fix a signed comparison warning.

llvm-svn: 126682
diff --git a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
index 76f4d3b..eeb83c1 100644
--- a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
+++ b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
@@ -166,7 +166,7 @@
 void DecodeUNPCKLPMask(EVT VT,
                        SmallVectorImpl<unsigned> &ShuffleMask) {
 
-  int NElts = VT.getVectorNumElements();
+  unsigned NElts = VT.getVectorNumElements();
 
   for (unsigned i = 0; i != NElts/2; ++i) {
     ShuffleMask.push_back(i);        // Reads from dest