Silence a warning

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73152 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 9e15a54..2f94b67 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -7696,7 +7696,7 @@
                                      SelectionDAG &DAG, MachineFrameInfo *MFI,
                                      const TargetLowering &TLI) {
   LDBase = NULL;
-  LastLoadedElt = -1;
+  LastLoadedElt = -1U;
   for (unsigned i = 0; i < NumElems; ++i) {
     if (N->getMaskElt(i) < 0) {
       if (!LDBase)