[tsan] For OS X thread finalization, remove g_thread_finalize_key in favor of libpthread hooks

[kubamracek]

Summary

On OS X, the thread finalization is fragile due to thread-local variables destruction order. I've seen cases where the we destroy the ThreadState too early and subsequent thread-local values' destructors call interceptors again. Let's replace the TLV-based thread finalization method with libpthread hooks. The notification PTHREAD_INTROSPECTION_THREAD_TERMINATE is called *after* all TLVs have been destroyed.

compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc

static ThreadSignalContext *SigCtx(ThreadState *thr) {
   if (ctx == 0 && !thr->is_dead) {
     ctx = (ThreadSignalContext*)MmapOrDie(sizeof(*ctx), "ThreadSignalContext");
     MemoryResetRange(thr, (uptr)&SigCtx, (uptr)ctx, sizeof(*ctx));
     thr->signal_ctx = ctx;
   }
   return ctx;
 }
 
+#if !SANITIZER_MAC
 static unsigned g_thread_finalize_key;
+#endif
 
 ScopedInterceptor::ScopedInterceptor(ThreadState *thr, const char *fname,
                                      uptr pc)
     : thr_(thr)
     , pc_(pc)
     , in_ignored_lib_(false) {
   if (!thr_->ignore_interceptors) {
     Initialize(thr);
void DestroyThreadState() {
   if (sctx) {
     thr->signal_ctx = 0;
     UnmapOrDie(sctx, sizeof(*sctx));
   }
   cur_thread_finalize();
 }
 }  // namespace __tsan
 
+#if !SANITIZER_MAC
 static void thread_finalize(void *v) {
   uptr iter = (uptr)v;
   if (iter > 1) {
     if (pthread_setspecific(g_thread_finalize_key, (void*)(iter - 1))) {
       Printf("ThreadSanitizer: failed to set thread key\n");
       Die();
     }
     return;
   }
   DestroyThreadState();
 }
+#endif
 
 
 struct ThreadParam {
   void* (*callback)(void *arg);
   void *param;
   atomic_uintptr_t tid;
 };
 
 extern "C" void *__tsan_thread_start_func(void *arg) {
   ThreadParam *p = (ThreadParam*)arg;
   void* (*callback)(void *arg) = p->callback;
   void *param = p->param;
   int tid = 0;
   {
     ThreadState *thr = cur_thread();
     // Thread-local state is not initialized yet.
     ScopedIgnoreInterceptors ignore;
+#if !SANITIZER_MAC
     ThreadIgnoreBegin(thr, 0);
     if (pthread_setspecific(g_thread_finalize_key,
                             (void *)GetPthreadDestructorIterations())) {
       Printf("ThreadSanitizer: failed to set thread key\n");
       Die();
     }
     ThreadIgnoreEnd(thr, 0);
+#endif
     while ((tid = atomic_load(&p->tid, memory_order_acquire)) == 0)
       internal_sched_yield();
     ThreadStart(thr, tid, GetTid());
     atomic_store(&p->tid, 0, memory_order_release);
   }
   void *res = callback(param);
   // Prevent the callback from being tail called,
   // it mixes up stack traces.
#if !SANITIZER_MAC
   REAL(atexit) = (int(*)(void(*)()))unreachable;
 #endif
 
   if (REAL(__cxa_atexit)(&finalize, 0, 0)) {
     Printf("ThreadSanitizer: failed to setup atexit callback\n");
     Die();
   }
 
+#if !SANITIZER_MAC
   if (pthread_key_create(&g_thread_finalize_key, &thread_finalize)) {
     Printf("ThreadSanitizer: failed to create thread key\n");
     Die();
   }
+#endif
 
   FdInit();
 }
 
 }  // namespace __tsan

compiler-rt/trunk/lib/tsan/rtl/tsan_platform_mac.cc

 // thread. If it's just a regular thread, this hook is called on the parent
 // thread.
 typedef void (*pthread_introspection_hook_t)(unsigned int event,
                                              pthread_t thread, void *addr,
                                              size_t size);
 extern "C" pthread_introspection_hook_t pthread_introspection_hook_install(
     pthread_introspection_hook_t hook);
 static const uptr PTHREAD_INTROSPECTION_THREAD_CREATE = 1;
-static const uptr PTHREAD_INTROSPECTION_THREAD_DESTROY = 4;
+static const uptr PTHREAD_INTROSPECTION_THREAD_TERMINATE = 3;
 static pthread_introspection_hook_t prev_pthread_introspection_hook;
 static void my_pthread_introspection_hook(unsigned int event, pthread_t thread,
                                           void *addr, size_t size) {
   if (event == PTHREAD_INTROSPECTION_THREAD_CREATE) {
     if (thread == pthread_self()) {
       // The current thread is a newly created GCD worker thread.
       ThreadState *parent_thread_state = nullptr;  // No parent.
       int tid = ThreadCreate(parent_thread_state, 0, (uptr)thread, true);
       CHECK_NE(tid, 0);
       ThreadState *thr = cur_thread();
       ThreadStart(thr, tid, GetTid());
     }
-  } else if (event == PTHREAD_INTROSPECTION_THREAD_DESTROY) {
+  } else if (event == PTHREAD_INTROSPECTION_THREAD_TERMINATE) {
+    if (thread == pthread_self()) {
       ThreadState *thr = cur_thread();
-    if (thr->tctx && thr->tctx->parent_tid == kInvalidTid) {
+      if (thr->tctx) {
         DestroyThreadState();
       }
     }
+  }
 
   if (prev_pthread_introspection_hook != nullptr)
     prev_pthread_introspection_hook(event, thread, addr, size);
 }
 #endif
 
 void InitializePlatform() {
   DisableCoreDumperIfNecessary();