AggressiveAntiDepBreaker needs to skip debug values because a debug value does not have a corresponding SUnit

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148260 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AggressiveAntiDepBreaker.cpp

@@ -780,6 +780,9 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
        I != E; --Count) {
     MachineInstr *MI = --I;
 
+    if (MI->isDebugValue())
+      continue;
+
     DEBUG(dbgs() << "Anti: ");
     DEBUG(MI->dump());