Handle UnreachableInst in isGuaranteedToTransferExecutionToSuccessor

A block with an UnreachableInst does not transfer execution to a successor.
The problem was exposed by GVN-hoist. This patch fixes bug 32153.

Patch by Aditya Kumar.

Differential Revision: https://reviews.llvm.org/D30667

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297254 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed