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696eef26e0
The new DIE scanner works more or less along the lines indicated by the text for the .debug_names section, disregarding the bugs in the specification. While working on this, I noticed that whether a DIE is interesting is a static property of the DIE's abbrev. It also turns out that many abbrevs imply a static size for the DIE data, and additionally that for many abbrevs, the sibling offset is stored at a constant offset from the start of the DIE. This patch changes the abbrev reader to analyze each abbrev and stash the results on the abbrev. These combine to speed up the new indexer. If the "interesting" flag is false, GDB knows to skip the DIE immediately. If the sibling offset is statically known, skipping can be done without reading any attributes; and in some other cases, the DIE can be skipped using simple arithmetic.
110 lines
3.2 KiB
C++
110 lines
3.2 KiB
C++
/* DWARF abbrev table
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Copyright (C) 1994-2022 Free Software Foundation, Inc.
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Adapted by Gary Funck (gary@intrepid.com), Intrepid Technology,
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Inc. with support from Florida State University (under contract
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with the Ada Joint Program Office), and Silicon Graphics, Inc.
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Initial contribution by Brent Benson, Harris Computer Systems, Inc.,
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based on Fred Fish's (Cygnus Support) implementation of DWARF 1
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support.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef GDB_DWARF2_ABBREV_H
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#define GDB_DWARF2_ABBREV_H
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#include "hashtab.h"
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struct attr_abbrev
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{
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ENUM_BITFIELD(dwarf_attribute) name : 16;
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ENUM_BITFIELD(dwarf_form) form : 16;
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/* It is valid only if FORM is DW_FORM_implicit_const. */
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LONGEST implicit_const;
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};
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/* This data structure holds the information of an abbrev. */
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struct abbrev_info
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{
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/* Number identifying abbrev. */
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unsigned int number;
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/* DWARF tag. */
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ENUM_BITFIELD (dwarf_tag) tag : 16;
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/* True if the DIE has children. */
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bool has_children;
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bool interesting;
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unsigned short size_if_constant;
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unsigned short sibling_offset;
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/* Number of attributes. */
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unsigned short num_attrs;
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/* An array of attribute descriptions, allocated using the struct
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hack. */
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struct attr_abbrev attrs[1];
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};
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struct abbrev_table;
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typedef std::unique_ptr<struct abbrev_table> abbrev_table_up;
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/* Top level data structure to contain an abbreviation table. */
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struct abbrev_table
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{
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/* Read an abbrev table from the indicated section, at the given
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offset. The caller is responsible for ensuring that the section
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has already been read. */
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static abbrev_table_up read (struct dwarf2_section_info *section,
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sect_offset sect_off);
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/* Look up an abbrev in the table.
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Returns NULL if the abbrev is not found. */
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const struct abbrev_info *lookup_abbrev (unsigned int abbrev_number) const
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{
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struct abbrev_info search;
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search.number = abbrev_number;
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return (struct abbrev_info *) htab_find_with_hash (m_abbrevs.get (),
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&search,
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abbrev_number);
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}
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/* Where the abbrev table came from.
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This is used as a sanity check when the table is used. */
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const sect_offset sect_off;
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struct dwarf2_section_info *section;
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private:
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abbrev_table (sect_offset off, struct dwarf2_section_info *sect);
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DISABLE_COPY_AND_ASSIGN (abbrev_table);
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/* Add an abbreviation to the table. */
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void add_abbrev (struct abbrev_info *abbrev);
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/* Hash table of abbrevs. */
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htab_up m_abbrevs;
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/* Storage for the abbrev table. */
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auto_obstack m_abbrev_obstack;
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};
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#endif /* GDB_DWARF2_ABBREV_H */
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