linux-kernel - Re: [PATCH v3 10/20] gendwarfksyms: Expand structure types

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Message-ID: <CABCJKudn0WcOAg89ouTQoEHQC5n90SdetxHYG7GvQWmWo6WQ5A@mail.gmail.com>
Date: Tue, 1 Oct 2024 21:20:41 +0000
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Petr Pavlu <petr.pavlu@...e.com>
Cc: Masahiro Yamada <masahiroy@...nel.org>, Luis Chamberlain <mcgrof@...nel.org>, 
	Miguel Ojeda <ojeda@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Matthew Maurer <mmaurer@...gle.com>, Alex Gaynor <alex.gaynor@...il.com>, 
	Wedson Almeida Filho <wedsonaf@...il.com>, Gary Guo <gary@...yguo.net>, Neal Gompa <neal@...pa.dev>, 
	Hector Martin <marcan@...can.st>, Janne Grunau <j@...nau.net>, Miroslav Benes <mbenes@...e.cz>, 
	Asahi Linux <asahi@...ts.linux.dev>, linux-kbuild@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org, 
	rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v3 10/20] gendwarfksyms: Expand structure types

On Tue, Oct 1, 2024 at 2:16 PM Petr Pavlu <petr.pavlu@...e.com> wrote:
>
> On 9/23/24 20:18, Sami Tolvanen wrote:
> > +static void process_variant_type(struct state *state, struct die *cache,
> > +                              Dwarf_Die *die)
> > +{
> > +     process_list_comma(state, cache);
> > +     process(cache, "variant {");
> > +     process_linebreak(cache, 1);
> > +     check(process_die_container(state, cache, die, process_type,
> > +                                 match_member_type));
> > +     process_linebreak(cache, -1);
> > +     process(cache, "}");
> > +}
> > +
> > +static void process_variant_part_type(struct state *state, struct die *cache,
> > +                                   Dwarf_Die *die)
> > +{
> > +     process_list_comma(state, cache);
> > +     process(cache, "variant_part {");
> > +     process_linebreak(cache, 1);
> > +     check(process_die_container(state, cache, die, process_type,
> > +                                 match_variant_type));
> > +     process_linebreak(cache, -1);
> > +     process(cache, "}");
> > +}
>
> For variant types, should the tool worry also about DW_AT_discr and
> DW_AT_discr_value?

Hmm, I initially thought they were not necessary, but looking at the
rustc DWARF output a bit more closely, it might actually be a good
idea to include this information. I'll add these both, although since
DW_AT_discr just points to a member DIE, it's probably enough to just
process all child DIEs for the variant_part instead of limiting
ourselves to variants only.

> > +static void process_unspecified_type(struct state *state, struct die *cache,
> > +                                  Dwarf_Die *die)
> > +{
> > +     /*
> > +      * These can be emitted for stand-elone assembly code, which means we
> > +      * might run into them in vmlinux.o.
> > +      */
>
> Nit: stand-elone -> stand-alone.

Oops, I'll fix this too. Thanks!

Sami