From 35a32aa7100b5f00805e9175e0f01a1d836fd101 Mon Sep 17 00:00:00 2001
From: zcfh <1412805291@qq.com>
Date: Fri, 12 Jul 2024 19:10:17 +0800
Subject: [PATCH] Ignore unexpected warnings in `PerfDataSampleReader::Append`

Recently, commit 623c777 upgraded perf_data_converter. There are some changes
in the `PerfParser::MapBranchStack`. In the new version, even if the mapping
of from_ip fails, the mapping process for to_ip will still proceed. This may
lead to a situation where from.offset_ equals the initial value 0 when from_ip
mapping fails, and to.offset_ equals the actual offset when to_ip mapping
succeeds. This inconsistency may cause the subsequent check to erroneously
warn about 'Bogus LBR data'. A large number of such warnings during use are
more likely to cause confusion and need to be filtered in advance.
---
 sample_reader.cc | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/sample_reader.cc b/sample_reader.cc
index f37be53..7674cb5 100644
--- a/sample_reader.cc
+++ b/sample_reader.cc
@@ -318,6 +318,13 @@ bool PerfDataSampleReader::Append(const std::string &profile_file) {
         continue;
       }
 
+      // if from_ip map in perf_data_converter PerfParser::MapBranchStack fails but to_ip map succeeeds.
+      // Then from.offset() == 0 and to.offset() == ${offset}.
+      // This will cause the following check to erroneously warning "Bogus LBR data".
+      if (event.branch_stack[i - 1].from.dso_info_ == NULL) {
+        continue;
+      }
+
       // TODO(b/62827958): Get rid of this temporary workaround once the issue
       // of duplicate entries in LBR is resolved. It only happens at the head
       // of the LBR. In addition, it is possible that the duplication is
@@ -333,7 +340,8 @@ bool PerfDataSampleReader::Append(const std::string &profile_file) {
           (event.branch_stack[0].from.offset() -
                event.branch_stack[0].to.offset() >
            absl::GetFlag(FLAGS_strip_dup_backedge_stride_limit))) {
-        LOG(WARNING) << "Bogus LBR data (duplicated top entry)";
+        if (event.branch_stack[1].from.dso_info_ == NULL)
+          LOG(WARNING) << "Bogus LBR data (duplicated top entry)";
         continue;
       }
       uint64_t begin = event.branch_stack[i].to.offset();