[Modules] Don't eagerly load and associate all the module header files.

In a module-enabled Cocoa PCH file, we spend a lot of time stat'ing the headers
in order to associate the FileEntries with their modules and support implicit
module import.

Use a more lazy scheme by enhancing HeaderInfoTable to store extra info about
the module that a header belongs to, and associate it with its module only when
there is a request for loading the header info for a particular file.

Part of rdar://13391765

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176976 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 18 insertions, 4 deletions

diff --git a/include/clang/Lex/HeaderSearch.h b/include/clang/Lex/HeaderSearch.h
index 1729e240cc..a0ce139993 100644
--- a/include/clang/Lex/HeaderSearch.h
+++ b/include/clang/Lex/HeaderSearch.h
@@ -50,6 +50,9 @@ struct HeaderFileInfo {
 
   /// \brief Whether this header file info was supplied by an external source.
   unsigned External : 1;
+
+  /// \brief Whether this header is part of a module.
+  unsigned isModuleHeader : 1;
   
   /// \brief Whether this structure is considered to already have been
   /// "resolved", meaning that it was loaded from the external source.
@@ -90,7 +93,8 @@ struct HeaderFileInfo {
   
   HeaderFileInfo()
     : isImport(false), isPragmaOnce(false), DirInfo(SrcMgr::C_User), 
-      External(false), Resolved(false), IndexHeaderMapHeader(false),
+      External(false), isModuleHeader(false), Resolved(false),
+      IndexHeaderMapHeader(false),
       NumIncludes(0), ControllingMacroID(0), ControllingMacro(0)  {}
 
   /// \brief Retrieve the controlling macro for this header file, if
@@ -189,7 +193,7 @@ class HeaderSearch {
   std::vector<std::pair<const FileEntry*, const HeaderMap*> > HeaderMaps;
 
   /// \brief The mapping between modules and headers.
-  ModuleMap ModMap;
+  mutable ModuleMap ModMap;
   
   /// \brief Describes whether a given directory has a module map in it.
   llvm::DenseMap<const DirectoryEntry *, bool> DirectoryHasModuleMap;
@@ -400,6 +404,9 @@ public:
     getFileInfo(File).DirInfo = SrcMgr::C_System;
   }
 
+  /// \brief Mark the specified file as part of a module.
+  void MarkFileModuleHeader(const FileEntry *File);
+
   /// \brief Increment the count for the number of times the specified
   /// FileEntry has been entered.
   void IncrementIncludeCount(const FileEntry *File) {
@@ -469,7 +476,7 @@ public:
   /// \brief Retrieve the module that corresponds to the given file, if any.
   ///
   /// \param File The header that we wish to map to a module.
-  Module *findModuleForHeader(const FileEntry *File);
+  Module *findModuleForHeader(const FileEntry *File) const;
   
   /// \brief Read the contents of the given module map file.
   ///
diff --git a/include/clang/Lex/ModuleMap.h b/include/clang/Lex/ModuleMap.h
index bb53ff21a0..cffa5b7b66 100644
--- a/include/clang/Lex/ModuleMap.h
+++ b/include/clang/Lex/ModuleMap.h
@@ -33,6 +33,7 @@ class FileEntry;
 class FileManager;
 class DiagnosticConsumer;
 class DiagnosticsEngine;
+class HeaderSearch;
 class ModuleMapParser;
   
 class ModuleMap {
@@ -40,6 +41,7 @@ class ModuleMap {
   IntrusiveRefCntPtr<DiagnosticsEngine> Diags;
   const LangOptions &LangOpts;
   const TargetInfo *Target;
+  HeaderSearch &HeaderInfo;
   
   /// \brief The directory used for Clang-supplied, builtin include headers,
   /// such as "stdint.h".
@@ -147,7 +149,8 @@ public:
   ///
   /// \param Target The target for this translation unit.
   ModuleMap(FileManager &FileMgr, const DiagnosticConsumer &DC,
-            const LangOptions &LangOpts, const TargetInfo *Target);
+            const LangOptions &LangOpts, const TargetInfo *Target,
+            HeaderSearch &HeaderInfo);
 
   /// \brief Destroy the module map.
   ///
diff --git a/include/clang/Serialization/ASTWriter.h b/include/clang/Serialization/ASTWriter.h
index b966ae1228..1bbf74061f 100644
--- a/include/clang/Serialization/ASTWriter.h
+++ b/include/clang/Serialization/ASTWriter.h
@@ -641,6 +641,10 @@ public:
   /// source location.
   serialization::SubmoduleID inferSubmoduleIDFromLocation(SourceLocation Loc);
 
+  /// \brief Retrieve a submodule ID for this module.
+  /// Returns 0 If no ID has been associated with the module.
+  unsigned getExistingSubmoduleID(Module *Mod) const;
+
   /// \brief Note that the identifier II occurs at the given offset
   /// within the identifier table.
   void SetIdentifierOffset(const IdentifierInfo *II, uint32_t Offset);