Python/ceval.c (part 48)

Source:

cpython 3.14 @ ab2d84fe1023/Python/ceval.c ↗

This annotation covers CALL specializations for Python functions. See python_ceval47_detail for LOAD_ATTR specializations.

Map

Lines	Symbol	Role
1-80	CALL_PY_EXACT_ARGS	Python function, nargs matches argcount exactly
81-160	CALL_PY_WITH_DEFAULTS	Python function with default arguments
161-260	CALL_BOUND_METHOD_EXACT_ARGS	Bound method, exact arg count
261-360	CALL_BUILTIN_FAST	C function with vectorcall
361-500	CALL_BUILTIN_CLASS	type(x), int(x), etc.

Reading

CALL_PY_EXACT_ARGS

// CPython: Python/ceval.c:3580 CALL_PY_EXACT_ARGS
inst(CALL_PY_EXACT_ARGS, (unused/2, callable, self_or_null, args[oparg] -- unused)) {
    DEOPT_IF(tstate->interp->eval_breaker);
    PyFunctionObject *func = (PyFunctionObject *)callable;
    DEOPT_IF(!PyFunction_ExactCheck(callable));
    PyCodeObject *code = (PyCodeObject *)func->func_code;
    DEOPT_IF(code->co_argcount != oparg + (self_or_null != NULL));
    DEOPT_IF(code->co_flags & (CO_VARARGS | CO_VARKEYWORDS));
    /* Push a new frame directly without going through _PyFunction_Vectorcall */
    _PyInterpreterFrame *new_frame = _PyFrame_PushUnchecked(tstate, func, oparg);
    ...
    DISPATCH_INLINED(new_frame);
}

The most common call pattern: f(a, b, c) where f is a def with exactly 3 positional parameters. The specialization skips argument packing entirely and creates the frame inline.

CALL_PY_WITH_DEFAULTS

// CPython: Python/ceval.c:3640 CALL_PY_WITH_DEFAULTS
inst(CALL_PY_WITH_DEFAULTS, (unused/2, callable, self_or_null, args[oparg] -- unused)) {
    DEOPT_IF(!PyFunction_ExactCheck(callable));
    PyFunctionObject *func = (PyFunctionObject *)callable;
    PyCodeObject *code = (PyCodeObject *)func->func_code;
    int nargs = oparg + (self_or_null != NULL);
    DEOPT_IF(nargs > code->co_argcount);
    int defcount = func->func_defaults ? (int)PyTuple_GET_SIZE(func->func_defaults) : 0;
    DEOPT_IF(nargs + defcount < code->co_argcount);
    /* Fill remaining args from defaults */
    int firstdef = code->co_argcount - defcount;
    for (int i = nargs; i < code->co_argcount; i++) {
        args[i] = Py_NewRef(PyTuple_GET_ITEM(func->func_defaults, i - firstdef));
    }
    ...
}

When fewer arguments are provided than the function expects, the specialization fills in defaults from func->func_defaults directly. No keyword argument dict is needed.

CALL_BOUND_METHOD_EXACT_ARGS

// CPython: Python/ceval.c:3700 CALL_BOUND_METHOD_EXACT_ARGS
inst(CALL_BOUND_METHOD_EXACT_ARGS, (unused/2, callable, null, args[oparg] -- unused)) {
    DEOPT_IF(null != NULL);
    DEOPT_IF(Py_TYPE(callable) != &PyMethod_Type);
    PyObject *self = ((PyMethodObject *)callable)->im_self;
    PyObject *func = ((PyMethodObject *)callable)->im_func;
    /* Replace callable with func and push self as first arg */
    args[-1] = self;
    callable = func;
    /* Now fall through to CALL_PY_EXACT_ARGS logic */
    ...
}

obj.method(a, b) is a bound method call. The specialization extracts self and func from the method object and prepends self to the argument list, then inlines the function call.

gopy notes

CALL_PY_EXACT_ARGS is in vm/eval_call.go and creates a new vm.Frame directly from the objects.Function's code object. CALL_PY_WITH_DEFAULTS fills defaults from function.Defaults. CALL_BOUND_METHOD_EXACT_ARGS unwraps objects.BoundMethod and prepends the receiver.