teach various passes about blockaddress.  We no longer
crash on any clang tests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85465 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/ValueMapper.cpp b/lib/Transforms/Utils/ValueMapper.cpp
index 21126c9..39331d7 100644
--- a/lib/Transforms/Utils/ValueMapper.cpp
+++ b/lib/Transforms/Utils/ValueMapper.cpp
@@ -113,8 +113,8 @@
   
   if (BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
     Function *F = cast<Function>(MapValue(BA->getFunction(), VM));
-    BasicBlock *BB = cast<BasicBlock>(MapValue(BA->getBasicBlock(), VM));
-    return VM[V] = BlockAddress::get(F, BB);
+    BasicBlock *BB = cast_or_null<BasicBlock>(MapValue(BA->getBasicBlock(),VM));
+    return VM[V] = BlockAddress::get(F, BB ? BB : BA->getBasicBlock());
   }
   
   llvm_unreachable("Unknown type of constant!");