[lldb] [llgs] Introduce an AppendThreadIDToResponse() helper

Introduce a helper function to append GDB Remote Serial Protocol "thread
IDs", with optional PID in multiprocess mode.

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.llvm.org/D128324

Author: mgorny

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp

@@ -826,10 +826,8 @@ GDBRemoteCommunicationServerLLGS::PrepareStopReplyPacketForThread(
 
   // Include the (pid and) tid.
   response.PutCString("thread:");
-  if (bool(m_extensions_supported &
-           NativeProcessProtocol::Extension::multiprocess))
-    response.Format("p{0:x-}.", process.GetID());
-  response.Format("{0:x-};", thread.GetID());
+  AppendThreadIDToResponse(response, process.GetID(), thread.GetID());
+  response.PutChar(';');
 
   // Include the thread name if there is one.
   const std::string thread_name = thread.GetName();
@@ -1425,9 +1423,8 @@ GDBRemoteCommunicationServerLLGS::Handle_qC(StringExtractorGDBRemote &packet) {
 
   StreamString response;
   response.PutCString("QC");
-  if (bool(m_extensions_supported & NativeProcessProtocol::Extension::multiprocess))
-    response.Format("p{0:x-}.", m_current_process->GetID());
-  response.Format("{0:x-}", thread->GetID());
+  AppendThreadIDToResponse(response, m_current_process->GetID(),
+                           thread->GetID());
 
   return SendPacketNoLock(response.GetString());
 }
@@ -1996,10 +1993,7 @@ void GDBRemoteCommunicationServerLLGS::AddProcessThreads(
     LLDB_LOG(log, "iterated thread {0} (tid={1})", thread_index,
              thread->GetID());
     response.PutChar(had_any ? ',' : 'm');
-    if (bool(m_extensions_supported &
-             NativeProcessProtocol::Extension::multiprocess))
-      response.Format("p{0:x-}.", pid);
-    response.Format("{0:x-}", thread->GetID());
+    AppendThreadIDToResponse(response, pid, thread->GetID());
     had_any = true;
   }
 }
@@ -4143,6 +4137,14 @@ GDBRemoteCommunicationServerLLGS::SendContinueSuccessResponse() {
   return m_non_stop ? SendOKResponse() : PacketResult::Success;
 }
 
+void GDBRemoteCommunicationServerLLGS::AppendThreadIDToResponse(
+    Stream &response, lldb::pid_t pid, lldb::tid_t tid) {
+  if (bool(m_extensions_supported &
+           NativeProcessProtocol::Extension::multiprocess))
+    response.Format("p{0:x-}.", pid);
+  response.Format("{0:x-}", tid);
+}
+
 std::string
 lldb_private::process_gdb_remote::LLGSArgToURL(llvm::StringRef url_arg,
                                                bool reverse_connect) {

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h

@@ -273,6 +273,9 @@ class GDBRemoteCommunicationServerLLGS
   // in non-stop mode, no response otherwise.
   PacketResult SendContinueSuccessResponse();
 
+  void AppendThreadIDToResponse(Stream &response, lldb::pid_t pid,
+                                lldb::tid_t tid);
+
 private:
   llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>> BuildTargetXml();