Add driver flag to precompile Swift-compatible explicit Clang modules.

include/swift/AST/DiagnosticsClangImporter.def

@@ -64,6 +64,12 @@ ERROR(bridging_header_pch_error,Fatal,
    "failed to emit precompiled header '%0' for bridging header '%1'",
    (StringRef, StringRef))
 
+ERROR(emit_pcm_error,Fatal,
+   "failed to emit precompiled module '%0' for module map '%1'",
+   (StringRef, StringRef))
+ERROR(dump_pcm_error,Fatal,
+   "failed to dump precompiled module '%0'", (StringRef))
+
 WARNING(invalid_swift_name_method,none,
   "too %select{few|many}0 parameters in swift_name attribute (expected %1; "
   "got %2)", (bool, unsigned, unsigned))

include/swift/ClangImporter/ClangImporter.h

@@ -112,6 +112,17 @@ class ClangImporter final : public ClangModuleLoader {
                 DependencyTracker *tracker,
                 DWARFImporterDelegate *dwarfImporterDelegate);
 
+  /// Creates a clone of Clang importer's compiler instance that has been
+  /// configured for operations on precompiled outputs (either emitting a
+  /// precompiled header, emitting a precompiled module, or dumping a
+  /// precompiled module).
+  ///
+  /// The caller of this method should set any action-specific invocation
+  /// options (like FrontendOptions::ProgramAction, input files, and output
+  /// paths), then create the appropriate FrontendAction and execute it.
+  std::unique_ptr<clang::CompilerInstance>
+  cloneCompilerInstanceForPrecompiling();
+
 public:
   /// Create a new Clang importer that can import a suitable Clang
   /// module into the given ASTContext.
@@ -333,6 +344,19 @@ class ClangImporter final : public ClangModuleLoader {
   /// if we need to persist a PCH for later reuse.
   bool canReadPCH(StringRef PCHFilename);
 
+  /// Makes a temporary replica of the ClangImporter's CompilerInstance, reads a
+  /// module map into the replica and emits a PCM file for one of the modules it
+  /// declares. Delegates to clang for everything except construction of the
+  /// replica.
+  bool emitPrecompiledModule(StringRef moduleMapPath, StringRef moduleName,
+                             StringRef outputPath);
+
+  /// Makes a temporary replica of the ClangImporter's CompilerInstance and
+  /// dumps information about a PCM file (assumed to be generated by -emit-pcm
+  /// or in the Swift module cache). Delegates to clang for everything except
+  /// construction of the replica.
+  bool dumpPrecompiledModule(StringRef modulePath, StringRef outputPath);
+
   const clang::Module *getClangOwningModule(ClangNode Node) const;
   bool hasTypedef(const clang::Decl *typeDecl) const;
 

include/swift/ClangImporter/ClangImporterOptions.h

@@ -60,7 +60,10 @@ class ClangImporterOptions {
     /// Swift code.
     Normal,
     /// Set up Clang for backend compilation only.
-    EmbedBitcode
+    EmbedBitcode,
+    /// Set up Clang to emit a precompiled module from a C/Objective-C module
+    /// map or dump debugging info about a precompiled module.
+    PrecompiledModule
   };
 
   /// Controls how Clang is initially set up.

include/swift/Frontend/Frontend.h

@@ -202,6 +202,12 @@ class CompilerInvocation {
 
   void setRuntimeResourcePath(StringRef Path);
 
+  /// Computes the runtime resource path relative to the given Swift
+  /// executable.
+  static void computeRuntimeResourcePathFromExecutablePath(
+      StringRef mainExecutablePath,
+      llvm::SmallString<128> &runtimeResourcePath);
+
   void setSDKPath(const std::string &Path);
 
   StringRef getSDKPath() const {

include/swift/Frontend/FrontendOptions.h

@@ -148,6 +148,9 @@ class FrontendOptions {
     EmitObject,   ///< Emit object file
 
     DumpTypeInfo, ///< Dump IRGen type info
+
+    EmitPCM, ///< Emit precompiled Clang module from a module map
+    DumpPCM, ///< Dump information about a precompiled Clang module
   };
 
   /// Indicates the action the user requested that the frontend perform.

include/swift/Option/Options.td

@@ -748,6 +748,9 @@ def emit_sibgen : Flag<["-"], "emit-sibgen">,
 def emit_imported_modules : Flag<["-"], "emit-imported-modules">,
   HelpText<"Emit a list of the imported modules">, ModeOpt,
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>;
+def emit_pcm : Flag<["-"], "emit-pcm">,
+  HelpText<"Emit a precompiled Clang module from a module map">, ModeOpt,
+  Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>;
 
 def c : Flag<["-"], "c">, Alias<emit_object>,
   Flags<[FrontendOption, NoInteractiveOption]>, ModeOpt;
@@ -792,6 +795,10 @@ def print_ast : Flag<["-"], "print-ast">,
   HelpText<"Parse and type-check input file(s) and pretty print AST(s)">,
   ModeOpt,
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>;
+def dump_pcm : Flag<["-"], "dump-pcm">,
+  HelpText<"Dump debugging information about a precompiled Clang module">,
+  ModeOpt,
+  Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>;
 
 // Other Modes
 def repl : Flag<["-"], "repl">,

lib/ClangImporter/ClangImporter.cpp

@@ -902,6 +902,7 @@ ClangImporter::create(ASTContext &ctx, const ClangImporterOptions &importerOpts,
   invocationArgStrs.push_back("clang");
   switch (importerOpts.Mode) {
   case ClangImporterOptions::Modes::Normal:
+  case ClangImporterOptions::Modes::PrecompiledModule:
     getNormalInvocationArguments(invocationArgStrs, ctx, importerOpts);
     break;
   case ClangImporterOptions::Modes::EmbedBitcode:
@@ -1062,7 +1063,17 @@ ClangImporter::create(ASTContext &ctx, const ClangImporterOptions &importerOpts,
   if (importerOpts.Mode == ClangImporterOptions::Modes::EmbedBitcode)
     return importer;
 
+  // ClangImporter always sets this in Normal mode, so we need to make sure to
+  // set it before bailing out early when configuring ClangImporter for
+  // precompiled modules. This is not a benign langopt, so forgetting this (for
+  // example, if we combined the early exit below with the one above) would make
+  // the compiler instance used to emit PCMs incompatible with the one used to
+  // read them later.
   instance.getLangOpts().NeededByPCHOrCompilationUsesPCH = true;
+
+  if (importerOpts.Mode == ClangImporterOptions::Modes::PrecompiledModule)
+    return importer;
+
   bool canBegin = action->BeginSourceFile(instance,
                                           instance.getFrontendOpts().Inputs[0]);
   if (!canBegin)
@@ -1446,43 +1457,82 @@ std::string ClangImporter::getBridgingHeaderContents(StringRef headerPath,
   return result;
 }
 
-bool
-ClangImporter::emitBridgingPCH(StringRef headerPath,
-                               StringRef outputPCHPath) {
+/// Returns the appropriate source input language based on language options.
+static clang::Language getLanguageFromOptions(
+    const clang::LangOptions *LangOpts) {
+  if (LangOpts->OpenCL)
+    return clang::Language::OpenCL;
+  if (LangOpts->CUDA)
+    return clang::Language::CUDA;
+  if (LangOpts->ObjC)
+    return LangOpts->CPlusPlus ?
+        clang::Language::ObjCXX : clang::Language::ObjC;
+  return LangOpts->CPlusPlus ? clang::Language::CXX : clang::Language::C;
+}
+
+/// Wraps the given frontend action in an index data recording action if the
+/// frontend options have an index store path specified.
+static
+std::unique_ptr<clang::FrontendAction> wrapActionForIndexingIfEnabled(
+    const clang::FrontendOptions &FrontendOpts,
+    std::unique_ptr<clang::FrontendAction> action) {
+  if (!FrontendOpts.IndexStorePath.empty()) {
+    return clang::index::createIndexDataRecordingAction(
+        FrontendOpts, std::move(action));
+  }
+  return action;
+}
+
+std::unique_ptr<clang::CompilerInstance>
+ClangImporter::cloneCompilerInstanceForPrecompiling() {
   auto invocation =
       std::make_shared<clang::CompilerInvocation>(*Impl.Invocation);
-  invocation->getFrontendOpts().DisableFree = false;
-  invocation->getFrontendOpts().Inputs.clear();
-  invocation->getFrontendOpts().Inputs.push_back(
-      clang::FrontendInputFile(headerPath, clang::Language::ObjC));
-  invocation->getFrontendOpts().OutputFile = outputPCHPath;
-  invocation->getFrontendOpts().ProgramAction = clang::frontend::GeneratePCH;
-  invocation->getPreprocessorOpts().resetNonModularOptions();
-  invocation->getLangOpts()->NeededByPCHOrCompilationUsesPCH = true;
-  invocation->getLangOpts()->CacheGeneratedPCH = true;
 
-  clang::CompilerInstance emitInstance(
+  auto &PPOpts = invocation->getPreprocessorOpts();
+  PPOpts.resetNonModularOptions();
+
+  auto &FrontendOpts = invocation->getFrontendOpts();
+  FrontendOpts.DisableFree = false;
+  FrontendOpts.Inputs.clear();
+
+  auto clonedInstance = llvm::make_unique<clang::CompilerInstance>(
     Impl.Instance->getPCHContainerOperations(),
     &Impl.Instance->getModuleCache());
-  emitInstance.setInvocation(std::move(invocation));
-  emitInstance.createDiagnostics(&Impl.Instance->getDiagnosticClient(),
-                                 /*ShouldOwnClient=*/false);
+  clonedInstance->setInvocation(std::move(invocation));
+  clonedInstance->createDiagnostics(&Impl.Instance->getDiagnosticClient(),
+                                    /*ShouldOwnClient=*/false);
 
   clang::FileManager &fileManager = Impl.Instance->getFileManager();
-  emitInstance.setFileManager(&fileManager);
-  emitInstance.createSourceManager(fileManager);
-  emitInstance.setTarget(&Impl.Instance->getTarget());
+  clonedInstance->setFileManager(&fileManager);
+  clonedInstance->createSourceManager(fileManager);
+  clonedInstance->setTarget(&Impl.Instance->getTarget());
 
-  std::unique_ptr<clang::FrontendAction> action;
-  action.reset(new clang::GeneratePCHAction());
-  if (!emitInstance.getFrontendOpts().IndexStorePath.empty()) {
-    action = clang::index::
-      createIndexDataRecordingAction(emitInstance.getFrontendOpts(),
-                                     std::move(action));
-  }
-  emitInstance.ExecuteAction(*action);
+  return clonedInstance;
+}
+
+bool
+ClangImporter::emitBridgingPCH(StringRef headerPath,
+                               StringRef outputPCHPath) {
+  auto emitInstance = cloneCompilerInstanceForPrecompiling();
+  auto &invocation = emitInstance->getInvocation();
+
+  auto LangOpts = invocation.getLangOpts();
+  LangOpts->NeededByPCHOrCompilationUsesPCH = true;
+  LangOpts->CacheGeneratedPCH = true;
+
+  auto language = getLanguageFromOptions(LangOpts);
+  auto inputFile = clang::FrontendInputFile(headerPath, language);
+
+  auto &FrontendOpts = invocation.getFrontendOpts();
+  FrontendOpts.Inputs = {inputFile};
+  FrontendOpts.OutputFile = outputPCHPath;
+  FrontendOpts.ProgramAction = clang::frontend::GeneratePCH;
 
-  if (emitInstance.getDiagnostics().hasErrorOccurred()) {
+  auto action = wrapActionForIndexingIfEnabled(
+      FrontendOpts, llvm::make_unique<clang::GeneratePCHAction>());
+  emitInstance->ExecuteAction(*action);
+
+  if (emitInstance->getDiagnostics().hasErrorOccurred()) {
     Impl.SwiftContext.Diags.diagnose({},
                                      diag::bridging_header_pch_error,
                                      outputPCHPath, headerPath);
@@ -1491,6 +1541,65 @@ ClangImporter::emitBridgingPCH(StringRef headerPath,
   return false;
 }
 
+bool ClangImporter::emitPrecompiledModule(StringRef moduleMapPath,
+                                          StringRef moduleName,
+                                          StringRef outputPath) {
+  auto emitInstance = cloneCompilerInstanceForPrecompiling();
+  auto &invocation = emitInstance->getInvocation();
+
+  auto LangOpts = invocation.getLangOpts();
+  LangOpts->setCompilingModule(clang::LangOptions::CMK_ModuleMap);
+  LangOpts->ModuleName = moduleName;
+  LangOpts->CurrentModule = LangOpts->ModuleName;
+
+  auto language = getLanguageFromOptions(LangOpts);
+  auto inputFile = clang::FrontendInputFile(
+      moduleMapPath, clang::InputKind(
+          language, clang::InputKind::ModuleMap, false));
+
+  auto &FrontendOpts = invocation.getFrontendOpts();
+  FrontendOpts.Inputs = {inputFile};
+  FrontendOpts.OriginalModuleMap = moduleMapPath;
+  FrontendOpts.OutputFile = outputPath;
+  FrontendOpts.ProgramAction = clang::frontend::GenerateModule;
+
+  auto action = wrapActionForIndexingIfEnabled(
+      FrontendOpts,
+      llvm::make_unique<clang::GenerateModuleFromModuleMapAction>());
+  emitInstance->ExecuteAction(*action);
+
+  if (emitInstance->getDiagnostics().hasErrorOccurred()) {
+    Impl.SwiftContext.Diags.diagnose({},
+                                     diag::emit_pcm_error,
+                                     outputPath, moduleMapPath);
+    return true;
+  }
+  return false;
+}
+
+bool ClangImporter::dumpPrecompiledModule(StringRef modulePath,
+                                          StringRef outputPath) {
+  auto dumpInstance = cloneCompilerInstanceForPrecompiling();
+  auto &invocation = dumpInstance->getInvocation();
+
+  auto inputFile = clang::FrontendInputFile(
+      modulePath, clang::InputKind(
+          clang::Language::Unknown, clang::InputKind::Precompiled, false));
+
+  auto &FrontendOpts = invocation.getFrontendOpts();
+  FrontendOpts.Inputs = {inputFile};
+  FrontendOpts.OutputFile = outputPath;
+
+  auto action = llvm::make_unique<clang::DumpModuleInfoAction>();
+  dumpInstance->ExecuteAction(*action);
+
+  if (dumpInstance->getDiagnostics().hasErrorOccurred()) {
+    Impl.SwiftContext.Diags.diagnose({}, diag::dump_pcm_error, modulePath);
+    return true;
+  }
+  return false;
+}
+
 void ClangImporter::collectVisibleTopLevelModuleNames(
     SmallVectorImpl<Identifier> &names) const {
   SmallVector<clang::Module *, 32> Modules;

lib/Driver/Driver.cpp

@@ -1410,6 +1410,11 @@ void Driver::buildOutputInfo(const ToolChain &TC, const DerivedArgList &Args,
       OI.CompilerOutputType = file_types::TY_PCH;
       break;
 
+    case options::OPT_emit_pcm:
+      OI.CompilerMode = OutputInfo::Mode::SingleCompile;
+      OI.CompilerOutputType = file_types::TY_ClangModuleFile;
+      break;
+
     case options::OPT_emit_imported_modules:
       OI.CompilerOutputType = file_types::TY_ImportedModules;
       // We want the imported modules from the module as a whole, not individual
@@ -1442,6 +1447,11 @@ void Driver::buildOutputInfo(const ToolChain &TC, const DerivedArgList &Args,
       OI.CompilerOutputType = file_types::TY_Nothing;
       break;
 
+    case options::OPT_dump_pcm:
+      OI.CompilerMode = OutputInfo::Mode::SingleCompile;
+      OI.CompilerOutputType = file_types::TY_Nothing;
+      break;
+
     case options::OPT_i:
       // Keep the default output/mode; this flag was removed and should already
       // have been diagnosed above.
@@ -1842,6 +1852,11 @@ void Driver::buildActions(SmallVectorImpl<const Action *> &TopLevelActions,
   }
   case OutputInfo::Mode::SingleCompile: {
     if (Inputs.empty()) break;
+    if (Args.hasArg(options::OPT_emit_pcm) && Inputs.size() != 1) {
+      // -emit-pcm mode requires exactly one input (the module map).
+      Diags.diagnose(SourceLoc(), diag::error_mode_requires_one_input_file);
+      return;
+    }
     if (Args.hasArg(options::OPT_embed_bitcode)) {
       // Make sure we can handle the inputs.
       bool HandledHere = true;

lib/Driver/ToolChains.cpp

@@ -499,6 +499,8 @@ const char *ToolChain::JobContext::computeFrontendModeForCompile() const {
     return "-emit-ir";
   case file_types::TY_LLVM_BC:
     return "-emit-bc";
+  case file_types::TY_ClangModuleFile:
+    return "-emit-pcm";
   case file_types::TY_Assembly:
     return "-S";
   case file_types::TY_SwiftModuleFile:
@@ -522,7 +524,6 @@ const char *ToolChain::JobContext::computeFrontendModeForCompile() const {
   case file_types::TY_AutolinkFile:
   case file_types::TY_Dependencies:
   case file_types::TY_SwiftModuleDocFile:
-  case file_types::TY_ClangModuleFile:
   case file_types::TY_SerializedDiagnostics:
   case file_types::TY_ObjCHeader:
   case file_types::TY_Image:
@@ -758,14 +759,14 @@ ToolChain::constructInvocation(const BackendJobAction &job,
     case file_types::TY_SIL:
     case file_types::TY_SIB:
     case file_types::TY_PCH:
+    case file_types::TY_ClangModuleFile:
     case file_types::TY_IndexData:
       llvm_unreachable("Cannot be output from backend job");
     case file_types::TY_Swift:
     case file_types::TY_dSYM:
     case file_types::TY_AutolinkFile:
     case file_types::TY_Dependencies:
     case file_types::TY_SwiftModuleDocFile:
-    case file_types::TY_ClangModuleFile:
     case file_types::TY_SerializedDiagnostics:
     case file_types::TY_ObjCHeader:
     case file_types::TY_Image:

lib/Frontend/ArgsToFrontendOptionsConverter.cpp

@@ -393,6 +393,10 @@ ArgsToFrontendOptionsConverter::determineRequestedAction(const ArgList &args) {
     return FrontendOptions::ActionType::DumpTypeInfo;
   if (Opt.matches(OPT_print_ast))
     return FrontendOptions::ActionType::PrintAST;
+  if (Opt.matches(OPT_emit_pcm))
+    return FrontendOptions::ActionType::EmitPCM;
+  if (Opt.matches(OPT_dump_pcm))
+    return FrontendOptions::ActionType::DumpPCM;
 
   if (Opt.matches(OPT_repl) || Opt.matches(OPT_deprecated_integrated_repl))
     return FrontendOptions::ActionType::REPL;