[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

1 files changed, 22 insertions, 15 deletions

diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 54fe424ddf..cc9b5d506a 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -1337,7 +1337,7 @@ HeaderFileInfoTrait::ReadKey(const unsigned char *d, unsigned) {
 }
 
 HeaderFileInfoTrait::data_type 
-HeaderFileInfoTrait::ReadData(internal_key_ref, const unsigned char *d,
+HeaderFileInfoTrait::ReadData(internal_key_ref key, const unsigned char *d,
                               unsigned DataLen) {
   const unsigned char *End = d + DataLen;
   using namespace clang::io;
@@ -1358,6 +1358,21 @@ HeaderFileInfoTrait::ReadData(internal_key_ref, const unsigned char *d,
     HFI.Framework = HS->getUniqueFrameworkName(FrameworkName);
   }
   
+  if (d != End) {
+    uint32_t LocalSMID = ReadUnalignedLE32(d);
+    if (LocalSMID) {
+      // This header is part of a module. Associate it with the module to enable
+      // implicit module import.
+      SubmoduleID GlobalSMID = Reader.getGlobalSubmoduleID(M, LocalSMID);
+      Module *Mod = Reader.getSubmodule(GlobalSMID);
+      HFI.isModuleHeader = true;
+      FileManager &FileMgr = Reader.getFileManager();
+      ModuleMap &ModMap =
+          Reader.getPreprocessor().getHeaderSearchInfo().getModuleMap();
+      ModMap.addHeader(Mod, FileMgr.getFile(key.Filename), /*Excluded=*/false);
+    }
+  }
+
   assert(End == d && "Wrong data length in HeaderFileInfo deserialization");
   (void)End;
         
@@ -3508,13 +3523,9 @@ bool ASTReader::ReadSubmoduleBlock(ModuleFile &F) {
       if (!CurrentModule)
         break;
       
-      // FIXME: Be more lazy about this!
-      if (const FileEntry *File = PP.getFileManager().getFile(Blob)) {
-        if (std::find(CurrentModule->Headers.begin(), 
-                      CurrentModule->Headers.end(), 
-                      File) == CurrentModule->Headers.end())
-          ModMap.addHeader(CurrentModule, File, false);
-      }
+      // We lazily associate headers with their modules via the HeaderInfoTable.
+      // FIXME: Re-evaluate this section; maybe only store InputFile IDs instead
+      // of complete filenames or remove it entirely.
       break;      
     }
 
@@ -3527,13 +3538,9 @@ bool ASTReader::ReadSubmoduleBlock(ModuleFile &F) {
       if (!CurrentModule)
         break;
       
-      // FIXME: Be more lazy about this!
-      if (const FileEntry *File = PP.getFileManager().getFile(Blob)) {
-        if (std::find(CurrentModule->Headers.begin(), 
-                      CurrentModule->Headers.end(), 
-                      File) == CurrentModule->Headers.end())
-          ModMap.addHeader(CurrentModule, File, true);
-      }
+      // We lazily associate headers with their modules via the HeaderInfoTable.
+      // FIXME: Re-evaluate this section; maybe only store InputFile IDs instead
+      // of complete filenames or remove it entirely.
       break;      
     }