Re: [PATCH v1 04/11] perf annotate-data: Improve type comparison from different scopes

[Namhyung Kim <namhyung@kernel.org>]

On Mon, Jan 26, 2026 at 09:04:57PM -0500, Zecheng Li wrote:
> From: Zecheng Li <zecheng@google.com>
> 
> When comparing types from different scopes, first compare their type
> offsets. A larger offset means the field belongs to an outer
> (enclosing) struct. This helps resolve cases where a pointer is found
> in an inner scope, but a struct containing that pointer exists in an
> outer scope. Previously, is_better_type would prefer the pointer type,
> but the struct type is actually more complete and should be chosen.
> 
> Prefer types from outer scopes when is_better_type cannot determine
> a better type. This is a heuristic for the case `struct A { struct B; }`
> where A and B have the same size but I think in most cases A is in the
> outer scope and should be preferred.
> 
> Signed-off-by: Zecheng Li <zecheng@google.com>
> Signed-off-by: Zecheng Li <zli94@ncsu.edu>

Reviewed-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung

> ---
>  tools/perf/util/annotate-data.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
> index 8ff1972981b7..8ea3e8b024e8 100644
> --- a/tools/perf/util/annotate-data.c
> +++ b/tools/perf/util/annotate-data.c
> @@ -1634,7 +1634,9 @@ static int find_data_type_die(struct data_loc_info *dloc, Dwarf_Die *type_die)
>  				pr_debug_dtp("type_offset=%#x\n", type_offset);
>  			}
>  
> -			if (!found || is_better_type(type_die, &mem_die)) {
> +			if (!found || dloc->type_offset < type_offset ||
> +			    (dloc->type_offset == type_offset &&
> +			     !is_better_type(&mem_die, type_die))) {
>  				*type_die = mem_die;
>  				dloc->type_offset = type_offset;
>  				found = true;
> -- 
> 2.52.0
>