ceval.c

/* Execute compiled code */

#include "ceval.h"
#include "pycore_long.h"

int
Py_GetRecursionLimit(void)
{
    PyInterpreterState *interp = _PyInterpreterState_GET();
    return interp->ceval.recursion_limit;
}

void
Py_SetRecursionLimit(int new_limit)
{
    PyInterpreterState *interp = _PyInterpreterState_GET();
    _PyEval_StopTheWorld(interp);
    interp->ceval.recursion_limit = new_limit;
    _Py_FOR_EACH_TSTATE_BEGIN(interp, p) {
        int depth = p->py_recursion_limit - p->py_recursion_remaining;
        p->py_recursion_limit = new_limit;
        p->py_recursion_remaining = new_limit - depth;
    }
    _Py_FOR_EACH_TSTATE_END(interp);
    _PyEval_StartTheWorld(interp);
}

int
_Py_ReachedRecursionLimitWithMargin(PyThreadState *tstate, int margin_count)
{
    uintptr_t here_addr = _Py_get_machine_stack_pointer();
    _PyThreadStateImpl *_tstate = (_PyThreadStateImpl *)tstate;
#if _Py_STACK_GROWS_DOWN
    if (here_addr > _tstate->c_stack_soft_limit + margin_count * _PyOS_STACK_MARGIN_BYTES) {
#else
    if (here_addr <= _tstate->c_stack_soft_limit - margin_count * _PyOS_STACK_MARGIN_BYTES) {
#endif
        return 0;
    }
    if (_tstate->c_stack_hard_limit == 0) {
        _Py_InitializeRecursionLimits(tstate);
    }
#if _Py_STACK_GROWS_DOWN
    return here_addr <= _tstate->c_stack_soft_limit + margin_count * _PyOS_STACK_MARGIN_BYTES &&
        here_addr >= _tstate->c_stack_soft_limit - 2 * _PyOS_STACK_MARGIN_BYTES;
#else
    return here_addr > _tstate->c_stack_soft_limit - margin_count * _PyOS_STACK_MARGIN_BYTES &&
        here_addr <= _tstate->c_stack_soft_limit + 2 * _PyOS_STACK_MARGIN_BYTES;
#endif
}

void
_Py_EnterRecursiveCallUnchecked(PyThreadState *tstate)
{
    uintptr_t here_addr = _Py_get_machine_stack_pointer();
    _PyThreadStateImpl *_tstate = (_PyThreadStateImpl *)tstate;
#if _Py_STACK_GROWS_DOWN
    if (here_addr < _tstate->c_stack_hard_limit) {
#else
    if (here_addr > _tstate->c_stack_hard_limit) {
#endif
        Py_FatalError("Unchecked stack overflow.");
    }
}

#if defined(__s390x__)
#  define Py_C_STACK_SIZE 320000
#elif defined(_WIN32)
   // Don't define Py_C_STACK_SIZE, ask the O/S
#elif defined(__ANDROID__)
#  define Py_C_STACK_SIZE 1200000
#elif defined(__sparc__)
#  define Py_C_STACK_SIZE 1600000
#elif defined(__hppa__) || defined(__powerpc64__)
#  define Py_C_STACK_SIZE 2000000
#else
#  define Py_C_STACK_SIZE 4000000
#endif

#if defined(__EMSCRIPTEN__)

// Temporary workaround to make `pthread_getattr_np` work on Emscripten.
// Emscripten 4.0.6 will contain a fix:
// https://github.com/emscripten-core/emscripten/pull/23887

#include "emscripten/stack.h"

#define pthread_attr_t workaround_pthread_attr_t
#define pthread_getattr_np workaround_pthread_getattr_np
#define pthread_attr_getguardsize workaround_pthread_attr_getguardsize
#define pthread_attr_getstack workaround_pthread_attr_getstack
#define pthread_attr_destroy workaround_pthread_attr_destroy

typedef struct {
    void *_a_stackaddr;
    size_t _a_stacksize, _a_guardsize;
} pthread_attr_t;

extern __attribute__((__visibility__("hidden"))) unsigned __default_guardsize;

// Modified version of pthread_getattr_np from the upstream PR.

int pthread_getattr_np(pthread_t thread, pthread_attr_t *attr) {
  attr->_a_stackaddr = (void*)emscripten_stack_get_base();
  attr->_a_stacksize = emscripten_stack_get_base() - emscripten_stack_get_end();
  attr->_a_guardsize = __default_guardsize;
  return 0;
}

// These three functions copied without any changes from Emscripten libc.

int pthread_attr_getguardsize(const pthread_attr_t *restrict a, size_t *restrict size)
{
	*size = a->_a_guardsize;
	return 0;
}

int pthread_attr_getstack(const pthread_attr_t *restrict a, void **restrict addr, size_t *restrict size)
{
/// XXX musl is not standard-conforming? It should not report EINVAL if _a_stackaddr is zero, and it should
///     report EINVAL if a is null: http://pubs.opengroup.org/onlinepubs/009695399/functions/pthread_attr_getstack.html
	if (!a) return EINVAL;
//	if (!a->_a_stackaddr)
//		return EINVAL;

	*size = a->_a_stacksize;
	*addr = (void *)(a->_a_stackaddr - *size);
	return 0;
}

int pthread_attr_destroy(pthread_attr_t *a)
{
	return 0;
}

#endif

static void
hardware_stack_limits(uintptr_t *base, uintptr_t *top, uintptr_t sp)
{
#ifdef WIN32
    ULONG_PTR low, high;
    GetCurrentThreadStackLimits(&low, &high);
    *top = (uintptr_t)high;
    ULONG guarantee = 0;
    SetThreadStackGuarantee(&guarantee);
    *base = (uintptr_t)low + guarantee;
#elif defined(__APPLE__)
    pthread_t this_thread = pthread_self();
    void *stack_addr = pthread_get_stackaddr_np(this_thread); // top of the stack
    size_t stack_size = pthread_get_stacksize_np(this_thread);
    *top = (uintptr_t)stack_addr;
    *base = ((uintptr_t)stack_addr) - stack_size;
#else
    /// XXX musl supports HAVE_PTHRED_GETATTR_NP, but the resulting stack size
    /// (on alpine at least) is much smaller than expected and imposes undue limits
    /// compared to the old stack size estimation.  (We assume musl is not glibc.)
#  if defined(HAVE_PTHREAD_GETATTR_NP) && !defined(_AIX) && \
        !defined(__NetBSD__) && (defined(__GLIBC__) || !defined(__linux__))
    size_t stack_size, guard_size;
    void *stack_addr;
    pthread_attr_t attr;
    int err = pthread_getattr_np(pthread_self(), &attr);
    if (err == 0) {
        err = pthread_attr_getguardsize(&attr, &guard_size);
        err |= pthread_attr_getstack(&attr, &stack_addr, &stack_size);
        err |= pthread_attr_destroy(&attr);
    }
    if (err == 0) {
        *base = ((uintptr_t)stack_addr) + guard_size;
        *top = (uintptr_t)stack_addr + stack_size;
        return;
    }
#  endif
    // Add some space for caller function then round to minimum page size
    // This is a guess at the top of the stack, but should be a reasonably
    // good guess if called from _PyThreadState_Attach when creating a thread.
    // If the thread is attached deep in a call stack, then the guess will be poor.
#if _Py_STACK_GROWS_DOWN
    uintptr_t top_addr = _Py_SIZE_ROUND_UP(sp + 8*sizeof(void*), SYSTEM_PAGE_SIZE);
    *top = top_addr;
    *base = top_addr - Py_C_STACK_SIZE;
#  else
    uintptr_t base_addr = _Py_SIZE_ROUND_DOWN(sp - 8*sizeof(void*), SYSTEM_PAGE_SIZE);
    *base = base_addr;
    *top = base_addr + Py_C_STACK_SIZE;
#endif
#endif
}

static void
tstate_set_stack(PyThreadState *tstate,
                 uintptr_t base, uintptr_t top)
{
    assert(base < top);
    assert((top - base) >= _PyOS_MIN_STACK_SIZE);

#ifdef _Py_THREAD_SANITIZER
    // Thread sanitizer crashes if we use more than half the stack.
    uintptr_t stacksize = top - base;
#  if _Py_STACK_GROWS_DOWN
    base += stacksize/2;
#  else
    top -= stacksize/2;
#  endif
#endif
    _PyThreadStateImpl *_tstate = (_PyThreadStateImpl *)tstate;
#if _Py_STACK_GROWS_DOWN
    _tstate->c_stack_top = top;
    _tstate->c_stack_hard_limit = base + _PyOS_STACK_MARGIN_BYTES;
    _tstate->c_stack_soft_limit = base + _PyOS_STACK_MARGIN_BYTES * 2;
#  ifndef NDEBUG
    // Sanity checks
    _PyThreadStateImpl *ts = (_PyThreadStateImpl *)tstate;
    assert(ts->c_stack_hard_limit <= ts->c_stack_soft_limit);
    assert(ts->c_stack_soft_limit < ts->c_stack_top);
#  endif
#else
    _tstate->c_stack_top = base;
    _tstate->c_stack_hard_limit = top - _PyOS_STACK_MARGIN_BYTES;
    _tstate->c_stack_soft_limit = top - _PyOS_STACK_MARGIN_BYTES * 2;
#  ifndef NDEBUG
    // Sanity checks
    _PyThreadStateImpl *ts = (_PyThreadStateImpl *)tstate;
    assert(ts->c_stack_hard_limit >= ts->c_stack_soft_limit);
    assert(ts->c_stack_soft_limit > ts->c_stack_top);
#  endif
#endif
}


void
_Py_InitializeRecursionLimits(PyThreadState *tstate)
{
    uintptr_t base, top;
    uintptr_t here_addr = _Py_get_machine_stack_pointer();
    hardware_stack_limits(&base, &top, here_addr);
    assert(top != 0);

    tstate_set_stack(tstate, base, top);
    _PyThreadStateImpl *ts = (_PyThreadStateImpl *)tstate;
    ts->c_stack_init_base = base;
    ts->c_stack_init_top = top;
}


int
PyUnstable_ThreadState_SetStackProtection(PyThreadState *tstate,
                                void *stack_start_addr, size_t stack_size)
{
    if (stack_size < _PyOS_MIN_STACK_SIZE) {
        PyErr_Format(PyExc_ValueError,
                     "stack_size must be at least %zu bytes",
                     _PyOS_MIN_STACK_SIZE);
        return -1;
    }

    uintptr_t base = (uintptr_t)stack_start_addr;
    uintptr_t top = base + stack_size;
    tstate_set_stack(tstate, base, top);
    return 0;
}


void
PyUnstable_ThreadState_ResetStackProtection(PyThreadState *tstate)
{
    _PyThreadStateImpl *ts = (_PyThreadStateImpl *)tstate;
    if (ts->c_stack_init_top != 0) {
        tstate_set_stack(tstate,
                         ts->c_stack_init_base,
                         ts->c_stack_init_top);
        return;
    }

    _Py_InitializeRecursionLimits(tstate);
}


/* The function _Py_EnterRecursiveCallTstate() only calls _Py_CheckRecursiveCall()
   if the stack pointer is between the stack base and c_stack_hard_limit. */
int
_Py_CheckRecursiveCall(PyThreadState *tstate, const char *where)
{
    _PyThreadStateImpl *_tstate = (_PyThreadStateImpl *)tstate;
    uintptr_t here_addr = _Py_get_machine_stack_pointer();
    assert(_tstate->c_stack_soft_limit != 0);
    assert(_tstate->c_stack_hard_limit != 0);
#if _Py_STACK_GROWS_DOWN
    assert(here_addr >= _tstate->c_stack_hard_limit - _PyOS_STACK_MARGIN_BYTES);
    if (here_addr < _tstate->c_stack_hard_limit) {
        /* Overflowing while handling an overflow. Give up. */
        int kbytes_used = (int)(_tstate->c_stack_top - here_addr)/1024;
#else
    assert(here_addr <= _tstate->c_stack_hard_limit + _PyOS_STACK_MARGIN_BYTES);
    if (here_addr > _tstate->c_stack_hard_limit) {
        /* Overflowing while handling an overflow. Give up. */
        int kbytes_used = (int)(here_addr - _tstate->c_stack_top)/1024;
#endif
        char buffer[80];
        snprintf(buffer, 80, "Unrecoverable stack overflow (used %d kB)%s", kbytes_used, where);
        Py_FatalError(buffer);
    }
    if (tstate->recursion_headroom) {
        return 0;
    }
    else {
#if _Py_STACK_GROWS_DOWN
        int kbytes_used = (int)(_tstate->c_stack_top - here_addr)/1024;
#else
        int kbytes_used = (int)(here_addr - _tstate->c_stack_top)/1024;
#endif
        tstate->recursion_headroom++;
        _PyErr_Format(tstate, PyExc_RecursionError,
                    "Stack overflow (used %d kB)%s",
                    kbytes_used,
                    where);
        tstate->recursion_headroom--;
        return -1;
    }
}


const binaryfunc _PyEval_BinaryOps[] = {
    [NB_ADD] = PyNumber_Add,
    [NB_AND] = PyNumber_And,
    [NB_FLOOR_DIVIDE] = PyNumber_FloorDivide,
    [NB_LSHIFT] = PyNumber_Lshift,
    [NB_MATRIX_MULTIPLY] = PyNumber_MatrixMultiply,
    [NB_MULTIPLY] = PyNumber_Multiply,
    [NB_REMAINDER] = PyNumber_Remainder,
    [NB_OR] = PyNumber_Or,
    [NB_POWER] = _PyNumber_PowerNoMod,
    [NB_RSHIFT] = PyNumber_Rshift,
    [NB_SUBTRACT] = PyNumber_Subtract,
    [NB_TRUE_DIVIDE] = PyNumber_TrueDivide,
    [NB_XOR] = PyNumber_Xor,
    [NB_INPLACE_ADD] = PyNumber_InPlaceAdd,
    [NB_INPLACE_AND] = PyNumber_InPlaceAnd,
    [NB_INPLACE_FLOOR_DIVIDE] = PyNumber_InPlaceFloorDivide,
    [NB_INPLACE_LSHIFT] = PyNumber_InPlaceLshift,
    [NB_INPLACE_MATRIX_MULTIPLY] = PyNumber_InPlaceMatrixMultiply,
    [NB_INPLACE_MULTIPLY] = PyNumber_InPlaceMultiply,
    [NB_INPLACE_REMAINDER] = PyNumber_InPlaceRemainder,
    [NB_INPLACE_OR] = PyNumber_InPlaceOr,
    [NB_INPLACE_POWER] = _PyNumber_InPlacePowerNoMod,
    [NB_INPLACE_RSHIFT] = PyNumber_InPlaceRshift,
    [NB_INPLACE_SUBTRACT] = PyNumber_InPlaceSubtract,
    [NB_INPLACE_TRUE_DIVIDE] = PyNumber_InPlaceTrueDivide,
    [NB_INPLACE_XOR] = PyNumber_InPlaceXor,
    [NB_SUBSCR] = PyObject_GetItem,
};

const conversion_func _PyEval_ConversionFuncs[4] = {
    [FVC_STR] = PyObject_Str,
    [FVC_REPR] = PyObject_Repr,
    [FVC_ASCII] = PyObject_ASCII
};

const _Py_SpecialMethod _Py_SpecialMethods[] = {
    [SPECIAL___ENTER__] = {
        .name = &_Py_ID(__enter__),
        .error = (
            "'%T' object does not support the context manager protocol "
            "(missed __enter__ method)"
        ),
        .error_suggestion = (
            "'%T' object does not support the context manager protocol "
            "(missed __enter__ method) but it supports the asynchronous "
            "context manager protocol. Did you mean to use 'async with'?"
        )
    },
    [SPECIAL___EXIT__] = {
        .name = &_Py_ID(__exit__),
        .error = (
            "'%T' object does not support the context manager protocol "
            "(missed __exit__ method)"
        ),
        .error_suggestion = (
            "'%T' object does not support the context manager protocol "
            "(missed __exit__ method) but it supports the asynchronous "
            "context manager protocol. Did you mean to use 'async with'?"
        )
    },
    [SPECIAL___AENTER__] = {
        .name = &_Py_ID(__aenter__),
        .error = (
            "'%T' object does not support the asynchronous "
            "context manager protocol (missed __aenter__ method)"
        ),
        .error_suggestion = (
            "'%T' object does not support the asynchronous context manager "
            "protocol (missed __aenter__ method) but it supports the context "
            "manager protocol. Did you mean to use 'with'?"
        )
    },
    [SPECIAL___AEXIT__] = {
        .name = &_Py_ID(__aexit__),
        .error = (
            "'%T' object does not support the asynchronous "
            "context manager protocol (missed __aexit__ method)"
        ),
        .error_suggestion = (
            "'%T' object does not support the asynchronous context manager "
            "protocol (missed __aexit__ method) but it supports the context "
            "manager protocol. Did you mean to use 'with'?"
        )
    }
};

const size_t _Py_FunctionAttributeOffsets[] = {
    [MAKE_FUNCTION_CLOSURE] = offsetof(PyFunctionObject, func_closure),
    [MAKE_FUNCTION_ANNOTATIONS] = offsetof(PyFunctionObject, func_annotations),
    [MAKE_FUNCTION_KWDEFAULTS] = offsetof(PyFunctionObject, func_kwdefaults),
    [MAKE_FUNCTION_DEFAULTS] = offsetof(PyFunctionObject, func_defaults),
    [MAKE_FUNCTION_ANNOTATE] = offsetof(PyFunctionObject, func_annotate),
};

// PEP 634: Structural Pattern Matching


// Return a tuple of values corresponding to keys, with error checks for
// duplicate/missing keys.
PyObject *
_PyEval_MatchKeys(PyThreadState *tstate, PyObject *map, PyObject *keys)
{
    assert(PyTuple_CheckExact(keys));
    Py_ssize_t nkeys = PyTuple_GET_SIZE(keys);
    if (!nkeys) {
        // No keys means no items.
        return PyTuple_New(0);
    }
    PyObject *seen = NULL;
    PyObject *dummy = NULL;
    PyObject *values = NULL;
    // We use the two argument form of map.get(key, default) for two reasons:
    // - Atomically check for a key and get its value without error handling.
    // - Don't cause key creation or resizing in dict subclasses like
    //   collections.defaultdict that define __missing__ (or similar).
    _PyCStackRef self, method;
    _PyThreadState_PushCStackRef(tstate, &self);
    _PyThreadState_PushCStackRef(tstate, &method);
    self.ref = PyStackRef_FromPyObjectBorrow(map);
    int res = _PyObject_GetMethodStackRef(tstate, &self.ref, &_Py_ID(get), &method.ref);
    if (res < 0) {
        goto fail;
    }
    PyObject *get = PyStackRef_AsPyObjectBorrow(method.ref);
    seen = PySet_New(NULL);
    if (seen == NULL) {
        goto fail;
    }
    // dummy = object()
    dummy = _PyObject_CallNoArgs((PyObject *)&PyBaseObject_Type);
    if (dummy == NULL) {
        goto fail;
    }
    values = PyTuple_New(nkeys);
    if (values == NULL) {
        goto fail;
    }
    for (Py_ssize_t i = 0; i < nkeys; i++) {
        PyObject *key = PyTuple_GET_ITEM(keys, i);
        if (PySet_Contains(seen, key) || PySet_Add(seen, key)) {
            if (!_PyErr_Occurred(tstate)) {
                // Seen it before!
                _PyErr_Format(tstate, PyExc_ValueError,
                              "mapping pattern checks duplicate key (%R)", key);
            }
            goto fail;
        }
        PyObject *self_obj = PyStackRef_AsPyObjectBorrow(self.ref);
        PyObject *args[] = { self_obj, key, dummy };
        PyObject *value = NULL;
        if (!PyStackRef_IsNull(self.ref)) {
            value = PyObject_Vectorcall(get, args, 3, NULL);
        }
        else {
            value = PyObject_Vectorcall(get, &args[1], 2, NULL);
        }
        if (value == NULL) {
            goto fail;
        }
        if (value == dummy) {
            // key not in map!
            Py_DECREF(value);
            Py_DECREF(values);
            // Return None:
            values = Py_NewRef(Py_None);
            goto done;
        }
        PyTuple_SET_ITEM(values, i, value);
    }
    // Success:
done:
    _PyThreadState_PopCStackRef(tstate, &method);
    _PyThreadState_PopCStackRef(tstate, &self);
    Py_DECREF(seen);
    Py_DECREF(dummy);
    return values;
fail:
    _PyThreadState_PopCStackRef(tstate, &method);
    _PyThreadState_PopCStackRef(tstate, &self);
    Py_XDECREF(seen);
    Py_XDECREF(dummy);
    Py_XDECREF(values);
    return NULL;
}

// Extract a named attribute from the subject, with additional bookkeeping to
// raise TypeErrors for repeated lookups. On failure, return NULL (with no
// error set). Use _PyErr_Occurred(tstate) to disambiguate.
static PyObject *
match_class_attr(PyThreadState *tstate, PyObject *subject, PyObject *type,
                 PyObject *name, PyObject *seen)
{
    assert(PyUnicode_CheckExact(name));
    // Only check for duplicates if seen is not NULL.
    if (seen != NULL) {
        assert(PySet_CheckExact(seen));
        if (PySet_Contains(seen, name) || PySet_Add(seen, name)) {
            if (!_PyErr_Occurred(tstate)) {
                // Seen it before!
                _PyErr_Format(tstate, PyExc_TypeError,
                            "%s() got multiple sub-patterns for attribute %R",
                            ((PyTypeObject*)type)->tp_name, name);
            }
            return NULL;
        }
    }
    PyObject *attr;
    (void)PyObject_GetOptionalAttr(subject, name, &attr);
    return attr;
}

// On success (match), return a tuple of extracted attributes. On failure (no
// match), return NULL. Use _PyErr_Occurred(tstate) to disambiguate.
PyObject*
_PyEval_MatchClass(PyThreadState *tstate, PyObject *subject, PyObject *type,
                   Py_ssize_t nargs, PyObject *kwargs)
{
    if (!PyType_Check(type)) {
        const char *e = "class pattern must refer to a class";
        _PyErr_Format(tstate, PyExc_TypeError, e);
        return NULL;
    }
    assert(PyTuple_CheckExact(kwargs));
    // First, an isinstance check:
    if (PyObject_IsInstance(subject, type) <= 0) {
        return NULL;
    }
    // Short circuit if there aren't any arguments:
    Py_ssize_t nkwargs = PyTuple_GET_SIZE(kwargs);
    Py_ssize_t nattrs = nargs + nkwargs;
    if (!nattrs) {
        return PyTuple_New(0);
    }
    // So far so good:
    PyObject *seen = NULL;
    // Only check for duplicates if there is at least one positional attribute
    // and two or more attributes in total. Duplicate keyword attributes are
    // detected during the compile stage and raise a SyntaxError.
    if (nargs > 0 && nattrs > 1) {
        seen = PySet_New(NULL);
        if (seen == NULL) {
            return NULL;
        }
    }
    PyObject *attrs = PyTuple_New(nattrs);
    if (attrs == NULL) {
        Py_XDECREF(seen);
        return NULL;
    }
    // NOTE: From this point on, goto fail on failure:
    PyObject *match_args = NULL;
    // First, the positional subpatterns:
    if (nargs) {
        int match_self = 0;
        if (PyObject_GetOptionalAttr(type, &_Py_ID(__match_args__), &match_args) < 0) {
            goto fail;
        }
        if (match_args) {
            if (!PyTuple_CheckExact(match_args)) {
                const char *e = "%s.__match_args__ must be a tuple (got %s)";
                _PyErr_Format(tstate, PyExc_TypeError, e,
                              ((PyTypeObject *)type)->tp_name,
                              Py_TYPE(match_args)->tp_name);
                goto fail;
            }
        }
        else {
            // _Py_TPFLAGS_MATCH_SELF is only acknowledged if the type does not
            // define __match_args__. This is natural behavior for subclasses:
            // it's as if __match_args__ is some "magic" value that is lost as
            // soon as they redefine it.
            match_args = PyTuple_New(0);
            match_self = PyType_HasFeature((PyTypeObject*)type,
                                            _Py_TPFLAGS_MATCH_SELF);
        }
        assert(PyTuple_CheckExact(match_args));
        Py_ssize_t allowed = match_self ? 1 : PyTuple_GET_SIZE(match_args);
        if (allowed < nargs) {
            const char *plural = (allowed == 1) ? "" : "s";
            _PyErr_Format(tstate, PyExc_TypeError,
                          "%s() accepts %zd positional sub-pattern%s (%zd given)",
                          ((PyTypeObject*)type)->tp_name,
                          allowed, plural, nargs);
            goto fail;
        }
        if (match_self) {
            // Easy. Copy the subject itself, and move on to kwargs.
            assert(PyTuple_GET_ITEM(attrs, 0) == NULL);
            PyTuple_SET_ITEM(attrs, 0, Py_NewRef(subject));
        }
        else {
            for (Py_ssize_t i = 0; i < nargs; i++) {
                PyObject *name = PyTuple_GET_ITEM(match_args, i);
                if (!PyUnicode_CheckExact(name)) {
                    _PyErr_Format(tstate, PyExc_TypeError,
                                  "__match_args__ elements must be strings "
                                  "(got %s)", Py_TYPE(name)->tp_name);
                    goto fail;
                }
                PyObject *attr = match_class_attr(tstate, subject, type, name,
                                                  seen);
                if (attr == NULL) {
                    goto fail;
                }
                assert(PyTuple_GET_ITEM(attrs, i) == NULL);
                PyTuple_SET_ITEM(attrs, i, attr);
            }
        }
        Py_CLEAR(match_args);
    }
    // Finally, the keyword subpatterns:
    for (Py_ssize_t i = 0; i < nkwargs; i++) {
        PyObject *name = PyTuple_GET_ITEM(kwargs, i);
        PyObject *attr = match_class_attr(tstate, subject, type, name, seen);
        if (attr == NULL) {
            goto fail;
        }
        assert(PyTuple_GET_ITEM(attrs, nargs + i) == NULL);
        PyTuple_SET_ITEM(attrs, nargs + i, attr);
    }
    Py_XDECREF(seen);
    return attrs;
fail:
    // We really don't care whether an error was raised or not... that's our
    // caller's problem. All we know is that the match failed.
    Py_XDECREF(match_args);
    Py_XDECREF(seen);
    Py_DECREF(attrs);
    return NULL;
}


static int do_raise(PyThreadState *tstate, PyObject *exc, PyObject *cause);

PyObject *
PyEval_EvalCode(PyObject *co, PyObject *globals, PyObject *locals)
{
    PyThreadState *tstate = _PyThreadState_GET();
    if (locals == NULL) {
        locals = globals;
    }
    PyObject *builtins = _PyDict_LoadBuiltinsFromGlobals(globals);
    if (builtins == NULL) {
        return NULL;
    }
    PyFrameConstructor desc = {
        .fc_globals = globals,
        .fc_builtins = builtins,
        .fc_name = ((PyCodeObject *)co)->co_name,
        .fc_qualname = ((PyCodeObject *)co)->co_name,
        .fc_code = co,
        .fc_defaults = NULL,
        .fc_kwdefaults = NULL,
        .fc_closure = NULL
    };
    PyFunctionObject *func = _PyFunction_FromConstructor(&desc);
    _Py_DECREF_BUILTINS(builtins);
    if (func == NULL) {
        return NULL;
    }
    EVAL_CALL_STAT_INC(EVAL_CALL_LEGACY);
    PyObject *res = _PyEval_Vector(tstate, func, locals, NULL, 0, NULL);
    Py_DECREF(func);
    return res;
}


/* Interpreter main loop */

PyObject *
PyEval_EvalFrame(PyFrameObject *f)
{
    /* Function kept for backward compatibility */
    PyThreadState *tstate = _PyThreadState_GET();
    return _PyEval_EvalFrame(tstate, f->f_frame, 0);
}

PyObject *
PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
{
    PyThreadState *tstate = _PyThreadState_GET();
    return _PyEval_EvalFrame(tstate, f->f_frame, throwflag);
}

#include "ceval_macros.h"


/* Helper functions to keep the size of the largest uops down */

PyObject *
_Py_VectorCall_StackRefSteal(
    _PyStackRef callable,
    _PyStackRef *arguments,
    int total_args,
    _PyStackRef kwnames)
{
    PyObject *res;
    STACKREFS_TO_PYOBJECTS(arguments, total_args, args_o);
    if (CONVERSION_FAILED(args_o)) {
        res = NULL;
        goto cleanup;
    }
    PyObject *callable_o = PyStackRef_AsPyObjectBorrow(callable);
    PyObject *kwnames_o = PyStackRef_AsPyObjectBorrow(kwnames);
    int positional_args = total_args;
    if (kwnames_o != NULL) {
        positional_args -= (int)PyTuple_GET_SIZE(kwnames_o);
    }
    res = PyObject_Vectorcall(
        callable_o, args_o,
        positional_args | PY_VECTORCALL_ARGUMENTS_OFFSET,
        kwnames_o);
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
cleanup:
    PyStackRef_XCLOSE(kwnames);
    // arguments is a pointer into the GC visible stack,
    // so we must NULL out values as we clear them.
    for (int i = total_args-1; i >= 0; i--) {
        _PyStackRef tmp = arguments[i];
        arguments[i] = PyStackRef_NULL;
        PyStackRef_CLOSE(tmp);
    }
    PyStackRef_CLOSE(callable);
    return res;
}

PyObject*
_Py_VectorCallInstrumentation_StackRefSteal(
    _PyStackRef callable,
    _PyStackRef* arguments,
    int total_args,
    _PyStackRef kwnames,
    bool call_instrumentation,
    _PyInterpreterFrame* frame,
    _Py_CODEUNIT* this_instr,
    PyThreadState* tstate)
{
    PyObject* res;
    STACKREFS_TO_PYOBJECTS(arguments, total_args, args_o);
    if (CONVERSION_FAILED(args_o)) {
        res = NULL;
        goto cleanup;
    }
    PyObject* callable_o = PyStackRef_AsPyObjectBorrow(callable);
    PyObject* kwnames_o = PyStackRef_AsPyObjectBorrow(kwnames);
    int positional_args = total_args;
    if (kwnames_o != NULL) {
        positional_args -= (int)PyTuple_GET_SIZE(kwnames_o);
    }
    res = PyObject_Vectorcall(
        callable_o, args_o,
        positional_args | PY_VECTORCALL_ARGUMENTS_OFFSET,
        kwnames_o);
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    if (call_instrumentation) {
        PyObject* arg = total_args == 0 ?
            &_PyInstrumentation_MISSING : PyStackRef_AsPyObjectBorrow(arguments[0]);
        if (res == NULL) {
            _Py_call_instrumentation_exc2(
                tstate, PY_MONITORING_EVENT_C_RAISE,
                frame, this_instr, callable_o, arg);
        }
        else {
            int err = _Py_call_instrumentation_2args(
                tstate, PY_MONITORING_EVENT_C_RETURN,
                frame, this_instr, callable_o, arg);
            if (err < 0) {
                Py_CLEAR(res);
            }
        }
    }
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
cleanup:
    PyStackRef_XCLOSE(kwnames);
    // arguments is a pointer into the GC visible stack,
    // so we must NULL out values as we clear them.
    for (int i = total_args - 1; i >= 0; i--) {
        _PyStackRef tmp = arguments[i];
        arguments[i] = PyStackRef_NULL;
        PyStackRef_CLOSE(tmp);
    }
    PyStackRef_CLOSE(callable);
    return res;
}

PyObject *
_Py_BuiltinCallFast_StackRef(
    _PyStackRef callable,
    _PyStackRef *arguments,
    int total_args)
{
    PyObject *res;
    STACKREFS_TO_PYOBJECTS(arguments, total_args, args_o);
    if (CONVERSION_FAILED(args_o)) {
        return NULL;
    }
    PyObject *callable_o = PyStackRef_AsPyObjectBorrow(callable);
    PyCFunction cfunc = PyCFunction_GET_FUNCTION(callable_o);
    res = _PyCFunctionFast_CAST(cfunc)(
        PyCFunction_GET_SELF(callable_o),
        args_o,
        total_args
    );
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
    return res;
}

PyObject *
_Py_BuiltinCallFastWithKeywords_StackRef(
    _PyStackRef callable,
    _PyStackRef *arguments,
    int total_args)
{
    PyObject *res;
    STACKREFS_TO_PYOBJECTS(arguments, total_args, args_o);
    if (CONVERSION_FAILED(args_o)) {
        return NULL;
    }
    PyObject *callable_o = PyStackRef_AsPyObjectBorrow(callable);
    PyCFunctionFastWithKeywords cfunc =
        _PyCFunctionFastWithKeywords_CAST(PyCFunction_GET_FUNCTION(callable_o));
    res = cfunc(PyCFunction_GET_SELF(callable_o), args_o, total_args, NULL);
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
    return res;
}

PyObject *
_PyCallMethodDescriptorFast_StackRef(
    _PyStackRef callable,
    PyCFunctionFast cfunc,
    PyObject *self,
    _PyStackRef *arguments,
    int total_args)
{
    PyObject *res;
    STACKREFS_TO_PYOBJECTS(arguments, total_args, args_o);
    if (CONVERSION_FAILED(args_o)) {
        return NULL;
    }
    assert(self == PyStackRef_AsPyObjectBorrow(arguments[0]));

    res = cfunc(self, (args_o + 1), total_args - 1);
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
    return res;
}

PyObject *
_PyCallMethodDescriptorFastWithKeywords_StackRef(
    _PyStackRef callable,
    PyCFunctionFastWithKeywords cfunc,
    PyObject *self,
    _PyStackRef *arguments,
    int total_args)
{
    PyObject *res;
    STACKREFS_TO_PYOBJECTS(arguments, total_args, args_o);
    if (CONVERSION_FAILED(args_o)) {
        return NULL;
    }
    assert(self == PyStackRef_AsPyObjectBorrow(arguments[0]));

    res = cfunc(self, (args_o + 1), total_args-1, NULL);
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
    return res;
}

PyObject *
_Py_CallBuiltinClass_StackRef(
    _PyStackRef callable,
    _PyStackRef *arguments,
    int total_args)
{
    PyObject *res;
    STACKREFS_TO_PYOBJECTS(arguments, total_args, args_o);
    if (CONVERSION_FAILED(args_o)) {
        return NULL;
    }
    PyTypeObject *tp = (PyTypeObject *)PyStackRef_AsPyObjectBorrow(callable);
    res = tp->tp_vectorcall((PyObject *)tp, args_o, total_args | PY_VECTORCALL_ARGUMENTS_OFFSET, NULL);
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
    return res;
}

PyObject *
_Py_BuildString_StackRefSteal(
    _PyStackRef *arguments,
    int total_args)
{
    PyObject *res;
    STACKREFS_TO_PYOBJECTS(arguments, total_args, args_o);
    if (CONVERSION_FAILED(args_o)) {
        res = NULL;
        goto cleanup;
    }
    res = _PyUnicode_JoinArray(&_Py_STR(empty), args_o, total_args);
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
cleanup:
    // arguments is a pointer into the GC visible stack,
    // so we must NULL out values as we clear them.
    for (int i = total_args-1; i >= 0; i--) {
        _PyStackRef tmp = arguments[i];
        arguments[i] = PyStackRef_NULL;
        PyStackRef_CLOSE(tmp);
    }
    return res;
}

PyObject *
_Py_BuildMap_StackRefSteal(
    _PyStackRef *arguments,
    int half_args)
{
    PyObject *res;
    STACKREFS_TO_PYOBJECTS(arguments, half_args*2, args_o);
    if (CONVERSION_FAILED(args_o)) {
        res = NULL;
        goto cleanup;
    }
    res = _PyDict_FromItems(
        args_o, 2,
        args_o+1, 2,
        half_args
    );
    STACKREFS_TO_PYOBJECTS_CLEANUP(args_o);
    assert((res != NULL) ^ (PyErr_Occurred() != NULL));
cleanup:
    // arguments is a pointer into the GC visible stack,
    // so we must NULL out values as we clear them.
    for (int i = half_args*2-1; i >= 0; i--) {
        _PyStackRef tmp = arguments[i];
        arguments[i] = PyStackRef_NULL;
        PyStackRef_CLOSE(tmp);
    }
    return res;
}

_PyStackRef
_Py_LoadAttr_StackRefSteal(
    PyThreadState *tstate, _PyStackRef owner,
    PyObject *name, _PyStackRef *self_or_null)
{
    // Use _PyCStackRefs to ensure that both method and self are visible to
    // the GC. Even though self_or_null is on the evaluation stack, it may be
    // after the stackpointer and therefore not visible to the GC.
    _PyCStackRef method, self;
    _PyThreadState_PushCStackRef(tstate, &method);
    _PyThreadState_PushCStackRef(tstate, &self);
    self.ref = owner;  // steal reference to owner
    // NOTE: method.ref is initialized to PyStackRef_NULL and remains null on
    // error, so we don't need to explicitly use the return code from the call.
    _PyObject_GetMethodStackRef(tstate, &self.ref, name, &method.ref);
    *self_or_null = _PyThreadState_PopCStackRefSteal(tstate, &self);
    return _PyThreadState_PopCStackRefSteal(tstate, &method);
}

#ifdef Py_DEBUG
void
_Py_assert_within_stack_bounds(
    _PyInterpreterFrame *frame, _PyStackRef *stack_pointer,
    const char *filename, int lineno
) {
    if (frame->owner == FRAME_OWNED_BY_INTERPRETER) {
        return;
    }
    int level = (int)(stack_pointer - _PyFrame_Stackbase(frame));
    if (level < 0) {
        printf("Stack underflow (depth = %d) at %s:%d\n", level, filename, lineno);
        fflush(stdout);
        abort();