[PATCH] D28520: Disable -Wthread-safety-analysis for some functions in __thread_support

[Dimitry Andric via Phabricator via cfe-commits]

dim updated this revision to Diff 84451.
dim added a comment.

Something like this might work, maybe.  (I haven't yet run the full test suite, as that takes quite a while on my machines.)

I did not re-use the `_LIBCPP_THREAD_SAFETY_ANNOTATION` macro from `__mutex_base`, since that is included *after* this file, and it is only enabled when the user defines `_LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS`.  The `_LIBCPP_THREAD_SAFETY_ATTRIBUTE` macro is defined iff clang supports any of the thread safety stuff.

Note that I had to add a capability attribute to the `__libcpp_mutex` types, otherwise this would not work.

Also, I had to place the thread safety attributes *after* the function declarations, since otherwise the compiler complains that it does not know the parameter name `__m`.

Furthermore, I am still not sure whether the `true` value for the `try_acquire_capability` attribute it correct.  If I understand the documentation correctly, `true` means that the function only succeeds when trying the lock actually acquires it, and it fails when the lock was already acquired.


https://reviews.llvm.org/D28520

Files:
  include/__threading_support


Index: include/__threading_support
===================================================================
--- include/__threading_support
+++ include/__threading_support
@@ -40,14 +40,22 @@
 #define _LIBCPP_THREAD_ABI_VISIBILITY inline _LIBCPP_INLINE_VISIBILITY
 #endif
 
+#if defined(__clang__) && __has_attribute(acquire_capability))
+#define _LIBCPP_THREAD_SAFETY_ATTRIBUTE(x) __attribute__((x))
+#else
+#define _LIBCPP_THREAD_SAFETY_ATTRIBUTE(x) __attribute__((x))
+#endif
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
 // Mutex
-typedef pthread_mutex_t __libcpp_mutex_t;
+typedef pthread_mutex_t __libcpp_mutex_t
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(capability("mutex"));
 #define _LIBCPP_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
 
-typedef pthread_mutex_t __libcpp_recursive_mutex_t;
+typedef pthread_mutex_t __libcpp_recursive_mutex_t
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(capability("mutex"));
 
 // Condition Variable
 typedef pthread_cond_t __libcpp_condvar_t;
@@ -99,25 +107,31 @@
 int __libcpp_recursive_mutex_init(__libcpp_recursive_mutex_t *__m);
 
 _LIBCPP_THREAD_ABI_VISIBILITY
-int __libcpp_recursive_mutex_lock(__libcpp_recursive_mutex_t *__m);
+int __libcpp_recursive_mutex_lock(__libcpp_recursive_mutex_t *__m)
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(acquire_capability(*__m));
 
 _LIBCPP_THREAD_ABI_VISIBILITY
-int __libcpp_recursive_mutex_trylock(__libcpp_recursive_mutex_t *__m);
+int __libcpp_recursive_mutex_trylock(__libcpp_recursive_mutex_t *__m)
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(try_acquire_capability(true, *__m));
 
 _LIBCPP_THREAD_ABI_VISIBILITY
-int __libcpp_recursive_mutex_unlock(__libcpp_recursive_mutex_t *__m);
+int __libcpp_recursive_mutex_unlock(__libcpp_recursive_mutex_t *__m)
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(release_capability(*__m));
 
 _LIBCPP_THREAD_ABI_VISIBILITY
 int __libcpp_recursive_mutex_destroy(__libcpp_recursive_mutex_t *__m);
 
 _LIBCPP_THREAD_ABI_VISIBILITY
-int __libcpp_mutex_lock(__libcpp_mutex_t *__m);
+int __libcpp_mutex_lock(__libcpp_mutex_t *__m)
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(acquire_capability(*__m));
 
 _LIBCPP_THREAD_ABI_VISIBILITY
-int __libcpp_mutex_trylock(__libcpp_mutex_t *__m);
+int __libcpp_mutex_trylock(__libcpp_mutex_t *__m)
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(try_acquire_capability(true, *__m));
 
 _LIBCPP_THREAD_ABI_VISIBILITY
-int __libcpp_mutex_unlock(__libcpp_mutex_t *__m);
+int __libcpp_mutex_unlock(__libcpp_mutex_t *__m)
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(release_capability(*__m));
 
 _LIBCPP_THREAD_ABI_VISIBILITY
 int __libcpp_mutex_destroy(__libcpp_mutex_t *__m);
@@ -130,11 +144,13 @@
 int __libcpp_condvar_broadcast(__libcpp_condvar_t* __cv);
 
 _LIBCPP_THREAD_ABI_VISIBILITY
-int __libcpp_condvar_wait(__libcpp_condvar_t* __cv, __libcpp_mutex_t* __m);
+int __libcpp_condvar_wait(__libcpp_condvar_t* __cv, __libcpp_mutex_t* __m)
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(requires_capability(*__m));
 
 _LIBCPP_THREAD_ABI_VISIBILITY
 int __libcpp_condvar_timedwait(__libcpp_condvar_t *__cv, __libcpp_mutex_t *__m,
-                               timespec *__ts);
+                               timespec *__ts)
+_LIBCPP_THREAD_SAFETY_ATTRIBUTE(requires_capability(*__m));
 
 _LIBCPP_THREAD_ABI_VISIBILITY
 int __libcpp_condvar_destroy(__libcpp_condvar_t* __cv);


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