[libc-commits] [libc] [libc] at_quick_exit function implemented (PR #94317)

[via libc-commits]

================
@@ -12,91 +12,29 @@
 #include "src/__support/common.h"
 #include "src/__support/fixedvector.h"
 #include "src/__support/threads/mutex.h"
+#include "src/stdlib/exit_handler.h"
 
 namespace LIBC_NAMESPACE {
 
-namespace {
-
-Mutex handler_list_mtx(/*timed=*/false, /*recursive=*/false, /*robust=*/false,
-                       /*pshared=*/false);
-
-using AtExitCallback = void(void *);
-using StdCAtExitCallback = void(void);
-
-struct AtExitUnit {
-  AtExitCallback *callback = nullptr;
-  void *payload = nullptr;
-  constexpr AtExitUnit() = default;
-  constexpr AtExitUnit(AtExitCallback *c, void *p) : callback(c), payload(p) {}
-};
-
-#if defined(LIBC_TARGET_ARCH_IS_GPU)
-// The GPU build cannot handle the potentially recursive definitions required by
-// the BlockStore class. Additionally, the liklihood that someone exceeds this
-// while executing on the GPU is extremely small.
-// FIXME: It is not generally safe to use 'atexit' on the GPU because the
-//        mutexes simply passthrough. We will need a lock free stack.
-using ExitCallbackList = FixedVector<AtExitUnit, 64>;
-#elif defined(LIBC_COPT_PUBLIC_PACKAGING)
-using ExitCallbackList = ReverseOrderBlockStore<AtExitUnit, 32>;
-#else
-// BlockStore uses dynamic memory allocation. To avoid dynamic memory
-// allocation in tests, we use a fixed size callback list when built for
-// tests.
-// If we use BlockStore, then we will have to pull in malloc etc into
-// the tests. While this is not bad, the problem we have currently is
-// that LLVM libc' allocator is SCUDO. So, we will end up pulling SCUDO's
-// deps also (some of which are not yet available in LLVM libc) into the
-// integration tests.
-using ExitCallbackList = FixedVector<AtExitUnit, CALLBACK_LIST_SIZE_FOR_TESTS>;
-#endif // LIBC_COPT_PUBLIC_PACKAGING
-
-constinit ExitCallbackList exit_callbacks;
-
-void stdc_at_exit_func(void *payload) {
-  reinterpret_cast<StdCAtExitCallback *>(payload)();
-}
-
-void call_exit_callbacks() {
-  handler_list_mtx.lock();
-  while (!exit_callbacks.empty()) {
-    AtExitUnit &unit = exit_callbacks.back();
-    exit_callbacks.pop_back();
-    handler_list_mtx.unlock();
-    unit.callback(unit.payload);
-    handler_list_mtx.lock();
-  }
-  ExitCallbackList::destroy(&exit_callbacks);
-}
-
-int add_atexit_unit(const AtExitUnit &unit) {
-  cpp::lock_guard lock(handler_list_mtx);
-  if (exit_callbacks.push_back(unit))
-    return 0;
-  return -1;
-}
-
-} // namespace
-
 extern "C" {
 
-// TODO: Handle the last dso handle argument.
 int __cxa_atexit(AtExitCallback *callback, void *payload, void *) {
-  return add_atexit_unit({callback, payload});
+  return add_atexit_unit(atexit_callbacks, {callback, payload});
 }
 
-// TODO: Handle the dso handle argument. call_exit_callbacks should only invoke
-// the callbacks from this DSO. Requires adding support for __dso_handle.
 void __cxa_finalize(void *dso) {
   if (!dso)
-    call_exit_callbacks();
+    call_exit_callbacks(atexit_callbacks);
 }
 
 } // extern "C"
 
 LLVM_LIBC_FUNCTION(int, atexit, (StdCAtExitCallback * callback)) {
   return add_atexit_unit(
+      atexit_callbacks,
       {&stdc_at_exit_func, reinterpret_cast<void *>(callback)});
 }
 
 } // namespace LIBC_NAMESPACE
+
+
----------------
RoseZhang03 wrote:

too many extra lines at end

https://github.com/llvm/llvm-project/pull/94317