bpo-39947: Move Py_EnterRecursiveCall() to internal C API (GH-18972)

Move the static inline function flavor of Py_EnterRecursiveCall() and
Py_LeaveRecursiveCall() to the internal C API: they access
PyThreadState attributes. The limited C API provides regular
functions which hide implementation details.

1 files changed, 60 insertions, 0 deletions

diff --git a/Include/internal/pycore_ceval.h b/Include/internal/pycore_ceval.h
index 23d8091..ae6ef9a 100644
--- a/Include/internal/pycore_ceval.h
+++ b/Include/internal/pycore_ceval.h
@@ -56,6 +56,66 @@ extern PyObject *_PyEval_EvalCode(
 extern int _PyEval_ThreadsInitialized(_PyRuntimeState *runtime);
 extern PyStatus _PyEval_InitThreads(PyThreadState *tstate);
 
+
+/* --- _Py_EnterRecursiveCall() ----------------------------------------- */
+
+PyAPI_DATA(int) _Py_CheckRecursionLimit;
+
+#ifdef USE_STACKCHECK
+/* With USE_STACKCHECK macro defined, trigger stack checks in
+   _Py_CheckRecursiveCall() on every 64th call to Py_EnterRecursiveCall. */
+static inline int _Py_MakeRecCheck(PyThreadState *tstate)  {
+    return (++tstate->recursion_depth > _Py_CheckRecursionLimit
+            || ++tstate->stackcheck_counter > 64);
+}
+#else
+static inline int _Py_MakeRecCheck(PyThreadState *tstate) {
+    return (++tstate->recursion_depth > _Py_CheckRecursionLimit);
+}
+#endif
+
+PyAPI_FUNC(int) _Py_CheckRecursiveCall(
+    PyThreadState *tstate,
+    const char *where);
+
+static inline int _Py_EnterRecursiveCall(PyThreadState *tstate,
+                                         const char *where) {
+    return (_Py_MakeRecCheck(tstate) && _Py_CheckRecursiveCall(tstate, where));
+}
+
+static inline int _Py_EnterRecursiveCall_inline(const char *where) {
+    PyThreadState *tstate = PyThreadState_GET();
+    return _Py_EnterRecursiveCall(tstate, where);
+}
+
+#define Py_EnterRecursiveCall(where) _Py_EnterRecursiveCall_inline(where)
+
+
+/* Compute the "lower-water mark" for a recursion limit. When
+ * Py_LeaveRecursiveCall() is called with a recursion depth below this mark,
+ * the overflowed flag is reset to 0. */
+#define _Py_RecursionLimitLowerWaterMark(limit) \
+    (((limit) > 200) \
+        ? ((limit) - 50) \
+        : (3 * ((limit) >> 2)))
+
+#define _Py_MakeEndRecCheck(x) \
+    (--(x) < _Py_RecursionLimitLowerWaterMark(_Py_CheckRecursionLimit))
+
+static inline void _Py_LeaveRecursiveCall(PyThreadState *tstate)  {
+    if (_Py_MakeEndRecCheck(tstate->recursion_depth)) {
+        tstate->overflowed = 0;
+    }
+}
+
+static inline void _Py_LeaveRecursiveCall_inline(void)  {
+    PyThreadState *tstate = PyThreadState_GET();
+    _Py_LeaveRecursiveCall(tstate);
+}
+
+#define Py_LeaveRecursiveCall() _Py_LeaveRecursiveCall_inline()
+
+
 #ifdef __cplusplus
 }
 #endif