restore atomic mem funcs

Author: tom-pytel

Include/cpython/pyatomic.h

@@ -545,6 +545,59 @@ static inline Py_ssize_t
 _Py_atomic_load_ssize_acquire(const Py_ssize_t *obj);
 
 
+// --- _Py_atomic_memcpy / _Py_atomic_memmove ------------
+
+static inline void *
+_Py_atomic_memcpy_ptr_store_relaxed(void *dest, void *src, size_t n)
+{
+    assert(_Py_IS_ALIGNED(dest, sizeof(void *)));
+    assert(_Py_IS_ALIGNED(src, sizeof(void *)));
+    assert(n % sizeof(void *) == 0);
+
+    if (dest != src) {
+        void **dest_ = (void **)dest;
+        void **src_ = (void **)src;
+        void **end = dest_ + n / sizeof(void *);
+
+        for (; dest_ != end; dest_++, src_++) {
+            _Py_atomic_store_ptr_relaxed(dest_, *src_);
+        }
+    }
+
+    return dest;
+}
+
+static inline void *
+_Py_atomic_memmove_ptr_store_relaxed(void *dest, void *src, size_t n)
+{
+    assert(_Py_IS_ALIGNED(dest, sizeof(void *)));
+    assert(_Py_IS_ALIGNED(src, sizeof(void *)));
+    assert(n % sizeof(void *) == 0);
+
+    if (dest < src || dest >= (void *)((char *)src + n)) {
+        void **dest_ = (void **)dest;
+        void **src_ = (void **)src;
+        void **end = dest_ + n / sizeof(void *);
+
+        for (; dest_ != end; dest_++, src_++) {
+            _Py_atomic_store_ptr_relaxed(dest_, *src_);
+        }
+    }
+    else if (dest > src) {
+        n = n / sizeof(void *) - 1;
+        void **dest_ = (void **)dest + n;
+        void **src_ = (void **)src + n;
+        void **end = (void **)dest - 1;
+
+        for (; dest_ != end; dest_--, src_--) {
+            _Py_atomic_store_ptr_relaxed(dest_, *src_);
+        }
+    }
+
+    return dest;
+}
+
+
 
 
 // --- _Py_atomic_fence ------------------------------------------------------

Include/internal/pycore_pyatomic_ft_wrappers.h

@@ -114,8 +114,10 @@ extern "C" {
 #define FT_MUTEX_LOCK(lock) PyMutex_Lock(lock)
 #define FT_MUTEX_UNLOCK(lock) PyMutex_Unlock(lock)
 
-#define FT_ATOMIC_MEMCPY_PTR_STORE_RELAXED(dest, src, n) memcpy(dest, src, n)
-#define FT_ATOMIC_MEMMOVE_PTR_STORE_RELAXED(dest, src, n) memmove(dest, src, n)
+#define FT_ATOMIC_MEMCPY_PTR_STORE_RELAXED(dest, src, n) \
+    _Py_atomic_memcpy_ptr_store_relaxed(dest, src, (size_t)(n))
+#define FT_ATOMIC_MEMMOVE_PTR_STORE_RELAXED(dest, src, n) \
+    _Py_atomic_memmove_ptr_store_relaxed(dest, src, (size_t)(n))
 
 
 #else