Add libc++ and libc++abi to third-party.

third_party/libc++abi/src/cxa_guard.cpp

+//===---------------------------- cxa_guard.cpp ---------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "abort_message.h"
+
+#include <pthread.h>
+#include <stdint.h>
+
+/*
+    This implementation must be careful to not call code external to this file
+    which will turn around and try to call __cxa_guard_acquire reentrantly.
+    For this reason, the headers of this file are as restricted as possible.
+    Previous implementations of this code for __APPLE__ have used
+    pthread_mutex_lock and the abort_message utility without problem.  This
+    implementation also uses pthread_cond_wait which has tested to not be a
+    problem.
+*/
+
+namespace __cxxabiv1
+{
+
+namespace
+{
+
+#if __arm__
+
+// A 32-bit, 4-byte-aligned static data value. The least significant 2 bits must
+// be statically initialized to 0.
+typedef uint32_t guard_type;
+
+// Test the lowest bit.
+inline bool is_initialized(guard_type* guard_object) {
+    return (*guard_object) & 1;
+}
+
+inline void set_initialized(guard_type* guard_object) {
+    *guard_object |= 1;
+}
+
+#else
+
+typedef uint64_t guard_type;
+
+bool is_initialized(guard_type* guard_object) {
+    char* initialized = (char*)guard_object;
+    return *initialized;
+}
+
+void set_initialized(guard_type* guard_object) {
+    char* initialized = (char*)guard_object;
+    *initialized = 1;
+}
+
+#endif
+
+pthread_mutex_t guard_mut = PTHREAD_MUTEX_INITIALIZER;
+pthread_cond_t  guard_cv  = PTHREAD_COND_INITIALIZER;
+
+#if defined(__APPLE__) && !defined(__arm__)
+
+typedef uint32_t lock_type;
+
+#if __LITTLE_ENDIAN__
+
+inline
+lock_type
+get_lock(uint64_t x)
+{
+    return static_cast<lock_type>(x >> 32);
+}
+
+inline
+void
+set_lock(uint64_t& x, lock_type y)
+{
+    x = static_cast<uint64_t>(y) << 32;
+}
+
+#else  // __LITTLE_ENDIAN__
+
+inline
+lock_type
+get_lock(uint64_t x)
+{
+    return static_cast<lock_type>(x);
+}
+
+inline
+void
+set_lock(uint64_t& x, lock_type y)
+{
+    x = y;
+}
+
+#endif  // __LITTLE_ENDIAN__
+
+#else  // !__APPLE__ || __arm__
+
+typedef bool lock_type;
+
+inline
+lock_type
+get_lock(uint64_t x)
+{
+    union
+    {
+        uint64_t guard;
+        uint8_t lock[2];
+    } f = {x};
+    return f.lock[1] != 0;
+}
+
+inline
+void
+set_lock(uint64_t& x, lock_type y)
+{
+    union
+    {
+        uint64_t guard;
+        uint8_t lock[2];
+    } f = {0};
+    f.lock[1] = y;
+    x = f.guard;
+}
+
+inline
+lock_type
+get_lock(uint32_t x)
+{
+    union
+    {
+        uint32_t guard;
+        uint8_t lock[2];
+    } f = {x};
+    return f.lock[1] != 0;
+}
+
+inline
+void
+set_lock(uint32_t& x, lock_type y)
+{
+    union
+    {
+        uint32_t guard;
+        uint8_t lock[2];
+    } f = {0};
+    f.lock[1] = y;
+    x = f.guard;
+}
+
+#endif  // __APPLE__
+
+}  // unnamed namespace
+
+extern "C"
+{
+
+int __cxa_guard_acquire(guard_type* guard_object)
+{
+    char* initialized = (char*)guard_object;
+    if (pthread_mutex_lock(&guard_mut))
+        abort_message("__cxa_guard_acquire failed to acquire mutex");
+    int result = *initialized == 0;
+    if (result)
+    {
+#if defined(__APPLE__) && !defined(__arm__)
+        const lock_type id = pthread_mach_thread_np(pthread_self());
+        lock_type lock = get_lock(*guard_object);
+        if (lock)
+        {
+            // if this thread set lock for this same guard_object, abort
+            if (lock == id)
+                abort_message("__cxa_guard_acquire detected deadlock");
+            do
+            {
+                if (pthread_cond_wait(&guard_cv, &guard_mut))
+                    abort_message("__cxa_guard_acquire condition variable wait failed");
+                lock = get_lock(*guard_object);
+            } while (lock);
+            result = !is_initialized(guard_object);
+            if (result)
+                set_lock(*guard_object, id);
+        }
+        else
+            set_lock(*guard_object, id);
+#else  // !__APPLE__ || __arm__
+        while (get_lock(*guard_object))
+            if (pthread_cond_wait(&guard_cv, &guard_mut))
+                abort_message("__cxa_guard_acquire condition variable wait failed");
+        result = *initialized == 0;
+        if (result)
+            set_lock(*guard_object, true);
+#endif  // !__APPLE__ || __arm__
+    }
+    if (pthread_mutex_unlock(&guard_mut))
+        abort_message("__cxa_guard_acquire failed to release mutex");
+    return result;
+}
+
+void __cxa_guard_release(guard_type* guard_object)
+{
+    if (pthread_mutex_lock(&guard_mut))
+        abort_message("__cxa_guard_release failed to acquire mutex");
+    *guard_object = 0;
+    set_initialized(guard_object);
+    if (pthread_mutex_unlock(&guard_mut))
+        abort_message("__cxa_guard_release failed to release mutex");
+    if (pthread_cond_broadcast(&guard_cv))
+        abort_message("__cxa_guard_release failed to broadcast condition variable");
+}
+
+void __cxa_guard_abort(guard_type* guard_object)
+{
+    if (pthread_mutex_lock(&guard_mut))
+        abort_message("__cxa_guard_abort failed to acquire mutex");
+    *guard_object = 0;
+    if (pthread_mutex_unlock(&guard_mut))
+        abort_message("__cxa_guard_abort failed to release mutex");
+    if (pthread_cond_broadcast(&guard_cv))
+        abort_message("__cxa_guard_abort failed to broadcast condition variable");
+}
+
+}  // extern "C"
+
+}  // __cxxabiv1