Fix stackTrace perf issue in lldb-dap

Author: jeffreytan81

lldb/tools/lldb-dap/DAP.cpp

@@ -36,6 +36,7 @@ DAP::DAP()
       focus_tid(LLDB_INVALID_THREAD_ID), stop_at_entry(false), is_attach(false),
       enable_auto_variable_summaries(false),
       enable_synthetic_child_debugging(false),
+      enable_display_extended_backtrace(false),
       restarting_process_id(LLDB_INVALID_PROCESS_ID),
       configuration_done_sent(false), waiting_for_run_in_terminal(false),
       progress_event_reporter(

lldb/tools/lldb-dap/DAP.h

@@ -177,6 +177,7 @@ struct DAP {
   bool is_attach;
   bool enable_auto_variable_summaries;
   bool enable_synthetic_child_debugging;
+  bool enable_display_extended_backtrace;
   // The process event thread normally responds to process exited events by
   // shutting down the entire adapter. When we're restarting, we keep the id of
   // the old process here so we can detect this case and keep running.

lldb/tools/lldb-dap/lldb-dap.cpp

@@ -701,6 +701,8 @@ void request_attach(const llvm::json::Object &request) {
       GetBoolean(arguments, "enableAutoVariableSummaries", false);
   g_dap.enable_synthetic_child_debugging =
       GetBoolean(arguments, "enableSyntheticChildDebugging", false);
+  g_dap.enable_display_extended_backtrace =
+      GetBoolean(arguments, "enableDisplayExtendedBacktrace", false);
   g_dap.command_escape_prefix =
       GetString(arguments, "commandEscapePrefix", "`");
   g_dap.SetFrameFormat(GetString(arguments, "customFrameFormat"));
@@ -3091,17 +3093,20 @@ void request_stackTrace(const llvm::json::Object &request) {
     // This will always return an invalid thread when
     // libBacktraceRecording.dylib is not loaded or if there is no extended
     // backtrace.
-    lldb::SBThread queue_backtrace_thread =
-        thread.GetExtendedBacktraceThread("libdispatch");
+    lldb::SBThread queue_backtrace_thread;
+    if (g_dap.enable_display_extended_backtrace)
+      queue_backtrace_thread = thread.GetExtendedBacktraceThread("libdispatch");
     if (queue_backtrace_thread.IsValid()) {
       // One extra frame as a label to mark the enqueued thread.
       totalFrames += queue_backtrace_thread.GetNumFrames() + 1;
     }
 
     // This will always return an invalid thread when there is no exception in
     // the current thread.
-    lldb::SBThread exception_backtrace_thread =
-        thread.GetCurrentExceptionBacktrace();
+    lldb::SBThread exception_backtrace_thread;
+    if (g_dap.enable_display_extended_backtrace)
+      exception_backtrace_thread = thread.GetCurrentExceptionBacktrace();
+
     if (exception_backtrace_thread.IsValid()) {
       // One extra frame as a label to mark the exception thread.
       totalFrames += exception_backtrace_thread.GetNumFrames() + 1;