linux-kernel - [PATCH v3 09/10] perf annotate: Improve type comparison from different scopes

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Message-ID: <20250917195808.2514277-10-zecheng@google.com>
Date: Wed, 17 Sep 2025 19:58:07 +0000
From: Zecheng Li <zecheng@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	"Liang, Kan" <kan.liang@...ux.intel.com>, Masami Hiramatsu <mhiramat@...nel.org>
Cc: Xu Liu <xliuprof@...gle.com>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Zecheng Li <zecheng@...gle.com>
Subject: [PATCH v3 09/10] perf annotate: 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 sometimes helps pick a more complete type.

Signed-off-by: Zecheng Li <zecheng@...gle.com>
---
 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 7e4c045d0f4d..51765bd36c47 100644
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -1622,7 +1622,9 @@ 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;
-- 
2.51.0.384.g4c02a37b29-goog