[ORC] Fix bot failure due to 7da6342 (ORC task dispatch unification).

Fixes the failure at https://lab.llvm.org/buildbot/#/builders/131/builds/62928,
and add comments about unused variable and update debugging output.

Coding my way home: 6.44615S, 128.16704W

Author: lhames

llvm/examples/OrcV2Examples/LLJITWithRemoteDebugging/RemoteJITUtils.cpp

@@ -129,7 +129,7 @@ launchLocalExecutor(StringRef ExecutablePath) {
   close(FromExecutor[WriteEnd]);
 
   auto EPC = SimpleRemoteEPC::Create<FDSimpleRemoteEPCTransport>(
-      std::make_unique<DynamicThreadPoolTaskDispatcher>(),
+      std::make_unique<DynamicThreadPoolTaskDispatcher>(std::nullopt),
       SimpleRemoteEPC::Setup(),
       FromExecutor[ReadEnd], ToExecutor[WriteEnd]);
   if (!EPC)
@@ -201,7 +201,7 @@ connectTCPSocket(StringRef NetworkAddress) {
     return CreateErr(toString(SockFD.takeError()));
 
   return SimpleRemoteEPC::Create<FDSimpleRemoteEPCTransport>(
-      std::make_unique<DynamicThreadPoolTaskDispatcher>(),
+      std::make_unique<DynamicThreadPoolTaskDispatcher>(std::nullopt),
       SimpleRemoteEPC::Setup(), *SockFD);
 }
 

llvm/lib/ExecutionEngine/Orc/LLJIT.cpp

@@ -681,8 +681,10 @@ Error LLJITBuilderState::prepareForConstruction() {
         inconvertibleErrorCode());
 #endif // !LLVM_ENABLE_THREADS
 
+  // Only used in debug builds.
   [[maybe_unused]] bool ConcurrentCompilationSettingDefaulted =
       !SupportConcurrentCompilation;
+
   if (!SupportConcurrentCompilation) {
 #if LLVM_ENABLE_THREADS
     SupportConcurrentCompilation = NumCompileThreads || ES || EPC;
@@ -719,7 +721,7 @@ Error LLJITBuilderState::prepareForConstruction() {
            << "  Support concurrent compilation: "
            << (*SupportConcurrentCompilation ? "Yes" : "No");
     if (ConcurrentCompilationSettingDefaulted)
-      dbgs() << " (defaulted based on ES / EPC)\n";
+      dbgs() << " (defaulted based on ES / EPC / NumCompileThreads)\n";
     else
       dbgs() << "\n";
     dbgs() << "  Number of compile threads: " << NumCompileThreads << "\n";