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perf annotate-data: Improve type comparison from different scopes

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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>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Zecheng Li 2026-03-09 13:55:17 -04:00 committed by Namhyung Kim
parent 8b8d8b8f17
commit 69953f9c65
1 changed files with 3 additions and 1 deletions
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4
tools/perf/util/annotate-data.c
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@ -1629,7 +1629,9 @@ 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;