[PM] Wire up support for writing bitcode with new PM.

This moves the old pass creation functionality to its own header and
updates the callers of that routine. Then it adds a new PM supporting
bitcode writer to the header file, and wires that up in the opt tool.
A test is added that round-trips code into bitcode and back out using
the new pass manager.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199078 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Bitcode/BitcodeWriterPass.h

@@ -0,0 +1,51 @@
+//===-- BitcodeWriterPass.h - Bitcode writing pass --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file provides a bitcode writing pass.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_BITCODE_BITCODE_WRITER_PASS_H
+#define LLVM_BITCODE_BITCODE_WRITER_PASS_H
+
+#include "llvm/ADT/StringRef.h"
+
+namespace llvm {
+class Module;
+class ModulePass;
+class raw_ostream;
+class PreservedAnalyses;
+
+/// \brief Create and return a pass that writes the module to the specified
+/// ostream. Note that this pass is designed for use with the legacy pass
+/// manager.
+ModulePass *createBitcodeWriterPass(raw_ostream &Str);
+
+/// \brief Pass for writing a module of IR out to a bitcode file.
+///
+/// Note that this is intended for use with the new pass manager. To construct
+/// a pass for the legacy pass manager, use the function above.
+class BitcodeWriterPass {
+  raw_ostream &OS;
+
+public:
+  /// \brief Construct a bitcode writer pass around a particular output stream.
+  explicit BitcodeWriterPass(raw_ostream &OS) : OS(OS) {}
+
+  /// \brief Run the bitcode writer pass, and output the module to the selected
+  /// \brief output stream.
+  PreservedAnalyses run(Module *M);
+
+  static StringRef name() { return "BitcodeWriterPass"; }
+};
+
+}
+
+#endif