Issue #22038: pyatomic.h now uses stdatomic.h or GCC built-in functions for
atomic memory access if available. Patch written by Vitor de Lima and Gustavo
Temple.
diff --git a/Include/pyatomic.h b/Include/pyatomic.h
index d4e19e0..80bd825 100644
--- a/Include/pyatomic.h
+++ b/Include/pyatomic.h
@@ -1,12 +1,15 @@
#ifndef Py_LIMITED_API
#ifndef Py_ATOMIC_H
#define Py_ATOMIC_H
-/* XXX: When compilers start offering a stdatomic.h with lock-free
- atomic_int and atomic_address types, include that here and rewrite
- the atomic operations in terms of it. */
#include "dynamic_annotations.h"
+#include "pyconfig.h"
+
+#if defined(HAVE_STD_ATOMIC)
+#include <stdatomic.h>
+#endif
+
#ifdef __cplusplus
extern "C" {
#endif
@@ -20,6 +23,76 @@
* Beware, the implementations here are deep magic.
*/
+#if defined(HAVE_STD_ATOMIC)
+
+typedef enum _Py_memory_order {
+ _Py_memory_order_relaxed = memory_order_relaxed,
+ _Py_memory_order_acquire = memory_order_acquire,
+ _Py_memory_order_release = memory_order_release,
+ _Py_memory_order_acq_rel = memory_order_acq_rel,
+ _Py_memory_order_seq_cst = memory_order_seq_cst
+} _Py_memory_order;
+
+typedef struct _Py_atomic_address {
+ _Atomic void *_value;
+} _Py_atomic_address;
+
+typedef struct _Py_atomic_int {
+ atomic_int _value;
+} _Py_atomic_int;
+
+#define _Py_atomic_signal_fence(/*memory_order*/ ORDER) \
+ atomic_signal_fence(ORDER)
+
+#define _Py_atomic_thread_fence(/*memory_order*/ ORDER) \
+ atomic_thread_fence(ORDER)
+
+#define _Py_atomic_store_explicit(ATOMIC_VAL, NEW_VAL, ORDER) \
+ atomic_store_explicit(&(ATOMIC_VAL)->_value, NEW_VAL, ORDER)
+
+#define _Py_atomic_load_explicit(ATOMIC_VAL, ORDER) \
+ atomic_load_explicit(&(ATOMIC_VAL)->_value, ORDER)
+
+/* Use builtin atomic operations in GCC >= 4.7 */
+#elif defined(HAVE_BUILTIN_ATOMIC)
+
+typedef enum _Py_memory_order {
+ _Py_memory_order_relaxed = __ATOMIC_RELAXED,
+ _Py_memory_order_acquire = __ATOMIC_ACQUIRE,
+ _Py_memory_order_release = __ATOMIC_RELEASE,
+ _Py_memory_order_acq_rel = __ATOMIC_ACQ_REL,
+ _Py_memory_order_seq_cst = __ATOMIC_SEQ_CST
+} _Py_memory_order;
+
+typedef struct _Py_atomic_address {
+ void *_value;
+} _Py_atomic_address;
+
+typedef struct _Py_atomic_int {
+ int _value;
+} _Py_atomic_int;
+
+#define _Py_atomic_signal_fence(/*memory_order*/ ORDER) \
+ __atomic_signal_fence(ORDER)
+
+#define _Py_atomic_thread_fence(/*memory_order*/ ORDER) \
+ __atomic_thread_fence(ORDER)
+
+#define _Py_atomic_store_explicit(ATOMIC_VAL, NEW_VAL, ORDER) \
+ (assert((ORDER) == __ATOMIC_RELAXED \
+ || (ORDER) == __ATOMIC_SEQ_CST \
+ || (ORDER) == __ATOMIC_RELEASE), \
+ __atomic_store_n(&(ATOMIC_VAL)->_value, NEW_VAL, ORDER))
+
+#define _Py_atomic_load_explicit(ATOMIC_VAL, ORDER) \
+ (assert((ORDER) == __ATOMIC_RELAXED \
+ || (ORDER) == __ATOMIC_SEQ_CST \
+ || (ORDER) == __ATOMIC_ACQUIRE \
+ || (ORDER) == __ATOMIC_CONSUME), \
+ __atomic_load_n(&(ATOMIC_VAL)->_value, ORDER))
+
+#else
+
typedef enum _Py_memory_order {
_Py_memory_order_relaxed,
_Py_memory_order_acquire,
@@ -162,6 +235,7 @@
((ATOMIC_VAL)->_value)
#endif /* !gcc x86 */
+#endif
/* Standardized shortcuts. */
#define _Py_atomic_store(ATOMIC_VAL, NEW_VAL) \