githubmirror/cpython

Modules/_testinternalcapi.c
3 470 строк101 KB
Petr Viktorin
gh-149202: Fix frame pointer unwinding on ppc64le and armv7/clang (#149409)
07 май 2026, 11:37
07 май 2026, 11:37612140e
/*
 * C Extension module to test Python internal C APIs (Include/internal).
 */

#ifndef Py_BUILD_CORE_BUILTIN
#  define Py_BUILD_CORE_MODULE 1
#endif

/* Always enable assertions */
#undef NDEBUG

#include "Python.h"
#include <string.h>
#include "pycore_backoff.h"       // JUMP_BACKWARD_INITIAL_VALUE
#include "pycore_bitutils.h"      // _Py_bswap32()
#include "pycore_bytesobject.h"   // _PyBytes_Find()
#include "pycore_ceval.h"         // _PyEval_AddPendingCall()
#include "pycore_code.h"          // _PyCode_GetTLBCFast()
#include "pycore_compile.h"       // _PyCompile_CodeGen()
#include "pycore_context.h"       // _PyContext_NewHamtForTests()
#include "pycore_dict.h"          // PyDictValues
#include "pycore_fileutils.h"     // _Py_normpath()
#include "pycore_flowgraph.h"     // _PyCompile_OptimizeCfg()
#include "pycore_frame.h"         // _PyInterpreterFrame
#include "pycore_function.h"      // _PyFunction_GET_BUILTINS
#include "pycore_gc.h"            // PyGC_Head
#include "pycore_hashtable.h"     // _Py_hashtable_new()
#include "pycore_import.h"        // _PyImport_ClearExtension()
#include "pycore_initconfig.h"    // _Py_GetConfigsAsDict()
#include "pycore_instruction_sequence.h"  // _PyInstructionSequence_New()
#include "pycore_interpframe.h"   // _PyFrame_GetFunction()
#include "pycore_jit.h"           // _PyJIT_AddressInJitCode()
#include "pycore_object.h"        // _PyObject_IsFreed()
#include "pycore_optimizer.h"     // _Py_Executor_DependsOn
#include "pycore_pathconfig.h"    // _PyPathConfig_ClearGlobal()
#include "pycore_pyerrors.h"      // _PyErr_ChainExceptions1()
#include "pycore_pylifecycle.h"   // _PyInterpreterConfig_InitFromDict()
#include "pycore_pystate.h"       // _PyThreadState_GET()
#include "pycore_runtime_structs.h" // _PY_NSMALLPOSINTS
#include "pycore_unicodeobject.h" // _PyUnicode_TransformDecimalAndSpaceToASCII()

#include "clinic/_testinternalcapi.c.h"

// Include test definitions from _testinternalcapi/
#include "_testinternalcapi/parts.h"

#if defined(HAVE_DLADDR) && !defined(__wasi__)
#  include <dlfcn.h>
#endif
#if defined(HAVE_EXECINFO_H)
#  include <execinfo.h>
#endif
#ifdef MS_WINDOWS
#  include <windows.h>
#  include <intrin.h>
#  include <winnt.h>
#  include <wchar.h>
#endif

#define MODULE_NAME "_testinternalcapi"


static const uintptr_t min_frame_pointer_addr = 0x1000;
#define MAX_UNWIND_FRAMES 200

#ifdef __s390x__
// Linux's s390 "Stack Frame Layout" table documents that z/Architecture
// backchain frames start with the backchain at offset 0 and store "saved r14
// of caller function" at offset 112.  The same document's register table
// identifies r14 as the return-address register, so this backchain unwinder
// reads the return address from fp + 112.
// https://www.kernel.org/doc/html/v5.3/s390/debugging390.html#stack-frame-layout
//
// This is only for Linux s390x backchain frames.  The s390x ELF ABI does not
// generally mandate where RA and FP are saved, or whether they are saved at all.
// https://sourceware.org/binutils/docs/sframe-spec.html#s390x
#  define S390X_FRAME_RETURN_ADDRESS_OFFSET 112
#endif

// The generic manual unwinder treats the frame pointer as a two-word record:
// fp[0] is the previous frame pointer and fp[1] is the return address.  That is
// not true for every architecture, even with frame pointers enabled, so these
// offsets describe the actual slots used by each supported frame layout.
#if defined(__arm__) && !defined(__thumb__) && !defined(__clang__)
// GCC ARM mode keeps the caller's fp one word below fp and the saved LR at
// fp[0], so the return address is not in the generic fp[1] slot.
#  define FRAME_POINTER_NEXT_OFFSET (-1)
#  define FRAME_POINTER_RETURN_OFFSET 0
#elif defined(__s390x__)
// s390x backchain frames keep the previous frame pointer at fp[0], but save the
// return-address register in the ABI register save area rather than fp[1].
#  define FRAME_POINTER_NEXT_OFFSET 0
#  define FRAME_POINTER_RETURN_OFFSET \
    (S390X_FRAME_RETURN_ADDRESS_OFFSET / (Py_ssize_t)sizeof(uintptr_t))
#elif defined(__powerpc64__) || defined(__ppc64__)
// ppc64le puts the return address at fp[2]; it saves the Condition Register
// in fp[1]. See:
// https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#STACK
#  define FRAME_POINTER_NEXT_OFFSET 0
#  define FRAME_POINTER_RETURN_OFFSET 2
#else
#  define FRAME_POINTER_NEXT_OFFSET 0
#  define FRAME_POINTER_RETURN_OFFSET 1
#endif


static PyObject *
_get_current_module(void)
{
    // We ensured it was imported in _run_script().
    PyObject *name = PyUnicode_FromString(MODULE_NAME);
    if (name == NULL) {
        return NULL;
    }
    PyObject *mod = PyImport_GetModule(name);
    Py_DECREF(name);
    if (mod == NULL) {
        return NULL;
    }
    assert(mod != Py_None);
    return mod;
}


/* module state *************************************************************/

typedef struct {
    PyObject *record_list;
} module_state;

static inline module_state *
get_module_state(PyObject *mod)
{
    assert(mod != NULL);
    module_state *state = PyModule_GetState(mod);
    assert(state != NULL);
    return state;
}

static int
traverse_module_state(module_state *state, visitproc visit, void *arg)
{
    Py_VISIT(state->record_list);
    return 0;
}

static int
clear_module_state(module_state *state)
{
    Py_CLEAR(state->record_list);
    return 0;
}


/* module functions *********************************************************/

/*[clinic input]
module _testinternalcapi
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=7bb583d8c9eb9a78]*/
static PyObject *
get_configs(PyObject *self, PyObject *Py_UNUSED(args))
{
    return _Py_GetConfigsAsDict();
}


static PyObject*
get_recursion_depth(PyObject *self, PyObject *Py_UNUSED(args))
{
    PyThreadState *tstate = _PyThreadState_GET();

    return PyLong_FromLong(tstate->py_recursion_limit - tstate->py_recursion_remaining);
}


static PyObject*
get_c_recursion_remaining(PyObject *self, PyObject *Py_UNUSED(args))
{
    PyThreadState *tstate = _PyThreadState_GET();
    uintptr_t here_addr = _Py_get_machine_stack_pointer();
    _PyThreadStateImpl *_tstate = (_PyThreadStateImpl *)tstate;
    int remaining = (int)((here_addr - _tstate->c_stack_soft_limit) / _PyOS_STACK_MARGIN_BYTES * 50);
    return PyLong_FromLong(remaining);
}

static PyObject*
get_stack_pointer(PyObject *self, PyObject *Py_UNUSED(args))
{
    uintptr_t here_addr = _Py_get_machine_stack_pointer();
    return PyLong_FromSize_t(here_addr);
}

static PyObject*
get_stack_margin(PyObject *self, PyObject *Py_UNUSED(args))
{
    return PyLong_FromSize_t(_PyOS_STACK_MARGIN_BYTES);
}

#ifdef MS_WINDOWS
static const char *
classify_address(uintptr_t addr, int jit_enabled, PyInterpreterState *interp)
{
    HMODULE module = NULL;
    if (GetModuleHandleExW(
            GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS
            | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
            (LPCWSTR)addr,
            &module)) {
        wchar_t path[MAX_PATH];
        DWORD len = GetModuleFileNameW(module, path, Py_ARRAY_LENGTH(path));
        if (len > 0 && len < Py_ARRAY_LENGTH(path)) {
            const wchar_t *base = wcsrchr(path, L'\\');
            base = base ? base + 1 : path;
            if (_wcsnicmp(base, L"python", 6) == 0) {
                return "python";
            }
            return "other";
        }
        /* Module resolved but path unavailable: treat as non-JIT. */
        return "other";
    }
#ifdef _Py_JIT
    if (jit_enabled && _PyJIT_AddressInJitCode(interp, addr)) {
        return "jit";
    }
#endif
    return "other";
}
#elif defined(HAVE_DLADDR) && !defined(__wasi__)
static const char *
classify_address(uintptr_t addr, int jit_enabled, PyInterpreterState *interp)
{
    Dl_info info;
    if (dladdr((void *)addr, &info) != 0
        && info.dli_fname != NULL
        && info.dli_fname[0] != '\0') {
        const char *base = strrchr(info.dli_fname, '/');
        base = base ? base + 1 : info.dli_fname;
        if (strncmp(base, "python", 6) == 0) {
            return "python";
        }
        // Match "libpython3.15.so.1.0"
        if (strncmp(base, "libpython", 9) == 0) {
            return "python";
        }
        return "other";
    }
#ifdef _Py_JIT
    if (jit_enabled && _PyJIT_AddressInJitCode(interp, addr)) {
        return "jit";
    }
#endif
    return "other";
}
#else
static const char *
classify_address(uintptr_t addr, int jit_enabled, PyInterpreterState *interp)
{
#ifdef _Py_JIT
    if (jit_enabled && _PyJIT_AddressInJitCode(interp, addr)) {
        return "jit";
    }
#endif
    return "other";
}
#endif

static PyObject *
classify_stack_addresses(PyObject *self, PyObject *args)
{
    PyObject *seq = NULL;
    int jit_enabled = 0;

    if (!PyArg_ParseTuple(args, "O|p:classify_stack_addresses",
                          &seq, &jit_enabled)) {
        return NULL;
    }
    PyObject *fast = PySequence_Fast(seq, "addresses must be iterable");
    if (fast == NULL) {
        return NULL;
    }
    Py_ssize_t n = PySequence_Fast_GET_SIZE(fast);
    PyObject *labels = PyList_New(n);
    if (labels == NULL) {
        Py_DECREF(fast);
        return NULL;
    }
    PyThreadState *tstate = _PyThreadState_GET();
    PyInterpreterState *interp = tstate ? tstate->interp : NULL;
    PyObject **items = PySequence_Fast_ITEMS(fast);
    for (Py_ssize_t i = 0; i < n; i++) {
        unsigned long long value = PyLong_AsUnsignedLongLong(items[i]);
        if (PyErr_Occurred()) {
            Py_DECREF(labels);
            Py_DECREF(fast);
            return NULL;
        }
        const char *label = classify_address((uintptr_t)value, jit_enabled, interp);
        PyObject *label_obj = PyUnicode_FromString(label);
        if (label_obj == NULL) {
            Py_DECREF(labels);
            Py_DECREF(fast);
            return NULL;
        }
        PyList_SET_ITEM(labels, i, label_obj);
    }
    Py_DECREF(fast);
    return labels;
}

static PyObject *
get_jit_code_ranges(PyObject *self, PyObject *Py_UNUSED(args))
{
    PyObject *ranges = PyList_New(0);
    if (ranges == NULL) {
        return NULL;
    }
#ifdef _Py_JIT
    PyThreadState *tstate = _PyThreadState_GET();
    PyInterpreterState *interp = tstate ? tstate->interp : NULL;
    if (interp == NULL) {
        return ranges;
    }
    for (size_t i = 0; i < interp->executor_count; i++) {
        _PyExecutorObject *exec = interp->executor_ptrs[i];
        if (exec->jit_code == NULL || exec->jit_size == 0) {
            continue;
        }
        uintptr_t start = (uintptr_t)exec->jit_code;
        uintptr_t end = start + exec->jit_size;
        PyObject *start_obj = PyLong_FromUnsignedLongLong(start);
        PyObject *end_obj = PyLong_FromUnsignedLongLong(end);
        if (start_obj == NULL || end_obj == NULL) {
            Py_XDECREF(start_obj);
            Py_XDECREF(end_obj);
            Py_DECREF(ranges);
            return NULL;
        }
        PyObject *pair = PyTuple_New(2);
        if (pair == NULL) {
            Py_DECREF(start_obj);
            Py_DECREF(end_obj);
            Py_DECREF(ranges);
            return NULL;
        }
        PyTuple_SET_ITEM(pair, 0, start_obj);
        PyTuple_SET_ITEM(pair, 1, end_obj);
        if (PyList_Append(ranges, pair) < 0) {
            Py_DECREF(pair);
            Py_DECREF(ranges);
            return NULL;
        }
        Py_DECREF(pair);
    }
#endif
    return ranges;
}

static PyObject *
get_jit_backend(PyObject *self, PyObject *Py_UNUSED(args))
{
#ifdef _Py_JIT
    return PyUnicode_FromString("jit");
#elif defined(_Py_TIER2)
    return PyUnicode_FromString("interpreter");
#else
    Py_RETURN_NONE;
#endif
}

static int
stack_address_is_valid(uintptr_t addr, uintptr_t stack_min, uintptr_t stack_max)
{
    if (addr < min_frame_pointer_addr) {
        return 0;
    }
    if (stack_min != 0 && (addr < stack_min || addr >= stack_max)) {
        return 0;
    }
    return 1;
}

static int
frame_pointer_slot_is_valid(uintptr_t *frame_pointer, Py_ssize_t offset,
                            uintptr_t stack_min, uintptr_t stack_max)
{
    uintptr_t fp_addr = (uintptr_t)frame_pointer;
    uintptr_t slot_addr;
    uintptr_t delta = (uintptr_t)Py_ABS(offset) * sizeof(uintptr_t);
    if (offset < 0) {
        if (fp_addr < delta) {
            return 0;
        }
        slot_addr = fp_addr - delta;
    }
    else {
        if (fp_addr > UINTPTR_MAX - delta) {
            return 0;
        }
        slot_addr = fp_addr + delta;
    }
    if (!stack_address_is_valid(slot_addr, stack_min, stack_max)) {
        return 0;
    }
    if (stack_max != 0) {
        if (slot_addr > UINTPTR_MAX - sizeof(uintptr_t)) {
            return 0;
        }
        if (slot_addr + sizeof(uintptr_t) > stack_max) {
            return 0;
        }
    }
    return 1;
}

static int
next_frame_pointer_is_valid(uintptr_t *frame_pointer, uintptr_t *next_fp,
                            uintptr_t stack_min, uintptr_t stack_max)
{
    uintptr_t fp_addr = (uintptr_t)frame_pointer;
    uintptr_t next_addr = (uintptr_t)next_fp;
    if (!stack_address_is_valid(next_addr, stack_min, stack_max)) {
        return 0;
    }
    if ((next_addr % sizeof(uintptr_t)) != 0) {
        return 0;
    }
#if _Py_STACK_GROWS_DOWN
    return next_addr > fp_addr;
#else
    return next_addr < fp_addr;
#endif
}

static PyObject *
manual_unwind_from_fp(uintptr_t *frame_pointer)
{
    uintptr_t stack_min = 0;
    uintptr_t stack_max = 0;

#ifdef __s390x__
    Py_BUILD_ASSERT(S390X_FRAME_RETURN_ADDRESS_OFFSET % sizeof(uintptr_t) == 0);
#endif

    if (frame_pointer == NULL) {
        return PyList_New(0);
    }

    PyThreadState *tstate = _PyThreadState_GET();
    if (tstate != NULL) {
        _PyThreadStateImpl *tstate_impl = (_PyThreadStateImpl *)tstate;
#if _Py_STACK_GROWS_DOWN
        stack_min = tstate_impl->c_stack_hard_limit;
        stack_max = tstate_impl->c_stack_top;
#else
        stack_min = tstate_impl->c_stack_top;
        stack_max = tstate_impl->c_stack_hard_limit;
#endif
    }

    PyObject *result = PyList_New(0);
    if (result == NULL) {
        return NULL;
    }

    Py_ssize_t depth = 0;
    while (frame_pointer != NULL) {
        uintptr_t fp_addr = (uintptr_t)frame_pointer;
        if ((fp_addr % sizeof(uintptr_t)) != 0) {
            break;
        }
        if (depth >= MAX_UNWIND_FRAMES) {
            Py_DECREF(result);
            PyErr_Format(
                PyExc_RuntimeError,
                "manual frame pointer unwind returned more than %d frames",
                MAX_UNWIND_FRAMES);
            return NULL;
        }
        if (!stack_address_is_valid(fp_addr, stack_min, stack_max)) {
            break;
        }
        if (!frame_pointer_slot_is_valid(frame_pointer,
                                         FRAME_POINTER_NEXT_OFFSET,
                                         stack_min, stack_max)) {
            break;
        }
        if (!frame_pointer_slot_is_valid(frame_pointer,
                                         FRAME_POINTER_RETURN_OFFSET,
                                         stack_min, stack_max)) {
            break;
        }
        uintptr_t *next_fp = (uintptr_t *)frame_pointer[FRAME_POINTER_NEXT_OFFSET];
        uintptr_t return_addr = frame_pointer[FRAME_POINTER_RETURN_OFFSET];

        PyObject *addr_obj = PyLong_FromUnsignedLongLong(return_addr);
        if (addr_obj == NULL) {
            Py_DECREF(result);
            return NULL;
        }
        if (PyList_Append(result, addr_obj) < 0) {
            Py_DECREF(addr_obj);
            Py_DECREF(result);
            return NULL;
        }
        Py_DECREF(addr_obj);
        depth++;

        if (!next_frame_pointer_is_valid(frame_pointer, next_fp,
                                         stack_min, stack_max)) {
            break;
        }
        frame_pointer = next_fp;
    }

    return result;
}

#if defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE)
static PyObject *
gnu_backtrace_unwind(PyObject *self, PyObject *Py_UNUSED(args))
{
    void *addresses[MAX_UNWIND_FRAMES + 1];
    int frame_count = backtrace(addresses, (int)Py_ARRAY_LENGTH(addresses));
    if (frame_count < 0) {
        PyErr_SetString(PyExc_RuntimeError, "backtrace() failed");
        return NULL;
    }
    if (frame_count > MAX_UNWIND_FRAMES) {
        PyErr_Format(
            PyExc_RuntimeError,
            "backtrace() returned more than %d frames",
            MAX_UNWIND_FRAMES);
        return NULL;
    }

    PyObject *result = PyList_New(frame_count);
    if (result == NULL) {
        return NULL;
    }
    for (int i = 0; i < frame_count; i++) {
        PyObject *addr_obj = PyLong_FromUnsignedLongLong((uintptr_t)addresses[i]);
        if (addr_obj == NULL) {
            Py_DECREF(result);
            return NULL;
        }
        PyList_SET_ITEM(result, i, addr_obj);
    }
    return result;
}
#else
static PyObject *
gnu_backtrace_unwind(PyObject *self, PyObject *Py_UNUSED(args))
{
    PyErr_SetString(PyExc_RuntimeError,
                    "gnu_backtrace_unwind is not supported on this platform");
    return NULL;
}
#endif

#if defined(__GNUC__) || defined(__clang__)
static PyObject *
manual_frame_pointer_unwind(PyObject *self, PyObject *args)
{
    uintptr_t *frame_pointer = (uintptr_t *)__builtin_frame_address(0);
    return manual_unwind_from_fp(frame_pointer);
}
#elif defined(MS_WINDOWS) && defined(_M_ARM64)
static PyObject *
manual_frame_pointer_unwind(PyObject *self, PyObject *args)
{
    CONTEXT ctx;
    uintptr_t *frame_pointer = NULL;

    RtlCaptureContext(&ctx);
    frame_pointer = (uintptr_t *)ctx.Fp;
    return manual_unwind_from_fp(frame_pointer);
}
#else
static PyObject *
manual_frame_pointer_unwind(PyObject *self, PyObject *Py_UNUSED(args))
{
    PyErr_SetString(PyExc_RuntimeError,
                    "manual_frame_pointer_unwind is not supported on this platform");
    return NULL;
}
#endif

static PyObject*
test_bswap(PyObject *self, PyObject *Py_UNUSED(args))
{
    uint16_t u16 = _Py_bswap16(UINT16_C(0x3412));
    if (u16 != UINT16_C(0x1234)) {
        PyErr_Format(PyExc_AssertionError,
                     "_Py_bswap16(0x3412) returns %d", u16);
        return NULL;
    }

    uint32_t u32 = _Py_bswap32(UINT32_C(0x78563412));
    if (u32 != UINT32_C(0x12345678)) {
        PyErr_Format(PyExc_AssertionError,
                     "_Py_bswap32(0x78563412) returns %u", u32);
        return NULL;
    }

    uint64_t u64 = _Py_bswap64(UINT64_C(0xEFCDAB9078563412));
    if (u64 != UINT64_C(0x1234567890ABCDEF)) {
        PyErr_Format(PyExc_AssertionError,
                     "_Py_bswap64(0xEFCDAB9078563412) returns %llu", u64);
        return NULL;
    }

    Py_RETURN_NONE;
}


static int
check_popcount(uint32_t x, int expected)
{
    // Use volatile to prevent the compiler to optimize out the whole test
    volatile uint32_t u = x;
    int bits = _Py_popcount32(u);
    if (bits != expected) {
        PyErr_Format(PyExc_AssertionError,
                     "_Py_popcount32(%lu) returns %i, expected %i",
                     (unsigned long)x, bits, expected);
        return -1;
    }
    return 0;
}


static PyObject*
test_popcount(PyObject *self, PyObject *Py_UNUSED(args))
{
#define CHECK(X, RESULT) \
    do { \
        if (check_popcount(X, RESULT) < 0) { \
            return NULL; \
        } \
    } while (0)

    CHECK(0, 0);
    CHECK(1, 1);
    CHECK(0x08080808, 4);
    CHECK(0x10000001, 2);
    CHECK(0x10101010, 4);
    CHECK(0x10204080, 4);
    CHECK(0xDEADCAFE, 22);
    CHECK(0xFFFFFFFF, 32);
    Py_RETURN_NONE;

#undef CHECK
}


static int
check_bit_length(unsigned long x, int expected)
{
    // Use volatile to prevent the compiler to optimize out the whole test
    volatile unsigned long u = x;
    int len = _Py_bit_length(u);
    if (len != expected) {
        PyErr_Format(PyExc_AssertionError,
                     "_Py_bit_length(%lu) returns %i, expected %i",
                     x, len, expected);
        return -1;
    }
    return 0;
}


static PyObject*
test_bit_length(PyObject *self, PyObject *Py_UNUSED(args))
{
#define CHECK(X, RESULT) \
    do { \
        if (check_bit_length(X, RESULT) < 0) { \
            return NULL; \
        } \
    } while (0)

    CHECK(0, 0);
    CHECK(1, 1);
    CHECK(0x1000, 13);
    CHECK(0x1234, 13);
    CHECK(0x54321, 19);
    CHECK(0x7FFFFFFF, 31);
    CHECK(0xFFFFFFFF, 32);
    Py_RETURN_NONE;

#undef CHECK
}


#define TO_PTR(ch) ((void*)(uintptr_t)ch)
#define FROM_PTR(ptr) ((uintptr_t)ptr)
#define VALUE(key) (1 + ((int)(key) - 'a'))

static Py_uhash_t
hash_char(const void *key)
{
    char ch = (char)FROM_PTR(key);
    return ch;
}


static int
hashtable_cb(_Py_hashtable_t *table,
             const void *key_ptr, const void *value_ptr,
             void *user_data)
{
    int *count = (int *)user_data;
    char key = (char)FROM_PTR(key_ptr);
    int value = (int)FROM_PTR(value_ptr);
    assert(value == VALUE(key));
    *count += 1;
    return 0;
}


static PyObject*
test_hashtable(PyObject *self, PyObject *Py_UNUSED(args))
{
    _Py_hashtable_t *table = _Py_hashtable_new(hash_char,
                                               _Py_hashtable_compare_direct);
    if (table == NULL) {
        return PyErr_NoMemory();
    }

    // Using an newly allocated table must not crash
    assert(table->nentries == 0);
    assert(table->nbuckets > 0);
    assert(_Py_hashtable_get(table, TO_PTR('x')) == NULL);

    // Test _Py_hashtable_set()
    char key;
    for (key='a'; key <= 'z'; key++) {
        int value = VALUE(key);
        if (_Py_hashtable_set(table, TO_PTR(key), TO_PTR(value)) < 0) {
            _Py_hashtable_destroy(table);
            return PyErr_NoMemory();
        }
    }
    assert(table->nentries == 26);
    assert(table->nbuckets > table->nentries);

    // Test _Py_hashtable_get_entry()
    for (key='a'; key <= 'z'; key++) {
        _Py_hashtable_entry_t *entry = _Py_hashtable_get_entry(table, TO_PTR(key));
        assert(entry != NULL);
        assert(entry->key == TO_PTR(key));
        assert(entry->value == TO_PTR(VALUE(key)));
    }

    // Test _Py_hashtable_get()
    for (key='a'; key <= 'z'; key++) {
        void *value_ptr = _Py_hashtable_get(table, TO_PTR(key));
        assert((int)FROM_PTR(value_ptr) == VALUE(key));
    }

    // Test _Py_hashtable_steal()
    key = 'p';
    void *value_ptr = _Py_hashtable_steal(table, TO_PTR(key));
    assert((int)FROM_PTR(value_ptr) == VALUE(key));
    assert(table->nentries == 25);
    assert(_Py_hashtable_get_entry(table, TO_PTR(key)) == NULL);

    // Test _Py_hashtable_foreach()
    int count = 0;
    int res = _Py_hashtable_foreach(table, hashtable_cb, &count);
    assert(res == 0);
    assert(count == 25);

    // Test _Py_hashtable_clear()
    _Py_hashtable_clear(table);
    assert(table->nentries == 0);
    assert(table->nbuckets > 0);
    assert(_Py_hashtable_get(table, TO_PTR('x')) == NULL);

    _Py_hashtable_destroy(table);
    Py_RETURN_NONE;
}


static PyObject *
test_reset_path_config(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(arg))
{
    _PyPathConfig_ClearGlobal();
    Py_RETURN_NONE;
}


static int
check_edit_cost(const char *a, const char *b, Py_ssize_t expected)
{
    int ret = -1;
    PyObject *a_obj = NULL;
    PyObject *b_obj = NULL;

    a_obj = PyUnicode_FromString(a);
    if (a_obj == NULL) {
        goto exit;
    }
    b_obj = PyUnicode_FromString(b);
    if (b_obj == NULL) {
        goto exit;
    }
    Py_ssize_t result = _Py_UTF8_Edit_Cost(a_obj, b_obj, -1);
    if (result != expected) {
        PyErr_Format(PyExc_AssertionError,
                     "Edit cost from '%s' to '%s' returns %zd, expected %zd",
                     a, b, result, expected);
        goto exit;
    }
    // Check that smaller max_edits thresholds are exceeded.
    Py_ssize_t max_edits = result;
    while (max_edits > 0) {
        max_edits /= 2;
        Py_ssize_t result2 = _Py_UTF8_Edit_Cost(a_obj, b_obj, max_edits);
        if (result2 <= max_edits) {
            PyErr_Format(PyExc_AssertionError,
                         "Edit cost from '%s' to '%s' (threshold %zd) "
                         "returns %zd, expected greater than %zd",
                         a, b, max_edits, result2, max_edits);
            goto exit;
        }
    }
    // Check that bigger max_edits thresholds don't change anything
    Py_ssize_t result3 = _Py_UTF8_Edit_Cost(a_obj, b_obj, result * 2 + 1);
    if (result3 != result) {
        PyErr_Format(PyExc_AssertionError,
                     "Edit cost from '%s' to '%s' (threshold %zd) "
                     "returns %zd, expected %zd",
                     a, b, result * 2, result3, result);
        goto exit;
    }
    ret = 0;
exit:
    Py_XDECREF(a_obj);
    Py_XDECREF(b_obj);
    return ret;
}

static PyObject *
test_edit_cost(PyObject *self, PyObject *Py_UNUSED(args))
{
    #define CHECK(a, b, n) do {              \
        if (check_edit_cost(a, b, n) < 0) {  \
            return NULL;                     \
        }                                    \
    } while (0)                              \

    CHECK("", "", 0);
    CHECK("", "a", 2);
    CHECK("a", "A", 1);
    CHECK("Apple", "Aple", 2);
    CHECK("Banana", "B@n@n@", 6);
    CHECK("Cherry", "Cherry!", 2);
    CHECK("---0---", "------", 2);
    CHECK("abc", "y", 6);
    CHECK("aa", "bb", 4);
    CHECK("aaaaa", "AAAAA", 5);
    CHECK("wxyz", "wXyZ", 2);
    CHECK("wxyz", "wXyZ123", 8);
    CHECK("Python", "Java", 12);
    CHECK("Java", "C#", 8);
    CHECK("AbstractFoobarManager", "abstract_foobar_manager", 3+2*2);
    CHECK("CPython", "PyPy", 10);
    CHECK("CPython", "pypy", 11);
    CHECK("AttributeError", "AttributeErrop", 2);
    CHECK("AttributeError", "AttributeErrorTests", 10);

    #undef CHECK
    Py_RETURN_NONE;
}


static int
check_bytes_find(const char *haystack0, const char *needle0,
                 Py_ssize_t offset, Py_ssize_t expected)
{
    Py_ssize_t len_haystack = strlen(haystack0);
    Py_ssize_t len_needle = strlen(needle0);
    Py_ssize_t result_1 = _PyBytes_Find(haystack0, len_haystack,
                                        needle0, len_needle, offset);
    if (result_1 != expected) {
        PyErr_Format(PyExc_AssertionError,
                    "Incorrect result_1: '%s' in '%s' (offset=%zd)",
                    needle0, haystack0, offset);
        return -1;
    }
    // Allocate new buffer with no NULL terminator.
    char *haystack = PyMem_Malloc(len_haystack);
    if (haystack == NULL) {
        PyErr_NoMemory();
        return -1;
    }
    char *needle = PyMem_Malloc(len_needle);
    if (needle == NULL) {
        PyMem_Free(haystack);
        PyErr_NoMemory();
        return -1;
    }
    memcpy(haystack, haystack0, len_haystack);
    memcpy(needle, needle0, len_needle);
    Py_ssize_t result_2 = _PyBytes_Find(haystack, len_haystack,
                                        needle, len_needle, offset);
    PyMem_Free(haystack);
    PyMem_Free(needle);
    if (result_2 != expected) {
        PyErr_Format(PyExc_AssertionError,
                    "Incorrect result_2: '%s' in '%s' (offset=%zd)",
                    needle0, haystack0, offset);
        return -1;
    }
    return 0;
}

static int
check_bytes_find_large(Py_ssize_t len_haystack, Py_ssize_t len_needle,
                       const char *needle)
{
    char *zeros = PyMem_RawCalloc(len_haystack, 1);
    if (zeros == NULL) {
        PyErr_NoMemory();
        return -1;
    }
    Py_ssize_t res = _PyBytes_Find(zeros, len_haystack, needle, len_needle, 0);
    PyMem_RawFree(zeros);
    if (res != -1) {
        PyErr_Format(PyExc_AssertionError,
                    "check_bytes_find_large(%zd, %zd) found %zd",
                    len_haystack, len_needle, res);
        return -1;
    }
    return 0;
}

static PyObject *
test_bytes_find(PyObject *self, PyObject *Py_UNUSED(args))
{
    #define CHECK(H, N, O, E) do {               \
        if (check_bytes_find(H, N, O, E) < 0) {  \
            return NULL;                         \
        }                                        \
    } while (0)

    CHECK("", "", 0, 0);
    CHECK("Python", "", 0, 0);
    CHECK("Python", "", 3, 3);
    CHECK("Python", "", 6, 6);
    CHECK("Python", "yth", 0, 1);
    CHECK("ython", "yth", 1, 1);
    CHECK("thon", "yth", 2, -1);
    CHECK("Python", "thon", 0, 2);
    CHECK("ython", "thon", 1, 2);
    CHECK("thon", "thon", 2, 2);
    CHECK("hon", "thon", 3, -1);
    CHECK("Pytho", "zz", 0, -1);
    CHECK("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", "ab", 0, -1);
    CHECK("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", "ba", 0, -1);
    CHECK("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", "bb", 0, -1);
    CHECK("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab", "ab", 0, 30);
    CHECK("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaba", "ba", 0, 30);
    CHECK("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaabb", "bb", 0, 30);
    #undef CHECK

    // Hunt for segfaults
    // n, m chosen here so that (n - m) % (m + 1) == 0
    // This would make default_find in fastsearch.h access haystack[n].
    if (check_bytes_find_large(2048, 2, "ab") < 0) {
        return NULL;
    }
    if (check_bytes_find_large(4096, 16, "0123456789abcdef") < 0) {
        return NULL;
    }
    if (check_bytes_find_large(8192, 2, "ab") < 0) {
        return NULL;
    }
    if (check_bytes_find_large(16384, 4, "abcd") < 0) {
        return NULL;
    }
    if (check_bytes_find_large(32768, 2, "ab") < 0) {
        return NULL;
    }
    Py_RETURN_NONE;
}


static PyObject *
normalize_path(PyObject *self, PyObject *filename)
{
    Py_ssize_t size = -1;
    wchar_t *encoded = PyUnicode_AsWideCharString(filename, &size);
    if (encoded == NULL) {
        return NULL;
    }

    PyObject *result = PyUnicode_FromWideChar(_Py_normpath(encoded, size), -1);
    PyMem_Free(encoded);

    return result;
}

static PyObject *
get_getpath_codeobject(PyObject *self, PyObject *Py_UNUSED(args)) {
    return _Py_Get_Getpath_CodeObject();
}


static PyObject *
encode_locale_ex(PyObject *self, PyObject *args)
{
    PyObject *unicode;
    int current_locale = 0;
    wchar_t *wstr;
    PyObject *res = NULL;
    const char *errors = NULL;

    if (!PyArg_ParseTuple(args, "U|is", &unicode, &current_locale, &errors)) {
        return NULL;
    }
    wstr = PyUnicode_AsWideCharString(unicode, NULL);
    if (wstr == NULL) {
        return NULL;
    }
    _Py_error_handler error_handler = _Py_GetErrorHandler(errors);

    char *str = NULL;
    size_t error_pos;
    const char *reason = NULL;
    int ret = _Py_EncodeLocaleEx(wstr,
                                 &str, &error_pos, &reason,
                                 current_locale, error_handler);
    PyMem_Free(wstr);

    switch(ret) {
    case 0:
        res = PyBytes_FromString(str);
        PyMem_RawFree(str);
        break;
    case -1:
        PyErr_NoMemory();
        break;
    case -2:
        PyErr_Format(PyExc_RuntimeError, "encode error: pos=%zu, reason=%s",
                     error_pos, reason);
        break;
    case -3:
        PyErr_SetString(PyExc_ValueError, "unsupported error handler");
        break;
    default:
        PyErr_SetString(PyExc_ValueError, "unknown error code");
        break;
    }
    return res;
}


static PyObject *
decode_locale_ex(PyObject *self, PyObject *args)
{
    char *str;
    int current_locale = 0;
    PyObject *res = NULL;
    const char *errors = NULL;

    if (!PyArg_ParseTuple(args, "y|is", &str, &current_locale, &errors)) {
        return NULL;
    }
    _Py_error_handler error_handler = _Py_GetErrorHandler(errors);

    wchar_t *wstr = NULL;
    size_t wlen = 0;
    const char *reason = NULL;
    int ret = _Py_DecodeLocaleEx(str,
                                 &wstr, &wlen, &reason,
                                 current_locale, error_handler);

    switch(ret) {
    case 0:
        res = PyUnicode_FromWideChar(wstr, wlen);
        PyMem_RawFree(wstr);
        break;
    case -1:
        PyErr_NoMemory();
        break;
    case -2:
        PyErr_Format(PyExc_RuntimeError, "decode error: pos=%zu, reason=%s",
                     wlen, reason);
        break;
    case -3:
        PyErr_SetString(PyExc_ValueError, "unsupported error handler");
        break;
    default:
        PyErr_SetString(PyExc_ValueError, "unknown error code");
        break;
    }
    return res;
}

static PyObject *
set_eval_frame_default(PyObject *self, PyObject *Py_UNUSED(args))
{
    module_state *state = get_module_state(self);
    _PyInterpreterState_SetEvalFrameFunc(_PyInterpreterState_GET(), _PyEval_EvalFrameDefault);
    Py_CLEAR(state->record_list);
    Py_RETURN_NONE;
}

static PyObject *
record_eval(PyThreadState *tstate, struct _PyInterpreterFrame *f, int exc)
{
    if (PyStackRef_FunctionCheck(f->f_funcobj)) {
        PyFunctionObject *func = _PyFrame_GetFunction(f);
        PyObject *module = _get_current_module();
        assert(module != NULL);
        module_state *state = get_module_state(module);
        Py_DECREF(module);
        int res = PyList_Append(state->record_list, func->func_name);
        if (res < 0) {
            return NULL;
        }
    }
    return _PyEval_EvalFrameDefault(tstate, f, exc);
}


static PyObject *
set_eval_frame_record(PyObject *self, PyObject *list)
{
    module_state *state = get_module_state(self);
    if (!PyList_Check(list)) {
        PyErr_SetString(PyExc_TypeError, "argument must be a list");
        return NULL;
    }
    Py_XSETREF(state->record_list, Py_NewRef(list));
    _PyInterpreterState_SetEvalFrameFunc(_PyInterpreterState_GET(), record_eval);
    Py_RETURN_NONE;
}

// Defined in interpreter.c
extern PyObject*
Test_EvalFrame(PyThreadState *tstate, _PyInterpreterFrame *frame, int throwflag);
extern int Test_EvalFrame_Resumes, Test_EvalFrame_Loads;

static PyObject *
get_eval_frame_stats(PyObject *self, PyObject *Py_UNUSED(args))
{
    PyObject *res = PyDict_New();
    if (res == NULL) {
        return NULL;
    }
    PyObject *resumes = PyLong_FromLong(Test_EvalFrame_Resumes);
    if (resumes == NULL || PyDict_SetItemString(res, "resumes", resumes) < 0) {
        Py_XDECREF(resumes);
        Py_DECREF(res);
        return NULL;
    }
    Py_DECREF(resumes);
    PyObject *loads = PyLong_FromLong(Test_EvalFrame_Loads);
    if (loads == NULL || PyDict_SetItemString(res, "loads", loads) < 0) {
        Py_XDECREF(loads);
        Py_DECREF(res);
        return NULL;
    }
    Py_DECREF(loads);
    Test_EvalFrame_Resumes = Test_EvalFrame_Loads = 0;
    return res;
}

static PyObject *
record_eval_interp(PyThreadState *tstate, struct _PyInterpreterFrame *f, int exc)
{
    if (PyStackRef_FunctionCheck(f->f_funcobj)) {
        PyFunctionObject *func = _PyFrame_GetFunction(f);
        PyObject *module = _get_current_module();
        assert(module != NULL);
        module_state *state = get_module_state(module);
        Py_DECREF(module);
        int res = PyList_Append(state->record_list, func->func_name);
        if (res < 0) {
            return NULL;
        }
    }

    return Test_EvalFrame(tstate, f, exc);
}

static PyObject *
set_eval_frame_interp(PyObject *self, PyObject *args)
{
    if (PyTuple_GET_SIZE(args) == 1) {
        module_state *state = get_module_state(self);
        PyObject *list = PyTuple_GET_ITEM(args, 0);
        if (!PyList_Check(list)) {
            PyErr_SetString(PyExc_TypeError, "argument must be a list");
            return NULL;
        }
        Py_XSETREF(state->record_list, Py_NewRef(list));
        _PyInterpreterState_SetEvalFrameFunc(_PyInterpreterState_GET(), record_eval_interp);
        _PyInterpreterState_SetEvalFrameAllowSpecialization(_PyInterpreterState_GET(), 1);
    } else {
        _PyInterpreterState_SetEvalFrameFunc(_PyInterpreterState_GET(), Test_EvalFrame);
        _PyInterpreterState_SetEvalFrameAllowSpecialization(_PyInterpreterState_GET(), 1);
    }

    Py_RETURN_NONE;
}

static PyObject *
is_specialization_enabled(PyObject *self, PyObject *Py_UNUSED(args))
{
    return PyBool_FromLong(
        _PyInterpreterState_IsSpecializationEnabled(_PyInterpreterState_GET()));
}

/*[clinic input]

_testinternalcapi.compiler_cleandoc -> object

    doc: unicode

C implementation of inspect.cleandoc().
[clinic start generated code]*/

static PyObject *
_testinternalcapi_compiler_cleandoc_impl(PyObject *module, PyObject *doc)
/*[clinic end generated code: output=2dd203a80feff5bc input=2de03fab931d9cdc]*/
{
    return _PyCompile_CleanDoc(doc);
}

/*[clinic input]

_testinternalcapi.new_instruction_sequence -> object

Return a new, empty InstructionSequence.
[clinic start generated code]*/

static PyObject *
_testinternalcapi_new_instruction_sequence_impl(PyObject *module)
/*[clinic end generated code: output=ea4243fddb9057fd input=1dec2591b173be83]*/
{
    return _PyInstructionSequence_New();
}

/*[clinic input]

_testinternalcapi.compiler_codegen -> object

  ast: object
  filename: object
  optimize: int
  compile_mode: int = 0

Apply compiler code generation to an AST.

Return (instruction_sequence, metadata).  metadata maps "argcount",
"posonlyargcount", "kwonlyargcount" to ints and "consts" to the list of
constants in LOAD_CONST index order (for use with optimize_cfg).
[clinic start generated code]*/

static PyObject *
_testinternalcapi_compiler_codegen_impl(PyObject *module, PyObject *ast,
                                        PyObject *filename, int optimize,
                                        int compile_mode)
/*[clinic end generated code: output=40a68f6e13951cc8 input=e0c65e5c80efe30e]*/
{
    PyCompilerFlags *flags = NULL;
    return _PyCompile_CodeGen(ast, filename, flags, optimize, compile_mode);
}


/*[clinic input]

_testinternalcapi.optimize_cfg -> object

  instructions: object
  consts: object
  nlocals: int

Apply compiler optimizations to an instruction list.

consts must be a list aligned with LOAD_CONST opargs (the "consts" entry
from the metadata dict returned by compiler_codegen for the same unit).
[clinic start generated code]*/

static PyObject *
_testinternalcapi_optimize_cfg_impl(PyObject *module, PyObject *instructions,
                                    PyObject *consts, int nlocals)
/*[clinic end generated code: output=57c53c3a3dfd1df0 input=905c3d935e063b27]*/
{
    return _PyCompile_OptimizeCfg(instructions, consts, nlocals);
}

static int
get_nonnegative_int_from_dict(PyObject *dict, const char *key) {
    PyObject *obj = PyDict_GetItemString(dict, key);
    if (obj == NULL) {
        return -1;
    }
    return PyLong_AsLong(obj);
}

/*[clinic input]

_testinternalcapi.assemble_code_object -> object

  filename: object
  instructions: object
  metadata: object

Create a code object for the given instructions.
[clinic start generated code]*/

static PyObject *
_testinternalcapi_assemble_code_object_impl(PyObject *module,
                                            PyObject *filename,
                                            PyObject *instructions,
                                            PyObject *metadata)
/*[clinic end generated code: output=38003dc16a930f48 input=e713ad77f08fb3a8]*/

{
    assert(PyDict_Check(metadata));
    _PyCompile_CodeUnitMetadata umd;

    umd.u_name = PyDict_GetItemString(metadata, "name");
    umd.u_qualname = PyDict_GetItemString(metadata, "qualname");

    assert(PyUnicode_Check(umd.u_name));
    assert(PyUnicode_Check(umd.u_qualname));

    umd.u_consts = PyDict_GetItemString(metadata, "consts");
    umd.u_names = PyDict_GetItemString(metadata, "names");
    umd.u_varnames = PyDict_GetItemString(metadata, "varnames");
    umd.u_cellvars = PyDict_GetItemString(metadata, "cellvars");
    umd.u_freevars = PyDict_GetItemString(metadata, "freevars");
    umd.u_fasthidden = PyDict_GetItemString(metadata, "fasthidden");

    assert(PyDict_Check(umd.u_consts));
    assert(PyDict_Check(umd.u_names));
    assert(PyDict_Check(umd.u_varnames));
    assert(PyDict_Check(umd.u_cellvars));
    assert(PyDict_Check(umd.u_freevars));
    assert(PyDict_Check(umd.u_fasthidden));

    umd.u_argcount = get_nonnegative_int_from_dict(metadata, "argcount");
    umd.u_posonlyargcount = get_nonnegative_int_from_dict(metadata, "posonlyargcount");
    umd.u_kwonlyargcount = get_nonnegative_int_from_dict(metadata, "kwonlyargcount");
    umd.u_firstlineno = get_nonnegative_int_from_dict(metadata, "firstlineno");

    assert(umd.u_argcount >= 0);
    assert(umd.u_posonlyargcount >= 0);
    assert(umd.u_kwonlyargcount >= 0);
    assert(umd.u_firstlineno >= 0);

    return (PyObject*)_PyCompile_Assemble(&umd, filename, instructions);
}


// Maybe this could be replaced by get_interpreter_config()?
static PyObject *
get_interp_settings(PyObject *self, PyObject *args)
{
    int interpid = -1;
    if (!PyArg_ParseTuple(args, "|i:get_interp_settings", &interpid)) {
        return NULL;
    }

    PyInterpreterState *interp = NULL;
    if (interpid < 0) {
        PyThreadState *tstate = _PyThreadState_GET();
        interp = tstate ? tstate->interp : _PyInterpreterState_Main();
    }
    else if (interpid == 0) {
        interp = _PyInterpreterState_Main();
    }
    else {
        PyErr_Format(PyExc_NotImplementedError,
                     "%d", interpid);
        return NULL;
    }
    assert(interp != NULL);

    PyObject *settings = PyDict_New();
    if (settings == NULL) {
        return NULL;
    }

    /* Add the feature flags. */
    PyObject *flags = PyLong_FromUnsignedLong(interp->feature_flags);
    if (flags == NULL) {
        Py_DECREF(settings);
        return NULL;
    }
    int res = PyDict_SetItemString(settings, "feature_flags", flags);
    Py_DECREF(flags);
    if (res != 0) {
        Py_DECREF(settings);
        return NULL;
    }

    /* "own GIL" */
    PyObject *own_gil = interp->ceval.own_gil ? Py_True : Py_False;
    if (PyDict_SetItemString(settings, "own_gil", own_gil) != 0) {
        Py_DECREF(settings);
        return NULL;
    }

    return settings;
}


static PyObject *
clear_extension(PyObject *self, PyObject *args)
{
    PyObject *name = NULL, *filename = NULL;
    if (!PyArg_ParseTuple(args, "OO:clear_extension", &name, &filename)) {
        return NULL;
    }
    if (_PyImport_ClearExtension(name, filename) < 0) {
        return NULL;
    }
    Py_RETURN_NONE;
}

static PyObject *
write_perf_map_entry(PyObject *self, PyObject *args)
{
    PyObject *code_addr_v;
    const void *code_addr;
    PyObject *code_size_s;
    size_t code_size;
    const char *entry_name;

    if (!PyArg_ParseTuple(args, "OOs", &code_addr_v, &code_size_s, &entry_name))
        return NULL;
    code_addr = PyLong_AsVoidPtr(code_addr_v);
    if (code_addr == NULL) {
        return NULL;
    }

    code_size = PyLong_AsSize_t(code_size_s);
    if (code_size == (size_t)-1 && PyErr_Occurred()) {
        return NULL;
    }

    int ret = PyUnstable_WritePerfMapEntry(code_addr, code_size, entry_name);
    if (ret < 0) {
        PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }
    return PyLong_FromLong(ret);
}

static PyObject *
perf_map_state_teardown(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(ignored))
{
    PyUnstable_PerfMapState_Fini();
    Py_RETURN_NONE;
}

static PyObject *
iframe_getcode(PyObject *self, PyObject *frame)
{
    if (!PyFrame_Check(frame)) {
        PyErr_SetString(PyExc_TypeError, "argument must be a frame");
        return NULL;
    }
    struct _PyInterpreterFrame *f = ((PyFrameObject *)frame)->f_frame;
    return PyUnstable_InterpreterFrame_GetCode(f);
}

static PyObject *
iframe_getline(PyObject *self, PyObject *frame)
{
    if (!PyFrame_Check(frame)) {
        PyErr_SetString(PyExc_TypeError, "argument must be a frame");
        return NULL;
    }
    struct _PyInterpreterFrame *f = ((PyFrameObject *)frame)->f_frame;
    return PyLong_FromLong(PyUnstable_InterpreterFrame_GetLine(f));
}

static PyObject *
iframe_getlasti(PyObject *self, PyObject *frame)
{
    if (!PyFrame_Check(frame)) {
        PyErr_SetString(PyExc_TypeError, "argument must be a frame");
        return NULL;
    }
    struct _PyInterpreterFrame *f = ((PyFrameObject *)frame)->f_frame;
    return PyLong_FromLong(PyUnstable_InterpreterFrame_GetLasti(f));
}

static PyObject *
code_returns_only_none(PyObject *self, PyObject *arg)
{
    if (!PyCode_Check(arg)) {
        PyErr_SetString(PyExc_TypeError, "argument must be a code object");
        return NULL;
    }
    PyCodeObject *code = (PyCodeObject *)arg;
    int res = _PyCode_ReturnsOnlyNone(code);
    return PyBool_FromLong(res);
}

static PyObject *
get_co_framesize(PyObject *self, PyObject *arg)
{
    if (!PyCode_Check(arg)) {
        PyErr_SetString(PyExc_TypeError, "argument must be a code object");
        return NULL;
    }
    PyCodeObject *code = (PyCodeObject *)arg;
    return PyLong_FromLong(code->co_framesize);
}

static PyObject *
get_co_localskinds(PyObject *self, PyObject *arg)
{
    if (!PyCode_Check(arg)) {
        PyErr_SetString(PyExc_TypeError, "argument must be a code object");
        return NULL;
    }
    PyCodeObject *co = (PyCodeObject *)arg;

    PyObject *kinds = PyDict_New();
    if (kinds == NULL) {
        return NULL;
    }
    for (int offset = 0; offset < co->co_nlocalsplus; offset++) {
        PyObject *name = PyTuple_GET_ITEM(co->co_localsplusnames, offset);
        _PyLocals_Kind k = _PyLocals_GetKind(co->co_localspluskinds, offset);
        PyObject *kind = PyLong_FromLong(k);
        if (kind == NULL) {
            Py_DECREF(kinds);
            return NULL;
        }
        int res = PyDict_SetItem(kinds, name, kind);
        Py_DECREF(kind);
        if (res < 0) {
            Py_DECREF(kinds);
            return NULL;
        }
    }
    return kinds;
}

static PyObject *
get_code_var_counts(PyObject *self, PyObject *_args, PyObject *_kwargs)
{
    PyThreadState *tstate = _PyThreadState_GET();
    PyObject *codearg;
    PyObject *globalnames = NULL;
    PyObject *attrnames = NULL;
    PyObject *globalsns = NULL;
    PyObject *builtinsns = NULL;
    static char *kwlist[] = {"code", "globalnames", "attrnames", "globalsns",
                             "builtinsns", NULL};
    if (!PyArg_ParseTupleAndKeywords(_args, _kwargs,
                    "O|OOO!O!:get_code_var_counts", kwlist,
                    &codearg, &globalnames, &attrnames,
                    &PyDict_Type, &globalsns, &PyDict_Type, &builtinsns))
    {
        return NULL;
    }
    if (PyFunction_Check(codearg)) {
        if (globalsns == NULL) {
            globalsns = PyFunction_GET_GLOBALS(codearg);
        }
        if (builtinsns == NULL) {
            builtinsns = _PyFunction_GET_BUILTINS(codearg);
        }
        codearg = PyFunction_GET_CODE(codearg);
    }
    else if (!PyCode_Check(codearg)) {
        PyErr_SetString(PyExc_TypeError,
                        "argument must be a code object or a function");
        return NULL;
    }
    PyCodeObject *code = (PyCodeObject *)codearg;

    _PyCode_var_counts_t counts = {0};
    _PyCode_GetVarCounts(code, &counts);
    if (_PyCode_SetUnboundVarCounts(
            tstate, code, &counts, globalnames, attrnames,
            globalsns, builtinsns) < 0)
    {
        return NULL;
    }

#define SET_COUNT(DICT, STRUCT, NAME) \
    do { \
        PyObject *count = PyLong_FromLong(STRUCT.NAME); \
        if (count == NULL) { \
            goto error; \
        } \
        int res = PyDict_SetItemString(DICT, #NAME, count); \
        Py_DECREF(count); \
        if (res < 0) { \
            goto error; \
        } \
    } while (0)

    PyObject *locals = NULL;
    PyObject *args = NULL;
    PyObject *cells = NULL;
    PyObject *hidden = NULL;
    PyObject *unbound = NULL;
    PyObject *globals = NULL;
    PyObject *countsobj = PyDict_New();
    if (countsobj == NULL) {
        return NULL;
    }
    SET_COUNT(countsobj, counts, total);

    // locals
    locals = PyDict_New();
    if (locals == NULL) {
        goto error;
    }
    if (PyDict_SetItemString(countsobj, "locals", locals) < 0) {
        goto error;
    }
    SET_COUNT(locals, counts.locals, total);

    // locals.args
    args = PyDict_New();
    if (args == NULL) {
        goto error;
    }
    if (PyDict_SetItemString(locals, "args", args) < 0) {
        goto error;
    }
    SET_COUNT(args, counts.locals.args, total);
    SET_COUNT(args, counts.locals.args, numposonly);
    SET_COUNT(args, counts.locals.args, numposorkw);
    SET_COUNT(args, counts.locals.args, numkwonly);
    SET_COUNT(args, counts.locals.args, varargs);
    SET_COUNT(args, counts.locals.args, varkwargs);

    // locals.numpure
    SET_COUNT(locals, counts.locals, numpure);

    // locals.cells
    cells = PyDict_New();
    if (cells == NULL) {
        goto error;
    }
    if (PyDict_SetItemString(locals, "cells", cells) < 0) {
        goto error;
    }
    SET_COUNT(cells, counts.locals.cells, total);
    SET_COUNT(cells, counts.locals.cells, numargs);
    SET_COUNT(cells, counts.locals.cells, numothers);

    // locals.hidden
    hidden = PyDict_New();
    if (hidden == NULL) {
        goto error;
    }
    if (PyDict_SetItemString(locals, "hidden", hidden) < 0) {
        goto error;
    }
    SET_COUNT(hidden, counts.locals.hidden, total);
    SET_COUNT(hidden, counts.locals.hidden, numpure);
    SET_COUNT(hidden, counts.locals.hidden, numcells);

    // numfree
    SET_COUNT(countsobj, counts, numfree);

    // unbound
    unbound = PyDict_New();
    if (unbound == NULL) {
        goto error;
    }
    if (PyDict_SetItemString(countsobj, "unbound", unbound) < 0) {
        goto error;
    }
    SET_COUNT(unbound, counts.unbound, total);
    SET_COUNT(unbound, counts.unbound, numattrs);
    SET_COUNT(unbound, counts.unbound, numunknown);

    // unbound.globals
    globals = PyDict_New();
    if (globals == NULL) {
        goto error;
    }
    if (PyDict_SetItemString(unbound, "globals", globals) < 0) {
        goto error;
    }
    SET_COUNT(globals, counts.unbound.globals, total);
    SET_COUNT(globals, counts.unbound.globals, numglobal);
    SET_COUNT(globals, counts.unbound.globals, numbuiltin);
    SET_COUNT(globals, counts.unbound.globals, numunknown);

#undef SET_COUNT

    Py_DECREF(locals);
    Py_DECREF(args);
    Py_DECREF(cells);
    Py_DECREF(hidden);
    Py_DECREF(unbound);
    Py_DECREF(globals);
    return countsobj;

error:
    Py_DECREF(countsobj);
    Py_XDECREF(locals);
    Py_XDECREF(args);
    Py_XDECREF(cells);
    Py_XDECREF(hidden);
    Py_XDECREF(unbound);
    Py_XDECREF(globals);
    return NULL;
}

static PyObject *
verify_stateless_code(PyObject *self, PyObject *args, PyObject *kwargs)
{
    PyThreadState *tstate = _PyThreadState_GET();
    PyObject *codearg;
    PyObject *globalnames = NULL;
    PyObject *globalsns = NULL;
    PyObject *builtinsns = NULL;
    static char *kwlist[] = {"code", "globalnames",
                             "globalsns", "builtinsns", NULL};
    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
                    "O|O!O!O!:get_code_var_counts", kwlist,
                    &codearg, &PySet_Type, &globalnames,
                    &PyDict_Type, &globalsns, &PyDict_Type, &builtinsns))
    {
        return NULL;
    }
    if (PyFunction_Check(codearg)) {
        if (globalsns == NULL) {
            globalsns = PyFunction_GET_GLOBALS(codearg);
        }
        if (builtinsns == NULL) {
            builtinsns = _PyFunction_GET_BUILTINS(codearg);
        }
        codearg = PyFunction_GET_CODE(codearg);
    }
    else if (!PyCode_Check(codearg)) {
        PyErr_SetString(PyExc_TypeError,
                        "argument must be a code object or a function");
        return NULL;
    }
    PyCodeObject *code = (PyCodeObject *)codearg;

    if (_PyCode_VerifyStateless(
                tstate, code, globalnames, globalsns, builtinsns) < 0)
    {
        return NULL;
    }
    Py_RETURN_NONE;
}

#ifdef _Py_TIER2

static PyObject *
add_executor_dependency(PyObject *self, PyObject *args)
{
    PyObject *exec;
    PyObject *obj;
    if (!PyArg_ParseTuple(args, "OO", &exec, &obj)) {
        return NULL;
    }
    _Py_Executor_DependsOn((_PyExecutorObject *)exec, obj);
    Py_RETURN_NONE;
}

static PyObject *
invalidate_executors(PyObject *self, PyObject *obj)
{
    PyInterpreterState *interp = PyInterpreterState_Get();
    _Py_Executors_InvalidateDependency(interp, obj, 1);
    Py_RETURN_NONE;
}

static PyObject *
clear_executor_deletion_list(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    PyInterpreterState *interp = PyInterpreterState_Get();
    _Py_ClearExecutorDeletionList(interp);
    Py_RETURN_NONE;
}

static PyObject *
get_exit_executor(PyObject *self, PyObject *arg)
{
    if (!PyLong_CheckExact(arg)) {
        PyErr_SetString(PyExc_TypeError, "argument must be an ID to an _PyExitData");
        return NULL;
    }
    uint64_t ptr;
    if (PyLong_AsUInt64(arg, &ptr) < 0) {
        // Error set by PyLong API
        return NULL;
    }
    _PyExitData *exit = (_PyExitData *)ptr;
    return Py_NewRef(exit->executor);
}

#endif

static int _pending_callback(void *arg)
{
    /* we assume the argument is callable object to which we own a reference */
    PyObject *callable = (PyObject *)arg;
    PyObject *r = PyObject_CallNoArgs(callable);
    Py_DECREF(callable);
    Py_XDECREF(r);
    return r != NULL ? 0 : -1;
}

/* The following requests n callbacks to _pending_callback.  It can be
 * run from any python thread.
 */
static PyObject *
pending_threadfunc(PyObject *self, PyObject *args, PyObject *kwargs)
{
    PyObject *callable;
    unsigned int num = 1;
    int blocking = 0;
    int ensure_added = 0;
    static char *kwlist[] = {"callback", "num",
                             "blocking", "ensure_added", NULL};
    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
                                     "O|I$pp:pending_threadfunc", kwlist,
                                     &callable, &num, &blocking, &ensure_added))
    {
        return NULL;
    }
    PyInterpreterState *interp = _PyInterpreterState_GET();

    /* create the reference for the callbackwhile we hold the lock */
    for (unsigned int i = 0; i < num; i++) {
        Py_INCREF(callable);
    }

    PyThreadState *save_tstate = NULL;
    if (!blocking) {
        save_tstate = PyEval_SaveThread();
    }

    unsigned int num_added = 0;
    for (; num_added < num; num_added++) {
        if (ensure_added) {
            _Py_add_pending_call_result r;
            do {
                r = _PyEval_AddPendingCall(interp, &_pending_callback, callable, 0);
                assert(r == _Py_ADD_PENDING_SUCCESS
                       || r == _Py_ADD_PENDING_FULL);
            } while (r == _Py_ADD_PENDING_FULL);
        }
        else {
            if (_PyEval_AddPendingCall(interp, &_pending_callback, callable, 0) < 0) {
                break;
            }
        }
    }

    if (!blocking) {
        PyEval_RestoreThread(save_tstate);
    }

    for (unsigned int i = num_added; i < num; i++) {
        Py_DECREF(callable); /* unsuccessful add, destroy the extra reference */
    }

    /* The callable is decref'ed in _pending_callback() above. */
    return PyLong_FromUnsignedLong((unsigned long)num_added);
}


static struct {
    int64_t interpid;
} pending_identify_result;

static int
_pending_identify_callback(void *arg)
{
    PyThread_type_lock mutex = (PyThread_type_lock)arg;
    assert(pending_identify_result.interpid == -1);
    PyThreadState *tstate = PyThreadState_Get();
    pending_identify_result.interpid = PyInterpreterState_GetID(tstate->interp);
    PyThread_release_lock(mutex);
    return 0;
}

static PyObject *
pending_identify(PyObject *self, PyObject *args)
{
    PyObject *interpid;
    if (!PyArg_ParseTuple(args, "O:pending_identify", &interpid)) {
        return NULL;
    }
    PyInterpreterState *interp = _PyInterpreterState_LookUpIDObject(interpid);
    if (interp == NULL) {
        if (!PyErr_Occurred()) {
            PyErr_SetString(PyExc_ValueError, "interpreter not found");
        }
        return NULL;
    }

    pending_identify_result.interpid = -1;

    PyThread_type_lock mutex = PyThread_allocate_lock();
    if (mutex == NULL) {
        return NULL;
    }
    PyThread_acquire_lock(mutex, WAIT_LOCK);
    /* It gets released in _pending_identify_callback(). */

    _Py_add_pending_call_result r;
    do {
        Py_BEGIN_ALLOW_THREADS
        r = _PyEval_AddPendingCall(interp,
                                   &_pending_identify_callback, (void *)mutex,
                                   0);
        Py_END_ALLOW_THREADS
        assert(r == _Py_ADD_PENDING_SUCCESS
               || r == _Py_ADD_PENDING_FULL);
    } while (r == _Py_ADD_PENDING_FULL);

    /* Wait for the pending call to complete. */
    PyThread_acquire_lock(mutex, WAIT_LOCK);
    PyThread_release_lock(mutex);
    PyThread_free_lock(mutex);

    PyObject *res = PyLong_FromLongLong(pending_identify_result.interpid);
    pending_identify_result.interpid = -1;
    if (res == NULL) {
        return NULL;
    }
    return res;
}

static PyObject *
tracemalloc_get_traceback(PyObject *self, PyObject *args)
{
    unsigned int domain;
    PyObject *ptr_obj;

    if (!PyArg_ParseTuple(args, "IO", &domain, &ptr_obj)) {
        return NULL;
    }
    void *ptr = PyLong_AsVoidPtr(ptr_obj);
    if (PyErr_Occurred()) {
        return NULL;
    }

    return _PyTraceMalloc_GetTraceback(domain, (uintptr_t)ptr);
}


// Test PyThreadState C API
static PyObject *
test_tstate_capi(PyObject *self, PyObject *Py_UNUSED(args))
{
    // PyThreadState_Get()
    PyThreadState *tstate = PyThreadState_Get();
    assert(tstate != NULL);

    // test _PyThreadState_GetDict()
    PyObject *dict = PyThreadState_GetDict();
    assert(dict != NULL);
    // dict is a borrowed reference

    PyObject *dict2 = _PyThreadState_GetDict(tstate);
    assert(dict2 == dict);
    // dict2 is a borrowed reference

    Py_RETURN_NONE;
}


/* Test _PyUnicode_TransformDecimalAndSpaceToASCII() */
static PyObject *
unicode_transformdecimalandspacetoascii(PyObject *self, PyObject *arg)
{
    if (arg == Py_None) {
        arg = NULL;
    }
    return _PyUnicode_TransformDecimalAndSpaceToASCII(arg);
}

static PyObject *
test_pyobject_is_freed(const char *test_name, PyObject *op)
{
    if (!_PyObject_IsFreed(op)) {
        PyErr_SetString(PyExc_AssertionError,
                        "object is not seen as freed");
        return NULL;
    }
    Py_RETURN_NONE;
}

static PyObject *
check_pyobject_null_is_freed(PyObject *self, PyObject *Py_UNUSED(args))
{
    PyObject *op = NULL;
    return test_pyobject_is_freed("check_pyobject_null_is_freed", op);
}


static PyObject *
check_pyobject_uninitialized_is_freed(PyObject *self,
                                      PyObject *Py_UNUSED(args))
{
    PyObject *op = (PyObject *)PyObject_Malloc(sizeof(PyObject));
    if (op == NULL) {
        return NULL;
    }
    /* Initialize reference count to avoid early crash in ceval or GC */
    Py_SET_REFCNT(op, 1);
    /* object fields like ob_type are uninitialized! */
    return test_pyobject_is_freed("check_pyobject_uninitialized_is_freed", op);
}


static PyObject *
check_pyobject_forbidden_bytes_is_freed(PyObject *self,
                                        PyObject *Py_UNUSED(args))
{
    /* Allocate an incomplete PyObject structure: truncate 'ob_type' field */
    PyObject *op = (PyObject *)PyObject_Malloc(offsetof(PyObject, ob_type));
    if (op == NULL) {
        return NULL;
    }
    /* Initialize reference count to avoid early crash in ceval or GC */
    Py_SET_REFCNT(op, 1);
    /* ob_type field is after the memory block: part of "forbidden bytes"
       when using debug hooks on memory allocators! */
    return test_pyobject_is_freed("check_pyobject_forbidden_bytes_is_freed", op);
}


static PyObject *
check_pyobject_freed_is_freed(PyObject *self, PyObject *Py_UNUSED(args))
{
    /* ASan or TSan would report an use-after-free error */
#if defined(_Py_ADDRESS_SANITIZER) || defined(_Py_THREAD_SANITIZER)
    Py_RETURN_NONE;
#else
    PyObject *op = PyObject_CallNoArgs((PyObject *)&PyBaseObject_Type);
    if (op == NULL) {
        return NULL;
    }
    Py_TYPE(op)->tp_dealloc(op);
    /* Reset reference count to avoid early crash in ceval or GC */
    Py_SET_REFCNT(op, 1);
    /* object memory is freed! */
    return test_pyobject_is_freed("check_pyobject_freed_is_freed", op);
#endif
}


static PyObject *
test_pymem_getallocatorsname(PyObject *self, PyObject *args)
{
    const char *name = _PyMem_GetCurrentAllocatorName();
    if (name == NULL) {
        PyErr_SetString(PyExc_RuntimeError, "cannot get allocators name");
        return NULL;
    }
    return PyUnicode_FromString(name);
}

static PyObject *
get_object_dict_values(PyObject *self, PyObject *obj)
{
    PyTypeObject *type = Py_TYPE(obj);
    if (!_PyType_HasFeature(type, Py_TPFLAGS_INLINE_VALUES)) {
        Py_RETURN_NONE;
    }
    PyDictValues *values = _PyObject_InlineValues(obj);
    if (!values->valid) {
        Py_RETURN_NONE;
    }
    PyDictKeysObject *keys = ((PyHeapTypeObject *)type)->ht_cached_keys;
    assert(keys != NULL);
    int size = (int)keys->dk_nentries;
    assert(size >= 0);
    PyObject *res = PyTuple_New(size);
    if (res == NULL) {
        return NULL;
    }
    _Py_DECLARE_STR(anon_null, "<NULL>");
    for(int i = 0; i < size; i++) {
        PyObject *item = values->values[i];
        if (item == NULL) {
            item = &_Py_STR(anon_null);
        }
        else {
            Py_INCREF(item);
        }
        PyTuple_SET_ITEM(res, i, item);
    }
    return res;
}


static PyObject*
new_hamt(PyObject *self, PyObject *args)
{
    return _PyContext_NewHamtForTests();
}


static PyObject*
dict_getitem_knownhash(PyObject *self, PyObject *args)
{
    PyObject *mp, *key, *result;
    Py_ssize_t hash;

    if (!PyArg_ParseTuple(args, "OOn:dict_getitem_knownhash",
                          &mp, &key, &hash)) {
        return NULL;
    }

    result = _PyDict_GetItem_KnownHash(mp, key, (Py_hash_t)hash);
    if (result == NULL && !PyErr_Occurred()) {
        _PyErr_SetKeyError(key);
        return NULL;
    }

    return Py_XNewRef(result);
}


static int
_init_interp_config_from_object(PyInterpreterConfig *config, PyObject *obj)
{
    if (obj == NULL) {
        *config = (PyInterpreterConfig)_PyInterpreterConfig_INIT;
        return 0;
    }

    PyObject *dict = PyObject_GetAttrString(obj, "__dict__");
    if (dict == NULL) {
        PyErr_Format(PyExc_TypeError, "bad config %R", obj);
        return -1;
    }
    int res = _PyInterpreterConfig_InitFromDict(config, dict);
    Py_DECREF(dict);
    if (res < 0) {
        return -1;
    }
    return 0;
}

static PyInterpreterState *
_new_interpreter(PyInterpreterConfig *config, long whence)
{
    if (whence == _PyInterpreterState_WHENCE_XI) {
        return _PyXI_NewInterpreter(config, &whence, NULL, NULL);
    }
    PyObject *exc = NULL;
    PyInterpreterState *interp = NULL;
    if (whence == _PyInterpreterState_WHENCE_UNKNOWN) {
        assert(config == NULL);
        interp = PyInterpreterState_New();
    }
    else if (whence == _PyInterpreterState_WHENCE_CAPI
             || whence == _PyInterpreterState_WHENCE_LEGACY_CAPI)
    {
        PyThreadState *tstate = NULL;
        PyThreadState *save_tstate = PyThreadState_Swap(NULL);
        if (whence == _PyInterpreterState_WHENCE_LEGACY_CAPI) {
            assert(config == NULL);
            tstate = Py_NewInterpreter();
            PyThreadState_Swap(save_tstate);
        }
        else {
            PyStatus status = Py_NewInterpreterFromConfig(&tstate, config);
            PyThreadState_Swap(save_tstate);
            if (PyStatus_Exception(status)) {
                assert(tstate == NULL);
                _PyErr_SetFromPyStatus(status);
                exc = PyErr_GetRaisedException();
            }
        }
        if (tstate != NULL) {
            interp = PyThreadState_GetInterpreter(tstate);
            // Throw away the initial tstate.
            PyThreadState_Swap(tstate);
            PyThreadState_Clear(tstate);
            PyThreadState_Swap(save_tstate);
            PyThreadState_Delete(tstate);
        }
    }
    else {
        PyErr_Format(PyExc_ValueError,
                     "unsupported whence %ld", whence);
        return NULL;
    }

    if (interp == NULL) {
        PyErr_SetString(PyExc_InterpreterError,
                        "sub-interpreter creation failed");
        if (exc != NULL) {
            _PyErr_ChainExceptions1(exc);
        }
    }
    return interp;
}

// This exists mostly for testing the _interpreters module, as an
// alternative to _interpreters.create()
static PyObject *
create_interpreter(PyObject *self, PyObject *args, PyObject *kwargs)
{
    static char *kwlist[] = {"config", "whence", NULL};
    PyObject *configobj = NULL;
    long whence = _PyInterpreterState_WHENCE_XI;
    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
                                     "|O$l:create_interpreter", kwlist,
                                     &configobj, &whence))
    {
        return NULL;
    }
    if (configobj == Py_None) {
        configobj = NULL;
    }

    // Resolve the config.
    PyInterpreterConfig *config = NULL;
    PyInterpreterConfig _config;
    if (whence == _PyInterpreterState_WHENCE_UNKNOWN
            || whence == _PyInterpreterState_WHENCE_LEGACY_CAPI)
    {
        if (configobj != NULL) {
            PyErr_SetString(PyExc_ValueError, "got unexpected config");
            return NULL;
        }
    }
    else {
        config = &_config;
        if (_init_interp_config_from_object(config, configobj) < 0) {
            return NULL;
        }
    }

    // Create the interpreter.
    PyInterpreterState *interp = _new_interpreter(config, whence);
    if (interp == NULL) {
        return NULL;
    }

    // Return the ID.
    PyObject *idobj = _PyInterpreterState_GetIDObject(interp);
    if (idobj == NULL) {
        _PyXI_EndInterpreter(interp, NULL, NULL);
        return NULL;
    }

    return idobj;
}

// This exists mostly for testing the _interpreters module, as an
// alternative to _interpreters.destroy()
static PyObject *
destroy_interpreter(PyObject *self, PyObject *args, PyObject *kwargs)
{
    static char *kwlist[] = {"id", "basic", NULL};
    PyObject *idobj = NULL;
    int basic = 0;
    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
                                     "O|p:destroy_interpreter", kwlist,
                                     &idobj, &basic))
    {
        return NULL;
    }

    PyInterpreterState *interp = _PyInterpreterState_LookUpIDObject(idobj);
    if (interp == NULL) {
        return NULL;
    }

    if (basic)
    {
        // Test the basic Py_EndInterpreter with weird out of order thread states
        PyThreadState *t1, *t2;
        PyThreadState *prev;
        t1 = interp->threads.head;
        if (t1 == NULL) {
            t1 = PyThreadState_New(interp);
        }
        t2 = PyThreadState_New(interp);
        prev = PyThreadState_Swap(t2);
        PyThreadState_Clear(t1);
        PyThreadState_Delete(t1);
        Py_EndInterpreter(t2);
        PyThreadState_Swap(prev);
    }
    else
    {
        // use the cross interpreter _PyXI_EndInterpreter normally
        _PyXI_EndInterpreter(interp, NULL, NULL);
    }
    Py_RETURN_NONE;
}

// This exists mostly for testing the _interpreters module, as an
// alternative to _interpreters.destroy()
static PyObject *
exec_interpreter(PyObject *self, PyObject *args, PyObject *kwargs)
{
    static char *kwlist[] = {"id", "code", "main", NULL};
    PyObject *idobj;
    const char *code;
    int runningmain = 0;
    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
                                     "Os|$p:exec_interpreter", kwlist,
                                     &idobj, &code, &runningmain))
    {
        return NULL;
    }

    PyInterpreterState *interp = _PyInterpreterState_LookUpIDObject(idobj);
    if (interp == NULL) {
        return NULL;
    }

    PyObject *res = NULL;
    PyThreadState *tstate =
        _PyThreadState_NewBound(interp, _PyThreadState_WHENCE_EXEC);

    PyThreadState *save_tstate = PyThreadState_Swap(tstate);

    if (runningmain) {
       if (_PyInterpreterState_SetRunningMain(interp) < 0) {
           goto finally;
       }
    }

    /* only initialise 'cflags.cf_flags' to test backwards compatibility */
    PyCompilerFlags cflags = {0};
    int r = PyRun_SimpleStringFlags(code, &cflags);
    if (PyErr_Occurred()) {
        PyErr_PrintEx(0);
    }

    if (runningmain) {
        _PyInterpreterState_SetNotRunningMain(interp);
    }

    res = PyLong_FromLong(r);

finally:
    PyThreadState_Clear(tstate);
    PyThreadState_Swap(save_tstate);
    PyThreadState_Delete(tstate);
    return res;
}


/* To run some code in a sub-interpreter.

Generally you can use the interpreters module,
but we keep this helper as a distinct implementation.
That's especially important for testing the interpreters module.
*/
static PyObject *
run_in_subinterp_with_config(PyObject *self, PyObject *args, PyObject *kwargs)
{
    const char *code;
    PyObject *configobj;
    int xi = 0;
    static char *kwlist[] = {"code", "config", "xi", NULL};
    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
                    "sO|$p:run_in_subinterp_with_config", kwlist,
                    &code, &configobj, &xi))
    {
        return NULL;
    }

    PyInterpreterConfig config;
    if (_init_interp_config_from_object(&config, configobj) < 0) {
        return NULL;
    }

    /* only initialise 'cflags.cf_flags' to test backwards compatibility */
    PyCompilerFlags cflags = {0};

    int r;
    if (xi) {
        PyThreadState *save_tstate;
        PyThreadState *tstate;

        /* Create an interpreter, staying switched to it. */
        PyInterpreterState *interp = \
                _PyXI_NewInterpreter(&config, NULL, &tstate, &save_tstate);
        if (interp == NULL) {
            return NULL;
        }

        /* Exec the code in the new interpreter. */
        r = PyRun_SimpleStringFlags(code, &cflags);

        /* clean up post-exec. */
        _PyXI_EndInterpreter(interp, tstate, &save_tstate);
    }
    else {
        PyThreadState *substate;
        PyThreadState *mainstate = PyThreadState_Swap(NULL);

        /* Create an interpreter, staying switched to it. */
        PyStatus status = Py_NewInterpreterFromConfig(&substate, &config);
        if (PyStatus_Exception(status)) {
            /* Since no new thread state was created, there is no exception to
               propagate; raise a fresh one after swapping in the old thread
               state. */
            PyThreadState_Swap(mainstate);
            _PyErr_SetFromPyStatus(status);
            PyObject *exc = PyErr_GetRaisedException();
            PyErr_SetString(PyExc_InterpreterError,
                            "sub-interpreter creation failed");
            _PyErr_ChainExceptions1(exc);
            return NULL;
        }

        /* Exec the code in the new interpreter. */
        r = PyRun_SimpleStringFlags(code, &cflags);

        /* clean up post-exec. */
        Py_EndInterpreter(substate);
        PyThreadState_Swap(mainstate);
    }

    return PyLong_FromLong(r);
}


static PyObject *
normalize_interp_id(PyObject *self, PyObject *idobj)
{
    int64_t interpid = _PyInterpreterState_ObjectToID(idobj);
    if (interpid < 0) {
        return NULL;
    }
    return PyLong_FromLongLong(interpid);
}

static PyObject *
next_interpreter_id(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    int64_t interpid = _PyRuntime.interpreters.next_id;
    return PyLong_FromLongLong(interpid);
}

static PyObject *
unused_interpreter_id(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    int64_t interpid = INT64_MAX;
    assert(interpid > _PyRuntime.interpreters.next_id);
    return PyLong_FromLongLong(interpid);
}

static PyObject *
interpreter_exists(PyObject *self, PyObject *idobj)
{
    PyInterpreterState *interp = _PyInterpreterState_LookUpIDObject(idobj);
    if (interp == NULL) {
        if (PyErr_ExceptionMatches(PyExc_InterpreterNotFoundError)) {
            PyErr_Clear();
            Py_RETURN_FALSE;
        }
        assert(PyErr_Occurred());
        return NULL;
    }
    Py_RETURN_TRUE;
}

static PyObject *
get_interpreter_refcount(PyObject *self, PyObject *idobj)
{
    PyInterpreterState *interp = _PyInterpreterState_LookUpIDObject(idobj);
    if (interp == NULL) {
        return NULL;
    }
    return PyLong_FromLongLong(interp->id_refcount);
}

static PyObject *
link_interpreter_refcount(PyObject *self, PyObject *idobj)
{
    PyInterpreterState *interp = _PyInterpreterState_LookUpIDObject(idobj);
    if (interp == NULL) {
        assert(PyErr_Occurred());
        return NULL;
    }
    _PyInterpreterState_RequireIDRef(interp, 1);
    Py_RETURN_NONE;
}

static PyObject *
unlink_interpreter_refcount(PyObject *self, PyObject *idobj)
{
    PyInterpreterState *interp = _PyInterpreterState_LookUpIDObject(idobj);
    if (interp == NULL) {
        assert(PyErr_Occurred());
        return NULL;
    }
    _PyInterpreterState_RequireIDRef(interp, 0);
    Py_RETURN_NONE;
}

static PyObject *
interpreter_refcount_linked(PyObject *self, PyObject *idobj)
{
    PyInterpreterState *interp = _PyInterpreterState_LookUpIDObject(idobj);
    if (interp == NULL) {
        return NULL;
    }
    if (_PyInterpreterState_RequiresIDRef(interp)) {
        Py_RETURN_TRUE;
    }
    Py_RETURN_FALSE;
}


static void
_xid_capsule_destructor(PyObject *capsule)
{
    _PyXIData_t *xidata = (_PyXIData_t *)PyCapsule_GetPointer(capsule, NULL);
    if (xidata != NULL) {
        assert(_PyXIData_Release(xidata) == 0);
        _PyXIData_Free(xidata);
    }
}

static PyObject *
get_crossinterp_data(PyObject *self, PyObject *args, PyObject *kwargs)
{
    PyObject *obj = NULL;
    PyObject *modeobj = NULL;
    static char *kwlist[] = {"obj", "mode", NULL};
    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
                    "O|O:get_crossinterp_data", kwlist,
                    &obj, &modeobj))
    {
        return NULL;
    }
    const char *mode = NULL;
    if (modeobj == NULL || modeobj == Py_None) {
        mode = "xidata";
    }
    else if (!PyUnicode_Check(modeobj)) {
        PyErr_Format(PyExc_TypeError, "expected mode str, got %R", modeobj);
        return NULL;
    }
    else {
        mode = PyUnicode_AsUTF8(modeobj);
        if (strlen(mode) == 0) {
            mode = "xidata";
        }
    }

    PyThreadState *tstate = _PyThreadState_GET();
    _PyXIData_t *xidata = _PyXIData_New();
    if (xidata == NULL) {
        return NULL;
    }
    if (strcmp(mode, "xidata") == 0) {
        if (_PyObject_GetXIDataNoFallback(tstate, obj, xidata) != 0) {
            goto error;
        }
    }
    else if (strcmp(mode, "fallback") == 0) {
        xidata_fallback_t fallback = _PyXIDATA_FULL_FALLBACK;
        if (_PyObject_GetXIData(tstate, obj, fallback, xidata) != 0)
        {
            goto error;
        }
    }
    else if (strcmp(mode, "pickle") == 0) {
        if (_PyPickle_GetXIData(tstate, obj, xidata) != 0) {
            goto error;
        }
    }
    else if (strcmp(mode, "marshal") == 0) {
        if (_PyMarshal_GetXIData(tstate, obj, xidata) != 0) {
            goto error;
        }
    }
    else if (strcmp(mode, "code") == 0) {
        if (_PyCode_GetXIData(tstate, obj, xidata) != 0) {
            goto error;
        }
    }
    else if (strcmp(mode, "func") == 0) {
        if (_PyFunction_GetXIData(tstate, obj, xidata) != 0) {
            goto error;
        }
    }
    else if (strcmp(mode, "script") == 0) {
        if (_PyCode_GetScriptXIData(tstate, obj, xidata) != 0) {
            goto error;
        }
    }
    else if (strcmp(mode, "script-pure") == 0) {
        if (_PyCode_GetPureScriptXIData(tstate, obj, xidata) != 0) {
            goto error;
        }
    }
    else {
        PyErr_Format(PyExc_ValueError, "unsupported mode %R", modeobj);
        goto error;
    }
    PyObject *capsule = PyCapsule_New(xidata, NULL, _xid_capsule_destructor);
    if (capsule == NULL) {
        assert(_PyXIData_Release(xidata) == 0);
        goto error;
    }
    return capsule;

error:
    _PyXIData_Free(xidata);
    return NULL;
}

static PyObject *
restore_crossinterp_data(PyObject *self, PyObject *args)
{
    PyObject *capsule = NULL;
    if (!PyArg_ParseTuple(args, "O:restore_crossinterp_data", &capsule)) {
        return NULL;
    }

    _PyXIData_t *xidata = (_PyXIData_t *)PyCapsule_GetPointer(capsule, NULL);
    if (xidata == NULL) {
        return NULL;
    }
    return _PyXIData_NewObject(xidata);
}


static PyObject *
raiseTestError(const char* test_name, const char* msg)
{
    PyErr_Format(PyExc_AssertionError, "%s: %s", test_name, msg);
    return NULL;
}


/*[clinic input]
_testinternalcapi.test_long_numbits
[clinic start generated code]*/

static PyObject *
_testinternalcapi_test_long_numbits_impl(PyObject *module)
/*[clinic end generated code: output=745d62d120359434 input=f14ca6f638e44dad]*/
{
    struct triple {
        long input;
        uint64_t nbits;
        int sign;
    } testcases[] = {{0, 0, 0},
                     {1L, 1, 1},
                     {-1L, 1, -1},
                     {2L, 2, 1},
                     {-2L, 2, -1},
                     {3L, 2, 1},
                     {-3L, 2, -1},
                     {4L, 3, 1},
                     {-4L, 3, -1},
                     {0x7fffL, 15, 1},          /* one Python int digit */
             {-0x7fffL, 15, -1},
             {0xffffL, 16, 1},
             {-0xffffL, 16, -1},
             {0xfffffffL, 28, 1},
             {-0xfffffffL, 28, -1}};
    size_t i;

    for (i = 0; i < Py_ARRAY_LENGTH(testcases); ++i) {
        uint64_t nbits;
        int sign = -7;
        PyObject *plong;

        plong = PyLong_FromLong(testcases[i].input);
        if (plong == NULL)
            return NULL;
        nbits = _PyLong_NumBits(plong);
        (void)PyLong_GetSign(plong, &sign);

        Py_DECREF(plong);
        if (nbits != testcases[i].nbits)
            return raiseTestError("test_long_numbits",
                            "wrong result for _PyLong_NumBits");
        if (sign != testcases[i].sign)
            return raiseTestError("test_long_numbits",
                            "wrong result for PyLong_GetSign()");
    }
    Py_RETURN_NONE;
}

static PyObject *
compile_perf_trampoline_entry(PyObject *self, PyObject *args)
{
    PyObject *co;
    if (!PyArg_ParseTuple(args, "O!", &PyCode_Type, &co)) {
        return NULL;
    }
    int ret = PyUnstable_PerfTrampoline_CompileCode((PyCodeObject *)co);
    if (ret != 0) {
        PyErr_SetString(PyExc_AssertionError, "Failed to compile trampoline");
        return NULL;
    }
    return PyLong_FromLong(ret);
}

static PyObject *
perf_trampoline_set_persist_after_fork(PyObject *self, PyObject *args)
{
    int enable;
    if (!PyArg_ParseTuple(args, "i", &enable)) {
        return NULL;
    }
    int ret = PyUnstable_PerfTrampoline_SetPersistAfterFork(enable);
    if (ret == 0) {
        PyErr_SetString(PyExc_AssertionError, "Failed to set persist_after_fork");
        return NULL;
    }
    return PyLong_FromLong(ret);
}


static PyObject *
get_rare_event_counters(PyObject *self, PyObject *type)
{
    PyInterpreterState *interp = PyInterpreterState_Get();

    return Py_BuildValue(
        "{sksksksksk}",
        "set_class", (unsigned long)interp->rare_events.set_class,
        "set_bases", (unsigned long)interp->rare_events.set_bases,
        "set_eval_frame_func", (unsigned long)interp->rare_events.set_eval_frame_func,
        "builtin_dict", (unsigned long)interp->rare_events.builtin_dict,
        "func_modification", (unsigned long)interp->rare_events.func_modification
    );
}

static PyObject *
reset_rare_event_counters(PyObject *self, PyObject *Py_UNUSED(type))
{
    PyInterpreterState *interp = PyInterpreterState_Get();

    interp->rare_events.set_class = 0;
    interp->rare_events.set_bases = 0;
    interp->rare_events.set_eval_frame_func = 0;
    interp->rare_events.builtin_dict = 0;
    interp->rare_events.func_modification = 0;

    return Py_None;
}


#ifdef Py_GIL_DISABLED
static PyObject *
get_py_thread_id(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    uintptr_t tid = _Py_ThreadId();
    Py_BUILD_ASSERT(sizeof(unsigned long long) >= sizeof(tid));
    return PyLong_FromUnsignedLongLong(tid);
}

static PyCodeObject *
get_code(PyObject *obj)
{
    if (PyCode_Check(obj)) {
        return (PyCodeObject *)obj;
    }
    else if (PyFunction_Check(obj)) {
        return (PyCodeObject *)PyFunction_GetCode(obj);
    }
    return (PyCodeObject *)PyErr_Format(
        PyExc_TypeError, "expected function or code object, got %T", obj);
}

static PyObject *
get_tlbc(PyObject *Py_UNUSED(module), PyObject *obj)
{
    PyCodeObject *code = get_code(obj);
    if (code == NULL) {
        return NULL;
    }
    _Py_CODEUNIT *bc = _PyCode_GetTLBCFast(PyThreadState_GET(), code);
    if (bc == NULL) {
        Py_RETURN_NONE;
    }
    return PyBytes_FromStringAndSize((const char *)bc, _PyCode_NBYTES(code));
}

static PyObject *
get_tlbc_id(PyObject *Py_UNUSED(module), PyObject *obj)
{
    PyCodeObject *code = get_code(obj);
    if (code == NULL) {
        return NULL;
    }
    _Py_CODEUNIT *bc = _PyCode_GetTLBCFast(PyThreadState_GET(), code);
    if (bc == NULL) {
        Py_RETURN_NONE;
    }
    return PyLong_FromVoidPtr(bc);
}

static PyObject *
get_long_lived_total(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    return PyLong_FromInt64(PyInterpreterState_Get()->gc.long_lived_total);
}

#endif

static PyObject *
has_inline_values(PyObject *self, PyObject *obj)
{
    if ((Py_TYPE(obj)->tp_flags & Py_TPFLAGS_INLINE_VALUES) &&
        _PyObject_InlineValues(obj)->valid) {
        Py_RETURN_TRUE;
    }
    Py_RETURN_FALSE;
}

static PyObject *
has_split_table(PyObject *self, PyObject *obj)
{
    if (PyDict_Check(obj) && _PyDict_HasSplitTable((PyDictObject *)obj)) {
        Py_RETURN_TRUE;
    }
    Py_RETURN_FALSE;
}

// Circumvents standard version assignment machinery - use with caution and only on
// short-lived heap types
static PyObject *
type_assign_specific_version_unsafe(PyObject *self, PyObject *args)
{
    PyTypeObject *type;
    unsigned int version;
    if (!PyArg_ParseTuple(args, "Oi:type_assign_specific_version_unsafe", &type, &version)) {
        return NULL;
    }
    assert(!PyType_HasFeature(type, Py_TPFLAGS_IMMUTABLETYPE));
    _PyType_SetVersion(type, version);
    Py_RETURN_NONE;
}

/*[clinic input]
gh_119213_getargs

    spam: object = None

Test _PyArg_Parser.kwtuple
[clinic start generated code]*/

static PyObject *
gh_119213_getargs_impl(PyObject *module, PyObject *spam)
/*[clinic end generated code: output=d8d9c95d5b446802 input=65ef47511da80fc2]*/
{
    // It must never have been called in the main interprer
    assert(!_Py_IsMainInterpreter(PyInterpreterState_Get()));
    return Py_NewRef(spam);
}

/*[clinic input]
get_next_dict_keys_version
[clinic start generated code]*/

static PyObject *
get_next_dict_keys_version_impl(PyObject *module)
/*[clinic end generated code: output=e5405a509cf9d423 input=bd1cee7c6b9d3a3c]*/
{
    PyInterpreterState *interp = _PyInterpreterState_GET();
    uint32_t keys_version = interp->dict_state.next_keys_version;
    return PyLong_FromLong(keys_version);
}

static PyObject *
get_static_builtin_types(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    return _PyStaticType_GetBuiltins();
}


static PyObject *
identify_type_slot_wrappers(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    return _PyType_GetSlotWrapperNames();
}


static PyObject *
has_deferred_refcount(PyObject *self, PyObject *op)
{
    return PyBool_FromLong(_PyObject_HasDeferredRefcount(op));
}

static PyObject *
get_tracked_heap_size(PyObject *self, PyObject *Py_UNUSED(ignored))
{
    return PyLong_FromInt64(PyInterpreterState_Get()->gc.heap_size);
}

static PyObject *
is_static_immortal(PyObject *self, PyObject *op)
{
    if (_Py_IsStaticImmortal(op)) {
        Py_RETURN_TRUE;
    }
    Py_RETURN_FALSE;
}

static PyObject *
incref_decref_delayed(PyObject *self, PyObject *op)
{
    _PyObject_XDecRefDelayed(Py_NewRef(op));
    Py_RETURN_NONE;
}

#ifdef __EMSCRIPTEN__
#include "emscripten.h"

EM_JS(int, emscripten_set_up_async_input_device_js, (void), {
    let idx = 0;
    const encoder = new TextEncoder();
    const bufs = [
        encoder.encode("ab\n"),
        encoder.encode("fi\n"),
        encoder.encode("xy\n"),
    ];
    function sleep(t) {
        return new Promise(res => setTimeout(res, t));
    }
    FS.createAsyncInputDevice("/dev", "blah", async () => {
        await sleep(5);
        return bufs[(idx ++) % 3];
    });
    return !!WebAssembly.promising;
});

static PyObject *
emscripten_set_up_async_input_device(PyObject *self, PyObject *Py_UNUSED(ignored)) {
    if (emscripten_set_up_async_input_device_js()) {
        Py_RETURN_TRUE;
    } else {
        Py_RETURN_FALSE;
    }
}
#endif

static PyObject *
simple_pending_call(PyObject *self, PyObject *callable)
{
    if (_PyEval_AddPendingCall(_PyInterpreterState_GET(), _pending_callback, Py_NewRef(callable), 0) < 0) {
        return NULL;
    }

    Py_RETURN_NONE;
}

static PyObject *
vectorcall_nop(PyObject *callable, PyObject *const *args,
               size_t nargsf, PyObject *kwnames)
{
    Py_RETURN_NONE;
}

static PyObject *
set_vectorcall_nop(PyObject *self, PyObject *func)
{
    if (!PyFunction_Check(func)) {
        PyErr_SetString(PyExc_TypeError, "expected function");
        return NULL;
    }

    ((PyFunctionObject*)func)->vectorcall = vectorcall_nop;
    Py_RETURN_NONE;
}

static PyObject *
module_get_gc_hooks(PyObject *self, PyObject *arg)
{
    PyModuleObject *mod = (PyModuleObject *)arg;
    PyObject *traverse = NULL;
    PyObject *clear = NULL;
    PyObject *free = NULL;
    PyObject *result = NULL;
    traverse = PyLong_FromVoidPtr(mod->md_state_traverse);
    if (!traverse) {
        goto finally;
    }
    clear = PyLong_FromVoidPtr(mod->md_state_clear);
    if (!clear) {
        goto finally;
    }
    free = PyLong_FromVoidPtr(mod->md_state_free);
    if (!free) {
        goto finally;
    }
    result = PyTuple_FromArray((PyObject*[]){ traverse, clear, free }, 3);
finally:
    Py_XDECREF(traverse);
    Py_XDECREF(clear);
    Py_XDECREF(free);
    return result;
}


static void
check_threadstate_set_stack_protection(PyThreadState *tstate,
                                       void *start, size_t size)
{
    assert(PyUnstable_ThreadState_SetStackProtection(tstate, start, size) == 0);
    assert(!PyErr_Occurred());

    _PyThreadStateImpl *ts = (_PyThreadStateImpl *)tstate;
    assert(ts->c_stack_top == (uintptr_t)start + size);
    assert(ts->c_stack_hard_limit <= ts->c_stack_soft_limit);
    assert(ts->c_stack_soft_limit < ts->c_stack_top);
}


static PyObject *
test_threadstate_set_stack_protection(PyObject *self, PyObject *Py_UNUSED(args))
{
    PyThreadState *tstate = PyThreadState_GET();
    _PyThreadStateImpl *ts = (_PyThreadStateImpl *)tstate;
    assert(!PyErr_Occurred());

    uintptr_t init_base = ts->c_stack_init_base;
    size_t init_top = ts->c_stack_init_top;

    // Test the minimum stack size
    size_t size = _PyOS_MIN_STACK_SIZE;
    void *start = (void*)(_Py_get_machine_stack_pointer() - size);
    check_threadstate_set_stack_protection(tstate, start, size);

    // Test a larger size
    size = 7654321;
    assert(size > _PyOS_MIN_STACK_SIZE);
    start = (void*)(_Py_get_machine_stack_pointer() - size);
    check_threadstate_set_stack_protection(tstate, start, size);

    // Test invalid size (too small)
    size = 5;
    start = (void*)(_Py_get_machine_stack_pointer() - size);
    assert(PyUnstable_ThreadState_SetStackProtection(tstate, start, size) == -1);
    assert(PyErr_ExceptionMatches(PyExc_ValueError));
    PyErr_Clear();

    // Test PyUnstable_ThreadState_ResetStackProtection()
    PyUnstable_ThreadState_ResetStackProtection(tstate);
    assert(ts->c_stack_init_base == init_base);
    assert(ts->c_stack_init_top == init_top);

    Py_RETURN_NONE;
}

#define NUM_GUARDS 100

static PyObject *
test_interp_guard_countdown(PyObject *self, PyObject *unused)
{
    PyThreadState *save_tstate = PyThreadState_Swap(NULL);

    // This test assumes that the interpreter has no guards active.
    // While this is currently true for the main interpreter as of writing,
    // this won't necessarily be true in the future. For the sake of
    // maintainance, we create a new interpreter to be sure that there aren't
    // any other guards.
    PyThreadState *interp_tstate = Py_NewInterpreter();
    assert(interp_tstate != NULL);
    PyInterpreterState *interp = PyInterpreterState_Get();
    assert(_PyInterpreterState_GuardCountdown(interp) == 0);

    PyInterpreterGuard *guards[NUM_GUARDS];
    for (int i = 0; i < NUM_GUARDS; ++i) {
        guards[i] = PyInterpreterGuard_FromCurrent();
        assert(guards[i] != 0);
        assert(_PyInterpreterState_GuardCountdown(interp) == i + 1);
    }

    for (int i = 0; i < NUM_GUARDS; ++i) {
        PyInterpreterGuard_Close(guards[i]);
        assert(_PyInterpreterState_GuardCountdown(interp) == (NUM_GUARDS - i - 1));
    }

    Py_EndInterpreter(interp_tstate);
    PyThreadState_Swap(save_tstate);
    Py_RETURN_NONE;
}

static PyObject *
test_interp_view_countdown(PyObject *self, PyObject *unused)
{
    PyInterpreterState *interp = PyInterpreterState_Get();
    PyInterpreterView *view = PyInterpreterView_FromCurrent();
    if (view == NULL) {
        return NULL;
    }
    assert(_PyInterpreterState_GuardCountdown(interp) == 0);

    PyInterpreterGuard *guards[NUM_GUARDS];

    for (int i = 0; i < NUM_GUARDS; ++i) {
        guards[i] = PyInterpreterGuard_FromView(view);
        assert(guards[i] != 0);
        assert(_PyInterpreterGuard_GetInterpreter(guards[i]) == interp);
        assert(_PyInterpreterState_GuardCountdown(interp) == i + 1);
    }

    for (int i = 0; i < NUM_GUARDS; ++i) {
        PyInterpreterGuard_Close(guards[i]);
        assert(_PyInterpreterState_GuardCountdown(interp) == (NUM_GUARDS - i - 1));
    }

    PyInterpreterView_Close(view);
    Py_RETURN_NONE;
}

#undef NUM_LOCKS

static PyObject *
_pyerr_setkeyerror(PyObject *self, PyObject *arg)
{
    // Test that _PyErr_SetKeyError() overrides the current exception
    // if an exception is set
    PyErr_NoMemory();

    _PyErr_SetKeyError(arg);

    assert(PyErr_Occurred());
    return NULL;
}

static PyObject *
test_thread_state_ensure_from_view_interp_switch(PyObject *self, PyObject *unused)
{
    /* The main tstate is already attached and was NOT created by
     * PyThreadState_Ensure, so delete_on_release == 0. */
    PyInterpreterState *interp = _PyInterpreterState_GET();
    assert(interp != NULL);
    PyInterpreterView *view = PyInterpreterView_FromCurrent();
    assert(view != NULL);

    /* First Ensure/Release pair on this pre-existing tstate. */
    assert(_PyThreadState_GET() != NULL);
    PyThreadStateToken *t1 = PyThreadState_EnsureFromView(view);
    assert(t1 != NULL);
    assert(_PyInterpreterState_GuardCountdown(interp) == 1);
    PyThreadState_Release(t1);
    assert(_PyInterpreterState_GuardCountdown(interp) == 0);
    assert(_PyThreadState_GET() != NULL);

    /* tstate->ensure.owned_guard now points at the freed guard. */

    /* Re-attach: Bug B detaches us as a side effect (separate repro). */
    PyThreadState *save = PyThreadState_Swap(NULL);

    PyThreadStateToken *t2 = PyThreadState_EnsureFromView(view);
    assert(_PyInterpreterState_GuardCountdown(interp) == 1);
    assert(t2 != NULL);
    PyThreadState_Release(t2);
    assert(_PyInterpreterState_GuardCountdown(interp) == 0);
    assert(_PyThreadState_GET() == NULL);

    PyThreadState_Swap(save);

    /* In a release build (no assertion) the second Ensure silently
     * skipped storing its guard and Release decremented the global
     * counter from 0, wrapping it to GUARDS_NOT_ALLOWED.  All future
     * guard acquisitions then fail: */
    PyInterpreterGuard *g = PyInterpreterGuard_FromCurrent();
    assert(g != NULL);
    assert(_PyInterpreterState_GuardCountdown(interp) == 1);
    PyInterpreterGuard_Close(g);
    assert(_PyInterpreterState_GuardCountdown(interp) == 0);

    PyInterpreterView_Close(view);
    Py_RETURN_NONE;
}

static PyMethodDef module_functions[] = {
    {"get_configs", get_configs, METH_NOARGS},
    {"get_eval_frame_stats", get_eval_frame_stats, METH_NOARGS, NULL},
    {"get_recursion_depth", get_recursion_depth, METH_NOARGS},
    {"get_c_recursion_remaining", get_c_recursion_remaining, METH_NOARGS},
    {"get_stack_pointer", get_stack_pointer, METH_NOARGS},
    {"get_stack_margin", get_stack_margin, METH_NOARGS},
    {"classify_stack_addresses", classify_stack_addresses, METH_VARARGS},
    {"get_jit_code_ranges", get_jit_code_ranges, METH_NOARGS},
    {"get_jit_backend", get_jit_backend, METH_NOARGS},
    {"gnu_backtrace_unwind", gnu_backtrace_unwind, METH_NOARGS},
    {"manual_frame_pointer_unwind", manual_frame_pointer_unwind, METH_NOARGS},
    {"test_bswap", test_bswap, METH_NOARGS},
    {"test_popcount", test_popcount, METH_NOARGS},
    {"test_bit_length", test_bit_length, METH_NOARGS},
    {"test_hashtable", test_hashtable, METH_NOARGS},
    {"reset_path_config", test_reset_path_config, METH_NOARGS},
    {"test_edit_cost", test_edit_cost, METH_NOARGS},
    {"test_bytes_find", test_bytes_find, METH_NOARGS},
    {"normalize_path", normalize_path, METH_O, NULL},
    {"get_getpath_codeobject", get_getpath_codeobject, METH_NOARGS, NULL},
    {"EncodeLocaleEx", encode_locale_ex, METH_VARARGS},
    {"DecodeLocaleEx", decode_locale_ex, METH_VARARGS},
    {"set_eval_frame_default", set_eval_frame_default, METH_NOARGS, NULL},
    {"set_eval_frame_interp", set_eval_frame_interp, METH_VARARGS, NULL},
    {"set_eval_frame_record", set_eval_frame_record, METH_O, NULL},
    {"is_specialization_enabled", is_specialization_enabled, METH_NOARGS, NULL},
    _TESTINTERNALCAPI_COMPILER_CLEANDOC_METHODDEF
    _TESTINTERNALCAPI_NEW_INSTRUCTION_SEQUENCE_METHODDEF
    _TESTINTERNALCAPI_COMPILER_CODEGEN_METHODDEF
    _TESTINTERNALCAPI_OPTIMIZE_CFG_METHODDEF
    _TESTINTERNALCAPI_ASSEMBLE_CODE_OBJECT_METHODDEF
    {"get_interp_settings", get_interp_settings, METH_VARARGS, NULL},
    {"clear_extension", clear_extension, METH_VARARGS, NULL},
    {"write_perf_map_entry", write_perf_map_entry, METH_VARARGS},
    {"perf_map_state_teardown", perf_map_state_teardown, METH_NOARGS},
    {"iframe_getcode", iframe_getcode, METH_O, NULL},
    {"iframe_getline", iframe_getline, METH_O, NULL},
    {"iframe_getlasti", iframe_getlasti, METH_O, NULL},
    {"code_returns_only_none", code_returns_only_none, METH_O, NULL},
    {"get_co_framesize", get_co_framesize, METH_O, NULL},
    {"get_co_localskinds", get_co_localskinds, METH_O, NULL},
    {"get_code_var_counts", _PyCFunction_CAST(get_code_var_counts),
     METH_VARARGS | METH_KEYWORDS, NULL},
    {"verify_stateless_code", _PyCFunction_CAST(verify_stateless_code),
     METH_VARARGS | METH_KEYWORDS, NULL},
#ifdef _Py_TIER2
    {"add_executor_dependency", add_executor_dependency, METH_VARARGS, NULL},
    {"invalidate_executors", invalidate_executors, METH_O, NULL},
    {"clear_executor_deletion_list", clear_executor_deletion_list, METH_NOARGS, NULL},
    {"get_exit_executor", get_exit_executor, METH_O, NULL},
#endif
    {"pending_threadfunc", _PyCFunction_CAST(pending_threadfunc),
     METH_VARARGS | METH_KEYWORDS},
    {"pending_identify", pending_identify, METH_VARARGS, NULL},
    {"_PyTraceMalloc_GetTraceback", tracemalloc_get_traceback, METH_VARARGS},
    {"test_tstate_capi", test_tstate_capi, METH_NOARGS, NULL},
    {"_PyUnicode_TransformDecimalAndSpaceToASCII", unicode_transformdecimalandspacetoascii, METH_O},
    {"check_pyobject_forbidden_bytes_is_freed",
                            check_pyobject_forbidden_bytes_is_freed, METH_NOARGS},
    {"check_pyobject_freed_is_freed", check_pyobject_freed_is_freed, METH_NOARGS},
    {"check_pyobject_null_is_freed",  check_pyobject_null_is_freed,  METH_NOARGS},
    {"check_pyobject_uninitialized_is_freed",
                              check_pyobject_uninitialized_is_freed, METH_NOARGS},
    {"pymem_getallocatorsname", test_pymem_getallocatorsname, METH_NOARGS},
    {"get_object_dict_values", get_object_dict_values, METH_O},
    {"hamt", new_hamt, METH_NOARGS},
    {"dict_getitem_knownhash",  dict_getitem_knownhash,          METH_VARARGS},
    {"create_interpreter", _PyCFunction_CAST(create_interpreter),
     METH_VARARGS | METH_KEYWORDS},
    {"destroy_interpreter", _PyCFunction_CAST(destroy_interpreter),
     METH_VARARGS | METH_KEYWORDS},
    {"exec_interpreter", _PyCFunction_CAST(exec_interpreter),
     METH_VARARGS | METH_KEYWORDS},
    {"run_in_subinterp_with_config",
     _PyCFunction_CAST(run_in_subinterp_with_config),
     METH_VARARGS | METH_KEYWORDS},
    {"normalize_interp_id", normalize_interp_id, METH_O},
    {"next_interpreter_id", next_interpreter_id, METH_NOARGS},
    {"unused_interpreter_id", unused_interpreter_id, METH_NOARGS},
    {"interpreter_exists", interpreter_exists, METH_O},
    {"get_interpreter_refcount", get_interpreter_refcount, METH_O},
    {"link_interpreter_refcount", link_interpreter_refcount,     METH_O},
    {"unlink_interpreter_refcount", unlink_interpreter_refcount, METH_O},
    {"interpreter_refcount_linked", interpreter_refcount_linked, METH_O},
    {"compile_perf_trampoline_entry", compile_perf_trampoline_entry, METH_VARARGS},
    {"perf_trampoline_set_persist_after_fork", perf_trampoline_set_persist_after_fork, METH_VARARGS},
    {"get_crossinterp_data",    _PyCFunction_CAST(get_crossinterp_data),
     METH_VARARGS | METH_KEYWORDS},
    {"restore_crossinterp_data", restore_crossinterp_data,       METH_VARARGS},
    _TESTINTERNALCAPI_TEST_LONG_NUMBITS_METHODDEF
    {"get_rare_event_counters", get_rare_event_counters, METH_NOARGS},
    {"reset_rare_event_counters", reset_rare_event_counters, METH_NOARGS},
    {"has_inline_values", has_inline_values, METH_O},
    {"has_split_table", has_split_table, METH_O},
    {"type_assign_specific_version_unsafe", type_assign_specific_version_unsafe, METH_VARARGS,
     PyDoc_STR("forcefully assign type->tp_version_tag")},

#ifdef Py_GIL_DISABLED
    {"py_thread_id", get_py_thread_id, METH_NOARGS},
    {"get_tlbc", get_tlbc, METH_O, NULL},
    {"get_tlbc_id", get_tlbc_id, METH_O, NULL},
    {"get_long_lived_total", get_long_lived_total, METH_NOARGS},
#endif
#ifdef _Py_TIER2
    {"uop_symbols_test", _Py_uop_symbols_test, METH_NOARGS},
#endif
    GH_119213_GETARGS_METHODDEF
    {"get_static_builtin_types", get_static_builtin_types, METH_NOARGS},
    {"identify_type_slot_wrappers", identify_type_slot_wrappers, METH_NOARGS},
    {"has_deferred_refcount", has_deferred_refcount, METH_O},
    {"get_tracked_heap_size", get_tracked_heap_size, METH_NOARGS},
    {"is_static_immortal", is_static_immortal, METH_O},
    {"incref_decref_delayed", incref_decref_delayed, METH_O},
    GET_NEXT_DICT_KEYS_VERSION_METHODDEF
#ifdef __EMSCRIPTEN__
    {"emscripten_set_up_async_input_device", emscripten_set_up_async_input_device, METH_NOARGS},
#endif
    {"simple_pending_call", simple_pending_call, METH_O},
    {"set_vectorcall_nop", set_vectorcall_nop, METH_O},
    {"module_get_gc_hooks", module_get_gc_hooks, METH_O},
    {"test_threadstate_set_stack_protection",
     test_threadstate_set_stack_protection, METH_NOARGS},
    {"_pyerr_setkeyerror", _pyerr_setkeyerror, METH_O},
    {"test_interp_guard_countdown", test_interp_guard_countdown, METH_NOARGS},
    {"test_interp_view_countdown", test_interp_view_countdown, METH_NOARGS},
    {"test_thread_state_ensure_from_view_interp_switch", test_thread_state_ensure_from_view_interp_switch, METH_NOARGS},
    {NULL, NULL} /* sentinel */
};


/* initialization function */

static int
module_exec(PyObject *module)
{
    PyInterpreterState *interp = PyInterpreterState_Get();

    if (_PyTestInternalCapi_Init_Lock(module) < 0) {
        return 1;
    }
    if (_PyTestInternalCapi_Init_PyTime(module) < 0) {
        return 1;
    }
    if (_PyTestInternalCapi_Init_Set(module) < 0) {
        return 1;
    }
    if (_PyTestInternalCapi_Init_Complex(module) < 0) {
        return 1;
    }
    if (_PyTestInternalCapi_Init_CriticalSection(module) < 0) {
        return 1;
    }
    if (_PyTestInternalCapi_Init_Tuple(module) < 0) {
        return 1;
    }

    Py_ssize_t sizeof_gc_head = 0;
#ifndef Py_GIL_DISABLED
    sizeof_gc_head = sizeof(PyGC_Head);
#endif

    if (PyModule_Add(module, "SIZEOF_PYGC_HEAD",
                        PyLong_FromSsize_t(sizeof_gc_head)) < 0) {
        return 1;
    }

    if (PyModule_Add(module, "SIZEOF_MANAGED_PRE_HEADER",
                        PyLong_FromSsize_t(2 * sizeof(PyObject*))) < 0) {
        return 1;
    }

    if (PyModule_Add(module, "SIZEOF_PYOBJECT",
                        PyLong_FromSsize_t(sizeof(PyObject))) < 0) {
        return 1;
    }

    if (PyModule_Add(module, "SIZEOF_TIME_T",
                        PyLong_FromSsize_t(sizeof(time_t))) < 0) {
        return 1;
    }

    // + 1 more due to one loop spent on tracing.
    unsigned long threshold = interp->opt_config.jump_backward_initial_value + 2;
    if (PyModule_Add(module, "TIER2_THRESHOLD",
                        PyLong_FromUnsignedLong(threshold)) < 0) {
        return 1;
    }

    // + 1 to specialize from RESUME to RESUME_CHECK_JIT
    // + 1 more due to one loop spent on tracing.
    long resume_threshold = interp->opt_config.resume_initial_value + 2;
    if (PyModule_Add(module, "TIER2_RESUME_THRESHOLD",
                    PyLong_FromLong(resume_threshold)) < 0) {
        return 1;
    }

    if (PyModule_Add(module, "SPECIALIZATION_THRESHOLD",
                        PyLong_FromLong(ADAPTIVE_WARMUP_VALUE + 1)) < 0) {
        return 1;
    }

    if (PyModule_Add(module, "SPECIALIZATION_COOLDOWN",
                        PyLong_FromLong(ADAPTIVE_COOLDOWN_VALUE + 1)) < 0) {
        return 1;
    }

    if (PyModule_Add(module, "SHARED_KEYS_MAX_SIZE",
                        PyLong_FromLong(SHARED_KEYS_MAX_SIZE)) < 0) {
        return 1;
    }

    if (PyModule_AddIntMacro(module, _PY_NSMALLPOSINTS) < 0) {
        return 1;
    }

#ifdef _Py_WITH_FRAME_POINTERS
    if (PyModule_AddIntMacro(module, _Py_WITH_FRAME_POINTERS) < 0) {
        return 1;
    }
#endif

    return 0;
}

PyABIInfo_VAR(abi_info);

static struct PyModuleDef_Slot module_slots[] = {
    {Py_mod_abi, &abi_info},
    {Py_mod_exec, module_exec},
    {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
    {Py_mod_gil, Py_MOD_GIL_NOT_USED},
    {0, NULL},
};

static int
module_traverse(PyObject *module, visitproc visit, void *arg)
{
    module_state *state = get_module_state(module);
    assert(state != NULL);
    traverse_module_state(state, visit, arg);
    return 0;
}

static int
module_clear(PyObject *module)
{
    module_state *state = get_module_state(module);
    assert(state != NULL);
    (void)clear_module_state(state);
    return 0;
}

static void
module_free(void *module)
{
    module_state *state = get_module_state(module);
    assert(state != NULL);
    (void)clear_module_state(state);
}

static struct PyModuleDef _testcapimodule = {
    .m_base = PyModuleDef_HEAD_INIT,
    .m_name = MODULE_NAME,
    .m_doc = NULL,
    .m_size = sizeof(module_state),
    .m_methods = module_functions,
    .m_slots = module_slots,
    .m_traverse = module_traverse,
    .m_clear = module_clear,
    .m_free = module_free,
};


PyMODINIT_FUNC
PyInit__testinternalcapi(void)
{
    return PyModuleDef_Init(&_testcapimodule);
}