| Message ID | alpine.LSU.2.11.1609230948030.26629@t29.fhfr.qr |
|---|---|
| State | New |
| Headers | show |
On Fri, 23 Sep 2016, Richard Biener wrote: > 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; Testing went fine if you consider moving + /* 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 ()); not being part of this patch. I did statistics over patched/unpatched GCC by means of readelf -wi gcc/<file>.o | grep 'DW_TAG_[_a-z]*type' | wc -l and the difference is in the noise (diff unpatched patched): -gcc/alias.o 2639 +gcc/alias.o 2640 -gcc/auto-profile.o 4941 -gcc/bb-reorder.o 2243 +gcc/auto-profile.o 4945 +gcc/bb-reorder.o 2315 -gcc/bt-load.o 1837 +gcc/bt-load.o 1836 -gcc/cfg.o 1350 +gcc/cfg.o 1349 ... There are DW_TAG_typedef no longer occuring (from vec.o): <1><e7db>: Abbrev Number: 180 (DW_TAG_subprogram) <e7dd> DW_AT_specification: <0x6a3a> <e7e1> DW_AT_inline : 3 (declared as inline and inlined) <e7e2> DW_AT_sibling : <0xe7ff> <2><e7e6>: Abbrev Number: 63 (DW_TAG_formal_parameter) <e7e7> DW_AT_name : (indirect string, offset: 0x3f48): alloc <e7eb> DW_AT_decl_file : 5 <e7ec> DW_AT_decl_line : 1050 <e7ee> DW_AT_type : <0x6d> <2><e7f2>: Abbrev Number: 51 (DW_TAG_typedef) <e7f3> DW_AT_name : (indirect string, offset: 0x1435f): vec_embedde d <e7f7> DW_AT_decl_file : 5 <e7f8> DW_AT_decl_line : 1052 <e7fa> DW_AT_type : <0x665a> <2><e7fe>: Abbrev Number: 0 The DW_TAG_typedef is missing in the patched variant. This DIE is not refered to in the the unpatched variant (I didn't check why we don't prune it). There appear some extra stray DW_TAG_typedef DIEs though: <13><11a28>: Abbrev Number: 207 (DW_TAG_typedef) <13><11a2a>: Abbrev Number: 0 I'll check where those come from. Thanks, Richard. > 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 <rguenther@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; > > } > > > >
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;