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GH-104584: Don't call executors from JUMP_BACKWARD #109347

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Merged
merged 2 commits into from
Sep 13, 2023
Merged

GH-104584: Don't call executors from JUMP_BACKWARD #109347

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83d0190
Don't call executors from JUMP_BACKWARD
brandtbucher Sep 8, 2023
4668bac
Add a helpful comment and assert
brandtbucher Sep 8, 2023
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2 changes: 1 addition & 1 deletion Include/cpython/optimizer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ PyAPI_FUNC(_PyOptimizerObject *) PyUnstable_GetOptimizer(void);

PyAPI_FUNC(_PyExecutorObject *) PyUnstable_GetExecutor(PyCodeObject *code, int offset);

struct _PyInterpreterFrame *
int
_PyOptimizer_BackEdge(struct _PyInterpreterFrame *frame, _Py_CODEUNIT *src, _Py_CODEUNIT *dest, PyObject **stack_pointer);

extern _PyOptimizerObject _PyOptimizer_Default;
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20 changes: 8 additions & 12 deletions Python/bytecodes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2246,21 +2246,17 @@ dummy_func(
here[1].cache += (1 << OPTIMIZER_BITS_IN_COUNTER);
if (here[1].cache > tstate->interp->optimizer_backedge_threshold &&
// Double-check that the opcode isn't instrumented or something:
here->op.code == JUMP_BACKWARD &&
// _PyOptimizer_BackEdge is going to change frame->prev_instr,
// which breaks line event calculations:
next_instr->op.code != INSTRUMENTED_LINE
)
here->op.code == JUMP_BACKWARD)
{
OBJECT_STAT_INC(optimization_attempts);
frame = _PyOptimizer_BackEdge(frame, here, next_instr, stack_pointer);
if (frame == NULL) {
frame = tstate->current_frame;
goto resume_with_error;
int optimized = _PyOptimizer_BackEdge(frame, here, next_instr, stack_pointer);
ERROR_IF(optimized < 0, error);
if (optimized) {
// Rewind and enter the executor:
assert(here->op.code == ENTER_EXECUTOR);
next_instr = here;
}
assert(frame == tstate->current_frame);
here[1].cache &= ((1 << OPTIMIZER_BITS_IN_COUNTER) -1);
goto resume_frame;
here[1].cache &= ((1 << OPTIMIZER_BITS_IN_COUNTER) - 1);
}
#endif /* ENABLE_SPECIALIZATION */
}
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20 changes: 8 additions & 12 deletions Python/generated_cases.c.h
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21 changes: 6 additions & 15 deletions Python/optimizer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -154,26 +154,22 @@ PyUnstable_SetOptimizer(_PyOptimizerObject *optimizer)
Py_DECREF(old);
}

_PyInterpreterFrame *
int
_PyOptimizer_BackEdge(_PyInterpreterFrame *frame, _Py_CODEUNIT *src, _Py_CODEUNIT *dest, PyObject **stack_pointer)
{
assert(src->op.code == JUMP_BACKWARD);
PyCodeObject *code = (PyCodeObject *)frame->f_executable;
assert(PyCode_Check(code));
PyInterpreterState *interp = _PyInterpreterState_GET();
if (!has_space_for_executor(code, src)) {
goto jump_to_destination;
return 0;
}
_PyOptimizerObject *opt = interp->optimizer;
_PyExecutorObject *executor = NULL;
int err = opt->optimize(opt, code, dest, &executor, (int)(stack_pointer - _PyFrame_Stackbase(frame)));
if (err <= 0) {
assert(executor == NULL);
if (err < 0) {
_PyFrame_SetStackPointer(frame, stack_pointer);
return NULL;
}
goto jump_to_destination;
return err;
}
int index = get_index_for_executor(code, src);
if (index < 0) {
Expand All @@ -184,16 +180,11 @@ _PyOptimizer_BackEdge(_PyInterpreterFrame *frame, _Py_CODEUNIT *src, _Py_CODEUNI
* it might get confused by the executor disappearing,
* but there is not much we can do about that here. */
Py_DECREF(executor);
goto jump_to_destination;
return 0;
}
insert_executor(code, src, index, executor);
assert(frame->prev_instr == src);
frame->prev_instr = dest - 1;
return executor->execute(executor, frame, stack_pointer);
jump_to_destination:
frame->prev_instr = dest - 1;
_PyFrame_SetStackPointer(frame, stack_pointer);
return frame;
Py_DECREF(executor);
return 1;
}

_PyExecutorObject *
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