[PATCH 2/2] perf diff: Fix -o/--order option behavior (again)

[Namhyung Kim <namhyung@kernel.org>]

The commit 21e6d8428664 changed list_add() to
perf_hpp__register_sort_field().  However this resulted in a behavior
change since the field was added to the tail instead of the head.  So
the -o option is mostly ignored due to its order in the list.

This patch fixes it by adding perf_hpp__prepend_sort_field().

Fixes: 21e6d8428664 ("perf diff: Use perf_hpp__register_sort_field interface")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/builtin-diff.c | 2 +-
 tools/perf/ui/hist.c      | 6 ++++++
 tools/perf/util/hist.h    | 7 +++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 9ff0db4e2d0c..933aeec46f4a 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -1199,7 +1199,7 @@ static int ui_init(void)
 		BUG_ON(1);
 	}
 
-	perf_hpp__register_sort_field(fmt);
+	perf_hpp__prepend_sort_field(fmt);
 	return 0;
 }
 
diff --git a/tools/perf/ui/hist.c b/tools/perf/ui/hist.c
index 4ec79b2f9416..18cfcdc90356 100644
--- a/tools/perf/ui/hist.c
+++ b/tools/perf/ui/hist.c
@@ -521,6 +521,12 @@ void perf_hpp_list__register_sort_field(struct perf_hpp_list *list,
 	list_add_tail(&format->sort_list, &list->sorts);
 }
 
+void perf_hpp_list__prepend_sort_field(struct perf_hpp_list *list,
+				       struct perf_hpp_fmt *format)
+{
+	list_add(&format->sort_list, &list->sorts);
+}
+
 void perf_hpp__column_unregister(struct perf_hpp_fmt *format)
 {
 	list_del(&format->list);
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index d4b6514eeef5..28c216e3d5b7 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -283,6 +283,8 @@ void perf_hpp_list__column_register(struct perf_hpp_list *list,
 				    struct perf_hpp_fmt *format);
 void perf_hpp_list__register_sort_field(struct perf_hpp_list *list,
 					struct perf_hpp_fmt *format);
+void perf_hpp_list__prepend_sort_field(struct perf_hpp_list *list,
+				       struct perf_hpp_fmt *format);
 
 static inline void perf_hpp__column_register(struct perf_hpp_fmt *format)
 {
@@ -294,6 +296,11 @@ static inline void perf_hpp__register_sort_field(struct perf_hpp_fmt *format)
 	perf_hpp_list__register_sort_field(&perf_hpp_list, format);
 }
 
+static inline void perf_hpp__prepend_sort_field(struct perf_hpp_fmt *format)
+{
+	perf_hpp_list__prepend_sort_field(&perf_hpp_list, format);
+}
+
 #define perf_hpp_list__for_each_format(_list, format) \
 	list_for_each_entry(format, &(_list)->fields, list)
 
-- 
2.11.0