gh-149196: Hide executor array layout from ABI tools

Author: Taeknology

Include/cpython/code.h

@@ -15,11 +15,7 @@ typedef struct {
     PyObject *_co_freevars;
 } _PyCoCached;
 
-typedef struct {
-    int size;
-    int capacity;
-    struct _PyExecutorObject *executors[1];
-} _PyExecutorArray;
+typedef struct _PyExecutorArray _PyExecutorArray;
 
 
 #ifdef Py_GIL_DISABLED

Include/internal/pycore_interp_structs.h

@@ -819,6 +819,8 @@ struct _Py_unique_id_pool {
 
 #endif
 
+struct _PyExecutorObject;
+
 typedef _Py_CODEUNIT *(*_PyJitEntryFuncPtr)(struct _PyExecutorObject *exec, _PyInterpreterFrame *frame, _PyStackRef *stack_pointer, PyThreadState *tstate);
 
 #define _PyInterpreterGuard_GUARDS_NOT_ALLOWED UINTPTR_MAX

Include/internal/pycore_optimizer.h

@@ -202,6 +202,30 @@ typedef struct _PyExecutorObject {
     _PyExitData exits[1];
 } _PyExecutorObject;
 
+typedef struct _PyExecutorArrayInternal {
+    int size;
+    int capacity;
+    _PyExecutorObject *executors[1];
+} _PyExecutorArrayInternal;
+
+static inline _PyExecutorArrayInternal *
+_PyExecutorArray_CAST(_PyExecutorArray *executors)
+{
+    return (_PyExecutorArrayInternal *)executors;
+}
+
+static inline int
+_PyExecutorArray_SIZE(_PyExecutorArray *executors)
+{
+    return _PyExecutorArray_CAST(executors)->size;
+}
+
+static inline _PyExecutorObject **
+_PyExecutorArray_EXECUTORS(_PyExecutorArray *executors)
+{
+    return _PyExecutorArray_CAST(executors)->executors;
+}
+
 // Export for '_opcode' shared extension (JIT compiler).
 PyAPI_FUNC(_PyExecutorObject*) _Py_GetExecutor(PyCodeObject *code, int offset);
 

Misc/NEWS.d/next/C_API/2026-07-29-23-26-43.gh-issue-149196.AxP7dS.rst

@@ -0,0 +1,2 @@
+Hide internal Tier 2 executor implementation details from ABI analysis tools
+by making the executor array referenced by :c:type:`PyCodeObject` opaque.

Modules/_testinternalcapi/test_cases.c.h

@@ -2181,10 +2181,10 @@ static void
 clear_executors(PyCodeObject *co)
 {
     assert(co->co_executors);
-    for (int i = 0; i < co->co_executors->size; i++) {
-        if (co->co_executors->executors[i]) {
-            _Py_ExecutorDetach(co->co_executors->executors[i]);
-            assert(co->co_executors->executors[i] == NULL);
+    for (int i = 0; i < _PyExecutorArray_SIZE(co->co_executors); i++) {
+        if (_PyExecutorArray_EXECUTORS(co->co_executors)[i]) {
+            _Py_ExecutorDetach(_PyExecutorArray_EXECUTORS(co->co_executors)[i]);
+            assert(_PyExecutorArray_EXECUTORS(co->co_executors)[i] == NULL);
         }
     }
     PyMem_Free(co->co_executors);

Objects/codeobject.c

@@ -3590,7 +3590,7 @@ dummy_func(
         tier1 inst(ENTER_EXECUTOR, (--)) {
             #ifdef _Py_TIER2
             PyCodeObject *code = _PyFrame_GetCode(frame);
-            _PyExecutorObject *executor = code->co_executors->executors[oparg & 255];
+            _PyExecutorObject *executor = _PyExecutorArray_EXECUTORS(code->co_executors)[oparg & 255];
             if (IS_JIT_TRACING()) {
                 int og_opcode = executor->vm_data.opcode;
                 int og_oparg = (oparg & ~255) | executor->vm_data.oparg;
@@ -6266,7 +6266,7 @@ dummy_func(
             _PyExecutorObject *executor;
             if (target->op.code == ENTER_EXECUTOR) {
                 PyCodeObject *code = _PyFrame_GetCode(frame);
-                executor = code->co_executors->executors[target->op.arg];
+                executor = _PyExecutorArray_EXECUTORS(code->co_executors)[target->op.arg];
                 if (executor == _PyExecutor_FromExit(exit)) {
                     _Py_ExecutorDetach(executor);
                     GOTO_TIER_ONE(target);

Python/bytecodes.c

@@ -647,7 +647,7 @@ _Py_GetBaseCodeUnit(PyCodeObject *code, int i)
         return inst;
     }
     if (opcode == ENTER_EXECUTOR) {
-        _PyExecutorObject *exec = code->co_executors->executors[inst.op.arg];
+        _PyExecutorObject *exec = _PyExecutorArray_EXECUTORS(code->co_executors)[inst.op.arg];
         opcode = _PyOpcode_Deopt[exec->vm_data.opcode];
         inst.op.code = opcode;
         inst.op.arg = exec->vm_data.oparg;