[Bug debug/107012] New: [debug, dwarf-5] Missing line information for evaluating macros

[Bug debug/107012] New: [debug, dwarf-5] Missing line information for evaluating macros

[gandalf at winds dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107012

            Bug ID: 107012
           Summary: [debug, dwarf-5] Missing line information for
                    evaluating macros
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gandalf at winds dot org
  Target Milestone: ---

Created attachment 53614
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53614&action=edit
objdump output for dwarf-4

GCC 12 now defaults to outputting debug information via dwarf-5. Compared to
dwarf-4 (which works), gdb's interpretation of dwarf-5 seems to show that we're
missing the correct line information, which causes gdb to not be able to
correctly find and evaluate a macro on the command line due to being in the
wrong context. It's not clear whether gcc is not correctly emitting all the
information, or if gdb is not correctly reading all the information.

Breaking at the "main" function and attempting to run "info macro X" produces
the error message, "The symbol `X' has no definition as a C/C++ preprocessor
macro at macro.c:-1".

The same behavior happens when breaking at any other point in a C program, and
not just at "main".

In both examples below, the breakpoint output shows we're at line 5 in macro.c:

$ cat macro.c
#define TEST_MACRO 42

int main()
{
  return 0;
}

### DWARF-4 Example ###

$ gcc -O3 -ggdb3 -gdwarf-4 macro.c -o macro
$ gdb macro 
GNU gdb (Gentoo 12.1 vanilla) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://bugs.gentoo.org/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from macro...
(gdb) break main
Breakpoint 1 at 0x401020: file macro.c, line 5.
(gdb) run
Starting program: /g/macro 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Breakpoint 1, main () at macro.c:5
5         return 0;
(gdb) info macro TEST_MACRO
Defined at /g/macro.c:1
#define TEST_MACRO 42
(gdb) p TEST_MACRO
$1 = 42
(gdb) quit

### DWARF-5 EXAMPLE ###

$ gcc -O3 -ggdb3 -gdwarf-5 macro.c -o macro
$ gdb macro
GNU gdb (Gentoo 12.1 vanilla) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://bugs.gentoo.org/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from macro...
(gdb) break main
Breakpoint 1 at 0x401020: file macro.c, line 5.
(gdb) run
Starting program: /g/macro 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Breakpoint 1, main () at macro.c:5
5         return 0;
(gdb) info macro TEST_MACRO
The symbol `TEST_MACRO' has no definition as a C/C++ preprocessor macro
at /g/macro.c:-1
(gdb) p TEST_MACRO
No symbol "TEST_MACRO" in current context.
(gdb) quit


Software versions:

$ gdb -v
GNU gdb (Gentoo 12.1 vanilla) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/12.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-12.2.0/work/gcc-12.2.0/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/12.2.0
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/12.2.0
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/12.2.0/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/12.2.0/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0/include/g++-v12
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/12.2.0/python
--enable-languages=c,c++ --enable-obsolete --enable-secureplt --disable-werror
--with-system-zlib --disable-nls --disable-libunwind-exceptions
--enable-checking=release --with-bugurl=https://bugs.gentoo.org/
--with-pkgversion='Gentoo 12.2.0 p1' --disable-esp --enable-libstdcxx-time
--disable-libstdcxx-pch --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu --enable-multilib
--with-multilib-list=m32,m64 --disable-fixed-point --enable-targets=all
--enable-libgomp --disable-libssp --disable-libada --disable-cet
--disable-systemtap --disable-valgrind-annotations --disable-vtable-verify
--disable-libvtv --with-zstd --enable-lto --without-isl --disable-libsanitizer
--disable-default-pie --disable-default-ssp
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.2.0 (Gentoo 12.2.0 p1) 

I've attached the output of "objdump -g macro" for both dwarf-4 and dwarf-5.

Thanks!

[Bug debug/107012] [debug, dwarf-5] Missing line information for evaluating macros

[gandalf at winds dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107012

--- Comment #1 from gandalf at winds dot org ---
Created attachment 53615
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53615&action=edit
objdump output for dwarf-5

[Bug debug/107012] [debug, dwarf-5] Missing line information for evaluating macros

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107012

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I don't see anything wrong on what GCC emits.
If I compile with -O3 -g3 -gdwarf-4 -dA -nostdinc so that stdc-predef.h isn't
included vs. -O3 -g3 -gdwarf-5 -dA -nostdinc, in .debug_macro I see for DWARF
4:
        .section        .debug_macro,"",@progbits
.Ldebug_macro0:
        .value  0x4     # DWARF macro version number
        .byte   0x2     # Flags: 32-bit, lineptr present
        .long   .Ldebug_line0
        .byte   0x7     # Import
        .long   .Ldebug_macro2
        .byte   0x3     # Start new file
        .byte   0       # uleb128 0; Included from line number 0
        .byte   0x1     # uleb128 0x1; file pr107012.c
        .byte   0x5     # Define macro strp
        .byte   0x1     # uleb128 0x1; At line number 1
        .long   .LASF372        # The macro: "TEST_MACRO 42"
        .byte   0x4     # End file
        .byte   0       # End compilation unit
where .Ldebug_macro2 is import of the predefined macros.
.debug_line then has:
        .ascii "pr107012.c\0"   # File Entry: 0x1
        .byte   0       # uleb128 0
        .byte   0       # uleb128 0
        .byte   0       # uleb128 0
i.e. file entry 1 is pr107012.c.
In DWARF 5 it is:
        .section        .debug_macro,"",@progbits
.Ldebug_macro0:
        .value  0x5     # DWARF macro version number
        .byte   0x2     # Flags: 32-bit, lineptr present
        .long   .Ldebug_line0
        .byte   0x7     # Import
        .long   .Ldebug_macro2
        .byte   0x3     # Start new file
        .byte   0       # uleb128 0; Included from line number 0
        .byte   0x1     # uleb128 0x1; file pr107012.c
        .byte   0x5     # Define macro strp
        .byte   0x1     # uleb128 0x1; At line number 1
        .long   .LASF374        # The macro: "TEST_MACRO 42"
        .byte   0x4     # End file
        .byte   0       # End compilation unit
so there are only minor differences related to macros:
-       .long   .Ldebug_macro0  # DW_AT_GNU_macros
+       .long   .Ldebug_macro0  # DW_AT_macros
in .debug_info section and
        .section        .debug_macro,"",@progbits
 .Ldebug_macro0:
-       .value  0x4     # DWARF macro version number
+       .value  0x5     # DWARF macro version number
        .byte   0x2     # Flags: 32-bit, lineptr present
        .long   .Ldebug_line0
        .byte   0x7     # Import
...
        .byte   0x1     # uleb128 0x1; file pr107012.c
        .byte   0x5     # Define macro strp
        .byte   0x1     # uleb128 0x1; At line number 1
-       .long   .LASF372        # The macro: "TEST_MACRO 42"
+       .long   .LASF374        # The macro: "TEST_MACRO 42"
        .byte   0x4     # End file
        .byte   0       # End compilation unit
in .debug_macro.  The line table then says that both file 0 and 1 are
pr107012.c:
        .byte   0x2     # File name entry format count
        .byte   0x1     # uleb128 0x1; DW_LNCT_path
        .byte   0x1f    # uleb128 0x1f; DW_FORM_line_strp
        .byte   0x2     # uleb128 0x2; DW_LNCT_directory_index
        .byte   0xb     # uleb128 0xb; DW_FORM_data1
        .byte   0x2     # uleb128 0x2; File names count
        .long   .LASF0  # File Entry: 0: "pr107012.c"
        .byte   0
        .long   .LASF0  # File Entry: 0: "pr107012.c"
        .byte   0
You'd better file this against gdb...

[Bug debug/107012] [debug, dwarf-5] Missing line information for evaluating macros

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107012

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |drepper.fsp+rhbz at gmail dot com

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 107414 has been marked as a duplicate of this bug. ***

[Bug debug/107012] [debug, dwarf-5] Missing line information for evaluating macros

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107012

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |MOVED
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
See https://sourceware.org/pipermail/gdb-patches/2022-April/187555.html So
moved to the gdb bug.