perf annotate-data: Improve type comparison from different scopes

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>

diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index 23a09bf58f864fefcf51adc2fceae6ec1368341b..6fe2efd48a832de115e31ef003b9c49ea7e30dcd 100644 (file)
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -1629,7 +1629,9 @@ retry:
                        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;