On Fri, Oct 9, 2020 at 12:26 PM Andrii Nakryiko <andrii@xxxxxxxxxx> wrote:
>
> Differentiate between struct and union forwards. For BTF_KIND_FWD this is
> determined by kflag. So teach btf_loader to use that bit to decide whether
> forward is for union or struct.
>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> ---
> N.B. This patch is based on top of tmp.libbtf_encoder branch.
>
> Also seems like non-forward declared union has a slightly different
> representation from struct (class). Not sure why it is so, but this change
> doesn't seem to break anything.
> ---
Ping on this one, let's include it with upcoming pahole 1.19 as well?
>
> btf_loader.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/btf_loader.c b/btf_loader.c
> index 9b5da3a4997a..0cb23967fec3 100644
> --- a/btf_loader.c
> +++ b/btf_loader.c
> @@ -134,12 +134,13 @@ static struct type *type__new(uint16_t tag, strings_t name, size_t size)
> return type;
> }
>
> -static struct class *class__new(strings_t name, size_t size)
> +static struct class *class__new(strings_t name, size_t size, bool is_union)
> {
> struct class *class = tag__alloc(sizeof(*class));
> + uint32_t tag = is_union ? DW_TAG_union_type : DW_TAG_structure_type;
>
> if (class != NULL) {
> - type__init(&class->type, DW_TAG_structure_type, name, size);
> + type__init(&class->type, tag, name, size);
> INIT_LIST_HEAD(&class->vtable);
> }
>
> @@ -228,7 +229,7 @@ static int create_members(struct btf_elf *btfe, const struct btf_type *tp,
>
> static int create_new_class(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id)
> {
> - struct class *class = class__new(tp->name_off, tp->size);
> + struct class *class = class__new(tp->name_off, tp->size, false);
> int member_size = create_members(btfe, tp, &class->type);
>
> if (member_size < 0)
> @@ -313,7 +314,7 @@ static int create_new_subroutine_type(struct btf_elf *btfe, const struct btf_typ
>
> static int create_new_forward_decl(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id)
> {
> - struct class *fwd = class__new(tp->name_off, 0);
> + struct class *fwd = class__new(tp->name_off, 0, btf_kind(tp));
>
> if (fwd == NULL)
> return -ENOMEM;
> --
> 2.24.1
>
