[clang-offload-bundler] Library-ize ClangOffloadBundler

Lifting the core functionalities of the clang-offload-bundler into a
user-facing library/API. This will allow online and JIT compilers to
bundle and unbundle files without spawning a new process.

This patch lifts the classes and functions used to implement
the clang-offload-bundler into a separate OffloadBundler.cpp,
and defines three top-level API functions in OfflaodBundler.h.
        BundleFiles()
        UnbundleFiles()
        UnbundleArchives()

This patch also introduces a Config class that locally stores the
previously global cl::opt options and arrays to allow users to call
the APIs in a multi-threaded context, and introduces an
OffloadBundler class to encapsulate the top-level API functions.

We also  lift the BundlerExecutable variable, which is specific
to the clang-offload-bundler tool, from the API, and replace
its use with an ObjcopyPath variable. This variable must be set
in order to internally call llvm-objcopy.

Finally, we move the API files from
clang/tools/clang-offload-bundler into clang/lib/Driver and
clang/include/clang/Driver.

Differential Revision: https://reviews.llvm.org/D129873

Author: lamb-j

clang/include/clang/Driver/OffloadBundler.h

@@ -0,0 +1,89 @@
+//===- OffloadBundler.h - File Bundling and Unbundling ----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file defines an offload bundling API that bundles different files
+/// that relate with the same source code but different targets into a single
+/// one. Also the implements the opposite functionality, i.e. unbundle files
+/// previous created by this API.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_DRIVER_OFFLOADBUNDLER_H
+#define LLVM_CLANG_DRIVER_OFFLOADBUNDLER_H
+
+#include "llvm/ADT/Triple.h"
+#include "llvm/Support/Error.h"
+#include <string>
+#include <vector>
+
+namespace clang {
+
+class OffloadBundlerConfig {
+public:
+  bool AllowNoHost = false;
+  bool AllowMissingBundles = false;
+  bool CheckInputArchive = false;
+  bool PrintExternalCommands = false;
+  bool HipOpenmpCompatible = false;
+
+  unsigned BundleAlignment = 1;
+  unsigned HostInputIndex = ~0u;
+
+  std::string FilesType;
+  std::string ObjcopyPath;
+
+  // TODO: Convert these to llvm::SmallVector
+  std::vector<std::string> TargetNames;
+  std::vector<std::string> InputFileNames;
+  std::vector<std::string> OutputFileNames;
+};
+
+class OffloadBundler {
+public:
+  const OffloadBundlerConfig &BundlerConfig;
+
+  // TODO: Add error checking from ClangOffloadBundler.cpp
+  OffloadBundler(const OffloadBundlerConfig &BC) : BundlerConfig(BC) {}
+
+  // List bundle IDs. Return true if an error was found.
+  static llvm::Error
+  ListBundleIDsInFile(llvm::StringRef InputFileName,
+                      const OffloadBundlerConfig &BundlerConfig);
+
+  llvm::Error BundleFiles();
+  llvm::Error UnbundleFiles();
+  llvm::Error UnbundleArchive();
+};
+
+/// Obtain the offload kind, real machine triple, and an optional GPUArch
+/// out of the target information specified by the user.
+/// Bundle Entry ID (or, Offload Target String) has following components:
+///  * Offload Kind - Host, OpenMP, or HIP
+///  * Triple - Standard LLVM Triple
+///  * GPUArch (Optional) - Processor name, like gfx906 or sm_30
+struct OffloadTargetInfo {
+  llvm::StringRef OffloadKind;
+  llvm::Triple Triple;
+  llvm::StringRef GPUArch;
+
+  const OffloadBundlerConfig &BundlerConfig;
+
+  OffloadTargetInfo(const llvm::StringRef Target,
+                    const OffloadBundlerConfig &BC);
+  bool hasHostKind() const;
+  bool isOffloadKindValid() const;
+  bool isOffloadKindCompatible(const llvm::StringRef TargetOffloadKind) const;
+  bool isTripleValid() const;
+  bool operator==(const OffloadTargetInfo &Target) const;
+  std::string str();
+};
+
+} // namespace clang
+
+#endif // LLVM_CLANG_DRIVER_OFFLOADBUNDLER_H

clang/lib/Driver/CMakeLists.txt

@@ -1,6 +1,7 @@
 set(LLVM_LINK_COMPONENTS
   BinaryFormat
   MC
+  Object
   Option
   ProfileData
   Support
@@ -20,6 +21,7 @@ add_clang_library(clangDriver
   DriverOptions.cpp
   Job.cpp
   Multilib.cpp
+  OffloadBundler.cpp
   OptionUtils.cpp
   Phases.cpp
   SanitizerArgs.cpp