[WinEH] Stop BranchFolding from merging across funclets

BranchFolding would merge two funclets together, this is not OK.
Disable this and strengthen the assertion in FuncletLayout.

llvm-svn: 249069

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index 2ef8889091f..2cc851f3973 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -94,9 +94,11 @@ bool BranchFolderPass::runOnMachineFunction(MachineFunction &MF) {
 
   TargetPassConfig *PassConfig = &getAnalysis<TargetPassConfig>();
   // TailMerge can create jump into if branches that make CFG irreducible for
-  // HW that requires structurized CFG.
+  // HW that requires structurized CFG.  It can also cause BBs to get shared
+  // between funclets.
   bool EnableTailMerge = !MF.getTarget().requiresStructuredCFG() &&
-      PassConfig->getEnableTailMerge();
+                         !MF.getMMI().hasEHFunclets() &&
+                         PassConfig->getEnableTailMerge();
   BranchFolder Folder(EnableTailMerge, /*CommonHoist=*/true,
                       getAnalysis<MachineBlockFrequencyInfo>(),
                       getAnalysis<MachineBranchProbabilityInfo>());