binutils-gdb/gdb/dwarf2/macro.h

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/* DWARF macro support for GDB.
Copyright (C) 2003-2023 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 GDB_DWARF2_MACRO_H
#define GDB_DWARF2_MACRO_H
struct buildsym_compunit;
extern void dwarf_decode_macros (dwarf2_per_objfile *per_objfile,
buildsym_compunit *builder,
const dwarf2_section_info *section,
const struct line_header *lh,
unsigned int offset_size,
unsigned int offset,
DWARFv5: Handle DW_MACRO_define_strx and DW_MACRO_undef_strx macro entries. GDB complaints "During symbol reading: unrecognized DW_MACFINO opcode 0xb" with the testcase given below. Clang is emitting DW_MACRO_define_strx and DW_MACRO_undef_strx entries in .debug_macro section which are not supported in GDB. This patch handles them. DW_MACRO_define_strx and DW_MACRO_undef_strx are added in DWARFv5. They have two operands. The first operand encodes the line number of the #define or #undef macro directive. The second operand identifies a string; it is represented using an unsigned LEB128 encoded value, which is interpreted as a zero-based index into an array of offsets in the .debug_str_offsets section. This is as per the section 6.3.2.1 of Dwarf Debugging Information Format Version 5. Test case used: #define MAX_SIZE 10 int main(void) { int size = 0; size = size + MAX_SIZE; printf("\n The value of size is [%d]\n",size); return 0; } clang -gdwarf-5 -fdebug-macro macro.c -o macro.out Before the patch: gdb/new_gdb/binutils-gdb/build/bin/gdb -q macro.out -ex "set complaints 1" -ex "start" Reading symbols from macro.out... During symbol reading: unrecognized DW_MACFINO opcode 0xb Temporary breakpoint 1 at 0x4004df: file macro.c, line 7. Starting program: /home/nitika/workspace/macro.out Temporary breakpoint 1, main () at macro.c:7 7 int size = 0; (gdb) Tested by running the testsuite before and after the patch with -gdwarf-5 and there is no increase in the number of test cases that fails. Used clang 11.0.0. gdb/ChangeLog: * dwarf2/macro.c (dwarf_decode_macro_bytes): Handle DW_MACRO_define_strx and DW_MACRO_undef_strx. (dwarf_decode_macros): Likewise * dwarf2/read.c (dwarf_decode_macros): Pass str_offsets_base in the parameters which is the value of DW_AT_str_offsets_base. * dwarf2/macro.h (dwarf_decode_macros): Modify the definition to include str_offsets_base.
2020-09-21 01:52:59 +08:00
dwarf2_section_info *str_section,
dwarf2_section_info *str_offsets_section,
gdb: avoid dereferencing empty str_offsets_base optional in dwarf_decode_macros Since 4d7188abfdf2 ("gdbsupport: add debug assertions in gdb::optional::get"), some macro-related tests fail on Ubuntu 20.04 with the system gcc 9.3.0 compiler when building with _GLIBCXX_DEBUG. For example, gdb.base/info-macros.exp results in: (gdb) break -qualified main /home/smarchi/src/binutils-gdb/gdb/../gdbsupport/gdb_optional.h:206: internal-error: T& gdb::optional<T>::get() [with T = long unsigned int]: Assertion `this->has_value ()' failed. The binary contains DWARF 4 debug info and includes a pre-standard (pre-DWARF 5) .debug_macro section. The CU doesn't have a DW_AT_str_offsets_base attribute (which doesn't exist in DWARF 4). The field dwarf2_cu::str_offsets_base is therefore empty. At dwarf2/read.c:24138, we unconditionally read the value in the optional, which triggers the assertion shown above. The same thing happens when building the test program with DWARF 5 with the same gcc compiler, as that version of gcc doesn't use indirect string forms, even with DWARF 5. So it still doesn't add a DW_AT_str_offsets_base attribute on the CU. Fix that by propagating down a gdb::optional<ULONGEST> for the str offsets base instead of ULONGEST. That value is only used in dwarf_decode_macro_bytes, when encountering an "strx" macro operation (DW_MACRO_define_strx or DW_MACRO_undef_strx). Add a check there that we indeed have a value in the optional before reading it. This is unlikely to happen, but could happen in theory with an erroneous file that uses DW_MACRO_define_strx but does not provide a DW_AT_str_offsets_base (in practice, some things would probably have failed before and stopped processing of debug info). I tested the complaint by inverting the condition and using a clang-compiled binary, which uses the strx operators. This is the result: During symbol reading: use of DW_MACRO_define_strx with unknown string offsets base [in module /home/simark/build/binutils-gdb/gdb/testsuite/outputs/gdb.base/info-macros/info-macros] The test now passes cleanly with the setup mentioned above, and the testsuite looks on par with how it was before 4d7188abfdf2. Change-Id: I7ebd2724beb7b9b4178872374c2a177aea696e77
2021-08-03 23:31:13 +08:00
gdb::optional<ULONGEST> str_offsets_base,
int section_is_gnu, struct dwarf2_cu *cu);
#endif /* GDB_DWARF2_MACRO_H */