Revert "[OpenMP] Group side-effects to improve guarding efficiency"

This reverts commit ca134c3.

There seems to be a problem with the tests, investigating now:
  https://lab.llvm.org/buildbot/#/builders/61/builds/14574

Author: jdoerfert

llvm/lib/Transforms/IPO/OpenMPOpt.cpp

@@ -3188,34 +3188,6 @@ struct AAKernelInfoFunction : AAKernelInfo {
             ->setDebugLoc(DL);
     };
 
-    auto &AllocSharedRFI = OMPInfoCache.RFIs[OMPRTL___kmpc_alloc_shared];
-    SmallPtrSet<BasicBlock *, 8> Visited;
-    for (Instruction *GuardedI : SPMDCompatibilityTracker) {
-      BasicBlock *BB = GuardedI->getParent();
-      if (!Visited.insert(BB).second)
-        continue;
-
-      SmallVector<std::pair<Instruction *, Instruction *>> Reorders;
-      Instruction *LastEffect = nullptr;
-      BasicBlock::reverse_iterator IP = BB->rbegin(), IPEnd = BB->rend();
-      while (++IP != IPEnd) {
-        if (!IP->mayHaveSideEffects() && !IP->mayReadFromMemory())
-          continue;
-        Instruction *I = &*IP;
-        if (OpenMPOpt::getCallIfRegularCall(*I, &AllocSharedRFI))
-          continue;
-        if (!I->user_empty() || !SPMDCompatibilityTracker.contains(I)) {
-          LastEffect = nullptr;
-          continue;
-        }
-        if (LastEffect)
-          Reorders.push_back({I, LastEffect});
-        LastEffect = &*IP;
-      }
-      for (auto &Reorder : Reorders)
-        Reorder.first->moveBefore(Reorder.second);
-    }
-
     SmallVector<std::pair<Instruction *, Instruction *>, 4> GuardedRegions;
 
     for (Instruction *GuardedI : SPMDCompatibilityTracker) {
@@ -4270,6 +4242,7 @@ void OpenMPOpt::registerAAs(bool IsModulePass) {
           DepClassTy::NONE, /* ForceUpdate */ false,
           /* UpdateAfterInit */ false);
 
+
     registerFoldRuntimeCall(OMPRTL___kmpc_is_generic_main_thread_id);
     registerFoldRuntimeCall(OMPRTL___kmpc_is_spmd_exec_mode);
     registerFoldRuntimeCall(OMPRTL___kmpc_parallel_level);