[tsan] Add interceptor for libcxx __shared_count::__release_shared()

We already have an interceptor for __shared_weak_count::__release_shared, this patch handles __shared_count::__release_shared in the same way. This should get rid of TSan false positives when using std::future.

Differential Revision: https://reviews.llvm.org/D27797

llvm-svn: 289831

1 files changed, 19 insertions, 3 deletions

diff --git a/compiler-rt/lib/tsan/rtl/tsan_interceptors_mac.cc b/compiler-rt/lib/tsan/rtl/tsan_interceptors_mac.cc
index 015e48eb52b..fc5eb049907 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_interceptors_mac.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_interceptors_mac.cc
@@ -297,18 +297,20 @@ struct fake_shared_weak_count {
 };
 }  // namespace
 
-// This adds a libc++ interceptor for:
+// The following code adds libc++ interceptors for:
 //     void __shared_weak_count::__release_shared() _NOEXCEPT;
+//     bool __shared_count::__release_shared() _NOEXCEPT;
 // Shared and weak pointers in C++ maintain reference counts via atomics in
 // libc++.dylib, which are TSan-invisible, and this leads to false positives in
-// destructor code.  This interceptor re-implements the whole function so that
+// destructor code. These interceptors re-implements the whole functions so that
 // the mo_acq_rel semantics of the atomic decrement are visible.
 //
-// Unfortunately, this interceptor cannot simply Acquire/Release some sync
+// Unfortunately, the interceptors cannot simply Acquire/Release some sync
 // object and call the original function, because it would have a race between
 // the sync and the destruction of the object.  Calling both under a lock will
 // not work because the destructor can invoke this interceptor again (and even
 // in a different thread, so recursive locks don't help).
+
 STDCXX_INTERCEPTOR(void, _ZNSt3__119__shared_weak_count16__release_sharedEv,
                    fake_shared_weak_count *o) {
   if (!flags()->shared_ptr_interceptor)
@@ -327,6 +329,20 @@ STDCXX_INTERCEPTOR(void, _ZNSt3__119__shared_weak_count16__release_sharedEv,
   }
 }
 
+STDCXX_INTERCEPTOR(bool, _ZNSt3__114__shared_count16__release_sharedEv,
+                   fake_shared_weak_count *o) {
+  if (!flags()->shared_ptr_interceptor)
+    return REAL(_ZNSt3__114__shared_count16__release_sharedEv)(o);
+
+  SCOPED_TSAN_INTERCEPTOR(_ZNSt3__114__shared_count16__release_sharedEv, o);
+  if (__tsan_atomic64_fetch_add(&o->shared_owners, -1, mo_release) == 0) {
+    Acquire(thr, pc, (uptr)&o->shared_owners);
+    o->on_zero_shared();
+    return true;
+  }
+  return false;
+}
+
 namespace {
 struct call_once_callback_args {
   void (*orig_func)(void *arg);