Update from https://crrev.com/305340

tools/clang/translation_unit/TranslationUnitGenerator.cpp

Index: tools/clang/translation_unit/TranslationUnitGenerator.cpp
diff --git a/tools/clang/translation_unit/TranslationUnitGenerator.cpp b/tools/clang/translation_unit/TranslationUnitGenerator.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..df9eaebb7cb08b280786e0aa784b95cdef245018
--- /dev/null
+++ b/tools/clang/translation_unit/TranslationUnitGenerator.cpp
@@ -0,0 +1,218 @@
+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// This implements a Clang tool to generate compilation information that is
+// sufficient to recompile the code with clang. For each compilation unit, all
+// source files which are necessary for compiling it are determined. For each
+// compilation unit, a file is created containing a list of all file paths of
+// included files.
+
+#include <assert.h>
+#include <unistd.h>
+#include <fstream>
+#include <iostream>
+#include <memory>
+#include <set>
+#include <stack>
+#include <string>
+#include <vector>
+
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/Lex/PPCallbacks.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Tooling/CommonOptionsParser.h"
+#include "clang/Tooling/CompilationDatabase.h"
+#include "clang/Tooling/Refactoring.h"
+#include "clang/Tooling/Tooling.h"
+#include "llvm/Support/CommandLine.h"
+
+using clang::tooling::CommonOptionsParser;
+using std::set;
+using std::stack;
+using std::string;
+using std::vector;
+
+namespace {
+// Set of preprocessor callbacks used to record files included.
+class IncludeFinderPPCallbacks : public clang::PPCallbacks {
+ public:
+  IncludeFinderPPCallbacks(clang::SourceManager* source_manager,
+                           string* main_source_file,
+                           set<string>* source_file_paths)
+      : source_manager_(source_manager),
+        main_source_file_(main_source_file),
+        source_file_paths_(source_file_paths) {}
+  void FileChanged(clang::SourceLocation /*loc*/,
+                   clang::PPCallbacks::FileChangeReason reason,
+                   clang::SrcMgr::CharacteristicKind /*file_type*/,
+                   clang::FileID /*prev_fid*/) override;
+  void AddFile(const string& path);
+  void InclusionDirective(clang::SourceLocation hash_loc,
+                          const clang::Token& include_tok,
+                          llvm::StringRef file_name,
+                          bool is_angled,
+                          clang::CharSourceRange range,
+                          const clang::FileEntry* file,
+                          llvm::StringRef search_path,
+                          llvm::StringRef relative_path,
+                          const clang::Module* imported) override;
+  void EndOfMainFile() override;
+
+ private:
+  clang::SourceManager* const source_manager_;
+  string* const main_source_file_;
+  set<string>* const source_file_paths_;
+  // The path of the file that was last referenced by an inclusion directive,
+  // normalized for includes that are relative to a different source file.
+  string last_inclusion_directive_;
+  // The stack of currently parsed files. top() gives the current file.
+  stack<string> current_files_;
+};
+
+void IncludeFinderPPCallbacks::FileChanged(
+    clang::SourceLocation /*loc*/,
+    clang::PPCallbacks::FileChangeReason reason,
+    clang::SrcMgr::CharacteristicKind /*file_type*/,
+    clang::FileID /*prev_fid*/) {
+  if (reason == clang::PPCallbacks::EnterFile) {
+    if (!last_inclusion_directive_.empty()) {
+      current_files_.push(last_inclusion_directive_);
+    } else {
+      current_files_.push(
+          source_manager_->getFileEntryForID(source_manager_->getMainFileID())
+              ->getName());
+    }
+  } else if (reason == ExitFile) {
+    current_files_.pop();
+  }
+  // Other reasons are not interesting for us.
+}
+
+void IncludeFinderPPCallbacks::AddFile(const string& path) {
+  source_file_paths_->insert(path);
+}
+
+void IncludeFinderPPCallbacks::InclusionDirective(
+    clang::SourceLocation hash_loc,
+    const clang::Token& include_tok,
+    llvm::StringRef file_name,
+    bool is_angled,
+    clang::CharSourceRange range,
+    const clang::FileEntry* file,
+    llvm::StringRef search_path,
+    llvm::StringRef relative_path,
+    const clang::Module* imported) {
+  if (!file)
+    return;
+
+  assert(!current_files_.top().empty());
+  const clang::DirectoryEntry* const search_path_entry =
+      source_manager_->getFileManager().getDirectory(search_path);
+  const clang::DirectoryEntry* const current_file_parent_entry =
+      source_manager_->getFileManager()
+          .getFile(current_files_.top().c_str())
+          ->getDir();
+
+  // If the include file was found relatively to the current file's parent
+  // directory or a search path, we need to normalize it. This is necessary
+  // because llvm internalizes the path by which an inode was first accessed,
+  // and always returns that path afterwards. If we do not normalize this
+  // we will get an error when we replay the compilation, as the virtual
+  // file system is not aware of inodes.
+  if (search_path_entry == current_file_parent_entry) {
+    string parent =
+        llvm::sys::path::parent_path(current_files_.top().c_str()).str();
+
+    // If the file is a top level file ("file.cc"), we normalize to a path
+    // relative to "./".
+    if (parent.empty() || parent == "/")
+      parent = ".";
+
+    // Otherwise we take the literal path as we stored it for the current
+    // file, and append the relative path.
+    last_inclusion_directive_ = parent + "/" + relative_path.str();
+  } else if (!search_path.empty()) {
+    last_inclusion_directive_ = string(search_path) + "/" + relative_path.str();
+  } else {
+    last_inclusion_directive_ = file_name.str();
+  }
+  AddFile(last_inclusion_directive_);
+}
+
+void IncludeFinderPPCallbacks::EndOfMainFile() {
+  const clang::FileEntry* main_file =
+      source_manager_->getFileEntryForID(source_manager_->getMainFileID());
+  assert(*main_source_file_ == main_file->getName());
+  AddFile(main_file->getName());
+}
+
+class CompilationIndexerAction : public clang::PreprocessorFrontendAction {
+ public:
+  CompilationIndexerAction() {}
+  void ExecuteAction() override;
+
+  // Runs the preprocessor over the translation unit.
+  // This triggers the PPCallbacks we register to intercept all required
+  // files for the compilation.
+  void Preprocess();
+  void EndSourceFileAction() override;
+
+ private:
+  // Set up the state extracted during the compilation, and run Clang over the
+  // input.
+  string main_source_file_;
+  // Maps file names to their contents as read by Clang's source manager.
+  set<string> source_file_paths_;
+};
+
+void CompilationIndexerAction::ExecuteAction() {
+  vector<clang::FrontendInputFile> inputs =
+      getCompilerInstance().getFrontendOpts().Inputs;
+  assert(inputs.size() == 1);
+  main_source_file_ = inputs[0].getFile();
+
+  Preprocess();
+}
+
+void CompilationIndexerAction::Preprocess() {
+  clang::Preprocessor& preprocessor = getCompilerInstance().getPreprocessor();
+  preprocessor.addPPCallbacks(llvm::make_unique<IncludeFinderPPCallbacks>(
+      &getCompilerInstance().getSourceManager(),
+      &main_source_file_,
+      &source_file_paths_));
+  preprocessor.IgnorePragmas();
+  preprocessor.SetSuppressIncludeNotFoundError(true);
+  preprocessor.EnterMainSourceFile();
+  clang::Token token;
+  do {
+    preprocessor.Lex(token);
+  } while (token.isNot(clang::tok::eof));
+}
+
+void CompilationIndexerAction::EndSourceFileAction() {
+  std::ofstream out(main_source_file_ + ".filepaths");
+  for (string path : source_file_paths_) {
+    out << path << std::endl;
+  }
+}
+}  // namespace
+
+static llvm::cl::extrahelp common_help(CommonOptionsParser::HelpMessage);
+
+int main(int argc, const char* argv[]) {
+  llvm::cl::OptionCategory category("TranslationUnitGenerator Tool");
+  CommonOptionsParser options(argc, argv, category);
+  std::unique_ptr<clang::tooling::FrontendActionFactory> frontend_factory =
+      clang::tooling::newFrontendActionFactory<CompilationIndexerAction>();
+  clang::tooling::ClangTool tool(options.getCompilations(),
+                                 options.getSourcePathList());
+  // This clang tool does not actually produce edits, but run_tool.py expects
+  // this. So we just print an empty edit block.
+  llvm::outs() << "==== BEGIN EDITS ====\n";
+  llvm::outs() << "==== END EDITS ====\n";
+  return tool.run(frontend_factory.get());
+}