2 files changed, 188 insertions, 0 deletions
diff --git a/include/clang/CrossTU/CrossTUDiagnostic.h b/include/clang/CrossTU/CrossTUDiagnostic.h
new file mode 100644
index 000000000000..dad38309fd1a
--- /dev/null
+++ b/include/clang/CrossTU/CrossTUDiagnostic.h
@@ -0,0 +1,29 @@
+//===--- CrossTUDiagnostic.h - Diagnostics for Cross TU ---------*- 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_CROSSTU_CROSSTUDIAGNOSTIC_H
+#define LLVM_CLANG_CROSSTU_CROSSTUDIAGNOSTIC_H
+
+#include "clang/Basic/Diagnostic.h"
+
+namespace clang {
+namespace diag {
+enum {
+#define DIAG(ENUM, FLAGS, DEFAULT_MAPPING, DESC, GROUP, SFINAE, NOWERROR,      \
+             SHOWINSYSHEADER, CATEGORY)                                        \
+  ENUM,
+#define CROSSTUSTART
+#include "clang/Basic/DiagnosticCrossTUKinds.inc"
+#undef DIAG
+  NUM_BUILTIN_CROSSTU_DIAGNOSTICS
+};
+} // end namespace diag
+} // end namespace clang
+
+#endif // LLVM_CLANG_FRONTEND_FRONTENDDIAGNOSTIC_H
diff --git a/include/clang/CrossTU/CrossTranslationUnit.h b/include/clang/CrossTU/CrossTranslationUnit.h
new file mode 100644
index 000000000000..f2a169025009
--- /dev/null
+++ b/include/clang/CrossTU/CrossTranslationUnit.h
@@ -0,0 +1,159 @@
+//===--- CrossTranslationUnit.h - -------------------------------*- 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 an interface to load binary AST dumps on demand. This
+//  feature can be utilized for tools that require cross translation unit
+//  support.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H
+#define LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H
+
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/Support/Error.h"
+
+namespace clang {
+class CompilerInstance;
+class ASTContext;
+class ASTImporter;
+class ASTUnit;
+class DeclContext;
+class FunctionDecl;
+class NamedDecl;
+class TranslationUnitDecl;
+
+namespace cross_tu {
+
+enum class index_error_code {
+  unspecified = 1,
+  missing_index_file,
+  invalid_index_format,
+  multiple_definitions,
+  missing_definition,
+  failed_import,
+  failed_to_get_external_ast,
+  failed_to_generate_usr
+};
+
+class IndexError : public llvm::ErrorInfo<IndexError> {
+public:
+  static char ID;
+  IndexError(index_error_code C) : Code(C), LineNo(0) {}
+  IndexError(index_error_code C, std::string FileName, int LineNo = 0)
+      : Code(C), FileName(std::move(FileName)), LineNo(LineNo) {}
+  void log(raw_ostream &OS) const override;
+  std::error_code convertToErrorCode() const override;
+  index_error_code getCode() const { return Code; }
+  int getLineNum() const { return LineNo; }
+  std::string getFileName() const { return FileName; }
+
+private:
+  index_error_code Code;
+  std::string FileName;
+  int LineNo;
+};
+
+/// \brief This function parses an index file that determines which
+///        translation unit contains which definition.
+///
+/// The index file format is the following:
+/// each line consists of an USR and a filepath separated by a space.
+///
+/// \return Returns a map where the USR is the key and the filepath is the value
+///         or an error.
+llvm::Expected<llvm::StringMap<std::string>>
+parseCrossTUIndex(StringRef IndexPath, StringRef CrossTUDir);
+
+std::string createCrossTUIndexString(const llvm::StringMap<std::string> &Index);
+
+/// \brief This class is used for tools that requires cross translation
+///        unit capability.
+///
+/// This class can load function definitions from external AST files.
+/// The loaded definition will be merged back to the original AST using the
+/// AST Importer.
+/// In order to use this class, an index file is required that describes
+/// the locations of the AST files for each function definition.
+///
+/// Note that this class also implements caching.
+class CrossTranslationUnitContext {
+public:
+  CrossTranslationUnitContext(CompilerInstance &CI);
+  ~CrossTranslationUnitContext();
+
+  /// \brief This function loads a function definition from an external AST
+  ///        file and merge it into the original AST.
+  ///
+  /// This method should only be used on functions that have no definitions in
+  /// the current translation unit. A function definition with the same
+  /// declaration will be looked up in the index file which should be in the
+  /// \p CrossTUDir directory, called \p IndexName. In case the declaration is
+  /// found in the index the corresponding AST file will be loaded and the
+  /// definition of the function will be merged into the original AST using
+  /// the AST Importer.
+  ///
+  /// \return The declaration with the definition will be returned.
+  /// If no suitable definition is found in the index file or multiple
+  /// definitions found error will be returned.
+  ///
+  /// Note that the AST files should also be in the \p CrossTUDir.
+  llvm::Expected<const FunctionDecl *>
+  getCrossTUDefinition(const FunctionDecl *FD, StringRef CrossTUDir,
+                       StringRef IndexName);
+
+  /// \brief This function loads a function definition from an external AST
+  ///        file.
+  ///
+  /// A function definition with the same declaration will be looked up in the
+  /// index file which should be in the \p CrossTUDir directory, called
+  /// \p IndexName. In case the declaration is found in the index the
+  /// corresponding AST file will be loaded.
+  ///
+  /// \return Returns an ASTUnit that contains the definition of the looked up
+  /// function.
+  ///
+  /// Note that the AST files should also be in the \p CrossTUDir.
+  llvm::Expected<ASTUnit *> loadExternalAST(StringRef LookupName,
+                                            StringRef CrossTUDir,
+                                            StringRef IndexName);
+
+  /// \brief This function merges a definition from a separate AST Unit into
+  ///        the current one which was created by the compiler instance that
+  ///        was passed to the constructor.
+  ///
+  /// \return Returns the resulting definition or an error.
+  llvm::Expected<const FunctionDecl *> importDefinition(const FunctionDecl *FD);
+
+  /// \brief Get a name to identify a function.
+  static std::string getLookupName(const NamedDecl *ND);
+
+  /// \brief Emit diagnostics for the user for potential configuration errors.
+  void emitCrossTUDiagnostics(const IndexError &IE);
+
+private:
+  ASTImporter &getOrCreateASTImporter(ASTContext &From);
+  const FunctionDecl *findFunctionInDeclContext(const DeclContext *DC,
+                                                StringRef LookupFnName);
+
+  llvm::StringMap<std::unique_ptr<clang::ASTUnit>> FileASTUnitMap;
+  llvm::StringMap<clang::ASTUnit *> FunctionASTUnitMap;
+  llvm::StringMap<std::string> FunctionFileMap;
+  llvm::DenseMap<TranslationUnitDecl *, std::unique_ptr<ASTImporter>>
+      ASTUnitImporterMap;
+  CompilerInstance &CI;
+  ASTContext &Context;
+};
+
+} // namespace cross_tu
+} // namespace clang
+
+#endif // LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H