Introduce module file extensions to piggy-back data onto module files.

Introduce the notion of a module file extension, which introduces
additional information into a module file at the time it is built that
can then be queried when the module file is read. Module file
extensions are identified by a block name (which must be unique to the
extension) and can write any bitstream records into their own
extension block within the module file. When a module file is loaded,
any extension blocks are matched up with module file extension
readers, that are per-module-file and are given access to the input
bitstream.

Note that module file extensions can only be introduced by
programmatic clients that have access to the CompilerInvocation. There
is only one such extension at the moment, which is used for testing
the module file extension harness. As a future direction, one could
imagine allowing the plugin mechanism to introduce new module file
extensions.

llvm-svn: 251955

1 files changed, 71 insertions, 0 deletions

diff --git a/clang/lib/Frontend/TestModuleFileExtension.h b/clang/lib/Frontend/TestModuleFileExtension.h
new file mode 100644
index 00000000000..2a7245463cf
--- /dev/null
+++ b/clang/lib/Frontend/TestModuleFileExtension.h
@@ -0,0 +1,71 @@
+//===-- TestModuleFileExtension.h - Module Extension Tester -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_CLANG_FRONTEND_TESTMODULEFILEEXTENSION_H
+#define LLVM_CLANG_FRONTEND_TESTMODULEFILEEXTENSION_H
+
+#include "clang/Serialization/ModuleFileExtension.h"
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Bitcode/BitstreamReader.h"
+#include <string>
+
+namespace clang {
+
+/// A module file extension used for testing purposes.
+class TestModuleFileExtension : public ModuleFileExtension {
+  std::string BlockName;
+  unsigned MajorVersion;
+  unsigned MinorVersion;
+  bool Hashed;
+  std::string UserInfo;
+
+  class Writer : public ModuleFileExtensionWriter {
+  public:
+    Writer(ModuleFileExtension *Ext) : ModuleFileExtensionWriter(Ext) { }
+    ~Writer() override;
+
+    void writeExtensionContents(llvm::BitstreamWriter &Stream) override;
+  };
+
+  class Reader : public ModuleFileExtensionReader {
+    llvm::BitstreamCursor Stream;
+
+  public:
+    ~Reader() override;
+
+    Reader(ModuleFileExtension *Ext, const llvm::BitstreamCursor &InStream);
+  };
+
+public:
+  TestModuleFileExtension(StringRef BlockName,
+                          unsigned MajorVersion,
+                          unsigned MinorVersion,
+                          bool Hashed,
+                          StringRef UserInfo)
+    : BlockName(BlockName),
+      MajorVersion(MajorVersion), MinorVersion(MinorVersion),
+      Hashed(Hashed), UserInfo(UserInfo) { }
+  ~TestModuleFileExtension() override;
+
+  ModuleFileExtensionMetadata getExtensionMetadata() const override;
+
+  llvm::hash_code hashExtension(llvm::hash_code Code) const override;
+
+  std::unique_ptr<ModuleFileExtensionWriter>
+  createExtensionWriter(ASTWriter &Writer) override;
+
+  std::unique_ptr<ModuleFileExtensionReader>
+  createExtensionReader(const ModuleFileExtensionMetadata &Metadata,
+                        ASTReader &Reader, serialization::ModuleFile &Mod,
+                        const llvm::BitstreamCursor &Stream) override;
+};
+
+} // end namespace clang
+
+#endif // LLVM_CLANG_FRONTEND_TESTMODULEFILEEXTENSION_H