE_MULTI_ARRAY_P (new) = TYPE_MULTI_ARRAY_P (t);
TYPE_CONVENTION_FORTRAN_P (new) = TYPE_CONVENTION_FORTRAN_P (t);
layout_type (new);