From 7bc94dbe3554d10092034c97462c5afc03353d5a Mon Sep 17 00:00:00 2001
From: Sam Gross <colesbury@gmail.com>
Date: Tue, 22 Aug 2023 11:45:01 -0700
Subject: [PATCH] fixes

---
 Include/pyatomic_msc.h       | 12 +++++++++++-
 Modules/_testcapi/pyatomic.c | 16 +++++++---------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/Include/pyatomic_msc.h b/Include/pyatomic_msc.h
index b6c00acd35cba40..cacfdcb4164d95f 100644
--- a/Include/pyatomic_msc.h
+++ b/Include/pyatomic_msc.h
@@ -200,7 +200,17 @@ _Py_atomic_exchange_int32(volatile int32_t *address, int32_t value)
 static inline int64_t
 _Py_atomic_exchange_int64(volatile int64_t *address, int64_t value)
 {
+#if defined(_M_X64) || defined(_M_ARM64)
     return (int64_t)_InterlockedExchange64((volatile __int64*)address, (__int64)value);
+#else
+    for (;;) {
+        int64_t old_value = *address;
+        int64_t new_value = value;
+        if (_InterlockedCompareExchange64((volatile __int64*)address, (__int64)new_value, (__int64)old_value)) {
+            return old_value;
+        }
+    }
+#endif
 }
 
 static inline intptr_t
@@ -240,7 +250,7 @@ _Py_atomic_exchange_uintptr(volatile uintptr_t *address, uintptr_t value)
 }
 
 static inline Py_ssize_t
-_Py_atomic_exchange_ssize(volatile Py_ssize_t *address, Py_ssize_t value);
+_Py_atomic_exchange_ssize(volatile Py_ssize_t *address, Py_ssize_t value)
 {
 #if SIZEOF_SIZE_T == 8
     return (Py_ssize_t)_InterlockedExchange64((volatile __int64*)address, (__int64)value);
diff --git a/Modules/_testcapi/pyatomic.c b/Modules/_testcapi/pyatomic.c
index 85f7fb597cf56c5..2bacd982f1dddce 100644
--- a/Modules/_testcapi/pyatomic.c
+++ b/Modules/_testcapi/pyatomic.c
@@ -36,21 +36,19 @@
 static PyObject * \
 test_atomic_add_##suffix(PyObject *self, PyObject *obj) { \
     dtype x = 0; \
-    dtype y = 1; \
-    dtype z = 2; \
-    assert(_Py_atomic_add_##suffix(&x, y) == 0); \
+    assert(_Py_atomic_add_##suffix(&x, 1) == 0); \
     assert("a" && x == 1); \
-    assert(_Py_atomic_add_##suffix(&x, z) == 1); \
+    assert(_Py_atomic_add_##suffix(&x, 2) == 1); \
     assert(x == 3); \
-    assert(_Py_atomic_add_##suffix(&x, -z) == 3); \
+    assert(_Py_atomic_add_##suffix(&x, -2) == 3); \
     assert("b" && x == 1); \
-    assert(_Py_atomic_add_##suffix(&x, -y) == 1); \
+    assert(_Py_atomic_add_##suffix(&x, -1) == 1); \
     assert(x == 0); \
-    assert(_Py_atomic_add_##suffix(&x, -y) == 0); \
+    assert(_Py_atomic_add_##suffix(&x, -1) == 0); \
     assert(x == (dtype)-1); \
-    assert(_Py_atomic_add_##suffix(&x, -z) == (dtype)-1); \
+    assert(_Py_atomic_add_##suffix(&x, -2) == (dtype)-1); \
     assert(x == (dtype)-3); \
-    assert(_Py_atomic_add_##suffix(&x, z) == (dtype)-3); \
+    assert(_Py_atomic_add_##suffix(&x, 2) == (dtype)-3); \
     assert(x == (dtype)-1); \
     Py_RETURN_NONE; \
 }