Scalar replacement of BINARY_SLICE #144569
Description
Feature or enhancement
Proposal:
Currently BINARY_SLICE looks like this:
op(_BINARY_SLICE, (container, start, stop -- res)) {
PyObject *slice = _PyBuildSlice_ConsumeRefs(PyStackRef_AsPyObjectSteal(start),
PyStackRef_AsPyObjectSteal(stop));
PyObject *res_o;
if (slice == NULL) {
res_o = NULL;
}
else {
res_o = PyObject_GetItem(PyStackRef_AsPyObjectBorrow(container), slice);
Py_DECREF(slice);
}
PyStackRef_CLOSE(container);
ERROR_IF(res_o == NULL);
res = PyStackRef_FromPyObjectSteal(res_o);
}Note that we build a slice just for getitem, only to throw it away immediately after.
We can scalar replace the slice in BINARY_SLICE after recording the types. If we record the container type, we can call the slice dispatcher underneath directly without boxing the slice object. See for example BINARY_OP_SUBSCR_LIST_SLICE
We'd need to guard on the type recorded.
I propose to do this in the current optimizer pass rather than the partial evaluation pass, as this is just a simple optimization within a single op, while the PE pass can handle inter-instruction optimization.
Has this already been discussed elsewhere?
No response given
Links to previous discussion of this feature:
No response