>
> It's now no longer necessary to preserve type related stuff for debug
> reasons so the following forgos with streaming TYPE_DECLs in TYPE_FIELDS,
> TYPE_DECLs for TYPE_NAME (where not necessary) and also BINFOs when
> not needed for devirtualization.
>
> I noticed the unpatched code
>
> if (TYPE_BINFO (type))
> {
> free_lang_data_in_binfo (TYPE_BINFO (type));
> /* We need to preserve link to bases and virtual table for all
> polymorphic types to make devirtualization machinery working.
> Debug output cares only about bases, but output also
> virtual table pointers so merging of -fdevirtualize and
> -fno-devirtualize units is easier. */
> if ((!BINFO_VTABLE (TYPE_BINFO (type))
> || !flag_devirtualize)
> && ((!BINFO_N_BASE_BINFOS (TYPE_BINFO (type))
> && !BINFO_VTABLE (TYPE_BINFO (type)))
> || debug_info_level != DINFO_LEVEL_NONE))
> TYPE_BINFO (type) = NULL;
> }
>
> where the condition
>
> && ((!BINFO_N_BASE_BINFOS (TYPE_BINFO (type))
> && !BINFO_VTABLE (TYPE_BINFO (type)))
> || debug_info_level != DINFO_LEVEL_NONE))
>
> makes no sense to me -- it implies that when -g is enabled we'll
> clear TYPE_BINFO but not with -g0 unless
> (!BINFO_N_BASE_BINFOS (TYPE_BINFO (type)) && !BINFO_VTABLE (TYPE_BINFO
> (type)).
The first part of conditional is testing when flag_devirtualize may need binfo
(when there is vtable). Second part is about when late dwarf2out was
accessing binfos (when there was bases) but indeed debug_info_level test
seems to be backwards.
I think the change is OK.
Honza
>
> I concluded this second condition is basically dead code (and at most
> prevented BINFO related debug for LTO), so I dropped it as well as the
> comment talking about the merging of -fdevirtualize vs. -fno-devirtualize.
> If I'd just remove the debug_info_level condition we'd end up with
>
> if (!BINFO_VTABLE (TYPE_BINFO (type))
> && !BINFO_N_BASE_BINFOS (TYPE_BINFO (type)))
> TYPE_BINFO (type) = NULL;
>
> which is not -fdevirtualize conditional anymore.
>
> Honza - can you shed light on the original intent?
>
> LTO bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
>
> Thanks,
> Richard.
>
> 2018-01-11 Richard Biener <rguent...@suse.de>
>
> * tree.c (free_lang_data_in_type): Always unlink TYPE_DECLs
> from TYPE_FIELDS. Free TYPE_BINFO if not used by devirtualization.
> Reset type names to their identifier if their TYPE_DECL doesn't
> have linkage (and thus is used for ODR and devirt).
> (save_debug_info_for_decl): Remove.
> (save_debug_info_for_type): Likewise.
> (add_tree_to_fld_list): Adjust.
>
> Index: gcc/tree.c
> ===================================================================
> --- gcc/tree.c (revision 256562)
> +++ gcc/tree.c (working copy)
> @@ -5127,15 +5127,10 @@ free_lang_data_in_type (tree type)
> TREE_PURPOSE (p) = NULL;
> else if (RECORD_OR_UNION_TYPE_P (type))
> {
> - /* Remove members that are not FIELD_DECLs (and maybe
> - TYPE_DECLs) from the field list of an aggregate. These occur
> - in C++. */
> + /* Remove members that are not FIELD_DECLs from the field list
> + of an aggregate. These occur in C++. */
> for (tree *prev = &TYPE_FIELDS (type), member; (member = *prev);)
> - if (TREE_CODE (member) == FIELD_DECL
> - || (TREE_CODE (member) == TYPE_DECL
> - && !DECL_IGNORED_P (member)
> - && debug_info_level > DINFO_LEVEL_TERSE
> - && !is_redundant_typedef (member)))
> + if (TREE_CODE (member) == FIELD_DECL)
> prev = &DECL_CHAIN (member);
> else
> *prev = DECL_CHAIN (member);
> @@ -5149,15 +5144,9 @@ free_lang_data_in_type (tree type)
> {
> free_lang_data_in_binfo (TYPE_BINFO (type));
> /* We need to preserve link to bases and virtual table for all
> - polymorphic types to make devirtualization machinery working.
> - Debug output cares only about bases, but output also
> - virtual table pointers so merging of -fdevirtualize and
> - -fno-devirtualize units is easier. */
> - if ((!BINFO_VTABLE (TYPE_BINFO (type))
> - || !flag_devirtualize)
> - && ((!BINFO_N_BASE_BINFOS (TYPE_BINFO (type))
> - && !BINFO_VTABLE (TYPE_BINFO (type)))
> - || debug_info_level != DINFO_LEVEL_NONE))
> + polymorphic types to make devirtualization machinery working. */
> + if (!BINFO_VTABLE (TYPE_BINFO (type))
> + || !flag_devirtualize)
> TYPE_BINFO (type) = NULL;
> }
> }
> @@ -5185,6 +5174,11 @@ free_lang_data_in_type (tree type)
> while (ctx && TREE_CODE (ctx) == BLOCK);
> TYPE_CONTEXT (type) = ctx;
> }
> +
> + /* Drop TYPE_DECLs in TYPE_NAME in favor of the identifier in the
> + TYPE_DECL if the type doesn't have linkage. */
> + if (! type_with_linkage_p (type))
> + TYPE_NAME (type) = TYPE_IDENTIFIER (type);
> }
>
>
> @@ -5407,34 +5401,6 @@ struct free_lang_data_d
> };
>
>
> -/* Save all language fields needed to generate proper debug information
> - for DECL. This saves most fields cleared out by free_lang_data_in_decl.
> */
> -
> -static void
> -save_debug_info_for_decl (tree t)
> -{
> - /*struct saved_debug_info_d *sdi;*/
> -
> - gcc_assert (debug_info_level > DINFO_LEVEL_TERSE && t && DECL_P (t));
> -
> - /* FIXME. Partial implementation for saving debug info removed. */
> -}
> -
> -
> -/* Save all language fields needed to generate proper debug information
> - for TYPE. This saves most fields cleared out by free_lang_data_in_type.
> */
> -
> -static void
> -save_debug_info_for_type (tree t)
> -{
> - /*struct saved_debug_info_d *sdi;*/
> -
> - gcc_assert (debug_info_level > DINFO_LEVEL_TERSE && t && TYPE_P (t));
> -
> - /* FIXME. Partial implementation for saving debug info removed. */
> -}
> -
> -
> /* Add type or decl T to one of the list of tree nodes that need their
> language data removed. The lists are held inside FLD. */
>
> @@ -5442,17 +5408,9 @@ static void
> add_tree_to_fld_list (tree t, struct free_lang_data_d *fld)
> {
> if (DECL_P (t))
> - {
> - fld->decls.safe_push (t);
> - if (debug_info_level > DINFO_LEVEL_TERSE)
> - save_debug_info_for_decl (t);
> - }
> + fld->decls.safe_push (t);
> else if (TYPE_P (t))
> - {
> - fld->types.safe_push (t);
> - if (debug_info_level > DINFO_LEVEL_TERSE)
> - save_debug_info_for_type (t);
> - }
> + fld->types.safe_push (t);
> else
> gcc_unreachable ();
> }
