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bpo-47045: Remove f_state field (GH-31963)

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* Remove the f_state field from _PyInterpreterFrame

*  Make ownership of the frame explicit, replacing the is_generator field with an owner field.
This commit is contained in:
Mark Shannon 2022-03-22 12:57:19 +00:00 • committed by GitHub
parent 88872a29f1
commit 49daf6dba8
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GPG key ID: 4AEE18F83AFDEB23
9 changed files with 260 additions and 220 deletions
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129
Objects/frameobject.c
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@ -412,6 +412,42 @@ frame_stack_pop(PyFrameObject *f)
Py_DECREF(v);
}
static PyFrameState
_PyFrame_GetState(PyFrameObject *frame)
{
if (frame->f_frame->stacktop == 0) {
return FRAME_CLEARED;
}
switch(frame->f_frame->owner) {
case FRAME_OWNED_BY_GENERATOR:
{
PyGenObject *gen = _PyFrame_GetGenerator(frame->f_frame);
return gen->gi_frame_state;
}
case FRAME_OWNED_BY_THREAD:
{
if (frame->f_frame->f_lasti < 0) {
return FRAME_CREATED;
}
uint8_t *code = (uint8_t *)frame->f_frame->f_code->co_code_adaptive;
int opcode = code[frame->f_frame->f_lasti*sizeof(_Py_CODEUNIT)];
switch(_PyOpcode_Deopt[opcode]) {
case COPY_FREE_VARS:
case MAKE_CELL:
case RETURN_GENERATOR:
/* Frame not fully initialized */
return FRAME_CREATED;
default:
return FRAME_EXECUTING;
}
}
case FRAME_OWNED_BY_FRAME_OBJECT:
return FRAME_COMPLETED;
}
Py_UNREACHABLE();
}
/* Setter for f_lineno - you can set f_lineno from within a trace function in
* order to jump to a given line of code, subject to some restrictions. Most
* lines are OK to jump to because they don't make any assumptions about the
@ -440,6 +476,7 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignore
return -1;
}
PyFrameState state = _PyFrame_GetState(f);
/*
* This code preserves the historical restrictions on
* setting the line number of a frame.
@ -448,28 +485,31 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignore
* In addition, jumps are forbidden when not tracing,
* as this is a debugging feature.
*/
switch(f->f_frame->f_state) {
case FRAME_CREATED:
PyErr_Format(PyExc_ValueError,
"can't jump from the 'call' trace event of a new frame");
return -1;
case FRAME_RETURNED:
case FRAME_UNWINDING:
case FRAME_RAISED:
case FRAME_CLEARED:
switch(PyThreadState_GET()->tracing_what) {
case PyTrace_EXCEPTION:
PyErr_SetString(PyExc_ValueError,
"can only jump from a 'line' trace event");
return -1;
case FRAME_EXECUTING:
case FRAME_SUSPENDED:
/* You can only do this from within a trace function, not via
* _getframe or similar hackery. */
if (!f->f_trace) {
PyErr_Format(PyExc_ValueError,
"f_lineno can only be set by a trace function");
return -1;
}
case PyTrace_CALL:
PyErr_Format(PyExc_ValueError,
"can't jump from the 'call' trace event of a new frame");
return -1;
case PyTrace_LINE:
break;
case PyTrace_RETURN:
if (state == FRAME_SUSPENDED) {
break;
}
/* fall through */
default:
PyErr_SetString(PyExc_ValueError,
"can only jump from a 'line' trace event");
return -1;
}
if (!f->f_trace) {
PyErr_Format(PyExc_ValueError,
"f_lineno can only be set by a trace function");
return -1;
}
int new_lineno;
@ -555,8 +595,7 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignore
PyErr_SetString(PyExc_ValueError, msg);
return -1;
}
/* Unwind block stack. */
if (f->f_frame->f_state == FRAME_SUSPENDED) {
if (state == FRAME_SUSPENDED) {
/* Account for value popped by yield */
start_stack = pop_value(start_stack);
}
@ -623,7 +662,9 @@ frame_dealloc(PyFrameObject *f)
{
/* It is the responsibility of the owning generator/coroutine
* to have cleared the generator pointer */
assert(!f->f_frame->is_generator);
assert(f->f_frame->owner != FRAME_OWNED_BY_GENERATOR ||
_PyFrame_GetGenerator(f->f_frame)->gi_frame_state == FRAME_CLEARED);
if (_PyObject_GC_IS_TRACKED(f)) {
_PyObject_GC_UNTRACK(f);
@ -633,8 +674,7 @@ frame_dealloc(PyFrameObject *f)
PyCodeObject *co = NULL;
/* Kill all local variables including specials, if we own them */
if (f->f_owns_frame) {
f->f_owns_frame = 0;
if (f->f_frame->owner == FRAME_OWNED_BY_FRAME_OBJECT) {
assert(f->f_frame == (_PyInterpreterFrame *)f->_f_frame_data);
_PyInterpreterFrame *frame = (_PyInterpreterFrame *)f->_f_frame_data;
/* Don't clear code object until the end */
@ -659,7 +699,7 @@ frame_traverse(PyFrameObject *f, visitproc visit, void *arg)
{
Py_VISIT(f->f_back);
Py_VISIT(f->f_trace);
if (f->f_owns_frame == 0) {
if (f->f_frame->owner != FRAME_OWNED_BY_FRAME_OBJECT) {
return 0;
}
assert(f->f_frame->frame_obj == NULL);
@ -669,13 +709,6 @@ frame_traverse(PyFrameObject *f, visitproc visit, void *arg)
static int
frame_tp_clear(PyFrameObject *f)
{
/* Before anything else, make sure that this frame is clearly marked
* as being defunct! Else, e.g., a generator reachable from this
* frame may also point to this frame, believe itself to still be
* active, and try cleaning up this frame again.
*/
f->f_frame->f_state = FRAME_CLEARED;
Py_CLEAR(f->f_trace);
/* locals and stack */
@ -691,19 +724,25 @@ frame_tp_clear(PyFrameObject *f)
static PyObject *
frame_clear(PyFrameObject *f, PyObject *Py_UNUSED(ignored))
{
if (_PyFrame_IsExecuting(f->f_frame)) {
PyErr_SetString(PyExc_RuntimeError,
"cannot clear an executing frame");
return NULL;
if (f->f_frame->owner == FRAME_OWNED_BY_GENERATOR) {
PyGenObject *gen = _PyFrame_GetGenerator(f->f_frame);
if (gen->gi_frame_state == FRAME_EXECUTING) {
goto running;
}
_PyGen_Finalize((PyObject *)gen);
}
if (f->f_frame->is_generator) {
assert(!f->f_owns_frame);
size_t offset_in_gen = offsetof(PyGenObject, gi_iframe);
PyObject *gen = (PyObject *)(((char *)f->f_frame) - offset_in_gen);
_PyGen_Finalize(gen);
else if (f->f_frame->owner == FRAME_OWNED_BY_THREAD) {
goto running;
}
else {
assert(f->f_frame->owner == FRAME_OWNED_BY_FRAME_OBJECT);
(void)frame_tp_clear(f);
}
(void)frame_tp_clear(f);
Py_RETURN_NONE;
running:
PyErr_SetString(PyExc_RuntimeError,
"cannot clear an executing frame");
return NULL;
}
PyDoc_STRVAR(clear__doc__,
@ -835,7 +874,7 @@ PyFrame_New(PyThreadState *tstate, PyCodeObject *code,
}
init_frame((_PyInterpreterFrame *)f->_f_frame_data, func, locals);
f->f_frame = (_PyInterpreterFrame *)f->_f_frame_data;
f->f_owns_frame = 1;
f->f_frame->owner = FRAME_OWNED_BY_FRAME_OBJECT;
Py_DECREF(func);
_PyObject_GC_TRACK(f);
return f;
@ -912,7 +951,7 @@ _PyFrame_FastToLocalsWithError(_PyInterpreterFrame *frame) {
PyObject *name = PyTuple_GET_ITEM(co->co_localsplusnames, i);
PyObject *value = fast[i];
if (frame->f_state != FRAME_CLEARED) {
if (frame->stacktop) {
if (kind & CO_FAST_FREE) {
// The cell was set by COPY_FREE_VARS.
assert(value != NULL && PyCell_Check(value));
@ -1049,7 +1088,7 @@ _PyFrame_LocalsToFast(_PyInterpreterFrame *frame, int clear)
void
PyFrame_LocalsToFast(PyFrameObject *f, int clear)
{
if (f == NULL || f->f_frame->f_state == FRAME_CLEARED) {
if (f == NULL || _PyFrame_GetState(f) == FRAME_CLEARED) {
return;
}
_PyFrame_LocalsToFast(f->f_frame, clear);
@ -1096,3 +1135,5 @@ _PyEval_BuiltinsFromGlobals(PyThreadState *tstate, PyObject *globals)
return _PyEval_GetBuiltins(tstate);
}