Fix build warning.

llvm-svn: 246908
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 3fd8c81..0277ed3 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2992,7 +2992,7 @@
  
       int Idx = DestPN->getBasicBlockIndex(BB);
       // Since BB unwinds to UnwindDest, it has to be in the PHI node.
-      assert(Idx != -1U);
+      assert(Idx != -1);
       // This PHI node has an incoming value that corresponds to a control
       // path through the cleanup pad we are removing.  If the incoming
       // value is in the cleanup pad, it must be a PHINode (because we