Fix what is _hopefully_ the last corner case for loops.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40503 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index f3aa796..d7e6228 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -738,8 +738,12 @@
     for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
       if (!visited.count(*PI))
         PN->addIncoming(performPHIConstruction(*PI, orig, Phis, visited), *PI);
-      else
-        PN->addIncoming(Phis[*PI], *PI);
+      else {
+        if (Phis[*PI])
+          PN->addIncoming(Phis[*PI], *PI);
+        else
+          PN->addIncoming(PN, *PI);
+      }
     visited.erase(BB);
     
     bool all_same = PN->getNumIncomingValues() != 1;