forkfd: Add C11 and C++11 atomic support

For forkfd, this is extremely useful, since users can rely on proper
atomic API, not the old GCC API or the internal API that backs the C11 /
C++11 implementation itself.

This also caught one more mistaken use of seq_cst.

Change-Id: Iec9c051acd73484c8d94fffd15b9985fe545e8b5
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/3rdparty/forkfd/forkfd.c

@@ -93,9 +93,7 @@
 #  endif
 #endif
 
-#ifndef FFD_ATOMIC_RELAXED
-#  include "forkfd_gcc.h"
-#endif
+#include "forkfd_atomic.h"
 
 #define CHILDREN_IN_SMALL_ARRAY     16
 #define CHILDREN_IN_BIG_ARRAY       256

src/3rdparty/forkfd/forkfd_atomic.h

@@ -0,0 +1,39 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 Intel Corporation.
+**
+** Permission is hereby granted, free of charge, to any person obtaining a copy
+** of this software and associated documentation files (the "Software"), to deal
+** in the Software without restriction, including without limitation the rights
+** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+** copies of the Software, and to permit persons to whom the Software is
+** furnished to do so, subject to the following conditions:
+**
+** The above copyright notice and this permission notice shall be included in
+** all copies or substantial portions of the Software.
+**
+** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+** OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+** THE SOFTWARE.
+**
+****************************************************************************/
+
+#if !defined(FFD_ATOMIC_H) & !defined(FFD_ATOMIC_RELAXED)
+#define FFD_ATOMIC_H
+
+#if defined(__cplusplus) && __cplusplus >= 201103L
+#  include "forkfd_c11.h"
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
+#  include "forkfd_c11.h"
+#elif defined(__GNUC__)
+#  include "forkfd_gcc.h"
+#endif
+
+#endif /* FFD_ATOMIC_h && FFD_ATOMIC_RELAXED */
+#ifndef FFD_ATOMIC_RELAXED
+#  error "Could not determine atomics for this platform"
+#endif

src/3rdparty/forkfd/forkfd_c11.h

@@ -0,0 +1,64 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 Intel Corporation.
+**
+** Permission is hereby granted, free of charge, to any person obtaining a copy
+** of this software and associated documentation files (the "Software"), to deal
+** in the Software without restriction, including without limitation the rights
+** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+** copies of the Software, and to permit persons to whom the Software is
+** furnished to do so, subject to the following conditions:
+**
+** The above copyright notice and this permission notice shall be included in
+** all copies or substantial portions of the Software.
+**
+** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+** OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+** THE SOFTWARE.
+**
+****************************************************************************/
+
+#ifndef FFD_ATOMIC_C11_H
+#define FFD_ATOMIC_C11_H
+
+/* atomics */
+/* Using the C11 <stdatomic.h> header or C++11's <atomic>
+ */
+
+#if defined(__cplusplus)
+#  include <atomic>
+#  define ffd_atomic_pointer(type)  std::atomic<type*>
+#  define FFD_ATOMIC_RELAXED        std::memory_order_relaxed
+#  define FFD_ATOMIC_ACQUIRE        std::memory_order_acquire
+#  define FFD_ATOMIC_RELEASE        std::memory_order_release
+// acq_rel & cst not necessary
+typedef std::atomic_int ffd_atomic_int;
+#else
+#  include <stdatomic.h>
+#  define ffd_atomic_pointer(type)  _Atomic(type*)
+#  define FFD_ATOMIC_RELAXED        memory_order_relaxed
+#  define FFD_ATOMIC_ACQUIRE        memory_order_acquire
+#  define FFD_ATOMIC_RELEASE        memory_order_release
+// acq_rel & cst not necessary
+
+typedef atomic_int ffd_atomic_int;
+#endif
+
+#define FFD_ATOMIC_INIT(val)        ATOMIC_VAR_INIT(val)
+
+#define ffd_atomic_load(ptr, order) \
+    atomic_load_explicit(ptr, order)
+#define ffd_atomic_store(ptr, val, order) \
+    atomic_store_explicit(ptr, val, order)
+#define ffd_atomic_exchange(ptr,val,order) \
+    atomic_exchange_explicit(ptr, val, order)
+#define ffd_atomic_compare_exchange(ptr, expected, desired, order1, order2) \
+    atomic_compare_exchange_strong_explicit(ptr, expected, desired, order1, order2)
+#define ffd_atomic_add_fetch(ptr, val, order) \
+    (atomic_fetch_add_explicit(ptr, val, order) + (val))
+
+#endif

src/corelib/io/forkfd_qt.cpp

@@ -37,37 +37,12 @@
 **
 ****************************************************************************/
 
-// these might be defined via precompiled headers
-#include <QtCore/qatomic.h>
+#include <QtCore/qglobal.h>
 
 #define FORKFD_NO_SPAWNFD
-
 #if defined(QT_NO_DEBUG) && !defined(NDEBUG)
 #  define NDEBUG
 #endif
 
-typedef QT_PREPEND_NAMESPACE(QBasicAtomicInt) ffd_atomic_int;
-#define ffd_atomic_pointer(type)    QT_PREPEND_NAMESPACE(QBasicAtomicPointer<type>)
-
-QT_BEGIN_NAMESPACE
-
-#define FFD_ATOMIC_INIT(val)    Q_BASIC_ATOMIC_INITIALIZER(val)
-
-#define FFD_ATOMIC_RELAXED  Relaxed
-#define FFD_ATOMIC_ACQUIRE  Acquire
-#define FFD_ATOMIC_RELEASE  Release
-
-#define FFD_CONCAT(x, y)    x ## y
-
-#define ffd_atomic_load(ptr,order)      (ptr)->FFD_CONCAT(load, order)()
-#define ffd_atomic_store(ptr,val,order) (ptr)->FFD_CONCAT(store, order)(val)
-#define ffd_atomic_exchange(ptr,val,order) (ptr)->FFD_CONCAT(fetchAndStore, order)(val)
-#define ffd_atomic_compare_exchange(ptr,expected,desired,order1,order2) \
-    (ptr)->FFD_CONCAT(testAndSet, order1)(*expected, desired, *expected)
-#define ffd_atomic_add_fetch(ptr,val,order) ((ptr)->FFD_CONCAT(fetchAndAdd, order)(val) + val)
-
-QT_END_NAMESPACE
-
-extern "C" {
+#include <forkfd.h>
 #include "../../3rdparty/forkfd/forkfd.c"
-}