[PATCH] D38493: [XRay] [compiler-rt] make sure single threaded programs get traced too

[Martin Pelikán via Phabricator via llvm-commits]

pelikan created this revision.

When the XRay user calls the API to finish writing the log, the thread
which is calling the API still hasn't finished and therefore won't get
its trace written.  Add a test for only the main thread to check this.


https://reviews.llvm.org/D38493

Files:
  lib/xray/xray_fdr_logging.cc
  test/xray/TestCases/Linux/fdr-single-thread.cc


Index: test/xray/TestCases/Linux/fdr-single-thread.cc
===================================================================
--- /dev/null
+++ test/xray/TestCases/Linux/fdr-single-thread.cc
@@ -0,0 +1,33 @@
+// RUN: %clangxx_xray -g -std=c++11 %s -o %t
+// RUN: XRAY_OPTIONS=XRAY_OPTIONS="verbosity=1 patch_premain=true xray_naive_log=false xray_fdr_log=true xray_fdr_log_func_duration_threshold_us=0 xray_logfile_base=fdr-logging-1thr-" %run %t 2>&1
+// RUN: %llvm_xray convert --output-format=yaml --symbolize --instr_map=%t "`ls fdr-logging-1thr-* | head -n1`" | FileCheck %s --check-prefix=TRACE
+// RUN: rm fdr-logging-1thr-*
+//
+// REQUIRES: x86_64-linux
+
+#include "xray/xray_log_interface.h"
+#include <cassert>
+
+constexpr auto kBufferSize = 16384;
+constexpr auto kBufferMax = 10;
+
+[[clang::xray_always_instrument]] void __attribute__((noinline)) fn() { }
+
+int main(int argc, char *argv[]) {
+  using namespace __xray;
+  FDRLoggingOptions Opts;
+
+  auto status = __xray_log_init(kBufferSize, kBufferMax, &Opts, sizeof(Opts));
+  assert(status == XRayLogInitStatus::XRAY_LOG_INITIALIZED);
+
+  __xray_patch();
+  fn();
+  __xray_unpatch();
+  assert(__xray_log_finalize() == XRAY_LOG_FINALIZED);
+  assert(__xray_log_flushLog() == XRAY_LOG_FLUSHED);
+  return 0;
+}
+
+// TRACE: records:
+// TRACE-NEXT: - { type: 0, func-id: [[FID1:[0-9]+]], function: {{.*fn.*}}, cpu: {{.*}}, thread: [[THREAD1:[0-9]+]], kind: function-enter, tsc: {{[0-9]+}} }
+// TRACE-NEXT: - { type: 0, func-id: [[FID1:[0-9]+]], function: {{.*fn.*}}, cpu: {{.*}}, thread: [[THREAD1:[0-9]+]], kind: function-exit, tsc: {{[0-9]+}} }
Index: lib/xray/xray_fdr_logging.cc
===================================================================
--- lib/xray/xray_fdr_logging.cc
+++ lib/xray/xray_fdr_logging.cc
@@ -116,6 +116,16 @@
                        reinterpret_cast<char *>(B.Buffer) + B.Size);
     }
   });
+
+  // The buffer for this particular thread would have been finalised after
+  // we've written everything to disk, and we'd lose the thread's trace.
+  auto &TLD = __xray::__xray_fdr_internal::getThreadLocalData();
+  if (TLD.Buffer.Buffer != nullptr) {
+    __xray::__xray_fdr_internal::writeEOBMetadata();
+    auto Start = reinterpret_cast<char *>(TLD.Buffer.Buffer);
+    retryingWriteAll(Fd, Start, Start + TLD.Buffer.Size);
+  }
+
   __sanitizer::atomic_store(&LogFlushStatus,
                             XRayLogFlushStatus::XRAY_LOG_FLUSHED,
                             __sanitizer::memory_order_release);


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