[lldb] [llgs] Include process ID in stop responses

Include the process identifier in the `T` stop responses when
multiprocess extension is enabled (i.e. prepend it to the thread
identifier).  Use the exposed identifier to simplify the fork-and-follow
tests.

The LLDB client accounts for the possible PID since the multiprocess
extension support was added in b601c6719226fb83c43dae62a581e5ee08bfb169.

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.llvm.org/D127192

1 files changed, 6 insertions, 2 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
index 2b491f50..e173f04 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
@@ -809,8 +809,12 @@ GDBRemoteCommunicationServerLLGS::SendStopReplyPacketForThread(
   // Print the signal number.
   response.PutHex8(signum & 0xff);
 
-  // Include the tid.
-  response.Printf("thread:%" PRIx64 ";", tid);
+  // Include the (pid and) tid.
+  response.PutCString("thread:");
+  if (bool(m_extensions_supported &
+           NativeProcessProtocol::Extension::multiprocess))
+    response.Format("p{0:x-}.", m_current_process->GetID());
+  response.Format("{0:x-};", tid);
 
   // Include the thread name if there is one.
   const std::string thread_name = thread->GetName();