[WinEH] Update CoreCLR EH for catchpad MBBs

[JosephTremoulet]

Summary

Set the pad MBB as a funclet entry for CoreCLR as well as MSVCCXX, and
update state numbering to put the catchpad block rather than its normal
successor into the unwind map.

[majnemer]

LGTM

lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

SDValue SelectionDAGBuilder::getValueImpl(const Value *V) {
 
   llvm_unreachable("Can't get register for value!");
 }
 
 void SelectionDAGBuilder::visitCatchPad(const CatchPadInst &I) {
   auto Pers = classifyEHPersonality(FuncInfo.Fn->getPersonalityFn());
   bool IsMSVCCXX = Pers == EHPersonality::MSVC_CXX;
   bool IsSEH = isAsynchronousEHPersonality(Pers);
+  bool IsCoreCLR = Pers == EHPersonality::CoreCLR;
   MachineBasicBlock *CatchPadMBB = FuncInfo.MBB;
-  // In MSVC C++, catchblocks are funclets and need prologues.
-  if (IsMSVCCXX)
+  // In MSVC C++ and CoreCLR, catchblocks are funclets and need prologues.
+  if (IsMSVCCXX || IsCoreCLR)
     CatchPadMBB->setIsEHFuncletEntry();
 
   MachineBasicBlock *NormalDestMBB = FuncInfo.MBBMap[I.getNormalDest()];
 
   // Update machine-CFG edge.
   FuncInfo.MBB->addSuccessor(NormalDestMBB);
 
   // CatchPads in SEH are not funclets, they are merely markers which indicate

lib/CodeGen/WinEHPrepare.cpp

if (const CleanupEndPadInst *EndPad = dyn_cast<CleanupEndPadInst>(Pad)) {
       FuncInfo.EHPadStateMap[Cleanup] = NewState;
       // Propagate the new state to all preds of the cleanup
       PredState = NewState;
     } else if (const CatchEndPadInst *EndPad = dyn_cast<CatchEndPadInst>(Pad)) {
       FuncInfo.EHPadStateMap[EndPad] = ParentState;
       // Preds of the endpad should get the parent state.
       PredState = ParentState;
     } else if (const CatchPadInst *Catch = dyn_cast<CatchPadInst>(Pad)) {
-      const BasicBlock *Handler = Catch->getNormalDest();
+      const BasicBlock *PadBlock = Catch->getParent();
       uint32_t TypeToken = static_cast<uint32_t>(
           cast<ConstantInt>(Catch->getArgOperand(0))->getZExtValue());
       int NewState = addClrEHHandler(FuncInfo, ParentState,
-                                     ClrHandlerType::Catch, TypeToken, Handler);
+                                     ClrHandlerType::Catch, TypeToken, PadBlock);
       FuncInfo.EHPadStateMap[Catch] = NewState;
       // Preds of the catch get its state
       PredState = NewState;
     } else {
       llvm_unreachable("Unexpected EH pad");
     }
 
     // Queue all predecessors with the given state