2 files changed, 106 insertions, 16 deletions

diff --git a/lib/Frontend/Rewrite/CMakeLists.txt b/lib/Frontend/Rewrite/CMakeLists.txt
index 924bf5d5ee28..61a22b5b13b4 100644
--- a/lib/Frontend/Rewrite/CMakeLists.txt
+++ b/lib/Frontend/Rewrite/CMakeLists.txt
@@ -19,4 +19,5 @@ add_clang_library(clangRewriteFrontend
   clangFrontend
   clangLex
   clangRewrite
+  clangSerialization
   )
diff --git a/lib/Frontend/Rewrite/FrontendActions.cpp b/lib/Frontend/Rewrite/FrontendActions.cpp
index b2dfd2941130..45feffbcb5b5 100644
--- a/lib/Frontend/Rewrite/FrontendActions.cpp
+++ b/lib/Frontend/Rewrite/FrontendActions.cpp
@@ -18,6 +18,11 @@
 #include "clang/Rewrite/Frontend/ASTConsumers.h"
 #include "clang/Rewrite/Frontend/FixItRewriter.h"
 #include "clang/Rewrite/Frontend/Rewriters.h"
+#include "clang/Serialization/ASTReader.h"
+#include "clang/Serialization/Module.h"
+#include "clang/Serialization/ModuleManager.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/Support/CrashRecoveryContext.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
@@ -86,8 +91,7 @@ public:
 };
 } // end anonymous namespace
 
-bool FixItAction::BeginSourceFileAction(CompilerInstance &CI,
-                                        StringRef Filename) {
+bool FixItAction::BeginSourceFileAction(CompilerInstance &CI) {
   const FrontendOptions &FEOpts = getCompilerInstance().getFrontendOpts();
   if (!FEOpts.FixItSuffix.empty()) {
     FixItOpts.reset(new FixItActionSuffixInserter(FEOpts.FixItSuffix,
@@ -190,27 +194,112 @@ void RewriteTestAction::ExecuteAction() {
   DoRewriteTest(CI.getPreprocessor(), OS.get());
 }
 
-void RewriteIncludesAction::ExecuteAction() {
-  CompilerInstance &CI = getCompilerInstance();
-  std::unique_ptr<raw_ostream> OS =
-      CI.createDefaultOutputFile(true, getCurrentFile());
-  if (!OS) return;
+class RewriteIncludesAction::RewriteImportsListener : public ASTReaderListener {
+  CompilerInstance &CI;
+  std::weak_ptr<raw_ostream> Out;
+
+  llvm::DenseSet<const FileEntry*> Rewritten;
+
+public:
+  RewriteImportsListener(CompilerInstance &CI, std::shared_ptr<raw_ostream> Out)
+      : CI(CI), Out(Out) {}
+
+  void visitModuleFile(StringRef Filename,
+                       serialization::ModuleKind Kind) override {
+    auto *File = CI.getFileManager().getFile(Filename);
+    assert(File && "missing file for loaded module?");
+
+    // Only rewrite each module file once.
+    if (!Rewritten.insert(File).second)
+      return;
+
+    serialization::ModuleFile *MF =
+        CI.getModuleManager()->getModuleManager().lookup(File);
+    assert(File && "missing module file for loaded module?");
+
+    // Not interested in PCH / preambles.
+    if (!MF->isModule())
+      return;
+
+    auto OS = Out.lock();
+    assert(OS && "loaded module file after finishing rewrite action?");
+
+    (*OS) << "#pragma clang module build " << MF->ModuleName << "\n";
+
+    // Rewrite the contents of the module in a separate compiler instance.
+    CompilerInstance Instance(CI.getPCHContainerOperations(),
+                              &CI.getPreprocessor().getPCMCache());
+    Instance.setInvocation(
+        std::make_shared<CompilerInvocation>(CI.getInvocation()));
+    Instance.createDiagnostics(
+        new ForwardingDiagnosticConsumer(CI.getDiagnosticClient()),
+        /*ShouldOwnClient=*/true);
+    Instance.getFrontendOpts().Inputs.clear();
+    Instance.getFrontendOpts().Inputs.emplace_back(
+        Filename, InputKind(InputKind::Unknown, InputKind::Precompiled));
+    // Don't recursively rewrite imports. We handle them all at the top level.
+    Instance.getPreprocessorOutputOpts().RewriteImports = false;
+
+    llvm::CrashRecoveryContext().RunSafelyOnThread([&]() {
+      RewriteIncludesAction Action;
+      Action.OutputStream = OS;
+      Instance.ExecuteAction(Action);
+    });
+
+    (*OS) << "#pragma clang module endbuild /*" << MF->ModuleName << "*/\n";
+  }
+};
+
+bool RewriteIncludesAction::BeginSourceFileAction(CompilerInstance &CI) {
+  if (!OutputStream) {
+    OutputStream = CI.createDefaultOutputFile(true, getCurrentFile());
+    if (!OutputStream)
+      return false;
+  }
+
+  auto &OS = *OutputStream;
 
   // If we're preprocessing a module map, start by dumping the contents of the
   // module itself before switching to the input buffer.
   auto &Input = getCurrentInput();
   if (Input.getKind().getFormat() == InputKind::ModuleMap) {
     if (Input.isFile()) {
-      (*OS) << "# 1 \"";
-      OS->write_escaped(Input.getFile());
-      (*OS) << "\"\n";
+      OS << "# 1 \"";
+      OS.write_escaped(Input.getFile());
+      OS << "\"\n";
     }
-    // FIXME: Include additional information here so that we don't need the
-    // original source files to exist on disk.
-    getCurrentModule()->print(*OS);
-    (*OS) << "#pragma clang module contents\n";
+    getCurrentModule()->print(OS);
+    OS << "#pragma clang module contents\n";
+  }
+
+  // If we're rewriting imports, set up a listener to track when we import
+  // module files.
+  if (CI.getPreprocessorOutputOpts().RewriteImports) {
+    CI.createModuleManager();
+    CI.getModuleManager()->addListener(
+        llvm::make_unique<RewriteImportsListener>(CI, OutputStream));
+  }
+
+  return true;
+}
+
+void RewriteIncludesAction::ExecuteAction() {
+  CompilerInstance &CI = getCompilerInstance();
+
+  // If we're rewriting imports, emit the module build output first rather
+  // than switching back and forth (potentially in the middle of a line).
+  if (CI.getPreprocessorOutputOpts().RewriteImports) {
+    std::string Buffer;
+    llvm::raw_string_ostream OS(Buffer);
+
+    RewriteIncludesInInput(CI.getPreprocessor(), &OS,
+                           CI.getPreprocessorOutputOpts());
+
+    (*OutputStream) << OS.str();
+  } else {
+    RewriteIncludesInInput(CI.getPreprocessor(), OutputStream.get(),
+                           CI.getPreprocessorOutputOpts());
   }
 
-  RewriteIncludesInInput(CI.getPreprocessor(), OS.get(),
-                         CI.getPreprocessorOutputOpts());
+  OutputStream.reset();
 }