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GH-113710: Backedge counter improvements. (GH-115166)

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Mark Shannon 2024-02-13 14:16:37 +00:00 • committed by GitHub
parent 7cce857622
commit f9f6156c5a
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7 changed files with 81 additions and 55 deletions
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48
Python/optimizer.c
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@ -109,6 +109,9 @@ never_optimize(
_PyExecutorObject **exec,
int Py_UNUSED(stack_entries))
{
/* Although it should be benign for this to be called,
* it shouldn't happen, so fail in debug builds. */
assert(0 && "never optimize should never be called");
return 0;
}
@ -120,13 +123,19 @@ PyTypeObject _PyDefaultOptimizer_Type = {
.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,
};
_PyOptimizerObject _PyOptimizer_Default = {
static _PyOptimizerObject _PyOptimizer_Default = {
PyObject_HEAD_INIT(&_PyDefaultOptimizer_Type)
.optimize = never_optimize,
.resume_threshold = INT16_MAX,
.backedge_threshold = INT16_MAX,
.resume_threshold = OPTIMIZER_UNREACHABLE_THRESHOLD,
.backedge_threshold = OPTIMIZER_UNREACHABLE_THRESHOLD,
};
static uint32_t
shift_and_offset_threshold(uint16_t threshold)
{
return (threshold << OPTIMIZER_BITS_IN_COUNTER) + (1 << 15);
}
_PyOptimizerObject *
PyUnstable_GetOptimizer(void)
{
@ -134,24 +143,33 @@ PyUnstable_GetOptimizer(void)
if (interp->optimizer == &_PyOptimizer_Default) {
return NULL;
}
assert(interp->optimizer_backedge_threshold == interp->optimizer->backedge_threshold);
assert(interp->optimizer_resume_threshold == interp->optimizer->resume_threshold);
assert(interp->optimizer_backedge_threshold ==
shift_and_offset_threshold(interp->optimizer->backedge_threshold));
assert(interp->optimizer_resume_threshold ==
shift_and_offset_threshold(interp->optimizer->resume_threshold));
Py_INCREF(interp->optimizer);
return interp->optimizer;
}
void
PyUnstable_SetOptimizer(_PyOptimizerObject *optimizer)
_PyOptimizerObject *
_Py_SetOptimizer(PyInterpreterState *interp, _PyOptimizerObject *optimizer)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
if (optimizer == NULL) {
optimizer = &_PyOptimizer_Default;
}
_PyOptimizerObject *old = interp->optimizer;
Py_INCREF(optimizer);
interp->optimizer = optimizer;
interp->optimizer_backedge_threshold = optimizer->backedge_threshold;
interp->optimizer_resume_threshold = optimizer->resume_threshold;
interp->optimizer_backedge_threshold = shift_and_offset_threshold(optimizer->backedge_threshold);
interp->optimizer_resume_threshold = shift_and_offset_threshold(optimizer->resume_threshold);
return old;
}
void
PyUnstable_SetOptimizer(_PyOptimizerObject *optimizer)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
_PyOptimizerObject *old = _Py_SetOptimizer(interp, optimizer);
Py_DECREF(old);
}
@ -860,10 +878,10 @@ PyUnstable_Optimizer_NewUOpOptimizer(void)
return NULL;
}
opt->optimize = uop_optimize;
opt->resume_threshold = INT16_MAX;
// Need at least 3 iterations to settle specializations.
// A few lower bits of the counter are reserved for other flags.
opt->backedge_threshold = 16 << OPTIMIZER_BITS_IN_COUNTER;
opt->resume_threshold = OPTIMIZER_UNREACHABLE_THRESHOLD;
// Need a few iterations to settle specializations,
// and to ammortize the cost of optimization.
opt->backedge_threshold = 16;
return (PyObject *)opt;
}
@ -950,7 +968,7 @@ PyUnstable_Optimizer_NewCounter(void)
return NULL;
}
opt->base.optimize = counter_optimize;
opt->base.resume_threshold = INT16_MAX;
opt->base.resume_threshold = OPTIMIZER_UNREACHABLE_THRESHOLD;
opt->base.backedge_threshold = 0;
opt->count = 0;
return (PyObject *)opt;