[SEH] Ensure that empty __except blocks have their own BB

The 32-bit lowering assumed that WinEHPrepare had this invariant.
WinEHPrepare did it for C++, but not SEH. The result was that we would
insert calls to llvm.x86.seh.restoreframe in normal basic blocks, which
corrupted the frame pointer.

llvm-svn: 241699

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index 0f84ba0a723..62ef1d4ae57 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -533,9 +533,9 @@ void WinEHPrepare::findSEHEHReturnPoints(
     BasicBlock *NextBB;
     Constant *Selector;
     if (isSelectorDispatch(BB, CatchHandler, Selector, NextBB)) {
-      // Split the edge if there is a phi node. Returning from EH to a phi node
-      // is just as impossible as having a phi after an indirectbr.
-      if (isa<PHINode>(CatchHandler->begin())) {
+      // Split the edge if there are multiple predecessors. This creates a place
+      // where we can insert EH recovery code.
+      if (!CatchHandler->getSinglePredecessor()) {
         DEBUG(dbgs() << "splitting EH return edge from " << BB->getName()
                      << " to " << CatchHandler->getName() << '\n');
         BBI = CatchHandler = SplitCriticalEdge(