ceval.c

/* Execute compiled code */

#define _PY_INTERPRETER

#include "Python.h"
#include "pycore_abstract.h"      // _PyIndex_Check()
#include "pycore_backoff.h"
#include "pycore_call.h"          // _PyObject_CallNoArgs()
#include "pycore_cell.h"          // PyCell_GetRef()
#include "pycore_ceval.h"
#include "pycore_code.h"
#include "pycore_emscripten_signal.h"  // _Py_CHECK_EMSCRIPTEN_SIGNALS
#include "pycore_function.h"
#include "pycore_instruments.h"
#include "pycore_intrinsics.h"
#include "pycore_jit.h"
#include "pycore_long.h"          // _PyLong_GetZero()
#include "pycore_moduleobject.h"  // PyModuleObject
#include "pycore_object.h"        // _PyObject_GC_TRACK()
#include "pycore_opcode_metadata.h" // EXTRA_CASES
#include "pycore_optimizer.h"     // _PyUOpExecutor_Type
#include "pycore_opcode_utils.h"  // MAKE_FUNCTION_*
#include "pycore_pyatomic_ft_wrappers.h" // FT_ATOMIC_*
#include "pycore_pyerrors.h"      // _PyErr_GetRaisedException()
#include "pycore_pystate.h"       // _PyInterpreterState_GET()
#include "pycore_range.h"         // _PyRangeIterObject
#include "pycore_setobject.h"     // _PySet_Update()
#include "pycore_sliceobject.h"   // _PyBuildSlice_ConsumeRefs
#include "pycore_sysmodule.h"     // _PySys_Audit()
#include "pycore_tuple.h"         // _PyTuple_ITEMS()
#include "pycore_typeobject.h"    // _PySuper_Lookup()
#include "pycore_uop_ids.h"       // Uops
#include "pycore_pyerrors.h"

#include "pycore_dict.h"
#include "dictobject.h"
#include "pycore_frame.h"
#include "frameobject.h"          // _PyInterpreterFrame_GetLine
#include "opcode.h"
#include "pydtrace.h"
#include "setobject.h"
#include "pycore_stackref.h"

#include <stdbool.h>              // bool

#ifdef Py_DEBUG
   /* For debugging the interpreter: */
#  define LLTRACE  1      /* Low-level trace feature */
#endif

#if !defined(Py_BUILD_CORE)
#  error "ceval.c must be build with Py_BUILD_CORE define for best performance"
#endif

#if !defined(Py_DEBUG) && !defined(Py_TRACE_REFS) && !defined(Py_GIL_DISABLED)
// GH-89279: The MSVC compiler does not inline these static inline functions
// in PGO build in _PyEval_EvalFrameDefault(), because this function is over
// the limit of PGO, and that limit cannot be configured.
// Define them as macros to make sure that they are always inlined by the
// preprocessor.
// TODO: implement Py_DECREF macro for Py_GIL_DISABLED

#undef Py_DECREF
#define Py_DECREF(arg) \
    do { \
        PyObject *op = _PyObject_CAST(arg); \
        if (_Py_IsImmortal(op)) { \
            break; \
        } \
        _Py_DECREF_STAT_INC(); \
        if (--op->ob_refcnt == 0) { \
            destructor dealloc = Py_TYPE(op)->tp_dealloc; \
            (*dealloc)(op); \
        } \
    } while (0)

#undef Py_XDECREF
#define Py_XDECREF(arg) \
    do { \
        PyObject *xop = _PyObject_CAST(arg); \
        if (xop != NULL) { \
            Py_DECREF(xop); \
        } \
    } while (0)

#undef Py_IS_TYPE
#define Py_IS_TYPE(ob, type) \
    (_PyObject_CAST(ob)->ob_type == (type))

#undef _Py_DECREF_SPECIALIZED
#define _Py_DECREF_SPECIALIZED(arg, dealloc) \
    do { \
        PyObject *op = _PyObject_CAST(arg); \
        if (_Py_IsImmortal(op)) { \
            break; \
        } \
        _Py_DECREF_STAT_INC(); \
        if (--op->ob_refcnt == 0) { \
            destructor d = (destructor)(dealloc); \
            d(op); \
        } \
    } while (0)
#endif


#ifdef LLTRACE
static void
dump_stack(_PyInterpreterFrame *frame, _PyStackRef *stack_pointer)
{
    _PyStackRef *stack_base = _PyFrame_Stackbase(frame);
    PyObject *exc = PyErr_GetRaisedException();
    printf("    stack=[");
    for (_PyStackRef *ptr = stack_base; ptr < stack_pointer; ptr++) {
        if (ptr != stack_base) {
            printf(", ");
        }
        PyObject *obj = PyStackRef_AsPyObjectBorrow(*ptr);
        if (obj == NULL) {
            printf("<nil>");
            continue;
        }
        if (
            obj == Py_None
            || PyBool_Check(obj)
            || PyLong_CheckExact(obj)
            || PyFloat_CheckExact(obj)
            || PyUnicode_CheckExact(obj)
        ) {
            if (PyObject_Print(obj, stdout, 0) == 0) {
                continue;
            }
            PyErr_Clear();
        }
        // Don't call __repr__(), it might recurse into the interpreter.
        printf("<%s at %p>", Py_TYPE(obj)->tp_name, (void *)(ptr->bits));
    }
    printf("]\n");
    fflush(stdout);
    PyErr_SetRaisedException(exc);
}

static void
lltrace_instruction(_PyInterpreterFrame *frame,
                    _PyStackRef *stack_pointer,
                    _Py_CODEUNIT *next_instr,
                    int opcode,
                    int oparg)
{
    if (frame->owner == FRAME_OWNED_BY_CSTACK) {
        return;
    }
    dump_stack(frame, stack_pointer);
    const char *opname = _PyOpcode_OpName[opcode];
    assert(opname != NULL);
    int offset = (int)(next_instr - _PyCode_CODE(_PyFrame_GetCode(frame)));
    if (OPCODE_HAS_ARG((int)_PyOpcode_Deopt[opcode])) {
        printf("%d: %s %d\n", offset * 2, opname, oparg);
    }
    else {
        printf("%d: %s\n", offset * 2, opname);
    }
    fflush(stdout);
}
static void
lltrace_resume_frame(_PyInterpreterFrame *frame)
{
    PyObject *fobj = frame->f_funcobj;
    if (!PyCode_Check(frame->f_executable) ||
        fobj == NULL ||
        !PyFunction_Check(fobj)
    ) {
        printf("\nResuming frame.\n");
        return;
    }
    PyFunctionObject *f = (PyFunctionObject *)fobj;
    PyObject *exc = PyErr_GetRaisedException();
    PyObject *name = f->func_qualname;
    if (name == NULL) {
        name = f->func_name;
    }
    printf("\nResuming frame");
    if (name) {
        printf(" for ");
        if (PyObject_Print(name, stdout, 0) < 0) {
            PyErr_Clear();
        }
    }
    if (f->func_module) {
        printf(" in module ");
        if (PyObject_Print(f->func_module, stdout, 0) < 0) {
            PyErr_Clear();
        }
    }
    printf("\n");
    fflush(stdout);
    PyErr_SetRaisedException(exc);
}

static int
maybe_lltrace_resume_frame(_PyInterpreterFrame *frame, _PyInterpreterFrame *skip_frame, PyObject *globals)
{
    if (globals == NULL) {
        return 0;
    }
    if (frame == skip_frame) {
        return 0;
    }
    int r = PyDict_Contains(globals, &_Py_ID(__lltrace__));
    if (r < 0) {
        return -1;
    }
    int lltrace = r * 5;  // Levels 1-4 only trace uops
    if (!lltrace) {
        // Can also be controlled by environment variable
        char *python_lltrace = Py_GETENV("PYTHON_LLTRACE");
        if (python_lltrace != NULL && *python_lltrace >= '0') {
            lltrace = *python_lltrace - '0';  // TODO: Parse an int and all that
        }
    }
    if (lltrace >= 5) {
        lltrace_resume_frame(frame);
    }
    return lltrace;
}

#endif

static void monitor_reraise(PyThreadState *tstate,
                 _PyInterpreterFrame *frame,
                 _Py_CODEUNIT *instr);
static int monitor_stop_iteration(PyThreadState *tstate,
                 _PyInterpreterFrame *frame,
                 _Py_CODEUNIT *instr,
                 PyObject *value);
static void monitor_unwind(PyThreadState *tstate,
                 _PyInterpreterFrame *frame,
                 _Py_CODEUNIT *instr);
static int monitor_handled(PyThreadState *tstate,
                 _PyInterpreterFrame *frame,
                 _Py_CODEUNIT *instr, PyObject *exc);
static void monitor_throw(PyThreadState *tstate,
                 _PyInterpreterFrame *frame,
                 _Py_CODEUNIT *instr);

static int check_args_iterable(PyThreadState *, PyObject *func, PyObject *vararg);
static int get_exception_handler(PyCodeObject *, int, int*, int*, int*);
static  _PyInterpreterFrame *
_PyEvalFramePushAndInit_Ex(PyThreadState *tstate, PyFunctionObject *func,
    PyObject *locals, Py_ssize_t nargs, PyObject *callargs, PyObject *kwargs);

#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif

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

void
Py_SetRecursionLimit(int new_limit)
{
    PyInterpreterState *interp = _PyInterpreterState_GET();
    interp->ceval.recursion_limit = new_limit;
    for (PyThreadState *p = interp->threads.head; p != NULL; p = p->next) {
        int depth = p->py_recursion_limit - p->py_recursion_remaining;
        p->py_recursion_limit = new_limit;
        p->py_recursion_remaining = new_limit - depth;
    }
}

/* The function _Py_EnterRecursiveCallTstate() only calls _Py_CheckRecursiveCall()
   if the recursion_depth reaches recursion_limit. */
int
_Py_CheckRecursiveCall(PyThreadState *tstate, const char *where)
{
#ifdef USE_STACKCHECK
    if (PyOS_CheckStack()) {
        ++tstate->c_recursion_remaining;
        _PyErr_SetString(tstate, PyExc_MemoryError, "Stack overflow");
        return -1;
    }
#endif
    if (tstate->recursion_headroom) {
        if (tstate->c_recursion_remaining < -50) {
            /* Overflowing while handling an overflow. Give up. */
            Py_FatalError("Cannot recover from stack overflow.");
        }
    }
    else {
        if (tstate->c_recursion_remaining <= 0) {
            tstate->recursion_headroom++;
            _PyErr_Format(tstate, PyExc_RecursionError,
                        "maximum recursion depth exceeded%s",
                        where);
            tstate->recursion_headroom--;
            ++tstate->c_recursion_remaining;
            return -1;
        }
    }
    return 0;
}


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,
};

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 = "'%.200s' object does not support the "
                 "context manager protocol (missed __enter__ method)",
    },
    [SPECIAL___EXIT__] = {
        .name = &_Py_ID(__exit__),
        .error = "'%.200s' object does not support the "
                 "context manager protocol (missed __exit__ method)",
    },
    [SPECIAL___AENTER__] = {
        .name = &_Py_ID(__aenter__),
        .error = "'%.200s' object does not support the asynchronous "
                 "context manager protocol (missed __aenter__ method)",
    },
    [SPECIAL___AEXIT__] = {
        .name = &_Py_ID(__aexit__),
        .error = "'%.200s' object does not support the asynchronous "
                 "context manager protocol (missed __aexit__ method)",
    }
};


// 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;
    PyObject *get = 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).
    int meth_found = _PyObject_GetMethod(map, &_Py_ID(get), &get);
    if (get == NULL) {
        goto fail;
    }
    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 *args[] = { map, key, dummy };
        PyObject *value = NULL;
        if (meth_found) {
            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:
    Py_DECREF(get);
    Py_DECREF(seen);
    Py_DECREF(dummy);
    return values;
fail:
    Py_XDECREF(get);
    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));
    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 = "called match pattern must be 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;
    }
    // So far so good:
    PyObject *seen = PySet_New(NULL);
    if (seen == NULL) {
        return NULL;
    }
    PyObject *attrs = PyList_New(0);
    if (attrs == NULL) {
        Py_DECREF(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 %d positional sub-pattern%s (%d given)",
                          ((PyTypeObject*)type)->tp_name,
                          allowed, plural, nargs);
            goto fail;
        }
        if (match_self) {
            // Easy. Copy the subject itself, and move on to kwargs.
            if (PyList_Append(attrs, subject) < 0) {
                goto fail;
            }
        }
        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;
                }
                if (PyList_Append(attrs, attr) < 0) {
                    Py_DECREF(attr);
                    goto fail;
                }
                Py_DECREF(attr);
            }
        }
        Py_CLEAR(match_args);
    }
    // Finally, the keyword subpatterns:
    for (Py_ssize_t i = 0; i < PyTuple_GET_SIZE(kwargs); i++) {
        PyObject *name = PyTuple_GET_ITEM(kwargs, i);
        PyObject *attr = match_class_attr(tstate, subject, type, name, seen);
        if (attr == NULL) {
            goto fail;
        }
        if (PyList_Append(attrs, attr) < 0) {
            Py_DECREF(attr);
            goto fail;
        }
        Py_DECREF(attr);
    }
    Py_SETREF(attrs, PyList_AsTuple(attrs));
    Py_DECREF(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_DECREF(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 = _PyEval_BuiltinsFromGlobals(tstate, globals); // borrowed ref
    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);
    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"

int _Py_CheckRecursiveCallPy(
    PyThreadState *tstate)
{
    if (tstate->recursion_headroom) {
        if (tstate->py_recursion_remaining < -50) {
            /* Overflowing while handling an overflow. Give up. */
            Py_FatalError("Cannot recover from Python stack overflow.");
        }
    }
    else {
        if (tstate->py_recursion_remaining <= 0) {
            tstate->recursion_headroom++;
            _PyErr_Format(tstate, PyExc_RecursionError,
                        "maximum recursion depth exceeded");
            tstate->recursion_headroom--;
            return -1;
        }
    }
    return 0;
}

static const _Py_CODEUNIT _Py_INTERPRETER_TRAMPOLINE_INSTRUCTIONS[] = {
    /* Put a NOP at the start, so that the IP points into
    * the code, rather than before it */
    { .op.code = NOP, .op.arg = 0 },
    { .op.code = INTERPRETER_EXIT, .op.arg = 0 },  /* reached on return */
    { .op.code = NOP, .op.arg = 0 },
    { .op.code = INTERPRETER_EXIT, .op.arg = 0 },  /* reached on yield */
    { .op.code = RESUME, .op.arg = RESUME_OPARG_DEPTH1_MASK | RESUME_AT_FUNC_START }
};

extern const struct _PyCode_DEF(8) _Py_InitCleanup;

#ifdef Py_DEBUG
extern void _PyUOpPrint(const _PyUOpInstruction *uop);
#endif


/* Disable unused label warnings.  They are handy for debugging, even
   if computed gotos aren't used. */

/* TBD - what about other compilers? */
#if defined(__GNUC__)
#  pragma GCC diagnostic push
#  pragma GCC diagnostic ignored "-Wunused-label"
#elif defined(_MSC_VER) /* MS_WINDOWS */
#  pragma warning(push)
#  pragma warning(disable:4102)
#endif


PyObject **
_PyObjectArray_FromStackRefArray(_PyStackRef *input, Py_ssize_t nargs, PyObject **scratch)
{
    PyObject **result;
    if (nargs > MAX_STACKREF_SCRATCH) {
        // +1 in case PY_VECTORCALL_ARGUMENTS_OFFSET is set.
        result = PyMem_Malloc((nargs + 1) * sizeof(PyObject *));
        if (result == NULL) {
            return NULL;
        }
        result++;
    }
    else {
        result = scratch;
    }
    for (int i = 0; i < nargs; i++) {
        result[i] = PyStackRef_AsPyObjectBorrow(input[i]);
    }
    return result;
}

void
_PyObjectArray_Free(PyObject **array, PyObject **scratch)
{
    if (array != scratch) {
        PyMem_Free(array);
    }
}

/* _PyEval_EvalFrameDefault() is a *big* function,
 * so consume 3 units of C stack */
#define PY_EVAL_C_STACK_UNITS 2

PyObject* _Py_HOT_FUNCTION
_PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int throwflag)
{
    _Py_EnsureTstateNotNULL(tstate);
    CALL_STAT_INC(pyeval_calls);

#if USE_COMPUTED_GOTOS
/* Import the static jump table */
#include "opcode_targets.h"
#endif

#ifdef Py_STATS
    int lastopcode = 0;
#endif
    uint8_t opcode;    /* Current opcode */
    int oparg;         /* Current opcode argument, if any */
#ifdef LLTRACE
    int lltrace = 0;
#endif

    _PyInterpreterFrame  entry_frame;



#ifdef Py_DEBUG
    /* Set these to invalid but identifiable values for debugging. */
    entry_frame.f_funcobj = (PyObject*)0xaaa0;
    entry_frame.f_locals = (PyObject*)0xaaa1;
    entry_frame.frame_obj = (PyFrameObject*)0xaaa2;
    entry_frame.f_globals = (PyObject*)0xaaa3;
    entry_frame.f_builtins = (PyObject*)0xaaa4;
#endif
    entry_frame.f_executable = Py_None;
    entry_frame.instr_ptr = (_Py_CODEUNIT *)_Py_INTERPRETER_TRAMPOLINE_INSTRUCTIONS + 1;
    entry_frame.stackpointer = entry_frame.localsplus;
    entry_frame.owner = FRAME_OWNED_BY_CSTACK;
    entry_frame.return_offset = 0;
    /* Push frame */
    entry_frame.previous = tstate->current_frame;
    frame->previous = &entry_frame;
    tstate->current_frame = frame;

    tstate->c_recursion_remaining -= (PY_EVAL_C_STACK_UNITS - 1);
    if (_Py_EnterRecursiveCallTstate(tstate, "")) {
        tstate->c_recursion_remaining--;
        tstate->py_recursion_remaining--;
        goto exit_unwind;
    }

    /* support for generator.throw() */
    if (throwflag) {
        if (_Py_EnterRecursivePy(tstate)) {
            goto exit_unwind;
        }
        /* Because this avoids the RESUME,
         * we need to update instrumentation */
        _Py_Instrument(_PyFrame_GetCode(frame), tstate->interp);
        monitor_throw(tstate, frame, frame->instr_ptr);
        /* TO DO -- Monitor throw entry. */
        goto resume_with_error;
    }

    /* Local "register" variables.
     * These are cached values from the frame and code object.  */
    _Py_CODEUNIT *next_instr;
    _PyStackRef *stack_pointer;

#if defined(_Py_TIER2) && !defined(_Py_JIT)
    /* Tier 2 interpreter state */
    _PyExecutorObject *current_executor = NULL;
    const _PyUOpInstruction *next_uop = NULL;
#endif

start_frame:
    if (_Py_EnterRecursivePy(tstate)) {
        goto exit_unwind;
    }

    next_instr = frame->instr_ptr;
resume_frame:
    stack_pointer = _PyFrame_GetStackPointer(frame);

#ifdef LLTRACE
    lltrace = maybe_lltrace_resume_frame(frame, &entry_frame, GLOBALS());
    if (lltrace < 0) {
        goto exit_unwind;
    }
#endif

#ifdef Py_DEBUG
    /* _PyEval_EvalFrameDefault() must not be called with an exception set,
       because it can clear it (directly or indirectly) and so the
       caller loses its exception */
    assert(!_PyErr_Occurred(tstate));
#endif

    DISPATCH();

    {
    /* Start instructions */
#if !USE_COMPUTED_GOTOS
    dispatch_opcode:
        switch (opcode)
#endif
        {

#include "generated_cases.c.h"


#if USE_COMPUTED_GOTOS
        _unknown_opcode:
#else
        EXTRA_CASES  // From pycore_opcode_metadata.h, a 'case' for each unused opcode
#endif
            /* Tell C compilers not to hold the opcode variable in the loop.
               next_instr points the current instruction without TARGET(). */
            opcode = next_instr->op.code;
            _PyErr_Format(tstate, PyExc_SystemError,
                          "%U:%d: unknown opcode %d",
                          _PyFrame_GetCode(frame)->co_filename,
                          PyUnstable_InterpreterFrame_GetLine(frame),
                          opcode);
            goto error;

        } /* End instructions */

        /* This should never be reached. Every opcode should end with DISPATCH()
           or goto error. */
        Py_UNREACHABLE();

pop_4_error:
    STACK_SHRINK(1);
pop_3_error:
    STACK_SHRINK(1);
pop_2_error:
    STACK_SHRINK(1);
pop_1_error:
    STACK_SHRINK(1);
error:
        /* Double-check exception status. */
#ifdef NDEBUG
        if (!_PyErr_Occurred(tstate)) {
            _PyErr_SetString(tstate, PyExc_SystemError,
                             "error return without exception set");
        }
#else
        assert(_PyErr_Occurred(tstate));
#endif

        /* Log traceback info. */
        assert(frame != &entry_frame);
        if (!_PyFrame_IsIncomplete(frame)) {
            PyFrameObject *f = _PyFrame_GetFrameObject(frame);
            if (f != NULL) {
                PyTraceBack_Here(f);
            }
        }
        _PyEval_MonitorRaise(tstate, frame, next_instr-1);
exception_unwind:
        {
            /* We can't use frame->instr_ptr here, as RERAISE may have set it */
            int offset = INSTR_OFFSET()-1;
            int level, handler, lasti;
            if (get_exception_handler(_PyFrame_GetCode(frame), offset, &level, &handler, &lasti) == 0) {
                // No handlers, so exit.
                assert(_PyErr_Occurred(tstate));

                /* Pop remaining stack entries. */
                _PyStackRef *stackbase = _PyFrame_Stackbase(frame);
                while (stack_pointer > stackbase) {
                    PyStackRef_XCLOSE(POP());
                }
                assert(STACK_LEVEL() == 0);
                _PyFrame_SetStackPointer(frame, stack_pointer);
                monitor_unwind(tstate, frame, next_instr-1);
                goto exit_unwind;
            }

            assert(STACK_LEVEL() >= level);
            _PyStackRef *new_top = _PyFrame_Stackbase(frame) + level;
            while (stack_pointer > new_top) {
                PyStackRef_XCLOSE(POP());
            }
            if (lasti) {
                int frame_lasti = _PyInterpreterFrame_LASTI(frame);
                PyObject *lasti = PyLong_FromLong(frame_lasti);
                if (lasti == NULL) {
                    goto exception_unwind;
                }
                PUSH(PyStackRef_FromPyObjectSteal(lasti));
            }

            /* Make the raw exception data
                available to the handler,
                so a program can emulate the
                Python main loop. */
            PyObject *exc = _PyErr_GetRaisedException(tstate);
            PUSH(PyStackRef_FromPyObjectSteal(exc));
            next_instr = _PyCode_CODE(_PyFrame_GetCode(frame)) + handler;

            if (monitor_handled(tstate, frame, next_instr, exc) < 0) {
                goto exception_unwind;
            }
            /* Resume normal execution */
#ifdef LLTRACE
            if (lltrace >= 5) {
                lltrace_resume_frame(frame);
            }
#endif
            DISPATCH();
        }
    }

exit_unwind:
    assert(_PyErr_Occurred(tstate));
    _Py_LeaveRecursiveCallPy(tstate);
    assert(frame != &entry_frame);
    // GH-99729: We need to unlink the frame *before* clearing it:
    _PyInterpreterFrame *dying = frame;
    frame = tstate->current_frame = dying->previous;
    _PyEval_FrameClearAndPop(tstate, dying);
    frame->return_offset = 0;
    if (frame == &entry_frame) {
        /* Restore previous frame and exit */
        tstate->current_frame = frame->previous;
        tstate->c_recursion_remaining += PY_EVAL_C_STACK_UNITS;
        return NULL;
    }

resume_with_error:
    next_instr = frame->instr_ptr;
    stack_pointer = _PyFrame_GetStackPointer(frame);
    goto error;


#ifdef _Py_TIER2

// Tier 2 is also here!
enter_tier_two:

#ifdef _Py_JIT
    assert(0);
#else

#undef LOAD_IP
#define LOAD_IP(UNUSED) (void)0

#undef GOTO_ERROR
#define GOTO_ERROR(LABEL) goto LABEL ## _tier_two

#ifdef Py_STATS
// Disable these macros that apply to Tier 1 stats when we are in Tier 2
#undef STAT_INC
#define STAT_INC(opname, name) ((void)0)
#undef STAT_DEC
#define STAT_DEC(opname, name) ((void)0)
#endif

#undef ENABLE_SPECIALIZATION
#define ENABLE_SPECIALIZATION 0

#ifdef Py_DEBUG
    #define DPRINTF(level, ...) \
        if (lltrace >= (level)) { printf(__VA_ARGS__); }
#else
    #define DPRINTF(level, ...)
#endif

    ; // dummy statement after a label, before a declaration
    uint16_t uopcode;
#ifdef Py_STATS
    int lastuop = 0;
    uint64_t trace_uop_execution_counter = 0;
#endif