Patch simplifyCFG back to merge one successor and check for compatibility

Author: HighW4y2H3ll

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -8339,7 +8339,7 @@ bool SimplifyCFGOpt::simplifyOnce(BasicBlock *BB) {
   // Merge basic blocks into their predecessor if there is only one distinct
   // pred, and if there is only one distinct successor of the predecessor, and
   // if there are no PHI nodes.
-  if (MergeBlockIntoPredecessor(BB, DTU, nullptr, nullptr, nullptr, true))
+  if (MergeBlockIntoPredecessor(BB, DTU))
     return true;
 
   if (SinkCommon && Options.SinkCommonInsts)