gh-100146: Steal references from stack when building a list (#100147)

When executing the BUILD_LIST opcode, steal the references from the stack,
in a manner similar to the BUILD_TUPLE opcode.  Implement this by offloading
the logic to a new private API, _PyList_FromArraySteal(), that works similarly
to _PyTuple_FromArraySteal().

This way, instead of performing multiple stack pointer adjustments while the
list is being initialized, the stack is adjusted only once and a fast memory
copy operation is performed in one fell swoop.
This commit is contained in:
L. A. F. Pereira 2023-01-03 10:49:49 -08:00 committed by GitHub
parent b3722ca058
commit e6d4440782
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5 changed files with 31 additions and 10 deletions

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@ -1390,13 +1390,10 @@ dummy_func(
// stack effect: (__array[oparg] -- __0)
inst(BUILD_LIST) {
PyObject *list = PyList_New(oparg);
STACK_SHRINK(oparg);
PyObject *list = _PyList_FromArraySteal(stack_pointer, oparg);
if (list == NULL)
goto error;
while (--oparg >= 0) {
PyObject *item = POP();
PyList_SET_ITEM(list, oparg, item);
}
PUSH(list);
}