JITServer: handle non-null compilation

When a JITServer stream failure is thrown, sometimes setting
the compilation object to NULL can be skipped to head straight
into exception handling. This causes an assert to be tripped.

In this particular case, there is a front-end call in
outOfProcessCompilationEnd (within computeDataForCHTableCommit)
which can cause a stream error. Since it isn't guarded
by a global try-catch, it results in the given
assert being tripped.

Addresses this issue:
#23845

Author: KavinSatheeskumar

runtime/compiler/control/CompilationThread.cpp

@@ -9426,6 +9426,20 @@ TR_MethodMetaData *TR::CompilationInfoPerThreadBase::compile(J9VMThread *vmThrea
             optimizationPlan);
 
         TRIGGER_J9HOOK_JIT_COMPILING_END(_jitConfig->hookInterface, vmThread, method);
+
+        if (_compiler && _methodBeingCompiled->isOutOfProcessCompReq()) {
+            // In JITServer mode preemtively call _compiler->retainedMethods() to
+            // create the retainedMethod set if it doesn't exist. If this operation
+            // is not done now, it will be done later during:
+            // postCompilationTasks
+            //   - compilationEnd
+            //     - outOfProcessCompilationEnd
+            //       - computeDataForCHTableCommit
+            //         - getDataForClient
+            // The server will send a message to the client, which could cause an
+            // exception and exceptions are not allowed to be triggerred from postCompilationTasks()
+            _compiler->retainedMethods();
+        }
     } catch (const std::exception &e) {
         const char *exceptionName;
 

runtime/compiler/control/JITServerCompilationThread.cpp

@@ -173,7 +173,7 @@ void outOfProcessCompilationEnd(TR_MethodToBeCompiled *entry, TR::Compilation *c
 
     auto clientData = comp->getClientData();
     bool aotCacheStore = comp->isAOTCacheStore();
-    bool useServerOffsets = aotCacheStore && clientData->useServerOffsets(entry->_stream);
+    bool useServerOffsets = aotCacheStore & clientData->useServerOffsets(entry->_stream);
     const CachedAOTMethod *methodRecord = NULL;
 
     if (compInfoPT->isAOTCacheStore()) {

runtime/compiler/env/J9RetainedMethodSet.cpp

@@ -583,6 +583,8 @@ void J9::RepeatRetainedMethodsAnalysis::getDataForClient(TR::Compilation *comp,
     }
 
     TR_ResolvedMethod *keepaliveMethod = NULL;
+    // retainedMethods is guaranteed to exist, so no messages
+    // will be sent to the server. See issue #23845
     auto keepaliveMethodsIter = comp->retainedMethods()->keepaliveMethods();
     while (keepaliveMethodsIter.next(&keepaliveMethod)) {
         keepaliveMethods.push_back(static_cast<TR_ResolvedJ9JITServerMethod *>(keepaliveMethod)->getRemoteMirror());