3 files changed, 27 insertions, 5 deletions
diff --git a/lib/Frontend/PCHReader.cpp b/lib/Frontend/PCHReader.cpp
index 37e11249f8..a0e3148bc7 100644
--- a/lib/Frontend/PCHReader.cpp
+++ b/lib/Frontend/PCHReader.cpp
@@ -1539,6 +1539,16 @@ PCHReader::ReadPCHBlock(PerFileData &F) {
       F.LocalNumDecls = Record[0];
       break;
 
+    case pch::TU_UPDATE_LEXICAL: {
+      DeclContextInfo Info = {
+        /* No visible information */ 0, 0,
+        reinterpret_cast<const pch::DeclID *>(BlobStart),
+        BlobLen / sizeof(pch::DeclID)
+      };
+      DeclContextOffsets[Context->getTranslationUnitDecl()].push_back(Info);
+      break;
+    }
+
     case pch::LANGUAGE_OPTIONS:
       if (ParseLanguageOptions(Record) && !DisableValidation)
         return IgnorePCH;
diff --git a/lib/Frontend/PCHReaderDecl.cpp b/lib/Frontend/PCHReaderDecl.cpp
index 6f6ed84df7..fe2947d64f 100644
--- a/lib/Frontend/PCHReaderDecl.cpp
+++ b/lib/Frontend/PCHReaderDecl.cpp
@@ -1520,7 +1520,11 @@ Decl *PCHReader::ReadDeclRecord(unsigned Index) {
       DeclContextInfo Info;
       if (ReadDeclContextStorage(DeclsCursor, Offsets, Info))
         return 0;
-      DeclContextOffsets[DC].push_back(Info);
+      DeclContextInfos &Infos = DeclContextOffsets[DC];
+      // Reading the TU will happen after reading its update blocks, so we need
+      // to make sure we insert in front. For all other contexts, the vector
+      // is empty here anyway, so there's no loss in efficiency.
+      Infos.insert(Infos.begin(), Info);
     }
   }
   assert(Idx == Record.size());
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index 0ade10f7f8..96c64169cf 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -2354,15 +2354,23 @@ void PCHWriter::WritePCHChain(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   // The TU was loaded before we managed to register ourselves as a listener.
   // Thus we need to add it manually.
   DeclIDs[TU] = 1;
-  Record.clear();
+  llvm::SmallVector<pch::DeclID, 64> NewGlobalDecls;
   for (DeclContext::decl_iterator I = TU->noload_decls_begin(),
                                   E = TU->noload_decls_end();
        I != E; ++I) {
-    if ((*I)->getPCHLevel() == 0) {
-      AddDeclRef(*I, Record);
-    }
+    if ((*I)->getPCHLevel() == 0)
+      NewGlobalDecls.push_back(GetDeclRef(*I));
   }
   // We also need to write a lexical updates block for the TU.
+  llvm::BitCodeAbbrev *Abv = new llvm::BitCodeAbbrev();
+  Abv->Add(llvm::BitCodeAbbrevOp(pch::TU_UPDATE_LEXICAL));
+  Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
+  unsigned TuUpdateLexicalAbbrev = Stream.EmitAbbrev(Abv);
+  Record.clear();
+  Record.push_back(pch::TU_UPDATE_LEXICAL);
+  Stream.EmitRecordWithBlob(TuUpdateLexicalAbbrev, Record,
+                          reinterpret_cast<const char*>(NewGlobalDecls.data()),
+                          NewGlobalDecls.size() * sizeof(pch::DeclID));
 
   Stream.EnterSubblock(pch::DECLTYPES_BLOCK_ID, 3);
   WriteDeclsBlockAbbrevs();