From 8adb84872b7b039c70f5448f6cf5fe7dfc79d367 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Wed, 27 May 2020 11:19:09 -0400 Subject: [PATCH] Split type_unit_group type_unit_group has links to the compunit_symtab and other symtabs. However, once this object is shared across objfiles, this will no longer be ok. This patch introduces a new type_unit_group_unshareable and arranges to store a map from type unit groups to type_unit_group_unshareable objects in dwarf2_per_objfile. gdb/ChangeLog: YYYY-MM-DD Tom Tromey YYYY-MM-DD Simon Marchi * dwarf2/read.h (struct type_unit_group_unshareable): New. (struct dwarf2_per_objfile) : New member. : New method. * dwarf2/read.c (struct type_unit_group) : Remove; move to type_unit_group_unshareable. (dwarf2_per_objfile::get_type_unit_group_unshareable): New. (process_full_type_unit, dwarf2_cu::setup_type_unit_groups) (dwarf2_cu::setup_type_unit_groups): Use type_unit_group_unshareable. Change-Id: I1fec2fab59e0ec40fee3614fc821172a469c0e41 --- gdb/ChangeLog | 13 +++++++++++ gdb/dwarf2/read.c | 58 ++++++++++++++++++++++++++--------------------- gdb/dwarf2/read.h | 38 +++++++++++++++++++++++++++++++ 3 files changed, 83 insertions(+), 26 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 64e5da9987c..f8213706243 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,16 @@ +2020-05-27 Tom Tromey + Simon Marchi + + * dwarf2/read.h (struct type_unit_group_unshareable): New. + (struct dwarf2_per_objfile) : New member. + : New method. + * dwarf2/read.c (struct type_unit_group) : Remove; move to + type_unit_group_unshareable. + (dwarf2_per_objfile::get_type_unit_group_unshareable): New. + (process_full_type_unit, dwarf2_cu::setup_type_unit_groups) + (dwarf2_cu::setup_type_unit_groups): Use type_unit_group_unshareable. + 2020-05-27 Simon Marchi * dwarf2/read.h (struct dwarf2_per_cu_data): diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index 88ab164d5b4..53def0c87eb 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -614,7 +614,9 @@ struct stmt_list_hash }; /* Each element of dwarf2_per_bfd->type_unit_groups is a pointer to - an object of this type. */ + an object of this type. This contains elements of type unit groups + that can be shared across objfiles. The non-shareable parts are in + type_unit_group_unshareable. */ struct type_unit_group { @@ -629,23 +631,8 @@ struct type_unit_group and is deleted afterwards and not used again. */ std::vector *tus; - /* The compunit symtab. - Type units in a group needn't all be defined in the same source file, - so we create an essentially anonymous symtab as the compunit symtab. */ - struct compunit_symtab *compunit_symtab; - /* The data used to construct the hash key. */ struct stmt_list_hash hash; - - /* The symbol tables for this TU (obtained from the files listed in - DW_AT_stmt_list). - WARNING: The order of entries here must match the order of entries - in the line header. After the first TU using this type_unit_group, the - line header for the subsequent TUs is recreated from this. This is done - because we need to use the same symtabs for each TU using the same - DW_AT_stmt_list value. Also note that symtabs may be repeated here, - there's no guarantee the line header doesn't have duplicate entries. */ - struct symtab **symtabs; }; /* These sections are what may appear in a (real or virtual) DWO file. */ @@ -9628,6 +9615,21 @@ rust_union_quirks (struct dwarf2_cu *cu) cu->rust_unions.clear (); } +/* See read.h. */ + +type_unit_group_unshareable * +dwarf2_per_objfile::get_type_unit_group_unshareable (type_unit_group *tu_group) +{ + auto iter = this->m_type_units.find (tu_group); + if (iter != this->m_type_units.end ()) + return iter->second.get (); + + type_unit_group_unshareable_up uniq (new type_unit_group_unshareable); + type_unit_group_unshareable *result = uniq.get (); + this->m_type_units[tu_group] = std::move (uniq); + return result; +} + /* A helper function for computing the list of all symbol tables included by PER_CU. */ @@ -9883,11 +9885,13 @@ process_full_type_unit (dwarf2_per_cu_data *per_cu, If this is the first TU to use this symtab, complete the construction of it with end_expandable_symtab. Otherwise, complete the addition of this TU's symbols to the existing symtab. */ - if (sig_type->type_unit_group->compunit_symtab == NULL) + type_unit_group_unshareable *tug_unshare = + dwarf2_per_objfile->get_type_unit_group_unshareable (sig_type->type_unit_group); + if (tug_unshare->compunit_symtab == NULL) { buildsym_compunit *builder = cu->get_builder (); cust = builder->end_expandable_symtab (0, SECT_OFF_TEXT (objfile)); - sig_type->type_unit_group->compunit_symtab = cust; + tug_unshare->compunit_symtab = cust; if (cust != NULL) { @@ -9903,7 +9907,7 @@ process_full_type_unit (dwarf2_per_cu_data *per_cu, else { cu->get_builder ()->augment_type_symtab (); - cust = sig_type->type_unit_group->compunit_symtab; + cust = tug_unshare->compunit_symtab; } dwarf2_per_objfile->set_symtab (per_cu, cust); @@ -11042,7 +11046,9 @@ dwarf2_cu::setup_type_unit_groups (struct die_info *die) do it again, we could fake it and just recreate the part we need (file name,index -> symtab mapping). If data shows this optimization is useful we can do it then. */ - first_time = tu_group->compunit_symtab == NULL; + type_unit_group_unshareable *tug_unshare + = per_objfile->get_type_unit_group_unshareable (tu_group); + first_time = tug_unshare->compunit_symtab == NULL; /* We have to handle the case of both a missing DW_AT_stmt_list or bad debug info. */ @@ -11058,9 +11064,9 @@ dwarf2_cu::setup_type_unit_groups (struct die_info *die) start_symtab ("", NULL, 0); else { - gdb_assert (tu_group->symtabs == NULL); + gdb_assert (tug_unshare->symtabs == NULL); gdb_assert (m_builder == nullptr); - struct compunit_symtab *cust = tu_group->compunit_symtab; + struct compunit_symtab *cust = tug_unshare->compunit_symtab; m_builder.reset (new struct buildsym_compunit (COMPUNIT_OBJFILE (cust), "", COMPUNIT_DIRNAME (cust), @@ -11083,7 +11089,7 @@ dwarf2_cu::setup_type_unit_groups (struct die_info *die) process_full_type_unit still needs to know if this is the first time. */ - tu_group->symtabs + tug_unshare->symtabs = XOBNEWVEC (&COMPUNIT_OBJFILE (cust)->objfile_obstack, struct symtab *, line_header->file_names_size ()); @@ -11106,13 +11112,13 @@ dwarf2_cu::setup_type_unit_groups (struct die_info *die) } fe.symtab = b->get_current_subfile ()->symtab; - tu_group->symtabs[i] = fe.symtab; + tug_unshare->symtabs[i] = fe.symtab; } } else { gdb_assert (m_builder == nullptr); - struct compunit_symtab *cust = tu_group->compunit_symtab; + struct compunit_symtab *cust = tug_unshare->compunit_symtab; m_builder.reset (new struct buildsym_compunit (COMPUNIT_OBJFILE (cust), "", COMPUNIT_DIRNAME (cust), @@ -11124,7 +11130,7 @@ dwarf2_cu::setup_type_unit_groups (struct die_info *die) for (i = 0; i < file_names.size (); ++i) { file_entry &fe = file_names[i]; - fe.symtab = tu_group->symtabs[i]; + fe.symtab = tug_unshare->symtabs[i]; } } diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h index 0a94036f4e9..13d31a97d3d 100644 --- a/gdb/dwarf2/read.h +++ b/gdb/dwarf2/read.h @@ -47,6 +47,7 @@ struct dwarf2_per_cu_data; struct mapped_index; struct mapped_debug_names; struct signatured_type; +struct type_unit_group; /* One item on the queue of compilation units to read in full symbols for. */ @@ -265,6 +266,30 @@ private: size_t m_num_psymtabs = 0; }; +/* This is the per-objfile data associated with a type_unit_group. */ + +struct type_unit_group_unshareable +{ + /* The compunit symtab. + Type units in a group needn't all be defined in the same source file, + so we create an essentially anonymous symtab as the compunit symtab. */ + struct compunit_symtab *compunit_symtab = nullptr; + + /* The number of symtabs from the line header. + The value here must match line_header.num_file_names. */ + unsigned int num_symtabs = 0; + + /* The symbol tables for this TU (obtained from the files listed in + DW_AT_stmt_list). + WARNING: The order of entries here must match the order of entries + in the line header. After the first TU using this type_unit_group, the + line header for the subsequent TUs is recreated from this. This is done + because we need to use the same symtabs for each TU using the same + DW_AT_stmt_list value. Also note that symtabs may be repeated here, + there's no guarantee the line header doesn't have duplicate entries. */ + struct symtab **symtabs = nullptr; +}; + /* Collection of data recorded per objfile. This hangs off of dwarf2_objfile_data_key. @@ -304,6 +329,11 @@ struct dwarf2_per_objfile /* Set the compunit_symtab associated to PER_CU. */ void set_symtab (const dwarf2_per_cu_data *per_cu, compunit_symtab *symtab); +/* Get the type_unit_group_unshareable corresponding to TU_GROUP. If one + does not exist, create it. */ + type_unit_group_unshareable *get_type_unit_group_unshareable + (type_unit_group *tu_group); + /* Find an integer type SIZE_IN_BYTES bytes in size and return it. UNSIGNED_P controls if the integer is unsigned or not. */ struct type *int_type (int size_in_bytes, bool unsigned_p) const; @@ -325,6 +355,14 @@ private: is indexed by dwarf2_per_cu_data::index. A NULL value means that the CU/TU has not been expanded yet. */ std::vector m_symtabs; + + /* Map from a type unit group to the corresponding unshared + structure. */ + typedef std::unique_ptr + type_unit_group_unshareable_up; + + std::unordered_map + m_type_units; }; /* Get the dwarf2_per_objfile associated to OBJFILE. */ -- 2.30.2