[PATCH v1 3/9] perf diff: Check if all data files with branch stacks

[Jin Yao <yao.jin@linux.intel.com>]

We will expand perf diff to support diff cycles of individual programs
blocks, so it requires all data files having branch stacks.

This patch checks HEADER_BRANCH_STACK in header, and only set the flag
has_br_stack when HEADER_BRANCH_STACK are set in all data files.

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
---
 tools/perf/builtin-diff.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 6e79207..6023f8c 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -32,6 +32,7 @@ struct perf_diff {
 	struct perf_time_interval	*ptime_range;
 	int				 range_size;
 	int				 range_num;
+	bool				 has_br_stack;
 };
 
 /* Diff command specific HPP columns. */
@@ -873,12 +874,41 @@ static int parse_time_str(struct data__file *d, char *abstime_ostr,
 	return ret;
 }
 
+static int check_file_brstack(void)
+{
+	struct data__file *d;
+	bool has_br_stack;
+	int i;
+
+	data__for_each_file(i, d) {
+		d->session = perf_session__new(&d->data, false, &pdiff.tool);
+		if (!d->session) {
+			pr_err("Failed to open %s\n", d->data.path);
+			return -1;
+		}
+
+		has_br_stack = perf_header__has_feat(&d->session->header,
+						     HEADER_BRANCH_STACK);
+		perf_session__delete(d->session);
+		if (!has_br_stack)
+			return 0;
+	}
+
+	/* Set only all files having branch stacks */
+	pdiff.has_br_stack = true;
+	return 0;
+}
+
 static int __cmd_diff(void)
 {
 	struct data__file *d;
 	int ret, i;
 	char *abstime_ostr, *abstime_tmp;
 
+	ret = check_file_brstack();
+	if (ret)
+		return ret;
+
 	ret = abstime_str_dup(&abstime_ostr);
 	if (ret)
 		return ret;
-- 
2.7.4