Implement support for precompiled headers, preambles, and serialized
"main" files that import modules. When loading any of these kinds of
AST files, we make the modules that were imported visible into the
translation unit that loaded the PCH file or preamble.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145737 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 3233a83..3d234d9 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -448,7 +448,11 @@
       OBJC_CHAINED_CATEGORIES,
 
       /// \brief Record code for a file sorted array of DeclIDs in a module.
-      FILE_SORTED_DECLS
+      FILE_SORTED_DECLS,
+      
+      /// \brief Record code for an array of all of the (sub)modules that were
+      /// imported by the AST file.
+      IMPORTED_MODULES
     };
 
     /// \brief Record types used within a source manager block.
diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index e984e30..203abe4 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -541,6 +541,9 @@
   /// \brief A list of the namespaces we've seen.
   SmallVector<uint64_t, 4> KnownNamespaces;
 
+  /// \brief A list of modules that were imported by precompiled headers or
+  /// any other non-module AST file.
+  SmallVector<serialization::SubmoduleID, 2> ImportedModules;
   //@}
 
   /// \brief The original file name that was used to build the primary AST file,
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 22e34d6..c7b6b51 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2385,6 +2385,20 @@
       for (unsigned I = 0, N = Record.size(); I != N; ++I)
         KnownNamespaces.push_back(getGlobalDeclID(F, Record[I]));
       break;
+        
+    case IMPORTED_MODULES: {
+      if (F.Kind != MK_Module) {
+        // If we aren't loading a module (which has its own exports), make
+        // all of the imported modules visible.
+        // FIXME: Deal with macros-only imports.
+        for (unsigned I = 0, N = Record.size(); I != N; ++I) {
+          if (unsigned GlobalID = getGlobalSubmoduleID(F, Record[I]))
+            ImportedModules.push_back(GlobalID);
+        }
+      }
+      break;
+      
+    }
     }
   }
   Error("premature end of bitstream in AST file");
@@ -2835,6 +2849,13 @@
     Context.setcudaConfigureCallDecl(
                            cast<FunctionDecl>(GetDecl(CUDASpecialDeclRefs[0])));
   }
+  
+  // Re-export any modules that were imported by a non-module AST file.
+  for (unsigned I = 0, N = ImportedModules.size(); I != N; ++I) {
+    if (Module *Imported = getSubmodule(ImportedModules[I]))
+      makeModuleVisible(Imported, Module::AllVisible);
+  }
+  ImportedModules.clear();
 }
 
 void ASTReader::finalizeForWriting() {
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 00dbfab..15db705 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -3335,6 +3335,27 @@
        I != E; ++I)
     WriteDeclContextVisibleUpdate(*I);
 
+  // Write the submodules that were imported, if any.
+  RecordData ImportedModules;
+  for (ASTContext::import_iterator I = Context.local_import_begin(),
+                                IEnd = Context.local_import_end();
+       I != IEnd; ++I) {
+    assert(SubmoduleIDs.find(I->getImportedModule()) != SubmoduleIDs.end());
+    ImportedModules.push_back(SubmoduleIDs[I->getImportedModule()]);
+  }
+  if (!ImportedModules.empty()) {
+    // Sort module IDs.
+    llvm::array_pod_sort(ImportedModules.begin(), ImportedModules.end());
+    
+    // Unique module IDs.
+    ImportedModules.erase(std::unique(ImportedModules.begin(), 
+                                      ImportedModules.end()),
+                          ImportedModules.end());
+    
+    Stream.EmitRecord(IMPORTED_MODULES, ImportedModules);
+    ImportedModules.clear();
+  }
+  
   WriteDeclUpdatesBlocks();
   WriteDeclReplacementsBlock();
   WriteChainedObjCCategories();
diff --git a/test/Modules/diamond-pch.c b/test/Modules/diamond-pch.c
index f5b0faa..d0f4590 100644
--- a/test/Modules/diamond-pch.c
+++ b/test/Modules/diamond-pch.c
@@ -3,11 +3,6 @@
 
 // in diamond-bottom.h: expected-note{{passing argument to parameter 'x' here}}
 
-// FIXME: The module import below shouldn't be necessary, because importing the
-// precompiled header should make all of the modules visible that were
-// visible when the PCH file was built.
-__import_module__ diamond_bottom;
-
 void test_diamond(int i, float f, double d, char c) {
   top(&i);
   left(&f);