bpo-45637: Store the frame pointer in the cframe

Include/cpython/pystate.h

@@ -46,6 +46,8 @@ typedef struct _cframe {
      * accessed outside of their lifetime.
      */
     int use_tracing;
+    /* Pointer to the currently executing frame (it can be NULL) */
+    struct _interpreter_frame *current_frame;
     struct _cframe *previous;
 } CFrame;
 
@@ -77,8 +79,6 @@ struct _ts {
     struct _ts *next;
     PyInterpreterState *interp;
 
-    /* Borrowed reference to the current frame (it can be NULL) */
-    struct _interpreter_frame *frame;
     int recursion_depth;
     int recursion_headroom; /* Allow 50 more calls to handle any errors. */
     int stackcheck_counter;

Modules/_tracemalloc.c

@@ -396,7 +396,7 @@ traceback_get_frames(traceback_t *traceback)
         return;
     }
 
-    InterpreterFrame *pyframe = tstate->frame;
+    InterpreterFrame *pyframe = tstate->cframe->current_frame;
     for (; pyframe != NULL;) {
         if (traceback->nframe < _Py_tracemalloc_config.max_nframe) {
             tracemalloc_get_frame(pyframe, &traceback->frames[traceback->nframe]);

Modules/_xxsubinterpretersmodule.c

@@ -1839,7 +1839,7 @@ _is_running(PyInterpreterState *interp)
     }
 
     assert(!PyErr_Occurred());
-    InterpreterFrame *frame = tstate->frame;
+    InterpreterFrame *frame = tstate->cframe->current_frame;
     if (frame == NULL) {
         return 0;
     }

Modules/signalmodule.c

@@ -1788,7 +1788,7 @@ _PyErr_CheckSignalsTstate(PyThreadState *tstate)
      */
     _Py_atomic_store(&is_tripped, 0);
 
-    InterpreterFrame *frame = tstate->frame;
+    InterpreterFrame *frame = tstate->cframe->current_frame;
     signal_state_t *state = &signal_global_state;
     for (int i = 1; i < NSIG; i++) {
         if (!_Py_atomic_load_relaxed(&Handlers[i].tripped)) {

Objects/genobject.c

@@ -193,7 +193,7 @@ gen_send_ex2(PyGenObject *gen, PyObject *arg, PyObject **presult,
     Py_INCREF(result);
     _PyFrame_StackPush(frame, result);
 
-    frame->previous = tstate->frame;
+    frame->previous = tstate->cframe->current_frame;
 
     gen->gi_exc_state.previous_item = tstate->exc_info;
     tstate->exc_info = &gen->gi_exc_state;
@@ -207,7 +207,7 @@ gen_send_ex2(PyGenObject *gen, PyObject *arg, PyObject **presult,
     tstate->exc_info = gen->gi_exc_state.previous_item;
     gen->gi_exc_state.previous_item = NULL;
 
-    assert(tstate->frame == frame->previous);
+    assert(tstate->cframe->current_frame == frame->previous);
     /* Don't keep the reference to previous any longer than necessary.  It
      * may keep a chain of frames alive or it could create a reference
      * cycle. */
@@ -435,17 +435,17 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
                will be reported correctly to the user. */
             /* XXX We should probably be updating the current frame
                somewhere in ceval.c. */
-            InterpreterFrame *prev = tstate->frame;
+            InterpreterFrame *prev = tstate->cframe->current_frame;
             frame->previous = prev;
-            tstate->frame = frame;
+            tstate->cframe->current_frame = frame;
             /* Close the generator that we are currently iterating with
                'yield from' or awaiting on with 'await'. */
             PyFrameState state = gen->gi_xframe->f_state;
             gen->gi_xframe->f_state = FRAME_EXECUTING;
             ret = _gen_throw((PyGenObject *)yf, close_on_genexit,
                              typ, val, tb);
             gen->gi_xframe->f_state = state;
-            tstate->frame = prev;
+            tstate->cframe->current_frame = prev;
             frame->previous = NULL;
         } else {
             /* `yf` is an iterator or a coroutine-like object. */

Python/ceval.c

@@ -1561,16 +1561,18 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
     tstate->cframe = &cframe;
 
     assert(frame->depth == 0);
-    /* push frame */
-    tstate->frame = frame;
+    /* Push frame */
+    frame->previous = prev_cframe->current_frame;
+    cframe.current_frame = frame;
 
 start_frame:
     if (_Py_EnterRecursiveCall(tstate, "")) {
         tstate->recursion_depth++;
         goto exit_eval_frame;
     }
 
-    assert(frame == tstate->frame);
+    assert(tstate->cframe == &cframe);
+    assert(frame == cframe.current_frame);
 
     if (cframe.use_tracing) {
         if (trace_function_entry(tstate, frame)) {
@@ -4641,8 +4643,9 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
                         goto error;
                     }
                     _PyFrame_SetStackPointer(frame, stack_pointer);
+                    new_frame->previous = frame;
+                    cframe.current_frame = frame = new_frame;
                     new_frame->depth = frame->depth + 1;
-                    tstate->frame = frame = new_frame;
                     goto start_frame;
                 }
             }
@@ -4723,9 +4726,9 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
             STACK_SHRINK(1);
             Py_DECREF(func);
             _PyFrame_SetStackPointer(frame, stack_pointer);
-            new_frame->previous = tstate->frame;
+            new_frame->previous = frame;
+            frame = cframe.current_frame = new_frame;
             new_frame->depth = frame->depth + 1;
-            tstate->frame = frame = new_frame;
             goto start_frame;
         }
 
@@ -5258,23 +5261,24 @@ MISS_WITH_OPARG_COUNTER(BINARY_MULTIPLY)
     _Py_LeaveRecursiveCall(tstate);
 
     if (frame->depth) {
-        _PyFrame_StackPush(frame->previous, retval);
+        cframe.current_frame = frame->previous;
+        _PyFrame_StackPush(cframe.current_frame, retval);
         if (_PyEvalFrameClearAndPop(tstate, frame)) {
             retval = NULL;
         }
-        frame = tstate->frame;
+        frame = cframe.current_frame;
         if (retval == NULL) {
             assert(_PyErr_Occurred(tstate));
             throwflag = 1;
         }
         retval = NULL;
         goto resume_frame;
     }
-    tstate->frame = frame->previous;
 
-    /* Restore previous cframe */
+    /* Restore previous cframe. */
     tstate->cframe = cframe.previous;
     tstate->cframe->use_tracing = cframe.use_tracing;
+    assert(tstate->cframe->current_frame == frame->previous);
     return _Py_CheckFunctionResult(tstate, NULL, retval, __func__);
 }
 
@@ -5891,8 +5895,6 @@ _PyEvalFramePushAndInit(PyThreadState *tstate, PyFrameConstructor *con,
         _PyFrame_Clear(frame, 0);
         return NULL;
     }
-    frame->previous = tstate->frame;
-    tstate->frame = frame;
     return frame;
 }
 
@@ -5906,7 +5908,6 @@ _PyEvalFrameClearAndPop(PyThreadState *tstate, InterpreterFrame * frame)
         return -1;
     }
     --tstate->recursion_depth;
-    tstate->frame = frame->previous;
     _PyThreadState_PopFrame(tstate, frame);
     return 0;
 }
@@ -6518,17 +6519,17 @@ InterpreterFrame *
 _PyEval_GetFrame(void)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    return tstate->frame;
+    return tstate->cframe->current_frame;
 }
 
 PyFrameObject *
 PyEval_GetFrame(void)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    if (tstate->frame == NULL) {
+    if (tstate->cframe->current_frame == NULL) {
         return NULL;
     }
-    PyFrameObject *f = _PyFrame_GetFrameObject(tstate->frame);
+    PyFrameObject *f = _PyFrame_GetFrameObject(tstate->cframe->current_frame);
     if (f == NULL) {
         PyErr_Clear();
     }
@@ -6538,7 +6539,7 @@ PyEval_GetFrame(void)
 PyObject *
 _PyEval_GetBuiltins(PyThreadState *tstate)
 {
-    InterpreterFrame *frame = tstate->frame;
+    InterpreterFrame *frame = tstate->cframe->current_frame;
     if (frame != NULL) {
         return frame->f_builtins;
     }
@@ -6571,7 +6572,7 @@ PyObject *
 PyEval_GetLocals(void)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-     InterpreterFrame *current_frame = tstate->frame;
+     InterpreterFrame *current_frame = tstate->cframe->current_frame;
     if (current_frame == NULL) {
         _PyErr_SetString(tstate, PyExc_SystemError, "frame does not exist");
         return NULL;
@@ -6590,7 +6591,7 @@ PyObject *
 PyEval_GetGlobals(void)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    InterpreterFrame *current_frame = tstate->frame;
+    InterpreterFrame *current_frame = tstate->cframe->current_frame;
     if (current_frame == NULL) {
         return NULL;
     }
@@ -6601,7 +6602,7 @@ int
 PyEval_MergeCompilerFlags(PyCompilerFlags *cf)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    InterpreterFrame *current_frame = tstate->frame;
+    InterpreterFrame *current_frame = tstate->cframe->current_frame;
     int result = cf->cf_flags != 0;
 
     if (current_frame != NULL) {
@@ -6651,7 +6652,7 @@ PyEval_GetFuncDesc(PyObject *func)
 #define C_TRACE(x, call) \
 if (use_tracing && tstate->c_profilefunc) { \
     if (call_trace(tstate->c_profilefunc, tstate->c_profileobj, \
-        tstate, tstate->frame, \
+        tstate, tstate->cframe->current_frame, \
         PyTrace_C_CALL, func)) { \
         x = NULL; \
     } \
@@ -6661,13 +6662,13 @@ if (use_tracing && tstate->c_profilefunc) { \
             if (x == NULL) { \
                 call_trace_protected(tstate->c_profilefunc, \
                     tstate->c_profileobj, \
-                    tstate, tstate->frame, \
+                    tstate, tstate->cframe->current_frame, \
                     PyTrace_C_EXCEPTION, func); \
                 /* XXX should pass (type, value, tb) */ \
             } else { \
                 if (call_trace(tstate->c_profilefunc, \
                     tstate->c_profileobj, \
-                    tstate, tstate->frame, \
+                    tstate, tstate->cframe->current_frame, \
                     PyTrace_C_RETURN, func)) { \
                     Py_DECREF(x); \
                     x = NULL; \

Python/pylifecycle.c

@@ -2031,7 +2031,7 @@ Py_EndInterpreter(PyThreadState *tstate)
     if (tstate != _PyThreadState_GET()) {
         Py_FatalError("thread is not current");
     }
-    if (tstate->frame != NULL) {
+    if (tstate->cframe->current_frame != NULL) {
         Py_FatalError("thread still has a frame");
     }
     interp->finalizing = 1;

Python/pystate.c

@@ -636,12 +636,12 @@ new_threadstate(PyInterpreterState *interp, int init)
 
     tstate->interp = interp;
 
-    tstate->frame = NULL;
     tstate->recursion_depth = 0;
     tstate->recursion_headroom = 0;
     tstate->stackcheck_counter = 0;
     tstate->tracing = 0;
     tstate->root_cframe.use_tracing = 0;
+    tstate->root_cframe.current_frame = NULL;
     tstate->cframe = &tstate->root_cframe;
     tstate->gilstate_counter = 0;
     tstate->async_exc = NULL;
@@ -861,7 +861,7 @@ PyThreadState_Clear(PyThreadState *tstate)
 {
     int verbose = _PyInterpreterState_GetConfig(tstate->interp)->verbose;
 
-    if (verbose && tstate->frame != NULL) {
+    if (verbose && tstate->cframe->current_frame != NULL) {
         /* bpo-20526: After the main thread calls
            _PyRuntimeState_SetFinalizing() in Py_FinalizeEx(), threads must
            exit when trying to take the GIL. If a thread exit in the middle of
@@ -1134,10 +1134,10 @@ PyFrameObject*
 PyThreadState_GetFrame(PyThreadState *tstate)
 {
     assert(tstate != NULL);
-    if (tstate->frame == NULL) {
+    if (tstate->cframe->current_frame == NULL) {
         return NULL;
     }
-    PyFrameObject *frame = _PyFrame_GetFrameObject(tstate->frame);
+    PyFrameObject *frame = _PyFrame_GetFrameObject(tstate->cframe->current_frame);
     if (frame == NULL) {
         PyErr_Clear();
     }
@@ -1277,7 +1277,7 @@ _PyThread_CurrentFrames(void)
     for (i = runtime->interpreters.head; i != NULL; i = i->next) {
         PyThreadState *t;
         for (t = i->tstate_head; t != NULL; t = t->next) {
-            InterpreterFrame *frame = t->frame;
+            InterpreterFrame *frame = t->cframe->current_frame;
             if (frame == NULL) {
                 continue;
             }

Python/sysmodule.c

@@ -1813,7 +1813,7 @@ sys__getframe_impl(PyObject *module, int depth)
 /*[clinic end generated code: output=d438776c04d59804 input=c1be8a6464b11ee5]*/
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    InterpreterFrame *frame = tstate->frame;
+    InterpreterFrame *frame = tstate->cframe->current_frame;
 
     if (_PySys_Audit(tstate, "sys._getframe", NULL) < 0) {
         return NULL;

Python/traceback.c

@@ -1082,7 +1082,7 @@ dump_traceback(int fd, PyThreadState *tstate, int write_header)
         PUTS(fd, "Stack (most recent call first):\n");
     }
 
-    frame = tstate->frame;
+    frame = tstate->cframe->current_frame;
     if (frame == NULL) {
         PUTS(fd, "  <no Python frame>\n");
         return;