6 files changed, 47 insertions, 10 deletions
diff --git a/include/clang/Frontend/CompilerInstance.h b/include/clang/Frontend/CompilerInstance.h
index 09b27e14df..90f84ef379 100644
--- a/include/clang/Frontend/CompilerInstance.h
+++ b/include/clang/Frontend/CompilerInstance.h
@@ -99,15 +99,9 @@ class CompilerInstance : public ModuleLoader {
   /// \brief Non-owning reference to the ASTReader, if one exists.
   ASTReader *ModuleManager;
 
-  /// \brief A module that we have already attempted to load, which is known
-  /// by either a file entry (FIXME: a temporary measure) or via its module
-  /// definition.
-  typedef llvm::PointerUnion<const FileEntry *, ModuleMap::Module *> 
-    KnownModule;
-  
   /// \brief The set of top-level modules that has already been loaded,
   /// along with the module map
-  llvm::DenseMap<const IdentifierInfo *, KnownModule> KnownModules;
+  llvm::DenseMap<const IdentifierInfo *, ModuleMap::Module *> KnownModules;
   
   /// \brief The location of the module-import keyword for the last module
   /// import. 
@@ -115,7 +109,7 @@ class CompilerInstance : public ModuleLoader {
   
   /// \brief The result of the last module import.
   ///
-  KnownModule LastModuleImportResult;
+  ModuleMap::Module *LastModuleImportResult;
   
   /// \brief Holds information about the output file.
   ///
diff --git a/include/clang/Lex/ModuleMap.h b/include/clang/Lex/ModuleMap.h
index 4f89f1e728..c5727a9c35 100644
--- a/include/clang/Lex/ModuleMap.h
+++ b/include/clang/Lex/ModuleMap.h
@@ -162,6 +162,24 @@ public:
   /// \returns The named module, if known; otherwise, returns null.
   Module *findModule(StringRef Name);
   
+  /// \brief Find a new module or submodule, or create it if it does not already
+  /// exist.
+  ///
+  /// \param Name The name of the module to find or create.
+  ///
+  /// \param Parent The module that will act as the parent of this submodule,
+  /// or NULL to indicate that this is a top-level module.
+  ///
+  /// \param IsFramework Whether this is a framework module.
+  ///
+  /// \param IsExplicit Whether this is an explicit submodule.
+  ///
+  /// \returns The found or newly-created module, along with a boolean value
+  /// that will be true if the module is newly-created.
+  std::pair<Module *, bool> findOrCreateModule(StringRef Name, Module *Parent, 
+                                               bool IsFramework,
+                                               bool IsExplicit);
+                       
   /// \brief Infer the contents of a framework module map from the given
   /// framework directory.
   Module *inferFrameworkModule(StringRef ModuleName, 
diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 53d970b684..22dc0b974c 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -198,7 +198,10 @@ namespace clang {
       DECL_UPDATES_BLOCK_ID,
       
       /// \brief The block containing the detailed preprocessing record.
-      PREPROCESSOR_DETAIL_BLOCK_ID
+      PREPROCESSOR_DETAIL_BLOCK_ID,
+      
+      /// \brief The block containing the submodule structure.
+      SUBMODULE_BLOCK_ID
     };
 
     /// \brief Record types that occur within the AST block itself.
@@ -492,6 +495,18 @@ namespace clang {
       PPD_INCLUSION_DIRECTIVE = 2
     };
     
+    /// \brief Record types used within a submodule description block.
+    enum SubmoduleRecordTypes {
+      /// \brief Defines the major attributes of a submodule, including its
+      /// name and parent.
+      SUBMODULE_DEFINITION = 0,
+      /// \brief Specifies the umbrella header used to create this module,
+      /// if any.
+      SUBMODULE_UMBRELLA = 1,
+      /// \brief Specifies a header that falls into this (sub)module.
+      SUBMODULE_HEADER = 2
+    };
+    
     /// \defgroup ASTAST AST file AST constants
     ///
     /// The constants in this group describe various components of the
diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index 7a9a15caf4..a641942fc5 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -692,8 +692,9 @@ private:
   ASTReadResult ReadSLocEntryRecord(int ID);
   llvm::BitstreamCursor &SLocCursorForID(int ID);
   SourceLocation getImportLocation(Module *F);
+  ASTReadResult ReadSubmoduleBlock(Module &F);
   bool ParseLanguageOptions(const SmallVectorImpl<uint64_t> &Record);
-
+  
   struct RecordLocation {
     RecordLocation(Module *M, uint64_t O)
       : F(M), Offset(O) {}
diff --git a/include/clang/Serialization/ASTWriter.h b/include/clang/Serialization/ASTWriter.h
index ac750c9196..5773c77d8f 100644
--- a/include/clang/Serialization/ASTWriter.h
+++ b/include/clang/Serialization/ASTWriter.h
@@ -358,6 +358,10 @@ private:
   /// in the order they should be written.
   SmallVector<QueuedCXXBaseSpecifiers, 2> CXXBaseSpecifiersToWrite;
 
+  /// \brief A mapping from each known submodule to its ID number, which will
+  /// be a positive integer.
+  llvm::DenseMap<ModuleMap::Module *, unsigned> SubmoduleIDs;
+                    
   /// \brief Write the given subexpression to the bitstream.
   void WriteSubStmt(Stmt *S,
                     llvm::DenseMap<Stmt *, uint64_t> &SubStmtEntries,
@@ -374,6 +378,7 @@ private:
   void WritePreprocessor(const Preprocessor &PP, bool IsModule);
   void WriteHeaderSearch(const HeaderSearch &HS, StringRef isysroot);
   void WritePreprocessorDetail(PreprocessingRecord &PPRec);
+  void WriteSubmodules(ModuleMap::Module *WritingModule);
   void WritePragmaDiagnosticMappings(const DiagnosticsEngine &Diag);
   void WriteCXXBaseSpecifiersOffsets();
   void WriteType(QualType T);
diff --git a/include/clang/Serialization/Module.h b/include/clang/Serialization/Module.h
index ca2046bf27..92ff8d8920 100644
--- a/include/clang/Serialization/Module.h
+++ b/include/clang/Serialization/Module.h
@@ -17,6 +17,7 @@
 
 #include "clang/Serialization/ASTBitCodes.h"
 #include "clang/Serialization/ContinuousRangeMap.h"
+#include "clang/Lex/ModuleMap.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/SetVector.h"
@@ -200,6 +201,9 @@ public:
   /// search information.
   const char *HeaderFileFrameworkStrings;
 
+  // === Submodule information ===
+  llvm::SmallVector<ModuleMap::Module *, 2> Submodules;
+  
   // === Selectors ===
 
   /// \brief The number of selectors new to this file.