Re: [PATCH] [debug] Fix dwarf v4 .debug_macro.dwo

[Jakub Jelinek <jakub@redhat.com>]

On Tue, May 14, 2024 at 01:35:30PM +0200, Tom de Vries wrote:
> Consider a hello world, compiled with -gsplit-dwarf and dwarf version 4, and -g3:
> ...
> $ gcc -gdwarf-4 -gsplit-dwarf /data/vries/hello.c -g3 -save-temps -dA
> ...
> 
> In section .debug_macro.dwo, we have:
> ...
> .Ldebug_macro0:
>         .value  0x4     # DWARF macro version number
>         .byte   0x2     # Flags: 32-bit, lineptr present
>         .long   .Lskeleton_debug_line0
>         .byte   0x3     # Start new file
>         .uleb128 0      # Included from line number 0
>         .uleb128 0x1    # file /data/vries/hello.c
>         .byte   0x5     # Define macro strp
>         .uleb128 0      # At line number 0
>         .uleb128 0x1d0  # The macro: "__STDC__ 1"
> ...
> 
> Given that we use a DW_MACRO_define_strp, we'd expect 0x1d0 to be an
> offset into a .debug_str.dwo section.
> 
> But in fact, 0x1d0 is an index into the string offset table in
> .debug_str_offsets.dwo:
> ...
>         .long   0x34f0  # indexed string 0x1d0: __STDC__ 1
> ...
> 
> Add asserts that catch this inconsistency, and fix this by using
> DW_MACRO_define_strx instead.
> 
> Tested on x86_64.
> 
> PR debug/115066

ChangeLog entry is missing.

Otherwise LGTM.

	Jakub