Use a heavy hammer to fix PR12573.

If the loop contains invoke instructions, whose unwind edge escapes the loop,
then don't try to unswitch the loop. Doing so may cause the unwind edge to be
split, which not only is non-trivial but doesn't preserve loop simplify
information.

Fixes PR12573


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154987 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index ee232687ff..00ecc749af 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -409,6 +409,15 @@ bool LoopUnswitch::processCurrentLoop() {
   if (!currentLoop->isSafeToClone())
     return false;
 
+  // Loops with invokes, whose unwind edge escapes the loop, cannot be
+  // unswitched because splitting their edges are non-trivial and don't preserve
+  // loop simplify information.
+  for (Loop::block_iterator I = currentLoop->block_begin(),
+         E = currentLoop->block_end(); I != E; ++I)
+    if (const InvokeInst *II = dyn_cast<InvokeInst>((*I)->getTerminator()))
+      if (!currentLoop->contains(II->getUnwindDest()))
+        return false;
+
   // Without dedicated exits, splitting the exit edge may fail.
   if (!currentLoop->hasDedicatedExits())
     return false;