Fix assertion in jump threading (PR13405).

GetBestDestForJumpOnUndef() assumes there is at least 1 successor, which isn't
true if the block ends in an indirect branch with no successors. Fix this by
bailing out earlier in this case.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160546 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index 429b61b..6b8430f 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -670,6 +670,8 @@
   } else if (SwitchInst *SI = dyn_cast<SwitchInst>(Terminator)) {
     Condition = SI->getCondition();
   } else if (IndirectBrInst *IB = dyn_cast<IndirectBrInst>(Terminator)) {
+    // Can't thread indirect branch with no successors.
+    if (IB->getNumSuccessors() == 0) return false;
     Condition = IB->getAddress()->stripPointerCasts();
     Preference = WantBlockAddress;
   } else {