Add a small utility class to configure IR printers. This will allow

printers to do neat and wonderful things when printing debug
information.  The ideas is to allow passes to configer printers to emit
pass-specific information when dumping IR.

llvm-svn: 76602

llvm/include/llvm/Support/Dump.h

@@ -0,0 +1,41 @@
+//===- llvm/Support/Dump.h - Easy way to tailor dump output -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the PrefixPrinter interface to pass to MachineFunction
+// and MachineBasicBlock print methods to output additional information before
+// blocks and instructions are printed.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_DUMP_H
+#define LLVM_SUPPORT_DUMP_H
+
+namespace llvm {
+
+class MachineBasicBlock;
+class MachineInstr;
+
+// PrefixPrinter - Print some additional information before printing
+// basic blocks and instructions.
+class PrefixPrinter {
+public:
+  virtual ~PrefixPrinter() {}
+
+  virtual std::string operator()(const MachineBasicBlock &) const {
+    return("");
+  };
+
+  virtual std::string operator()(const MachineInstr &) const {
+    return("");
+  };  
+};
+ 
+} // End llvm namespace
+
+#endif