Re-land r235154-r235156 under the existing -sehprepare flag

Keep the old SEH fan-in lowering on by default for now, since projects
rely on it.  This will make it easy to test this change with a simple
flag flip.

llvm-svn: 235399
diff --git a/llvm/lib/CodeGen/MachineModuleInfo.cpp b/llvm/lib/CodeGen/MachineModuleInfo.cpp
index e8bd1f8..e4f2aea 100644
--- a/llvm/lib/CodeGen/MachineModuleInfo.cpp
+++ b/llvm/lib/CodeGen/MachineModuleInfo.cpp
@@ -469,6 +469,25 @@
   return ClauseLabel;
 }
 
+void MachineModuleInfo::addSEHCatchHandler(MachineBasicBlock *LandingPad,
+                                           const Function *Filter,
+                                           const BlockAddress *RecoverBA) {
+  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
+  SEHHandler Handler;
+  Handler.FilterOrFinally = Filter;
+  Handler.RecoverBA = RecoverBA;
+  LP.SEHHandlers.push_back(Handler);
+}
+
+void MachineModuleInfo::addSEHCleanupHandler(MachineBasicBlock *LandingPad,
+                                             const Function *Cleanup) {
+  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
+  SEHHandler Handler;
+  Handler.FilterOrFinally = Cleanup;
+  Handler.RecoverBA = nullptr;
+  LP.SEHHandlers.push_back(Handler);
+}
+
 /// TidyLandingPads - Remap landing pad labels and remove any deleted landing
 /// pads.
 void MachineModuleInfo::TidyLandingPads(DenseMap<MCSymbol*, uintptr_t> *LPMap) {