Stop leaking memory from Module and FileUnit.

Also, disallow creating Modules and FileUnits on the stack. They must always
live as long as the ASTContext.

<rdar://problem/15596964>

Swift SVN r13671

Author: jrose-apple

Diff for: include/swift/AST/ASTContext.h

@@ -392,6 +392,13 @@ class ASTContext {
   /// Add a cleanup function to be called when the ASTContext is deallocated.
   void addCleanup(std::function<void(void)> cleanup);
 
+  /// Add a cleanup to run the given object's destructor when the ASTContext is
+  /// deallocated.
+  template<typename T>
+  void addDestructorCleanup(T &object) {
+    addCleanup([&object]{ object.~T(); });
+  }
+
   /// Create a context for the initializer of a non-local variable,
   /// like a global or a field.  To reduce memory usage, if the
   /// context goes unused, it should be returned to the ASTContext

Diff for: include/swift/AST/Module.h

@@ -172,13 +172,12 @@ class Module : public DeclContext {
   // FIXME: Do we really need to bloat all modules with this?
   DebuggerClient *DebugClient = nullptr;
 
-  // FIXME: This storage is never freed, because Modules are allocated on the
-  // ASTContext.
   TinyPtrVector<FileUnit *> Files;
 
+  Module(Identifier name, ASTContext &ctx);
 public:
-  Module(Identifier Name, ASTContext &C)
-    : DeclContext(DeclContextKind::Module, nullptr), Ctx(C), Name(Name) {
+  static Module *create(Identifier name, ASTContext &ctx) {
+    return new (ctx) Module(name, ctx);
   }
 
   ArrayRef<FileUnit *> getFiles() {
@@ -413,9 +412,9 @@ class FileUnit : public DeclContext {
     : DeclContext(DeclContextKind::FileUnit, &M), Kind(kind) {
   }
 
-public:
   virtual ~FileUnit() = default;
 
+public:
   FileUnitKind getKind() const {
     return Kind;
   }
@@ -571,6 +570,8 @@ class SourceFile final : public FileUnit {
   /// May be -1, to indicate no association with a buffer.
   int BufferID;
 
+  friend ASTContext;
+  ~SourceFile();
 public:
   /// The list of top-level declarations in the source file.
   std::vector<Decl*> Decls;
@@ -606,7 +607,6 @@ class SourceFile final : public FileUnit {
 
   SourceFile(Module &M, SourceFileKind K, Optional<unsigned> bufferID,
              bool hasBuiltinModuleAccess = false);
-  ~SourceFile();
 
   ArrayRef<std::pair<Module::ImportedModule, bool>> getImports() const {
     assert(ASTStage >= Parsed || Kind == SourceFileKind::SIL);
@@ -714,6 +714,9 @@ class BuiltinUnit final : public FileUnit {
   std::unique_ptr<LookupCache> Cache;
   LookupCache &getCache() const;
 
+  friend ASTContext;
+  ~BuiltinUnit() = default;
+
 public:
   explicit BuiltinUnit(Module &M);
 
@@ -733,6 +736,7 @@ class BuiltinUnit final : public FileUnit {
 /// Represents an externally-loaded file of some kind.
 class LoadedFile : public FileUnit {
 protected:
+  ~LoadedFile() = default;
   LoadedFile(FileUnitKind Kind, Module &M) noexcept
     : FileUnit(Kind, M) {
     assert(classof(this) && "invalid kind");

Diff for: include/swift/ClangImporter/ClangModule.h

@@ -37,6 +37,8 @@ class ClangModuleUnit final : public LoadedFile {
 
   Module *getAdapterModule() const;
 
+  ~ClangModuleUnit() = default;
+
 public:
   ClangModuleUnit(Module &M, ClangImporter &owner,
                   clang::Module *clangModule);

Diff for: include/swift/Serialization/SerializedModuleLoader.h

@@ -132,6 +132,8 @@ class SerializedASTFile final : public LoadedFile {
 
   ModuleFile &File;
 
+  ~SerializedASTFile() = default;
+
   SerializedASTFile(Module &M, ModuleFile &file)
     : LoadedFile(FileUnitKind::SerializedAST, M), File(file) {}
 

Diff for: lib/AST/ASTContext.cpp

@@ -244,7 +244,7 @@ ConstraintCheckerArenaRAII::~ConstraintCheckerArenaRAII() {
 }
 
 static Module *createBuiltinModule(ASTContext &ctx) {
-  auto M = new (ctx) Module(ctx.getIdentifier("Builtin"), ctx);
+  auto M = Module::create(ctx.getIdentifier("Builtin"), ctx);
   M->addFile(*new (ctx) BuiltinUnit(*M));
   return M;
 }

Diff for: lib/AST/Module.cpp

@@ -84,6 +84,7 @@ void BuiltinUnit::LookupCache::lookupValue(Identifier Name, NLKind LookupKind,
 // Out-of-line because std::unique_ptr wants LookupCache to be complete.
 BuiltinUnit::BuiltinUnit(Module &M)
    : FileUnit(FileUnitKind::Builtin, M) {
+  M.Ctx.addDestructorCleanup(*this);
 }
 
 //===----------------------------------------------------------------------===//
@@ -269,6 +270,12 @@ void SourceLookupCache::lookupClassMember(AccessPathTy accessPath,
 // Module Implementation
 //===----------------------------------------------------------------------===//
 
+Module::Module(Identifier name, ASTContext &ctx)
+    : DeclContext(DeclContextKind::Module, nullptr), Ctx(ctx), Name(name) {
+  ctx.addDestructorCleanup(*this);
+}
+
+
 void Module::addFile(FileUnit &newFile) {
   // Require Main and REPL files to be the first file added.
   assert(Files.empty() ||
@@ -1099,6 +1106,7 @@ SourceFile::SourceFile(Module &M, SourceFileKind K,
                        Optional<unsigned> bufferID, bool hasBuiltinModuleAccess)
   : FileUnit(FileUnitKind::Source, M),
     BufferID(bufferID ? *bufferID : -1), Kind(K) {
+  M.Ctx.addDestructorCleanup(*this);
   performAutoImport(*this, hasBuiltinModuleAccess);
 }
 

Diff for: lib/ClangImporter/ClangImporter.cpp

@@ -304,7 +304,7 @@ Module *ClangImporter::loadModule(
   // FIXME: The name of this module could end up as a key in the ASTContext,
   // but that's not correct for submodules.
   Identifier name = Impl.SwiftContext.getIdentifier((*clangModule).Name);
-  auto result = new (Impl.SwiftContext) Module(name, Impl.SwiftContext);
+  auto result = Module::create(name, Impl.SwiftContext);
 
   auto file = new (Impl.SwiftContext) ClangModuleUnit(*result, *this,
                                                       clangModule);
@@ -332,7 +332,7 @@ ClangImporter::Implementation::getWrapperForModule(ClangImporter &importer,
 
   // FIXME: Handle hierarchical names better.
   Identifier name = SwiftContext.getIdentifier(underlying->Name);
-  auto wrapper = new (SwiftContext) Module(name, SwiftContext);
+  auto wrapper = Module::create(name, SwiftContext);
 
   auto file = new (SwiftContext) ClangModuleUnit(*wrapper, importer,
                                                  underlying);

Diff for: lib/Frontend/Frontend.cpp

@@ -161,7 +161,7 @@ bool swift::CompilerInstance::setup(const CompilerInvocation &Invok) {
 void CompilerInstance::performParse() {
   const SourceFileKind Kind = Invocation.getInputKind();
   Identifier ID = Context->getIdentifier(Invocation.getModuleName());
-  MainModule = new (*Context) Module(ID, *Context);
+  MainModule = Module::create(ID, *Context);
   Context->LoadedModules[ID.str()] = MainModule;
 
   if (Kind == SourceFileKind::SIL) {

Diff for: lib/IDE/Utils.cpp

@@ -33,8 +33,8 @@ bool ide::isSourceInputComplete(std::unique_ptr<llvm::MemoryBuffer> MemBuf) {
   ASTContext Ctx(LangOpts, SearchPathOpts, SM, Diags);
   auto ModName = Ctx.getIdentifier("input");
 
-  Module Mod(ModName, Ctx);
-  SourceFile SF(Mod, SourceFileKind::Main, BufferID);
+  Module &Mod = *Module::create(ModName, Ctx);
+  SourceFile &SF = *new (Ctx) SourceFile(Mod, SourceFileKind::Main, BufferID);
 
   PersistentParserState PersistentState;
   Parser P(BufferID, SF, /*SIL=*/nullptr, &PersistentState);

Diff for: lib/Sema/SourceLoader.cpp

@@ -93,7 +93,7 @@ Module *SourceLoader::loadModule(SourceLoc importLoc,
   else
     bufferID = Ctx.SourceMgr.addNewSourceBuffer(inputFile.take());
 
-  auto *importMod = new (Ctx) Module(moduleID.first, Ctx);
+  auto *importMod = Module::create(moduleID.first, Ctx);
   Ctx.LoadedModules[moduleID.first.str()] = importMod;
 
   auto *importFile = new (Ctx) SourceFile(*importMod, SourceFileKind::Library,

Diff for: lib/Serialization/SerializedModuleLoader.cpp

@@ -218,7 +218,7 @@ Module *SerializedModuleLoader::loadModule(SourceLoc importLoc,
 
   assert(inputFile);
 
-  auto M = new (Ctx) Module(moduleID.first, Ctx);
+  auto M = Module::create(moduleID.first, Ctx);
   Ctx.LoadedModules[moduleID.first.str()] = M;
 
   (void)loadAST(*M, moduleID.second, std::move(inputFile));