[WinEH] Don't emit state stores or EH thunks for available_externally functions

The exception handler thunk needs to reference the LSDA of the parent
function, which won't be emitted if it's available_externally.

Fixes PR35736. ThinLTO ends up producing available_externally functions
that use _CxxFrameHandler3.

llvm-svn: 321532

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86WinEHState.cpp b/llvm/lib/Target/X86/X86WinEHState.cpp
index 0472a85f50d..6d6dedc6073 100644
--- a/llvm/lib/Target/X86/X86WinEHState.cpp
+++ b/llvm/lib/Target/X86/X86WinEHState.cpp
@@ -149,6 +149,12 @@ void WinEHStatePass::getAnalysisUsage(AnalysisUsage &AU) const {
 }
 
 bool WinEHStatePass::runOnFunction(Function &F) {
+  // Don't insert state stores or exception handler thunks for
+  // available_externally functions. The handler needs to reference the LSDA,
+  // which will not be emitted in this case.
+  if (F.hasAvailableExternallyLinkage())
+    return false;
+
   // Check the personality. Do nothing if this personality doesn't use funclets.
   if (!F.hasPersonalityFn())
     return false;