Fix narrowing conversion.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154171 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 7f008a2..e8c0d4f 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -5847,7 +5847,7 @@
     // input vectors to use as shuffle operands (recorded in InputUsed).
     // If building a suitable shuffle vector proves too hard, then bail
     // out with useBuildVector set.
-    int InputUsed[2] = { -1U, -1U }; // Not yet discovered.
+    int InputUsed[2] = { -1, -1 }; // Not yet discovered.
     unsigned LaneStart = l * NumLaneElems;
     for (unsigned i = 0; i != NumLaneElems; ++i) {
       // The mask element.  This indexes into the input.