linux-kernel - [PATCH 2/3] perf annotate-data: Prefer struct/union over base type

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Message-ID: <20240821065408.285548-2-namhyung@kernel.org>
Date: Tue, 20 Aug 2024 23:54:07 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Kan Liang <kan.liang@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org,
	Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Subject: [PATCH 2/3] perf annotate-data: Prefer struct/union over base type

Sometimes a compound type can have a single field and the size is the
same as the base type.  But it's still preferred as struct or union
could carry more information than the base type.

Also put a slight priority on the typedef for the same reason.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/annotate-data.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index 25105b3b9a13..d3db945afac9 100644
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -382,6 +382,13 @@ static bool is_pointer_type(Dwarf_Die *type_die)
 	return tag == DW_TAG_pointer_type || tag == DW_TAG_array_type;
 }
 
+static bool is_compound_type(Dwarf_Die *type_die)
+{
+	int tag = dwarf_tag(type_die);
+
+	return tag == DW_TAG_structure_type || tag == DW_TAG_union_type;
+}
+
 /* returns if Type B has better information than Type A */
 static bool is_better_type(Dwarf_Die *type_a, Dwarf_Die *type_b)
 {
@@ -411,7 +418,18 @@ static bool is_better_type(Dwarf_Die *type_a, Dwarf_Die *type_b)
 	    dwarf_aggregate_size(type_b, &size_b) < 0)
 		return false;
 
-	return size_a < size_b;
+	if (size_a != size_b)
+		return size_a < size_b;
+
+	/* struct or union is preferred */
+	if (is_compound_type(type_a) != is_compound_type(type_b))
+		return is_compound_type(type_b);
+
+	/* typedef is preferred */
+	if (dwarf_tag(type_b) == DW_TAG_typedef)
+		return true;
+
+	return false;
 }
 
 /* The type info will be saved in @type_die */
-- 
2.46.0.184.g6999bdac58-goog