Fix signed/unsigned comparison warning on MSVC

llvm-svn: 295962
diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp
index 6f1f5c0..79b02c7 100644
--- a/llvm/lib/CodeGen/MachineScheduler.cpp
+++ b/llvm/lib/CodeGen/MachineScheduler.cpp
@@ -1048,7 +1048,7 @@
       ++CritIdx;
     if (CritIdx != CritEnd && RegionCriticalPSets[CritIdx].getPSet() == ID) {
       if ((int)NewMaxPressure[ID] > RegionCriticalPSets[CritIdx].getUnitInc()
-          && NewMaxPressure[ID] <= std::numeric_limits<int16_t>::max())
+          && NewMaxPressure[ID] <= (unsigned)std::numeric_limits<int16_t>::max())
         RegionCriticalPSets[CritIdx].setUnitInc(NewMaxPressure[ID]);
     }
     unsigned Limit = RegClassInfo->getRegPressureSetLimit(ID);