Re: [PATCH 2/3] Handle DWARF 5 separate debug sections

[Simon Marchi <simark@simark.ca>]

On 2025-03-23 15:20, Tom Tromey wrote:
> DWARF 5 standardized the .gnu_debugaltlink section that dwz emits in
> multi-file mode.  This is handled via some new forms, and a new
> .debug_sup section.
> 
> This patch adds support for this to gdb.  It is largely
> straightforward, I think, though one oddity is that I chose not to
> have this code search the system build-id directories for the
> supplementary file.  My feeling was that, while it makes sense for a
> distro to unify the build-id concept with the hash stored in the
> .debug_sup section, there's no intrinsic need to do so.
> 
> This in turn means that a few tests -- for example those that test the
> index cache -- will not work in this mode.
> 
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32808

I just had a few minutes to spare, so I just scanned the patch, I'm
happy with it.  More support for standard DWARF is nice.

Acked-By: Simon Marchi <simon.marchi@efficios.com>

Some random comments:

> @@ -87,6 +88,139 @@ locate_dwz_sections (struct objfile *objfile, bfd *abfd, asection *sectp,
>      }
>  }
>  
> +/* Helper that throws an exception when reading the .debug_sup
> +   section.  */
> +
> +static void
> +debug_sup_failure (const char *text, bfd *abfd)
> +{
> +  error (_("%s [in modules %s]"), text, bfd_get_filename (abfd));

modules -> module?

> +  if (*buildid_len != 0)
> +    buildid->reset ((bfd_byte *) xmemdup (contents, *buildid_len,
> +					  *buildid_len));

Could we return a view inside the section, instead of copying the bytes?
It seems like we are just copying the bytes as is.

Simon