Python/ceval.c (part 42)

Source:

cpython 3.14 @ ab2d84fe1023/Python/ceval.c

This annotation covers specializing adaptive interpreter CALL opcodes. See python_ceval41_detail for RESUME, PUSH_EXC_INFO, RERAISE, and CHECK_EXC_MATCH.

Map

Lines	Symbol	Role
1-80	`CALL_PY_EXACT_ARGS`	Call a Python function with exact arity
81-160	`CALL_PY_WITH_DEFAULTS`	Call with default arguments
161-240	`CALL_BUILTIN_O`	Call a C function with one argument
241-340	`CALL_BUILTIN_CLASS`	Call a type (constructor)
341-500	`CALL_BOUND_METHOD_EXACT_ARGS`	Optimized bound method call

Reading

`CALL_PY_EXACT_ARGS`

// CPython: Python/ceval.c:4920 CALL_PY_EXACT_ARGS
inst(CALL_PY_EXACT_ARGS, (unused, unused, callable, self_or_null, args[oparg] -- unused, unused, result)) {
    /* Specialized for Python functions called with exactly co_argcount args, no defaults */
    PyFunctionObject *func = (PyFunctionObject *)callable;
    PyCodeObject *code = (PyCodeObject *)func->func_code;
    DEOPT_IF(tstate->interp->eval_breaker, CALL);
    DEOPT_IF(code->co_argcount != oparg + (self_or_null != NULL), CALL);
    /* Inline the frame push */
    _PyInterpreterFrame *new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + (self_or_null != NULL));
    JUMPBY(INLINE_CACHE_ENTRIES_CALL);
    DISPATCH_INLINED(new_frame);
}

CALL_PY_EXACT_ARGS is a specialization of CALL for the common case: a Python function with no defaults, no *args/**kwargs, called with the exact number of positional arguments. It bypasses argument parsing entirely and pushes the frame directly.

`CALL_BUILTIN_O`

// CPython: Python/ceval.c:5020 CALL_BUILTIN_O
inst(CALL_BUILTIN_O, (unused, unused, callable, self_or_null, args[oparg] -- unused, unused, res)) {
    /* Specialized for C functions that take exactly one argument */
    PyCFunction cfunc = PyCFunction_GET_FUNCTION(callable);
    int nargs = oparg + (self_or_null != NULL);
    DEOPT_IF(nargs != 1, CALL);
    Py_BEGIN_ALLOW_THREADS
    res = _PyCFunction_TrampolineCall(cfunc, PyCFunction_GET_SELF(callable), args[0]);
    Py_END_ALLOW_THREADS
}

CALL_BUILTIN_O handles C functions with the METH_O flag (exactly one argument, no keywords). len(x), str(x), bool(x) all qualify. The GIL is released around the call to allow other threads to run.

`CALL_BUILTIN_CLASS`

// CPython: Python/ceval.c:5060 CALL_BUILTIN_CLASS
inst(CALL_BUILTIN_CLASS, (unused, unused, callable, self_or_null, args[oparg] -- unused, unused, res)) {
    /* Specialized for type.__call__ when callable is a type */
    int total_args = oparg + (self_or_null != NULL);
    DEOPT_IF(!PyType_Check(callable), CALL);
    PyTypeObject *tp = (PyTypeObject *)callable;
    DEOPT_IF(tp->tp_new == NULL, CALL);
    res = tp->tp_new(tp, NULL, NULL);  /* simplified */
    if (tp->tp_init != NULL && tp->tp_init != object_init) {
        tp->tp_init(res, args, ...);
    }
}

CALL_BUILTIN_CLASS short-circuits type.__call__ for common cases: int(x), list(x), dict(). It directly calls tp_new then tp_init, avoiding the generic type.__call__ overhead.

`CALL_BOUND_METHOD_EXACT_ARGS`

// CPython: Python/ceval.c:5120 CALL_BOUND_METHOD_EXACT_ARGS
inst(CALL_BOUND_METHOD_EXACT_ARGS, (unused, unused, callable, self_or_null, args[oparg] -- unused, unused, res)) {
    /* Specialized for bound method calls: obj.method(args) */
    DEOPT_IF(!PyMethod_Check(callable), CALL);
    PyObject *self = ((PyMethodObject *)callable)->im_self;
    PyObject *func = ((PyMethodObject *)callable)->im_func;
    /* Replace callable with func, prepend self */
    Py_INCREF(self);
    STACK_GROW(1);
    args[-1] = self;
    callable = func;
    /* Fall through to CALL_PY_EXACT_ARGS */
    ...
}

Bound method calls extract self and func from the PyMethodObject and reorganize the stack so the frame push sees a plain function with self as the first argument. This avoids the generic attribute lookup on every call.

gopy notes

CALL_PY_EXACT_ARGS is in vm/eval_call.go; it pushes a new Frame directly without argument parsing. CALL_BUILTIN_O calls Go functions registered with METH_O. CALL_BUILTIN_CLASS calls objects.TypeCall. CALL_BOUND_METHOD_EXACT_ARGS extracts self from objects.Method and recurses.

Map​

Reading​

CALL_PY_EXACT_ARGS​

CALL_BUILTIN_O​

CALL_BUILTIN_CLASS​

CALL_BOUND_METHOD_EXACT_ARGS​

gopy notes​

Map