On Wed, 7 Nov 2018, Jan Hubicka wrote:
> Hi,
> this patch enables bit more merging by clearing more flags that are
> unnecesary and differ in practice across different copies of same ODR
> types.
>
> lto-bootstrapped/regtested x86_64-linux, OK?
> * tree.c (fld_incomplete_type_of): Clear TREE_ADDRESSABLE flag.
> (free_lang_data_in_decl): Set TREE_ADDRESSABLE for public functions
> and variables; clear DECL_EXTERNAL, TYPE_DECL_SUPPRESS_DEBUG and
> DECL_MODE on TYPE_DECLs.
> Index: tree.c
> ===================================================================
> --- tree.c (revision 265875)
> +++ tree.c (working copy)
> @@ -5197,6 +5197,7 @@ fld_incomplete_type_of (tree t, struct f
> TYPE_SIZE_UNIT (copy) = NULL;
> TYPE_CANONICAL (copy) = TYPE_CANONICAL (t);
> TYPE_TYPELESS_STORAGE (copy) = 0;
> + TREE_ADDRESSABLE (copy) = 0;
> if (AGGREGATE_TYPE_P (t))
> {
> TYPE_FIELDS (copy) = NULL;
> @@ -5496,6 +5497,17 @@ free_lang_data_in_decl (tree decl, struc
> if (TREE_CODE (decl) == FUNCTION_DECL)
> {
> struct cgraph_node *node;
> + /* Frontends do not set TREE_ADDRESSABLE on public variables even
> though
> + the address may be taken in other unit, so this flag has no practical
> + use for middle-end.
> +
> + It would make more sense if frontends set TREE_ADDRESSABLE to 0 only
> + for public objects that indeed can not be adressed, but it is not
> + the case. Set the flag to true so we do not get merge failures for
> + i.e. virtual tables between units that take address of it and
> + units that don't. */
> + if (TREE_PUBLIC (decl))
> + TREE_ADDRESSABLE (decl) = true;
> TREE_TYPE (decl) = fld_simplified_type (TREE_TYPE (decl), fld);
> if (!(node = cgraph_node::get (decl))
> || (!node->definition && !node->clones))
> @@ -5551,6 +5563,9 @@ free_lang_data_in_decl (tree decl, struc
> }
> else if (VAR_P (decl))
> {
> + /* See comment above why we set the flag for functions. */
> + if (TREE_PUBLIC (decl))
> + TREE_ADDRESSABLE (decl) = true;
> if ((DECL_EXTERNAL (decl)
> && (!TREE_STATIC (decl) || !TREE_READONLY (decl)))
> || (decl_function_context (decl) && !TREE_STATIC (decl)))
> @@ -5560,8 +5575,12 @@ free_lang_data_in_decl (tree decl, struc
> {
> DECL_VISIBILITY (decl) = VISIBILITY_DEFAULT;
> DECL_VISIBILITY_SPECIFIED (decl) = 0;
> + /* TREE_PUBLIC is used to tell if type is anonymous. */
> + DECL_EXTERNAL (decl) = 0;
> + TYPE_DECL_SUPPRESS_DEBUG (decl) = 0;
DECL_EXTERNAL and TYPE_DECL_SUPPRESS_DEBUG map to the same decl_flag_1 ...
so I'd say you should use TYPE_DECL_SUPPRESS_DEBUG only here.
> DECL_INITIAL (decl) = NULL_TREE;
> DECL_ORIGINAL_TYPE (decl) = NULL_TREE;
> + DECL_MODE (decl) = VOIDmode;
> TREE_TYPE (decl) = void_type_node;
> SET_DECL_ALIGN (decl, 0);
> }
OK with that change.
Thanks,
Richard.
