Add a command line option 'fregister_global_dtors_with_atexit' to

register destructor functions annotated with __attribute__((destructor))
using __cxa_atexit or atexit.

Register destructor functions annotated with __attribute__((destructor))
calling __cxa_atexit in a synthesized constructor function instead of
emitting references to the functions in a special section.

The primary reason for adding this option is that we are planning to
deprecate the __mod_term_funcs section on Darwin in the future. This
feature is enabled by default only on Darwin. Users who do not want this
can use command line option 'fno_register_global_dtors_with_atexit' to
disable it.

rdar://problem/33887655

Differential Revision: https://reviews.llvm.org/D45578

llvm-svn: 330199

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 42a8cd800fad..a21527abba1f 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -397,6 +397,7 @@ void CodeGenModule::Release() {
   emitMultiVersionFunctions();
   EmitCXXGlobalInitFunc();
   EmitCXXGlobalDtorFunc();
+  registerGlobalDtorsWithAtExit();
   EmitCXXThreadLocalInitFunc();
   if (ObjCRuntime)
     if (llvm::Function *ObjCInitFunction = ObjCRuntime->ModuleInitFunction())
@@ -1026,6 +1027,11 @@ void CodeGenModule::AddGlobalCtor(llvm::Function *Ctor, int Priority,
 /// AddGlobalDtor - Add a function to the list that will be called
 /// when the module is unloaded.
 void CodeGenModule::AddGlobalDtor(llvm::Function *Dtor, int Priority) {
+  if (CodeGenOpts.RegisterGlobalDtorsWithAtExit) {
+    DtorsUsingAtExit[Priority].push_back(Dtor);
+    return;
+  }
+
   // FIXME: Type coercion of void()* types.
   GlobalDtors.push_back(Structor(Priority, Dtor, nullptr));
 }