Empty the C/DtorLists once emitted. This is essential when running in incremental processing mode, because we don't want to reemit the 'tors over and over again.

[v.g.vassilev]

Summary

Currently it is done unconditionally and if performance is concerned we could move Preprocessor::isIncrementalProcessing enabled somewhere accessible to CodeGen.

[v.g.vassilev]

Landed in r285277.

lib/CodeGen/CodeGenModule.h

                      llvm::Constant *AssociatedData = nullptr);
   void AddGlobalDtor(llvm::Function *Dtor, int Priority = 65535);
 
-  /// Generates a global array of functions and priorities using the given list
-  /// and name. This array will have appending linkage and is suitable for use
-  /// as a LLVM constructor or destructor array.
-  void EmitCtorList(const CtorList &Fns, const char *GlobalName);
+  /// EmitCtorList - Generates a global array of functions and priorities using
+  /// the given list and name. This array will have appending linkage and is
+  /// suitable for use as a LLVM constructor or destructor array. Clears Fns.
+  void EmitCtorList(CtorList &Fns, const char *GlobalName);
 
   /// Emit any needed decls for which code generation was deferred.
   void EmitDeferred();

lib/CodeGen/CodeGenModule.cpp

   GlobalDtors.push_back(Structor(Priority, Dtor, nullptr));
 }
 
-void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
+void CodeGenModule::EmitCtorList(CtorList &Fns, const char *GlobalName) {
   // Ctor function type is void()*.
   llvm::FunctionType* CtorFTy = llvm::FunctionType::get(VoidTy, false);
   llvm::Type *CtorPFTy = llvm::PointerType::getUnqual(CtorFTy);

                              llvm::ConstantArray::get(AT, Ctors),
                              GlobalName);
   }
+  Fns.clear();
 }
 
 llvm::GlobalValue::LinkageTypes