[WIP][AbstractAttributor] Fix an issue that causes program hang

[tianshilei1992]

Summary

Current implementation still uses invalid ReachingKernels, which causes the
folded value is incorrect eventually.

[tianshilei1992]

update

[tianshilei1992]

This patch will be abandoned as the fault commit has been reverted.

llvm/lib/Transforms/IPO/OpenMPOpt.cpp

ChangeStatus updateImpl(Attributor &A) override {
     if (!IsKernelEntry)
       updateReachingKernelEntries(A);
 
     // Callback to check a call instruction.
     auto CheckCallInst = [&](Instruction &I) {
       auto &CB = cast<CallBase>(I);
       auto &CBAA = A.getAAFor<AAKernelInfo>(
           *this, IRPosition::callsite_function(CB), DepClassTy::OPTIONAL);
-      if (CBAA.getState().isValidState())
-        getState() ^= CBAA.getState();
 
       Function *Callee = CB.getCalledFunction();
       if (Callee) {
         // We need to propagate information to the callee, but since the
         // construction of AA always starts with kernel entries, we have to
         // create AAKernelInfoFunction for all called functions. However, here
         // the caller doesn't depend on the callee.
         // TODO: We might want to change the dependence here later if we need
private:
   void updateReachingKernelEntries(Attributor &A) {
     auto PredCallSite = [&](AbstractCallSite ACS) {
       Function *Caller = ACS.getInstruction()->getFunction();
 
       assert(Caller && "Caller is nullptr");
 
       auto &CAA =
           A.getOrCreateAAFor<AAKernelInfo>(IRPosition::function(*Caller));
-      if (CAA.isValidState()) {
+      if (CAA.ReachingKernelEntries.isValidState()) {
         ReachingKernelEntries ^= CAA.ReachingKernelEntries;
         return true;
       }
 
       // We lost track of the caller of the associated function, any kernel
       // could reach now.
       ReachingKernelEntries.indicatePessimisticFixpoint();
 
if (SimplifiedValue.hasValue() && SimplifiedValue.getValue()) {
       A.changeValueAfterManifest(CB, **SimplifiedValue);
       A.deleteAfterManifest(CB);
       Changed = ChangeStatus::CHANGED;
     }
 
     return Changed;
   }
 
+  ChangeStatus indicatePessimisticFixpoint() override {
+    SimplifiedValue = nullptr;
+    return AAFoldRuntimeCall::indicateOptimisticFixpoint();
+  }
+
 private:
   /// Fold __kmpc_is_spmd_exec_mode into a constant if possible.
   ChangeStatus foldIsSPMDExecMode(Attributor &A) {
     BooleanState StateBefore = getState();
 
     unsigned AssumedSPMDCount = 0, KnownSPMDCount = 0;
     unsigned AssumedNonSPMDCount = 0, KnownNonSPMDCount = 0;
     auto &CallerKernelInfoAA = A.getAAFor<AAKernelInfo>(
         *this, IRPosition::function(*getAnchorScope()), DepClassTy::REQUIRED);
 
+    if (!CallerKernelInfoAA.ReachingKernelEntries.isValidState())
+      return indicatePessimisticFixpoint();
+
     for (Kernel K : CallerKernelInfoAA.ReachingKernelEntries) {
       auto &AA = A.getAAFor<AAKernelInfo>(*this, IRPosition::function(*K),
                                           DepClassTy::REQUIRED);
 
       if (!AA.isValidState()) {
         SimplifiedValue = nullptr;
         return indicatePessimisticFixpoint();
       }