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Diffstat (limited to 'gdb/dwarf2read.h')
| -rw-r--r-- | gdb/dwarf2read.h | 375 |
1 files changed, 375 insertions, 0 deletions
diff --git a/gdb/dwarf2read.h b/gdb/dwarf2read.h new file mode 100644 index 0000000..46a1052 --- /dev/null +++ b/gdb/dwarf2read.h @@ -0,0 +1,375 @@ +/* DWARF 2 debugging format support for GDB. + + Copyright (C) 1994-2018 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +#ifndef DWARF2READ_H +#define DWARF2READ_H + +#include "filename-seen-cache.h" +#include "gdb_obstack.h" + +typedef struct dwarf2_per_cu_data *dwarf2_per_cu_ptr; +DEF_VEC_P (dwarf2_per_cu_ptr); + +/* A descriptor for dwarf sections. + + S.ASECTION, SIZE are typically initialized when the objfile is first + scanned. BUFFER, READIN are filled in later when the section is read. + If the section contained compressed data then SIZE is updated to record + the uncompressed size of the section. + + DWP file format V2 introduces a wrinkle that is easiest to handle by + creating the concept of virtual sections contained within a real section. + In DWP V2 the sections of the input DWO files are concatenated together + into one section, but section offsets are kept relative to the original + input section. + If this is a virtual dwp-v2 section, S.CONTAINING_SECTION is a backlink to + the real section this "virtual" section is contained in, and BUFFER,SIZE + describe the virtual section. */ + +struct dwarf2_section_info +{ + union + { + /* If this is a real section, the bfd section. */ + asection *section; + /* If this is a virtual section, pointer to the containing ("real") + section. */ + struct dwarf2_section_info *containing_section; + } s; + /* Pointer to section data, only valid if readin. */ + const gdb_byte *buffer; + /* The size of the section, real or virtual. */ + bfd_size_type size; + /* If this is a virtual section, the offset in the real section. + Only valid if is_virtual. */ + bfd_size_type virtual_offset; + /* True if we have tried to read this section. */ + char readin; + /* True if this is a virtual section, False otherwise. + This specifies which of s.section and s.containing_section to use. */ + char is_virtual; +}; + +typedef struct dwarf2_section_info dwarf2_section_info_def; +DEF_VEC_O (dwarf2_section_info_def); + +/* Read the contents of the section INFO. + OBJFILE is the main object file, but not necessarily the file where + the section comes from. E.g., for DWO files the bfd of INFO is the bfd + of the DWO file. + If the section is compressed, uncompress it before returning. */ + +void dwarf2_read_section (struct objfile *objfile, dwarf2_section_info *info); + +struct tu_stats +{ + int nr_uniq_abbrev_tables; + int nr_symtabs; + int nr_symtab_sharers; + int nr_stmt_less_type_units; + int nr_all_type_units_reallocs; +}; + +struct dwarf2_debug_sections; +struct mapped_index; +struct mapped_debug_names; + +/* Collection of data recorded per objfile. + This hangs off of dwarf2_objfile_data_key. */ + +struct dwarf2_per_objfile : public allocate_on_obstack +{ + /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the + dwarf2 section names, or is NULL if the standard ELF names are + used. */ + dwarf2_per_objfile (struct objfile *objfile, + const dwarf2_debug_sections *names); + + ~dwarf2_per_objfile (); + + DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile); + + /* Free all cached compilation units. */ + void free_cached_comp_units (); +private: + /* This function is mapped across the sections and remembers the + offset and size of each of the debugging sections we are + interested in. */ + void locate_sections (bfd *abfd, asection *sectp, + const dwarf2_debug_sections &names); + +public: + dwarf2_section_info info {}; + dwarf2_section_info abbrev {}; + dwarf2_section_info line {}; + dwarf2_section_info loc {}; + dwarf2_section_info loclists {}; + dwarf2_section_info macinfo {}; + dwarf2_section_info macro {}; + dwarf2_section_info str {}; + dwarf2_section_info line_str {}; + dwarf2_section_info ranges {}; + dwarf2_section_info rnglists {}; + dwarf2_section_info addr {}; + dwarf2_section_info frame {}; + dwarf2_section_info eh_frame {}; + dwarf2_section_info gdb_index {}; + dwarf2_section_info debug_names {}; + dwarf2_section_info debug_aranges {}; + + VEC (dwarf2_section_info_def) *types = NULL; + + /* Back link. */ + struct objfile *objfile = NULL; + + /* Table of all the compilation units. This is used to locate + the target compilation unit of a particular reference. */ + struct dwarf2_per_cu_data **all_comp_units = NULL; + + /* The number of compilation units in ALL_COMP_UNITS. */ + int n_comp_units = 0; + + /* The number of .debug_types-related CUs. */ + int n_type_units = 0; + + /* The number of elements allocated in all_type_units. + If there are skeleton-less TUs, we add them to all_type_units lazily. */ + int n_allocated_type_units = 0; + + /* The .debug_types-related CUs (TUs). + This is stored in malloc space because we may realloc it. */ + struct signatured_type **all_type_units = NULL; + + /* Table of struct type_unit_group objects. + The hash key is the DW_AT_stmt_list value. */ + htab_t type_unit_groups {}; + + /* A table mapping .debug_types signatures to its signatured_type entry. + This is NULL if the .debug_types section hasn't been read in yet. */ + htab_t signatured_types {}; + + /* Type unit statistics, to see how well the scaling improvements + are doing. */ + struct tu_stats tu_stats {}; + + /* A chain of compilation units that are currently read in, so that + they can be freed later. */ + dwarf2_per_cu_data *read_in_chain = NULL; + + /* A table mapping DW_AT_dwo_name values to struct dwo_file objects. + This is NULL if the table hasn't been allocated yet. */ + htab_t dwo_files {}; + + /* True if we've checked for whether there is a DWP file. */ + bool dwp_checked = false; + + /* The DWP file if there is one, or NULL. */ + struct dwp_file *dwp_file = NULL; + + /* The shared '.dwz' file, if one exists. This is used when the + original data was compressed using 'dwz -m'. */ + struct dwz_file *dwz_file = NULL; + + /* A flag indicating whether this objfile has a section loaded at a + VMA of 0. */ + bool has_section_at_zero = false; + + /* True if we are using the mapped index, + or we are faking it for OBJF_READNOW's sake. */ + bool using_index = false; + + /* The mapped index, or NULL if .gdb_index is missing or not being used. */ + mapped_index *index_table = NULL; + + /* The mapped index, or NULL if .debug_names is missing or not being used. */ + std::unique_ptr<mapped_debug_names> debug_names_table; + + /* When using index_table, this keeps track of all quick_file_names entries. + TUs typically share line table entries with a CU, so we maintain a + separate table of all line table entries to support the sharing. + Note that while there can be way more TUs than CUs, we've already + sorted all the TUs into "type unit groups", grouped by their + DW_AT_stmt_list value. Therefore the only sharing done here is with a + CU and its associated TU group if there is one. */ + htab_t quick_file_names_table {}; + + /* Set during partial symbol reading, to prevent queueing of full + symbols. */ + bool reading_partial_symbols = false; + + /* Table mapping type DIEs to their struct type *. + This is NULL if not allocated yet. + The mapping is done via (CU/TU + DIE offset) -> type. */ + htab_t die_type_hash {}; + + /* The CUs we recently read. */ + VEC (dwarf2_per_cu_ptr) *just_read_cus = NULL; + + /* Table containing line_header indexed by offset and offset_in_dwz. */ + htab_t line_header_hash {}; + + /* Table containing all filenames. This is an optional because the + table is lazily constructed on first access. */ + gdb::optional<filename_seen_cache> filenames_cache; +}; + +/* Get the dwarf2_per_objfile associated to OBJFILE. */ + +dwarf2_per_objfile *get_dwarf2_per_objfile (struct objfile *objfile); + +/* Persistent data held for a compilation unit, even when not + processing it. We put a pointer to this structure in the + read_symtab_private field of the psymtab. */ + +struct dwarf2_per_cu_data +{ + /* The start offset and length of this compilation unit. + NOTE: Unlike comp_unit_head.length, this length includes + initial_length_size. + If the DIE refers to a DWO file, this is always of the original die, + not the DWO file. */ + sect_offset sect_off; + unsigned int length; + + /* DWARF standard version this data has been read from (such as 4 or 5). */ + short dwarf_version; + + /* Flag indicating this compilation unit will be read in before + any of the current compilation units are processed. */ + unsigned int queued : 1; + + /* This flag will be set when reading partial DIEs if we need to load + absolutely all DIEs for this compilation unit, instead of just the ones + we think are interesting. It gets set if we look for a DIE in the + hash table and don't find it. */ + unsigned int load_all_dies : 1; + + /* Non-zero if this CU is from .debug_types. + Struct dwarf2_per_cu_data is contained in struct signatured_type iff + this is non-zero. */ + unsigned int is_debug_types : 1; + + /* Non-zero if this CU is from the .dwz file. */ + unsigned int is_dwz : 1; + + /* Non-zero if reading a TU directly from a DWO file, bypassing the stub. + This flag is only valid if is_debug_types is true. + We can't read a CU directly from a DWO file: There are required + attributes in the stub. */ + unsigned int reading_dwo_directly : 1; + + /* Non-zero if the TU has been read. + This is used to assist the "Stay in DWO Optimization" for Fission: + When reading a DWO, it's faster to read TUs from the DWO instead of + fetching them from random other DWOs (due to comdat folding). + If the TU has already been read, the optimization is unnecessary + (and unwise - we don't want to change where gdb thinks the TU lives + "midflight"). + This flag is only valid if is_debug_types is true. */ + unsigned int tu_read : 1; + + /* The section this CU/TU lives in. + If the DIE refers to a DWO file, this is always the original die, + not the DWO file. */ + struct dwarf2_section_info *section; + + /* Set to non-NULL iff this CU is currently loaded. When it gets freed out + of the CU cache it gets reset to NULL again. This is left as NULL for + dummy CUs (a CU header, but nothing else). */ + struct dwarf2_cu *cu; + + /* The corresponding dwarf2_per_objfile. */ + struct dwarf2_per_objfile *dwarf2_per_objfile; + + /* When dwarf2_per_objfile->using_index is true, the 'quick' field + is active. Otherwise, the 'psymtab' field is active. */ + union + { + /* The partial symbol table associated with this compilation unit, + or NULL for unread partial units. */ + struct partial_symtab *psymtab; + + /* Data needed by the "quick" functions. */ + struct dwarf2_per_cu_quick_data *quick; + } v; + + /* The CUs we import using DW_TAG_imported_unit. This is filled in + while reading psymtabs, used to compute the psymtab dependencies, + and then cleared. Then it is filled in again while reading full + symbols, and only deleted when the objfile is destroyed. + + This is also used to work around a difference between the way gold + generates .gdb_index version <=7 and the way gdb does. Arguably this + is a gold bug. For symbols coming from TUs, gold records in the index + the CU that includes the TU instead of the TU itself. This breaks + dw2_lookup_symbol: It assumes that if the index says symbol X lives + in CU/TU Y, then one need only expand Y and a subsequent lookup in Y + will find X. Alas TUs live in their own symtab, so after expanding CU Y + we need to look in TU Z to find X. Fortunately, this is akin to + DW_TAG_imported_unit, so we just use the same mechanism: For + .gdb_index version <=7 this also records the TUs that the CU referred + to. Concurrently with this change gdb was modified to emit version 8 + indices so we only pay a price for gold generated indices. + http://sourceware.org/bugzilla/show_bug.cgi?id=15021. */ + VEC (dwarf2_per_cu_ptr) *imported_symtabs; +}; + +/* Entry in the signatured_types hash table. */ + +struct signatured_type +{ + /* The "per_cu" object of this type. + This struct is used iff per_cu.is_debug_types. + N.B.: This is the first member so that it's easy to convert pointers + between them. */ + struct dwarf2_per_cu_data per_cu; + + /* The type's signature. */ + ULONGEST signature; + + /* Offset in the TU of the type's DIE, as read from the TU header. + If this TU is a DWO stub and the definition lives in a DWO file + (specified by DW_AT_GNU_dwo_name), this value is unusable. */ + cu_offset type_offset_in_tu; + + /* Offset in the section of the type's DIE. + If the definition lives in a DWO file, this is the offset in the + .debug_types.dwo section. + The value is zero until the actual value is known. + Zero is otherwise not a valid section offset. */ + sect_offset type_offset_in_section; + + /* Type units are grouped by their DW_AT_stmt_list entry so that they + can share them. This points to the containing symtab. */ + struct type_unit_group *type_unit_group; + + /* The type. + The first time we encounter this type we fully read it in and install it + in the symbol tables. Subsequent times we only need the type. */ + struct type *type; + + /* Containing DWO unit. + This field is valid iff per_cu.reading_dwo_directly. */ + struct dwo_unit *dwo_unit; +}; + +typedef struct signatured_type *sig_type_ptr; +DEF_VEC_P (sig_type_ptr); + +#endif /* DWARF2READ_H */ |