Instructions to be redone only if from the same BB

While adding instructions(possible roots) to be redone, make sure they
are from the same basic block.

llvm-svn: 257112
diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 401a740..bcadd4e 100644
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -2155,7 +2155,8 @@
     // During the initial run we will get to the root of the tree.
     // But if we get here while we are redoing instructions, there is no
     // guarantee that the root will be visited. So Redo later
-    if (BO->user_back() != BO)
+    if (BO->user_back() != BO &&
+        BO->getParent() == BO->user_back()->getParent())
       RedoInsts.insert(BO->user_back());
     return;
   }