From f6137e4d15cb6bbd10547267babfc699c1945873 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Sat, 3 Dec 2011 00:59:55 +0000
Subject: [PATCH] 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
---
 include/clang/Serialization/ASTBitCodes.h |  6 +++++-
 include/clang/Serialization/ASTReader.h   |  3 +++
 lib/Serialization/ASTReader.cpp           | 21 +++++++++++++++++++++
 lib/Serialization/ASTWriter.cpp           | 21 +++++++++++++++++++++
 test/Modules/diamond-pch.c                |  5 -----
 5 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 3233a83931..3d234d9085 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -448,7 +448,11 @@ namespace clang {
       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 e984e306c8..203abe403c 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -541,6 +541,9 @@ private:
   /// \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 22e34d62af..c7b6b512a5 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2385,6 +2385,20 @@ ASTReader::ReadASTBlock(ModuleFile &F) {
       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 @@ void ASTReader::InitializeContext() {
     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 00dbfabb45..15db7050e9 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -3335,6 +3335,27 @@ void ASTWriter::WriteASTCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
        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 f5b0faa424..d0f45908cf 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);
-- 
2.40.0