CodeGen: Stop using DIDescriptor::is*() and auto-casting

Same as r234255, but for lib/CodeGen and lib/Target.

llvm-svn: 234258
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index c56b5f4..46a5df3 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -504,7 +504,7 @@
       DebugLoc DL = MI->getDebugLoc();
       bool IsIndirect = MI->isIndirectDebugValue();
       unsigned Offset = IsIndirect ? MI->getOperand(1).getImm() : 0;
-      assert(DIVariable(Variable)->isValidLocationForIntrinsic(DL) &&
+      assert(cast<MDLocalVariable>(Variable)->isValidLocationForIntrinsic(DL) &&
              "Expected inlined-at fields to agree");
       // Def is never a terminator here, so it is ok to increment InsertPos.
       BuildMI(*EntryMBB, ++InsertPos, DL, TII->get(TargetOpcode::DBG_VALUE),