Avoid compiler warning: comparison between signed and unsigned integer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116119 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index c0fa9dd..537561d 100644
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -529,7 +529,7 @@
   if (DefIdx != -1) {
     const MachineOperand &MO = DefMI->getOperand(DefIdx);
     if (MO.isReg() && MO.isImplicit() &&
-        DefIdx >= DefMI->getDesc().getNumOperands()) {
+        DefIdx >= (int)DefMI->getDesc().getNumOperands()) {
       // This is an implicit def, getOperandLatency() won't return the correct
       // latency. e.g.
       //   %D6<def>, %D7<def> = VLD1q16 %R2<kill>, 0, ..., %Q3<imp-def>