[lldb] Add extra verbose logging to flaky TestTsanSwiftAccessRace.py

We have seen another failure of TestTsanSwiftAccessRace.py, indicating that we recieved the stop reason eStopReasonSignal rather than the expected eStopReasonInstrumentation. This alone has not been enough to diagnose the root cause of the failure.

This PR adds in verbose logging, as well as capturing the value of the signal, in the hope of diagnosing the issue fully in the next occurrence.

Author: DanBlackwell

lldb/test/API/functionalities/tsan/swift-access-race/TestTsanSwiftAccessRace.py

@@ -28,7 +28,7 @@ class TsanSwiftAccessRaceTestCase(lldbtest.TestBase):
     @swiftTest
     @skipIfLinux
     @skipUnlessSwiftThreadSanitizer
-    @skipIfAsan # This test does not behave reliable with an ASANified LLDB.
+    @skipIfAsan  # This test does not behave reliable with an ASANified LLDB.
     def test_tsan_swift(self):
         self.build()
         self.do_test()
@@ -50,9 +50,15 @@ def do_test(self):
         for m in target.module_iter():
             libspec = m.GetFileSpec()
             if "clang_rt" in libspec.GetFilename():
-                runtimes.append(os.path.join(libspec.GetDirectory(), libspec.GetFilename()))
+                runtimes.append(
+                    os.path.join(libspec.GetDirectory(), libspec.GetFilename())
+                )
         self.registerSharedLibrariesWithTarget(target, runtimes)
 
+        # Enable verbose logging to help diagnose rdar://153220781
+        self.runCmd("log enable lldb break platform process target thread")
+        self.addTearDownHook(lambda: self.runCmd("log disable gdb-remote packets"))
+
         # Unfortunately the runtime itself isn't 100% reliable in reporting TSAN errors.
         failure_reasons = []
         stop_reason = None
@@ -62,36 +68,47 @@ def do_test(self):
             info.SetWorkingDirectory(self.get_process_working_directory())
             process = target.Launch(info, error)
             if not error.success:
-                failure_reasons.append(f"Failed to bring up process, error: {error.value}")
+                failure_reasons.append(
+                    f"Failed to bring up process, error: {error.value}"
+                )
                 continue
 
             stop_reason = process.GetSelectedThread().GetStopReason()
             if stop_reason == lldb.eStopReasonInstrumentation:
                 break
-            failure_reasons.append(f"Invalid stop_reason: {stop_reason}")
+
+            thread = process.GetSelectedThread()
+            stop_reason_data = [
+                thread.GetStopReasonDataAtIndex(index)
+                for index in range(thread.GetStopReasonDataCount())
+            ]
+            failure_reasons.append(
+                f"Invalid stop_reason: {stop_reason}, stop_reason_data: {stop_reason_data}"
+            )
 
         self.assertEqual(
-            stop_reason, 
+            stop_reason,
             lldb.eStopReasonInstrumentation,
-            f"Failed with {len(failure_reasons)} attempts with reasons: {failure_reasons}")
-            
+            f"Failed with {len(failure_reasons)} attempts with reasons: {failure_reasons}",
+        )
+
         # the stop reason of the thread should be a TSan report.
-        self.expect("thread list", "A Swift access race should be detected",
-                    substrs=['stopped', 'stop reason = Swift access race detected'])
+        self.expect(
+            "thread list",
+            "A Swift access race should be detected",
+            substrs=["stopped", "stop reason = Swift access race detected"],
+        )
 
         self.expect(
             "thread info -s",
             "The extended stop info should contain the TSan provided fields",
-            substrs=[
-                "instrumentation_class",
-                "description",
-                "mops"])
+            substrs=["instrumentation_class", "description", "mops"],
+        )
 
-        output_lines = self.res.GetOutput().split('\n')
-        json_line = '\n'.join(output_lines[2:])
+        output_lines = self.res.GetOutput().split("\n")
+        json_line = "\n".join(output_lines[2:])
         data = json.loads(json_line)
         self.assertEqual(data["instrumentation_class"], "ThreadSanitizer")
         self.assertEqual(data["issue_type"], "external-race")
         self.assertEqual(len(data["mops"]), 2)
         self.assertTrue(data["location_filename"].endswith("/main.swift"))
-