Be lazier when loading KeyFunctions from PCH/modules. We don't need to load

these in eagerly if we're not actually processing a translation unit. The added
laziness here also avoids us loading in parts of a CXXRecordDecl earlier than an
upcoming class template specialization merging patch would like.

Ideally, we should mark the vtable as used when we see a definition for the key
function, rather than having a separate pass over dynamic classes at the end of
the TU. The existing approach is pretty bad for PCH/modules, since it forcibly
loads the declarations of all key functions in all imported modules, whether or
not those key functions are defined.

llvm-svn: 189627

1 files changed, 3 insertions, 3 deletions

diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 3c93340f5ef..a224aefa8fa 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -1276,11 +1276,11 @@ ASTDeclReader::VisitCXXRecordDeclImpl(CXXRecordDecl *D) {
   }
   }
 
-  // Load the key function to avoid deserializing every method so we can
+  // Lazily load the key function to avoid deserializing every method so we can
   // compute it.
   if (D->IsCompleteDefinition) {
-    if (CXXMethodDecl *Key = ReadDeclAs<CXXMethodDecl>(Record, Idx))
-      C.KeyFunctions[D] = Key;
+    if (DeclID KeyFn = ReadDeclID(Record, Idx))
+      C.KeyFunctions[D] = KeyFn;
   }
 
   return Redecl;