Rework our handling of key functions. We used to track a complete list of all

dynamic classes in the translation unit and check whether each one's key
function is defined when we got to the end of the TU (and when we got to the
end of each module). This is really terrible for modules performance, since it
causes unnecessary deserialization of every dynamic class in every compilation.

We now use a much simpler (and, in a modules build, vastly more efficient)
system: when we see an out-of-line definition of a virtual function, we check
whether that function was in fact its class's key function. (If so, we need to
emit the vtable.)

llvm-svn: 230830

1 files changed, 2 insertions, 16 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 5170c244bbf..a851ce14556 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -621,22 +621,6 @@ void Sema::ActOnEndOfTranslationUnit() {
   if (TUKind != TU_Prefix) {
     DiagnoseUseOfUnimplementedSelectors();
 
-    // If any dynamic classes have their key function defined within
-    // this translation unit, then those vtables are considered "used" and must
-    // be emitted.
-    for (DynamicClassesType::iterator I = DynamicClasses.begin(ExternalSource),
-                                      E = DynamicClasses.end();
-         I != E; ++I) {
-      assert(!(*I)->isDependentType() &&
-             "Should not see dependent types here!");
-      if (const CXXMethodDecl *KeyFunction =
-              Context.getCurrentKeyFunction(*I)) {
-        const FunctionDecl *Definition = nullptr;
-        if (KeyFunction->hasBody(Definition))
-          MarkVTableUsed(Definition->getLocation(), *I, true);
-      }
-    }
-
     // If DefinedUsedVTables ends up marking any virtual member functions it
     // might lead to more pending template instantiations, which we then need
     // to instantiate.
@@ -668,6 +652,8 @@ void Sema::ActOnEndOfTranslationUnit() {
 
   // All delayed member exception specs should be checked or we end up accepting
   // incompatible declarations.
+  // FIXME: This is wrong for TUKind == TU_Prefix. In that case, we need to
+  // write out the lists to the AST file (if any).
   assert(DelayedDefaultedMemberExceptionSpecs.empty());
   assert(DelayedExceptionSpecChecks.empty());