Add MachineBasicBlock::getName, and use it in place of getBasicBlock()->getName.

Fix debug code that assumes getBasicBlock never returns NULL.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89428 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index cd52825..2e6bd8a 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -172,6 +172,13 @@
     os << " %reg" << RegNo;
 }
 
+StringRef MachineBasicBlock::getName() const {
+  if (const BasicBlock *LBB = getBasicBlock())
+    return LBB->getName();
+  else
+    return "(null)";
+}
+
 void MachineBasicBlock::print(raw_ostream &OS) const {
   const MachineFunction *MF = getParent();
   if (!MF) {