[PATCH v1] perf branch: Avoid incrementing NULL

[Ian Rogers <irogers@google.com>]

If the entry is NULL the value is meaningless so early return NULL to
avoid an increment of NULL. This was happening in calls from
has_stitched_lbr when running the "perf record LBR tests". The return
value isn't used in that case, so returning NULL as no effect.

Fixes: 42bbabed09ce ("perf tools: Add hw_idx in struct branch_stack")
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/branch.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/util/branch.h b/tools/perf/util/branch.h
index 7429530fa774..a1d4736497c4 100644
--- a/tools/perf/util/branch.h
+++ b/tools/perf/util/branch.h
@@ -66,6 +66,9 @@ static inline struct branch_entry *perf_sample__branch_entries(struct perf_sampl
 {
 	u64 *entry = (u64 *)sample->branch_stack;
 
+	if (entry == NULL)
+		return NULL;
+
 	entry++;
 	if (sample->no_hw_idx)
 		return (struct branch_entry *)entry;
-- 
2.53.0.851.ga537e3e6e9-goog