Make sched class unsigned

llvm-svn: 4336
diff --git a/llvm/lib/Target/TargetSchedInfo.cpp b/llvm/lib/Target/TargetSchedInfo.cpp
index 9eb3d98..40e822d 100644
--- a/llvm/lib/Target/TargetSchedInfo.cpp
+++ b/llvm/lib/Target/TargetSchedInfo.cpp
@@ -126,7 +126,7 @@
   // First get the resource usage information from the class resource usages.
   for (MachineOpCode op = 0; op < numOpCodes; ++op) {
     InstrSchedClass sc = getSchedClass(op);
-    assert(sc >= 0 && sc < numSchedClasses);
+    assert(sc < numSchedClasses);
     instrRUsages[op] = instrRUForClasses[sc];
   }