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GH-104584: Allow optimizers to opt out of optimizing.#105244

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Merged
markshannon merged 1 commit into from
Jun 5, 2023
Merged

GH-104584: Allow optimizers to opt out of optimizing. #105244

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3 changes: 2 additions & 1 deletion Include/cpython/optimizer.h
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Original file line numberDiff line numberDiff line change
Expand Up@@ -21,7 +21,8 @@ typedef struct _PyExecutorObject {

typedef struct _PyOptimizerObject _PyOptimizerObject;

typedef _PyExecutorObject *(*optimize_func)(_PyOptimizerObject* self, PyCodeObject *code, _Py_CODEUNIT *instr);
/* Should return > 0 if a new executor is created. O if no executor is produced and < 0 if an error occurred. */
typedef int (*optimize_func)(_PyOptimizerObject* self, PyCodeObject *code, _Py_CODEUNIT *instr, _PyExecutorObject **);

typedef struct _PyOptimizerObject {
PyObject_HEAD
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29 changes: 18 additions & 11 deletions Python/optimizer.c
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Expand Up@@ -93,14 +93,15 @@ PyUnstable_Replace_Executor(PyCodeObject *code, _Py_CODEUNIT *instr, _PyExecutor
return 0;
}

static _PyExecutorObject *
static int
error_optimize(
_PyOptimizerObject* self,
PyCodeObject *code,
_Py_CODEUNIT *instr)
_Py_CODEUNIT *instr,
_PyExecutorObject **exec)
{
PyErr_Format(PyExc_SystemError, "Should never call error_optimize");
return NULL;
return -1;
}

static PyTypeObject DefaultOptimizer_Type = {
Expand DownExpand Up@@ -154,15 +155,19 @@ _PyOptimizer_BackEdge(_PyInterpreterFrame *frame, _Py_CODEUNIT *src, _Py_CODEUNI
return frame;
}
_PyOptimizerObject *opt = interp->optimizer;
_PyExecutorObject *executor = opt->optimize(opt, frame->f_code, dest);
if (executor == NULL) {
return NULL;
_PyExecutorObject *executor;
int err = opt->optimize(opt, frame->f_code, dest, &executor);
if (err <= 0) {
if (err < 0) {
return NULL;
}
_PyFrame_SetStackPointer(frame, stack_pointer);
return frame;
Comment on lines +164 to +165

@carljmcarljmJun 2, 2023

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We could also complicate the signature of _PyOptimizer_BackEdge to signal this case back to the caller so we could avoid the stack pointer write, and the caller could just continue regular interpretation instead of needing to goto resume_frame and update interpreter state from the frame again. But probably not worth it I guess, if optimizers declining to optimize should be rare?

@markshannonmarkshannonJun 5, 2023

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Most calls to _PyOptimizer_BackEdge will return the same frame. We could add a check for it in JUMP_BACKWARD, but I think we would still need to save the stack pointer.
Even if we could avoid it, I suspect a single unconditional write is faster than the additional logic to avoid it.

}
insert_executor(frame->f_code, src, index, executor);
return executor->execute(executor, frame, stack_pointer);
}


/** Test support **/


Expand DownExpand Up@@ -202,21 +207,23 @@ counter_execute(_PyExecutorObject *self, _PyInterpreterFrame *frame, PyObject **
return frame;
}

static _PyExecutorObject *
static int
counter_optimize(
_PyOptimizerObject* self,
PyCodeObject *code,
_Py_CODEUNIT *instr)
_Py_CODEUNIT *instr,
_PyExecutorObject **exec_ptr)
{
_PyCounterExecutorObject *executor = (_PyCounterExecutorObject *)_PyObject_New(&CounterExecutor_Type);
if (executor == NULL) {
return NULL;
return -1;
}
executor->executor.execute = counter_execute;
Py_INCREF(self);
executor->optimizer = (_PyCounterOptimizerObject *)self;
executor->next_instr = instr;
return (_PyExecutorObject *)executor;
*exec_ptr = (_PyExecutorObject *)executor;
return 1;
}

static PyObject *
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