973db6fae3
There are two methods to factor out type information in a dwarf4 executable:
- use -fdebug-info-types to generate type units in a .debug_types section, and
- use dwz to create partial units.
The dwz method has an extra benefit: it also allows to factor out information
between executables into a newly created .dwz file, pointed to by a
.gnu_debugaltlink section.
There is nothing prohibiting a .gnu_debugaltlink file to contain a
.debug_types section.
It's just not generated by dwz or any other tool atm, and consequently gdb has
no support for it. Enhancement PR symtab/30838 is open about the lack of
support.
Make the current situation explicit by emitting a dwarf error:
...
(gdb) file struct-with-sig-2^M
Reading symbols from struct-with-sig-2...^M
Dwarf Error: .debug_types section not supported in dwz file^M
...
and add an assert in write_gdbindex:
...
+ /* See enhancement PR symtab/30838. */
+ gdb_assert (!(per_cu->is_dwz && per_cu->is_debug_types));
...
to clarify why we can use:
...
data_buf &cu_list = (per_cu->is_debug_types
? types_cu_list
: per_cu->is_dwz ? dwz_cu_list : objfile_cu_list);
...
The test-case is a modified copy from gdb.dwarf2/struct-with-sig.exp, so it
keeps the copyright years range.
Tested on x86_64-linux.
Tested-By: Guinevere Larsen <blarsen@redhat.com>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30838
77 lines
2.5 KiB
C++
77 lines
2.5 KiB
C++
/* DWARF DWZ handling for GDB.
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Copyright (C) 2003-2023 Free Software Foundation, Inc.
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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_DWZ_H
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#define GDB_DWARF2_DWZ_H
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#include "gdb_bfd.h"
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#include "dwarf2/index-cache.h"
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#include "dwarf2/section.h"
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struct dwarf2_per_bfd;
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/* This represents a '.dwz' file. */
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struct dwz_file
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{
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dwz_file (gdb_bfd_ref_ptr &&bfd)
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: dwz_bfd (std::move (bfd))
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{
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}
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const char *filename () const
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{
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return bfd_get_filename (this->dwz_bfd.get ());
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}
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/* A dwz file can only contain a few sections. */
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struct dwarf2_section_info abbrev {};
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struct dwarf2_section_info info {};
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struct dwarf2_section_info str {};
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struct dwarf2_section_info line {};
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struct dwarf2_section_info macro {};
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struct dwarf2_section_info gdb_index {};
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struct dwarf2_section_info debug_names {};
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struct dwarf2_section_info types {};
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/* The dwz's BFD. */
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gdb_bfd_ref_ptr dwz_bfd;
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/* If we loaded the index from an external file, this contains the
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resources associated to the open file, memory mapping, etc. */
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std::unique_ptr<index_cache_resource> index_cache_res;
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/* Read a string at offset STR_OFFSET in the .debug_str section from
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this dwz file. Throw an error if the offset is too large. If
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the string consists of a single NUL byte, return NULL; otherwise
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return a pointer to the string. */
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const char *read_string (struct objfile *objfile, LONGEST str_offset);
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};
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/* Open the separate '.dwz' debug file, if needed. If there is no
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.gnu_debugaltlink section in the file, then the result depends on
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REQUIRE: if REQUIRE is true, then error; if REQUIRE is false,
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return NULL. Always error if there is such a section but the file
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cannot be found. */
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extern dwz_file *dwarf2_get_dwz_file (dwarf2_per_bfd *per_bfd,
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bool require = false);
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#endif /* GDB_DWARF2_DWZ_H */
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