On Thu, 22 Sep 2016, Richard Biener wrote: > > This merges moving of unused type pruning from late to early finish as > well as handling of debug types and dwarf2 dups elimination. It adds > a flag to DIEs so we can mark them as removed in case sth after > early finish tries to lookup a DIE for a removed DIE again - we shouldn't > re-use the removed DIE (w/o parent) there. > > I suppose at some point we should re-think how pruning of "unused" > stuff is supposed to work. Given my grand plan is to get rid of > debug hooks and allow FEs direct control over the DWARF it should > be ultimatively their decision what to remove (err, not create, in > the first place). > > Bootstrap and regtest running on x86_64-unknown-linux-gnu, ok for trunk?
Testing this separately shows the need to port another hunk. If we prune types early we have to make sure to not re-create them late via typedefs in BLOCKs. Index: gcc/dwarf2out.c =================================================================== --- gcc/dwarf2out.c (revision 240363) +++ gcc/dwarf2out.c (working copy) @@ -23255,7 +23242,13 @@ process_scope_var (tree stmt, tree decl, die = lookup_decl_die (decl_or_origin); else if (TREE_CODE (decl_or_origin) == TYPE_DECL && TYPE_DECL_IS_STUB (decl_or_origin)) - die = lookup_type_die (TREE_TYPE (decl_or_origin)); + { + /* Avoid re-creating the DIE late if it was optimized + as unused early (this BLOCK reference does not count as "use"). */ + die = lookup_type_die (TREE_TYPE (decl_or_origin)); + if (! die) + return; + } else die = NULL; Richard. > I believe this is the last part I can reasonably split out (but I'll > have a second look after merging back from trunk once this and the other > pending patch is approved). > > Thanks, > Richard. > > 2016-09-22 Richard Biener <rguent...@suse.de> > > * dwarf2out.c (struct die_struct): Add removed flag. > (lookup_type_die): If the DIE is marked as removed, clear > TYPE_SYMTAB_DIE and return NULL. > (lookup_decl_die): If the DIE is marked as removed, remove it > from the hash and return NULL. > (mark_removed): New helper. > (prune_unused_types_prune): Call it for removed DIEs. > (dwarf2out_finish): Move unused type pruning debug_types handling > and breaking out includes ... > (dwarf2out_early_finish): ... here. > > Index: gcc/dwarf2out.c > =================================================================== > --- gcc/dwarf2out.c (revision 240353) > +++ gcc/dwarf2out.c (working copy) > @@ -2705,6 +2705,10 @@ typedef struct GTY((chain_circular ("%h. > /* Die is used and must not be pruned as unused. */ > BOOL_BITFIELD die_perennial_p : 1; > BOOL_BITFIELD comdat_type_p : 1; /* DIE has a type signature */ > + /* Whether this DIE was removed from the DIE tree, for example via > + prune_unused_types. We don't consider those present from the > + DIE lookup routines. */ > + BOOL_BITFIELD removed : 1; > /* Lots of spare bits. */ > } > die_node; > @@ -5098,7 +5102,13 @@ new_die (enum dwarf_tag tag_value, dw_di > static inline dw_die_ref > lookup_type_die (tree type) > { > - return TYPE_SYMTAB_DIE (type); > + dw_die_ref die = TYPE_SYMTAB_DIE (type); > + if (die && die->removed) > + { > + TYPE_SYMTAB_DIE (type) = NULL; > + return NULL; > + } > + return die; > } > > /* Given a TYPE_DIE representing the type TYPE, if TYPE is an > @@ -5163,7 +5173,16 @@ decl_die_hasher::equal (die_node *x, tre > static inline dw_die_ref > lookup_decl_die (tree decl) > { > - return decl_die_table->find_with_hash (decl, DECL_UID (decl)); > + dw_die_ref *die = decl_die_table->find_slot_with_hash (decl, DECL_UID > (decl), > + NO_INSERT); > + if (!die) > + return NULL; > + if ((*die)->removed) > + { > + decl_die_table->clear_slot (die); > + return NULL; > + } > + return *die; > } > > /* Returns a hash value for X (which really is a var_loc_list). */ > @@ -26195,6 +26214,16 @@ prune_unused_types_update_strings (dw_di > } > } > > +/* Mark DIE and its children as removed. */ > + > +static void > +mark_removed (dw_die_ref die) > +{ > + dw_die_ref c; > + die->removed = true; > + FOR_EACH_CHILD (die, c, mark_removed (c)); > +} > + > /* Remove from the tree DIE any dies that aren't marked. */ > > static void > @@ -26224,12 +26253,14 @@ prune_unused_types_prune (dw_die_ref die > die->die_child = prev; > } > c->die_sib = NULL; > + mark_removed (c); > return; > } > else > { > next = c->die_sib; > c->die_sib = NULL; > + mark_removed (c); > } > > if (c != prev->die_sib) > @@ -27835,37 +27866,6 @@ dwarf2out_finish (const char *) > resolve_addr (comp_unit_die ()); > move_marked_base_types (); > > - if (flag_eliminate_unused_debug_types) > - prune_unused_types (); > - > - /* Generate separate COMDAT sections for type DIEs. */ > - if (use_debug_types) > - { > - break_out_comdat_types (comp_unit_die ()); > - > - /* Each new type_unit DIE was added to the limbo die list when created. > - Since these have all been added to comdat_type_list, clear the > - limbo die list. */ > - limbo_die_list = NULL; > - > - /* For each new comdat type unit, copy declarations for incomplete > - types to make the new unit self-contained (i.e., no direct > - references to the main compile unit). */ > - for (ctnode = comdat_type_list; ctnode != NULL; ctnode = ctnode->next) > - copy_decls_for_unworthy_types (ctnode->root_die); > - copy_decls_for_unworthy_types (comp_unit_die ()); > - > - /* In the process of copying declarations from one unit to another, > - we may have left some declarations behind that are no longer > - referenced. Prune them. */ > - prune_unused_types (); > - } > - > - /* Generate separate CUs for each of the include files we've seen. > - They will go into limbo_die_list. */ > - if (flag_eliminate_dwarf2_dups) > - break_out_includes (comp_unit_die ()); > - > /* Traverse the DIE's and add sibling attributes to those DIE's that > have children. */ > add_sibling_attributes (comp_unit_die ()); > @@ -28193,6 +28193,38 @@ dwarf2out_early_finish (const char *file > } > deferred_asm_name = NULL; > > + if (flag_eliminate_unused_debug_types) > + prune_unused_types (); > + > + /* Generate separate COMDAT sections for type DIEs. */ > + if (use_debug_types) > + { > + break_out_comdat_types (comp_unit_die ()); > + > + /* Each new type_unit DIE was added to the limbo die list when created. > + Since these have all been added to comdat_type_list, clear the > + limbo die list. */ > + limbo_die_list = NULL; > + > + /* For each new comdat type unit, copy declarations for incomplete > + types to make the new unit self-contained (i.e., no direct > + references to the main compile unit). */ > + for (comdat_type_node *ctnode = comdat_type_list; > + ctnode != NULL; ctnode = ctnode->next) > + copy_decls_for_unworthy_types (ctnode->root_die); > + copy_decls_for_unworthy_types (comp_unit_die ()); > + > + /* In the process of copying declarations from one unit to another, > + we may have left some declarations behind that are no longer > + referenced. Prune them. */ > + prune_unused_types (); > + } > + > + /* Generate separate CUs for each of the include files we've seen. > + They will go into limbo_die_list. */ > + if (flag_eliminate_dwarf2_dups) > + break_out_includes (comp_unit_die ()); > + > /* The early debug phase is now finished. */ > early_dwarf_finished = true; > } > -- Richard Biener <rguent...@suse.de> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)