OK.
On Wed, Apr 17, 2019 at 11:25 PM Jakub Jelinek <ja...@redhat.com> wrote:
>
> Hi!
>
> As reported, the newly added testcase ICEs with --param ggc-min-heapsize=0.
> The problem is that while the remove type is not referenced by anything
> else, it is a distinct type created to hold the attributes, there is another
> type with TYPE_NAME equal to the newdecl we want to tree. That one is
> created in common_handle_aligned_attribute:
> {
> if ((flags & (int) ATTR_FLAG_TYPE_IN_PLACE))
> /* OK, modify the type in place. */;
> /* If we have a TYPE_DECL, then copy the type, so that we
> don't accidentally modify a builtin type. See pushdecl. */
> else if (decl && TREE_TYPE (decl) != error_mark_node
> && DECL_ORIGINAL_TYPE (decl) == NULL_TREE)
> {
> tree tt = TREE_TYPE (decl);
> *type = build_variant_type_copy (*type);
> DECL_ORIGINAL_TYPE (decl) = tt;
> TYPE_NAME (*type) = decl;
> TREE_USED (*type) = TREE_USED (decl);
> TREE_TYPE (decl) = *type;
> }
> else
> *type = build_variant_type_copy (*type);
> where we create a variant type and set the TYPE_NAME too. I've tried to
> remove that else if ... and just do *type = build_variant_type_copy (*type);
> but that regressed some DWARF DW_AT_alignment tests.
>
> So, the following patch instead removes the remove type from the variants
> list if it is not a main variant (as before), otherwise tries to find in
> TYPE_MAIN_VARIANT (DECL_ORIGINAL_TYPE (newdecl)) variant list a type
> with TYPE_NAME equal to newdecl and remove that one.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2019-04-18 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/90108
> * c-decl.c (merge_decls): If remove is main variant and
> DECL_ORIGINAL_TYPE is some other type, remove a DECL_ORIGINAL_TYPE
> variant that has newdecl as TYPE_NAME if any.
>
> * decl.c (duplicate_decls): If remove is main variant and
> DECL_ORIGINAL_TYPE is some other type, remove a DECL_ORIGINAL_TYPE
> variant that has newdecl as TYPE_NAME if any.
>
> * c-c++-common/pr90108.c: New test.
>
> --- gcc/c/c-decl.c.jj 2019-04-17 21:21:39.936133112 +0200
> +++ gcc/c/c-decl.c 2019-04-17 23:25:08.098936888 +0200
> @@ -2513,7 +2513,24 @@ merge_decls (tree newdecl, tree olddecl,
> {
> tree remove = TREE_TYPE (newdecl);
> if (TYPE_MAIN_VARIANT (remove) == remove)
> - gcc_assert (TYPE_NEXT_VARIANT (remove) == NULL_TREE);
> + {
> + gcc_assert (TYPE_NEXT_VARIANT (remove) == NULL_TREE);
> + /* If remove is the main variant, no need to remove that
> + from the list. One of the DECL_ORIGINAL_TYPE
> + variants, e.g. created for aligned attribute, might still
> + refer to the newdecl TYPE_DECL though, so remove that one
> + in that case. */
> + if (DECL_ORIGINAL_TYPE (newdecl)
> + && DECL_ORIGINAL_TYPE (newdecl) != remove)
> + for (tree t = TYPE_MAIN_VARIANT (DECL_ORIGINAL_TYPE
> (newdecl));
> + t; t = TYPE_MAIN_VARIANT (t))
> + if (TYPE_NAME (TYPE_NEXT_VARIANT (t)) == newdecl)
> + {
> + TYPE_NEXT_VARIANT (t)
> + = TYPE_NEXT_VARIANT (TYPE_NEXT_VARIANT (t));
> + break;
> + }
> + }
> else
> for (tree t = TYPE_MAIN_VARIANT (remove); ;
> t = TYPE_NEXT_VARIANT (t))
> --- gcc/cp/decl.c.jj 2019-04-17 21:21:39.753136091 +0200
> +++ gcc/cp/decl.c 2019-04-17 23:27:13.995875527 +0200
> @@ -2133,7 +2133,24 @@ next_arg:;
> {
> tree remove = TREE_TYPE (newdecl);
> if (TYPE_MAIN_VARIANT (remove) == remove)
> - gcc_assert (TYPE_NEXT_VARIANT (remove) == NULL_TREE);
> + {
> + gcc_assert (TYPE_NEXT_VARIANT (remove) == NULL_TREE);
> + /* If remove is the main variant, no need to remove that
> + from the list. One of the DECL_ORIGINAL_TYPE
> + variants, e.g. created for aligned attribute, might still
> + refer to the newdecl TYPE_DECL though, so remove that one
> + in that case. */
> + if (tree orig = DECL_ORIGINAL_TYPE (newdecl))
> + if (orig != remove)
> + for (tree t = TYPE_MAIN_VARIANT (orig); t;
> + t = TYPE_MAIN_VARIANT (t))
> + if (TYPE_NAME (TYPE_NEXT_VARIANT (t)) == newdecl)
> + {
> + TYPE_NEXT_VARIANT (t)
> + = TYPE_NEXT_VARIANT (TYPE_NEXT_VARIANT (t));
> + break;
> + }
> + }
> else
> for (tree t = TYPE_MAIN_VARIANT (remove); ;
> t = TYPE_NEXT_VARIANT (t))
> --- gcc/testsuite/c-c++-common/pr90108.c.jj 2019-04-17 23:18:23.466566296
> +0200
> +++ gcc/testsuite/c-c++-common/pr90108.c 2019-04-17 23:18:23.466566296
> +0200
> @@ -0,0 +1,6 @@
> +/* PR c++/90108 */
> +/* { dg-do compile } */
> +/* { dg-options "--param ggc-min-heapsize=0" } */
> +
> +typedef unsigned int a __attribute__ ((__aligned__(8), __may_alias__));
> +typedef unsigned int a __attribute__ ((__aligned__(8), __may_alias__));
>
> Jakub
