Sync contrib/tools/python3 layout with upstream

* Move src/ subdir contents to the top of the layout
* Rename self-written lib -> lib2 to avoid CaseFolding warning from the VCS
* Regenerate contrib/libs/python proxy-headers accordingly
4ccc62ac1511abcf0fed14ccade38e984e088f1e

1 files changed, 2273 insertions, 0 deletions

diff --git a/contrib/tools/python3/Python/specialize.c b/contrib/tools/python3/Python/specialize.c
new file mode 100644
index 0000000000..2c0d99b04e
--- /dev/null
+++ b/contrib/tools/python3/Python/specialize.c
@@ -0,0 +1,2273 @@
+#include "Python.h"
+#include "pycore_code.h"
+#include "pycore_dict.h"
+#include "pycore_function.h"      // _PyFunction_GetVersionForCurrentState()
+#include "pycore_global_strings.h"  // _Py_ID()
+#include "pycore_long.h"
+#include "pycore_moduleobject.h"
+#include "pycore_object.h"
+#include "pycore_opcode.h"        // _PyOpcode_Caches
+#include "structmember.h"         // struct PyMemberDef, T_OFFSET_EX
+#include "pycore_descrobject.h"
+
+#include <stdlib.h> // rand()
+
+/* For guidance on adding or extending families of instructions see
+ * ./adaptive.md
+ */
+
+#ifdef Py_STATS
+PyStats _py_stats_struct = { 0 };
+PyStats *_py_stats = NULL;
+
+#define ADD_STAT_TO_DICT(res, field) \
+    do { \
+        PyObject *val = PyLong_FromUnsignedLongLong(stats->field); \
+        if (val == NULL) { \
+            Py_DECREF(res); \
+            return NULL; \
+        } \
+        if (PyDict_SetItemString(res, #field, val) == -1) { \
+            Py_DECREF(res); \
+            Py_DECREF(val); \
+            return NULL; \
+        } \
+        Py_DECREF(val); \
+    } while(0);
+
+static PyObject*
+stats_to_dict(SpecializationStats *stats)
+{
+    PyObject *res = PyDict_New();
+    if (res == NULL) {
+        return NULL;
+    }
+    ADD_STAT_TO_DICT(res, success);
+    ADD_STAT_TO_DICT(res, failure);
+    ADD_STAT_TO_DICT(res, hit);
+    ADD_STAT_TO_DICT(res, deferred);
+    ADD_STAT_TO_DICT(res, miss);
+    ADD_STAT_TO_DICT(res, deopt);
+    PyObject *failure_kinds = PyTuple_New(SPECIALIZATION_FAILURE_KINDS);
+    if (failure_kinds == NULL) {
+        Py_DECREF(res);
+        return NULL;
+    }
+    for (int i = 0; i < SPECIALIZATION_FAILURE_KINDS; i++) {
+        PyObject *stat = PyLong_FromUnsignedLongLong(stats->failure_kinds[i]);
+        if (stat == NULL) {
+            Py_DECREF(res);
+            Py_DECREF(failure_kinds);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(failure_kinds, i, stat);
+    }
+    if (PyDict_SetItemString(res, "failure_kinds", failure_kinds)) {
+        Py_DECREF(res);
+        Py_DECREF(failure_kinds);
+        return NULL;
+    }
+    Py_DECREF(failure_kinds);
+    return res;
+}
+#undef ADD_STAT_TO_DICT
+
+static int
+add_stat_dict(
+    PyObject *res,
+    int opcode,
+    const char *name) {
+
+    SpecializationStats *stats = &_py_stats_struct.opcode_stats[opcode].specialization;
+    PyObject *d = stats_to_dict(stats);
+    if (d == NULL) {
+        return -1;
+    }
+    int err = PyDict_SetItemString(res, name, d);
+    Py_DECREF(d);
+    return err;
+}
+
+#ifdef Py_STATS
+PyObject*
+_Py_GetSpecializationStats(void) {
+    PyObject *stats = PyDict_New();
+    if (stats == NULL) {
+        return NULL;
+    }
+    int err = 0;
+    err += add_stat_dict(stats, LOAD_SUPER_ATTR, "load_super_attr");
+    err += add_stat_dict(stats, LOAD_ATTR, "load_attr");
+    err += add_stat_dict(stats, LOAD_GLOBAL, "load_global");
+    err += add_stat_dict(stats, BINARY_SUBSCR, "binary_subscr");
+    err += add_stat_dict(stats, STORE_SUBSCR, "store_subscr");
+    err += add_stat_dict(stats, STORE_ATTR, "store_attr");
+    err += add_stat_dict(stats, CALL, "call");
+    err += add_stat_dict(stats, BINARY_OP, "binary_op");
+    err += add_stat_dict(stats, COMPARE_OP, "compare_op");
+    err += add_stat_dict(stats, UNPACK_SEQUENCE, "unpack_sequence");
+    err += add_stat_dict(stats, FOR_ITER, "for_iter");
+    if (err < 0) {
+        Py_DECREF(stats);
+        return NULL;
+    }
+    return stats;
+}
+#endif
+
+
+#define PRINT_STAT(i, field) \
+    if (stats[i].field) { \
+        fprintf(out, "    opcode[%d]." #field " : %" PRIu64 "\n", i, stats[i].field); \
+    }
+
+static void
+print_spec_stats(FILE *out, OpcodeStats *stats)
+{
+    /* Mark some opcodes as specializable for stats,
+     * even though we don't specialize them yet. */
+    fprintf(out, "opcode[%d].specializable : 1\n", BINARY_SLICE);
+    fprintf(out, "opcode[%d].specializable : 1\n", COMPARE_OP);
+    fprintf(out, "opcode[%d].specializable : 1\n", STORE_SLICE);
+    fprintf(out, "opcode[%d].specializable : 1\n", SEND);
+    for (int i = 0; i < 256; i++) {
+        if (_PyOpcode_Caches[i]) {
+            fprintf(out, "opcode[%d].specializable : 1\n", i);
+        }
+        PRINT_STAT(i, specialization.success);
+        PRINT_STAT(i, specialization.failure);
+        PRINT_STAT(i, specialization.hit);
+        PRINT_STAT(i, specialization.deferred);
+        PRINT_STAT(i, specialization.miss);
+        PRINT_STAT(i, specialization.deopt);
+        PRINT_STAT(i, execution_count);
+        for (int j = 0; j < SPECIALIZATION_FAILURE_KINDS; j++) {
+            uint64_t val = stats[i].specialization.failure_kinds[j];
+            if (val) {
+                fprintf(out, "    opcode[%d].specialization.failure_kinds[%d] : %"
+                    PRIu64 "\n", i, j, val);
+            }
+        }
+        for (int j = 0; j < 256; j++) {
+            if (stats[i].pair_count[j]) {
+                fprintf(out, "opcode[%d].pair_count[%d] : %" PRIu64 "\n",
+                        i, j, stats[i].pair_count[j]);
+            }
+        }
+    }
+}
+#undef PRINT_STAT
+
+
+static void
+print_call_stats(FILE *out, CallStats *stats)
+{
+    fprintf(out, "Calls to PyEval_EvalDefault: %" PRIu64 "\n", stats->pyeval_calls);
+    fprintf(out, "Calls to Python functions inlined: %" PRIu64 "\n", stats->inlined_py_calls);
+    fprintf(out, "Frames pushed: %" PRIu64 "\n", stats->frames_pushed);
+    fprintf(out, "Frame objects created: %" PRIu64 "\n", stats->frame_objects_created);
+    for (int i = 0; i < EVAL_CALL_KINDS; i++) {
+        fprintf(out, "Calls via PyEval_EvalFrame[%d] : %" PRIu64 "\n", i, stats->eval_calls[i]);
+    }
+}
+
+static void
+print_object_stats(FILE *out, ObjectStats *stats)
+{
+    fprintf(out, "Object allocations from freelist: %" PRIu64 "\n", stats->from_freelist);
+    fprintf(out, "Object frees to freelist: %" PRIu64 "\n", stats->to_freelist);
+    fprintf(out, "Object allocations: %" PRIu64 "\n", stats->allocations);
+    fprintf(out, "Object allocations to 512 bytes: %" PRIu64 "\n", stats->allocations512);
+    fprintf(out, "Object allocations to 4 kbytes: %" PRIu64 "\n", stats->allocations4k);
+    fprintf(out, "Object allocations over 4 kbytes: %" PRIu64 "\n", stats->allocations_big);
+    fprintf(out, "Object frees: %" PRIu64 "\n", stats->frees);
+    fprintf(out, "Object new values: %" PRIu64 "\n", stats->new_values);
+    fprintf(out, "Object interpreter increfs: %" PRIu64 "\n", stats->interpreter_increfs);
+    fprintf(out, "Object interpreter decrefs: %" PRIu64 "\n", stats->interpreter_decrefs);
+    fprintf(out, "Object increfs: %" PRIu64 "\n", stats->increfs);
+    fprintf(out, "Object decrefs: %" PRIu64 "\n", stats->decrefs);
+    fprintf(out, "Object materialize dict (on request): %" PRIu64 "\n", stats->dict_materialized_on_request);
+    fprintf(out, "Object materialize dict (new key): %" PRIu64 "\n", stats->dict_materialized_new_key);
+    fprintf(out, "Object materialize dict (too big): %" PRIu64 "\n", stats->dict_materialized_too_big);
+    fprintf(out, "Object materialize dict (str subclass): %" PRIu64 "\n", stats->dict_materialized_str_subclass);
+    fprintf(out, "Object method cache hits: %" PRIu64 "\n", stats->type_cache_hits);
+    fprintf(out, "Object method cache misses: %" PRIu64 "\n", stats->type_cache_misses);
+    fprintf(out, "Object method cache collisions: %" PRIu64 "\n", stats->type_cache_collisions);
+    fprintf(out, "Object method cache dunder hits: %" PRIu64 "\n", stats->type_cache_dunder_hits);
+    fprintf(out, "Object method cache dunder misses: %" PRIu64 "\n", stats->type_cache_dunder_misses);
+}
+
+static void
+print_stats(FILE *out, PyStats *stats) {
+    print_spec_stats(out, stats->opcode_stats);
+    print_call_stats(out, &stats->call_stats);
+    print_object_stats(out, &stats->object_stats);
+}
+
+void
+_Py_StatsClear(void)
+{
+    _py_stats_struct = (PyStats) { 0 };
+}
+
+void
+_Py_PrintSpecializationStats(int to_file)
+{
+    FILE *out = stderr;
+    if (to_file) {
+        /* Write to a file instead of stderr. */
+# ifdef MS_WINDOWS
+        const char *dirname = "c:\\temp\\py_stats\\";
+# else
+        const char *dirname = "/tmp/py_stats/";
+# endif
+        /* Use random 160 bit number as file name,
+        * to avoid both accidental collisions and
+        * symlink attacks. */
+        unsigned char rand[20];
+        char hex_name[41];
+        _PyOS_URandomNonblock(rand, 20);
+        for (int i = 0; i < 20; i++) {
+            hex_name[2*i] = "0123456789abcdef"[rand[i]&15];
+            hex_name[2*i+1] = "0123456789abcdef"[(rand[i]>>4)&15];
+        }
+        hex_name[40] = '\0';
+        char buf[64];
+        assert(strlen(dirname) + 40 + strlen(".txt") < 64);
+        sprintf(buf, "%s%s.txt", dirname, hex_name);
+        FILE *fout = fopen(buf, "w");
+        if (fout) {
+            out = fout;
+        }
+    }
+    else {
+        fprintf(out, "Specialization stats:\n");
+    }
+    print_stats(out, &_py_stats_struct);
+    if (out != stderr) {
+        fclose(out);
+    }
+}
+
+#ifdef Py_STATS
+
+#define SPECIALIZATION_FAIL(opcode, kind) \
+do { \
+    if (_py_stats) { \
+        _py_stats->opcode_stats[opcode].specialization.failure_kinds[kind]++; \
+    } \
+} while (0)
+
+#endif
+#endif
+
+#ifndef SPECIALIZATION_FAIL
+#define SPECIALIZATION_FAIL(opcode, kind) ((void)0)
+#endif
+
+// Initialize warmup counters and insert superinstructions. This cannot fail.
+void
+_PyCode_Quicken(PyCodeObject *code)
+{
+    #if ENABLE_SPECIALIZATION
+    int opcode = 0;
+    _Py_CODEUNIT *instructions = _PyCode_CODE(code);
+    for (int i = 0; i < Py_SIZE(code); i++) {
+        int previous_opcode = opcode;
+        opcode = _Py_GetBaseOpcode(code, i);
+        assert(opcode < MIN_INSTRUMENTED_OPCODE);
+        int caches = _PyOpcode_Caches[opcode];
+        if (caches) {
+            instructions[i + 1].cache = adaptive_counter_warmup();
+            i += caches;
+            continue;
+        }
+        switch (previous_opcode << 8 | opcode) {
+            case LOAD_CONST << 8 | LOAD_FAST:
+                instructions[i - 1].op.code = LOAD_CONST__LOAD_FAST;
+                break;
+            case LOAD_FAST << 8 | LOAD_CONST:
+                instructions[i - 1].op.code = LOAD_FAST__LOAD_CONST;
+                break;
+            case LOAD_FAST << 8 | LOAD_FAST:
+                instructions[i - 1].op.code = LOAD_FAST__LOAD_FAST;
+                break;
+            case STORE_FAST << 8 | LOAD_FAST:
+                instructions[i - 1].op.code = STORE_FAST__LOAD_FAST;
+                break;
+            case STORE_FAST << 8 | STORE_FAST:
+                instructions[i - 1].op.code = STORE_FAST__STORE_FAST;
+                break;
+        }
+    }
+    #endif /* ENABLE_SPECIALIZATION */
+}
+
+#define SIMPLE_FUNCTION 0
+
+/* Common */
+
+#define SPEC_FAIL_OTHER 0
+#define SPEC_FAIL_NO_DICT 1
+#define SPEC_FAIL_OVERRIDDEN 2
+#define SPEC_FAIL_OUT_OF_VERSIONS 3
+#define SPEC_FAIL_OUT_OF_RANGE 4
+#define SPEC_FAIL_EXPECTED_ERROR 5
+#define SPEC_FAIL_WRONG_NUMBER_ARGUMENTS 6
+#define SPEC_FAIL_CODE_COMPLEX_PARAMETERS 7
+#define SPEC_FAIL_CODE_NOT_OPTIMIZED 8
+
+
+#define SPEC_FAIL_LOAD_GLOBAL_NON_DICT 17
+#define SPEC_FAIL_LOAD_GLOBAL_NON_STRING_OR_SPLIT 18
+
+/* Super */
+
+#define SPEC_FAIL_SUPER_BAD_CLASS 9
+#define SPEC_FAIL_SUPER_SHADOWED 10
+
+/* Attributes */
+
+#define SPEC_FAIL_ATTR_OVERRIDING_DESCRIPTOR 9
+#define SPEC_FAIL_ATTR_NON_OVERRIDING_DESCRIPTOR 10
+#define SPEC_FAIL_ATTR_NOT_DESCRIPTOR 11
+#define SPEC_FAIL_ATTR_METHOD 12
+#define SPEC_FAIL_ATTR_MUTABLE_CLASS 13
+#define SPEC_FAIL_ATTR_PROPERTY 14
+#define SPEC_FAIL_ATTR_NON_OBJECT_SLOT 15
+#define SPEC_FAIL_ATTR_READ_ONLY 16
+#define SPEC_FAIL_ATTR_AUDITED_SLOT 17
+#define SPEC_FAIL_ATTR_NOT_MANAGED_DICT 18
+#define SPEC_FAIL_ATTR_NON_STRING_OR_SPLIT 19
+#define SPEC_FAIL_ATTR_MODULE_ATTR_NOT_FOUND 20
+
+#define SPEC_FAIL_ATTR_SHADOWED 21
+#define SPEC_FAIL_ATTR_BUILTIN_CLASS_METHOD 22
+#define SPEC_FAIL_ATTR_CLASS_METHOD_OBJ 23
+#define SPEC_FAIL_ATTR_OBJECT_SLOT 24
+#define SPEC_FAIL_ATTR_HAS_MANAGED_DICT 25
+#define SPEC_FAIL_ATTR_INSTANCE_ATTRIBUTE 26
+#define SPEC_FAIL_ATTR_METACLASS_ATTRIBUTE 27
+#define SPEC_FAIL_ATTR_PROPERTY_NOT_PY_FUNCTION 28
+#define SPEC_FAIL_ATTR_NOT_IN_KEYS 29
+#define SPEC_FAIL_ATTR_NOT_IN_DICT 30
+#define SPEC_FAIL_ATTR_CLASS_ATTR_SIMPLE 31
+#define SPEC_FAIL_ATTR_CLASS_ATTR_DESCRIPTOR 32
+#define SPEC_FAIL_ATTR_BUILTIN_CLASS_METHOD_OBJ 33
+
+/* Binary subscr and store subscr */
+
+#define SPEC_FAIL_SUBSCR_ARRAY_INT 9
+#define SPEC_FAIL_SUBSCR_ARRAY_SLICE 10
+#define SPEC_FAIL_SUBSCR_LIST_SLICE 11
+#define SPEC_FAIL_SUBSCR_TUPLE_SLICE 12
+#define SPEC_FAIL_SUBSCR_STRING_INT 13
+#define SPEC_FAIL_SUBSCR_STRING_SLICE 14
+#define SPEC_FAIL_SUBSCR_BUFFER_INT 15
+#define SPEC_FAIL_SUBSCR_BUFFER_SLICE 16
+#define SPEC_FAIL_SUBSCR_SEQUENCE_INT 17
+
+/* Store subscr */
+#define SPEC_FAIL_SUBSCR_BYTEARRAY_INT 18
+#define SPEC_FAIL_SUBSCR_BYTEARRAY_SLICE 19
+#define SPEC_FAIL_SUBSCR_PY_SIMPLE 20
+#define SPEC_FAIL_SUBSCR_PY_OTHER 21
+#define SPEC_FAIL_SUBSCR_DICT_SUBCLASS_NO_OVERRIDE 22
+#define SPEC_FAIL_SUBSCR_NOT_HEAP_TYPE 23
+
+/* Binary op */
+
+#define SPEC_FAIL_BINARY_OP_ADD_DIFFERENT_TYPES          9
+#define SPEC_FAIL_BINARY_OP_ADD_OTHER                   10
+#define SPEC_FAIL_BINARY_OP_AND_DIFFERENT_TYPES         11
+#define SPEC_FAIL_BINARY_OP_AND_INT                     12
+#define SPEC_FAIL_BINARY_OP_AND_OTHER                   13
+#define SPEC_FAIL_BINARY_OP_FLOOR_DIVIDE                14
+#define SPEC_FAIL_BINARY_OP_LSHIFT                      15
+#define SPEC_FAIL_BINARY_OP_MATRIX_MULTIPLY             16
+#define SPEC_FAIL_BINARY_OP_MULTIPLY_DIFFERENT_TYPES    17
+#define SPEC_FAIL_BINARY_OP_MULTIPLY_OTHER              18
+#define SPEC_FAIL_BINARY_OP_OR                          19
+#define SPEC_FAIL_BINARY_OP_POWER                       20
+#define SPEC_FAIL_BINARY_OP_REMAINDER                   21
+#define SPEC_FAIL_BINARY_OP_RSHIFT                      22
+#define SPEC_FAIL_BINARY_OP_SUBTRACT_DIFFERENT_TYPES    23
+#define SPEC_FAIL_BINARY_OP_SUBTRACT_OTHER              24
+#define SPEC_FAIL_BINARY_OP_TRUE_DIVIDE_DIFFERENT_TYPES 25
+#define SPEC_FAIL_BINARY_OP_TRUE_DIVIDE_FLOAT           26
+#define SPEC_FAIL_BINARY_OP_TRUE_DIVIDE_OTHER           27
+#define SPEC_FAIL_BINARY_OP_XOR                         28
+
+/* Calls */
+
+#define SPEC_FAIL_CALL_INSTANCE_METHOD 11
+#define SPEC_FAIL_CALL_CMETHOD 12
+#define SPEC_FAIL_CALL_CFUNC_VARARGS 13
+#define SPEC_FAIL_CALL_CFUNC_VARARGS_KEYWORDS 14
+#define SPEC_FAIL_CALL_CFUNC_NOARGS 15
+#define SPEC_FAIL_CALL_CFUNC_METHOD_FASTCALL_KEYWORDS 16
+#define SPEC_FAIL_CALL_METH_DESCR_VARARGS 17
+#define SPEC_FAIL_CALL_METH_DESCR_VARARGS_KEYWORDS 18
+#define SPEC_FAIL_CALL_METH_DESCR_METHOD_FASTCALL_KEYWORDS 19
+#define SPEC_FAIL_CALL_BAD_CALL_FLAGS 20
+#define SPEC_FAIL_CALL_PYTHON_CLASS 21
+#define SPEC_FAIL_CALL_PEP_523 22
+#define SPEC_FAIL_CALL_BOUND_METHOD 23
+#define SPEC_FAIL_CALL_STR 24
+#define SPEC_FAIL_CALL_CLASS_NO_VECTORCALL 25
+#define SPEC_FAIL_CALL_CLASS_MUTABLE 26
+#define SPEC_FAIL_CALL_KWNAMES 27
+#define SPEC_FAIL_CALL_METHOD_WRAPPER 28
+#define SPEC_FAIL_CALL_OPERATOR_WRAPPER 29
+
+/* COMPARE_OP */
+#define SPEC_FAIL_COMPARE_OP_DIFFERENT_TYPES 12
+#define SPEC_FAIL_COMPARE_OP_STRING 13
+#define SPEC_FAIL_COMPARE_OP_BIG_INT 14
+#define SPEC_FAIL_COMPARE_OP_BYTES 15
+#define SPEC_FAIL_COMPARE_OP_TUPLE 16
+#define SPEC_FAIL_COMPARE_OP_LIST 17
+#define SPEC_FAIL_COMPARE_OP_SET 18
+#define SPEC_FAIL_COMPARE_OP_BOOL 19
+#define SPEC_FAIL_COMPARE_OP_BASEOBJECT 20
+#define SPEC_FAIL_COMPARE_OP_FLOAT_LONG 21
+#define SPEC_FAIL_COMPARE_OP_LONG_FLOAT 22
+
+/* FOR_ITER and SEND */
+#define SPEC_FAIL_ITER_GENERATOR 10
+#define SPEC_FAIL_ITER_COROUTINE 11
+#define SPEC_FAIL_ITER_ASYNC_GENERATOR 12
+#define SPEC_FAIL_ITER_LIST 13
+#define SPEC_FAIL_ITER_TUPLE 14
+#define SPEC_FAIL_ITER_SET 15
+#define SPEC_FAIL_ITER_STRING 16
+#define SPEC_FAIL_ITER_BYTES 17
+#define SPEC_FAIL_ITER_RANGE 18
+#define SPEC_FAIL_ITER_ITERTOOLS 19
+#define SPEC_FAIL_ITER_DICT_KEYS 20
+#define SPEC_FAIL_ITER_DICT_ITEMS 21
+#define SPEC_FAIL_ITER_DICT_VALUES 22
+#define SPEC_FAIL_ITER_ENUMERATE 23
+#define SPEC_FAIL_ITER_MAP 24
+#define SPEC_FAIL_ITER_ZIP 25
+#define SPEC_FAIL_ITER_SEQ_ITER 26
+#define SPEC_FAIL_ITER_REVERSED_LIST 27
+#define SPEC_FAIL_ITER_CALLABLE 28
+#define SPEC_FAIL_ITER_ASCII_STRING 29
+#define SPEC_FAIL_ITER_ASYNC_GENERATOR_SEND 30
+
+// UNPACK_SEQUENCE
+
+#define SPEC_FAIL_UNPACK_SEQUENCE_ITERATOR 9
+#define SPEC_FAIL_UNPACK_SEQUENCE_SEQUENCE 10
+
+static int function_kind(PyCodeObject *code);
+static bool function_check_args(PyObject *o, int expected_argcount, int opcode);
+static uint32_t function_get_version(PyObject *o, int opcode);
+static uint32_t type_get_version(PyTypeObject *t, int opcode);
+
+static int
+specialize_module_load_attr(
+    PyObject *owner, _Py_CODEUNIT *instr, PyObject *name
+) {
+    _PyAttrCache *cache = (_PyAttrCache *)(instr + 1);
+    PyModuleObject *m = (PyModuleObject *)owner;
+    assert((owner->ob_type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0);
+    PyDictObject *dict = (PyDictObject *)m->md_dict;
+    if (dict == NULL) {
+        SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_NO_DICT);
+        return -1;
+    }
+    if (dict->ma_keys->dk_kind != DICT_KEYS_UNICODE) {
+        SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_NON_STRING_OR_SPLIT);
+        return -1;
+    }
+    Py_ssize_t index = _PyDict_LookupIndex(dict, &_Py_ID(__getattr__));
+    assert(index != DKIX_ERROR);
+    if (index != DKIX_EMPTY) {
+        SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_MODULE_ATTR_NOT_FOUND);
+        return -1;
+    }
+    index = _PyDict_LookupIndex(dict, name);
+    assert (index != DKIX_ERROR);
+    if (index != (uint16_t)index) {
+        SPECIALIZATION_FAIL(LOAD_ATTR,
+                            index == DKIX_EMPTY ?
+                            SPEC_FAIL_ATTR_MODULE_ATTR_NOT_FOUND :
+                            SPEC_FAIL_OUT_OF_RANGE);
+        return -1;
+    }
+    uint32_t keys_version = _PyDictKeys_GetVersionForCurrentState(
+            _PyInterpreterState_GET(), dict->ma_keys);
+    if (keys_version == 0) {
+        SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OUT_OF_VERSIONS);
+        return -1;
+    }
+    write_u32(cache->version, keys_version);
+    cache->index = (uint16_t)index;
+    instr->op.code = LOAD_ATTR_MODULE;
+    return 0;
+}
+
+
+
+/* Attribute specialization */
+
+void
+_Py_Specialize_LoadSuperAttr(PyObject *global_super, PyObject *cls, _Py_CODEUNIT *instr, int load_method) {
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[LOAD_SUPER_ATTR] == INLINE_CACHE_ENTRIES_LOAD_SUPER_ATTR);
+    _PySuperAttrCache *cache = (_PySuperAttrCache *)(instr + 1);
+    if (global_super != (PyObject *)&PySuper_Type) {
+        SPECIALIZATION_FAIL(LOAD_SUPER_ATTR, SPEC_FAIL_SUPER_SHADOWED);
+        goto fail;
+    }
+    if (!PyType_Check(cls)) {
+        SPECIALIZATION_FAIL(LOAD_SUPER_ATTR, SPEC_FAIL_SUPER_BAD_CLASS);
+        goto fail;
+    }
+    instr->op.code = load_method ? LOAD_SUPER_ATTR_METHOD : LOAD_SUPER_ATTR_ATTR;
+    goto success;
+
+fail:
+    STAT_INC(LOAD_SUPER_ATTR, failure);
+    assert(!PyErr_Occurred());
+    instr->op.code = LOAD_SUPER_ATTR;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(LOAD_SUPER_ATTR, success);
+    assert(!PyErr_Occurred());
+    cache->counter = adaptive_counter_cooldown();
+}
+
+typedef enum {
+    OVERRIDING, /* Is an overriding descriptor, and will remain so. */
+    METHOD, /* Attribute has Py_TPFLAGS_METHOD_DESCRIPTOR set */
+    PROPERTY, /* Is a property */
+    OBJECT_SLOT, /* Is an object slot descriptor */
+    OTHER_SLOT, /* Is a slot descriptor of another type */
+    NON_OVERRIDING, /* Is another non-overriding descriptor, and is an instance of an immutable class*/
+    BUILTIN_CLASSMETHOD, /* Builtin methods with METH_CLASS */
+    PYTHON_CLASSMETHOD, /* Python classmethod(func) object */
+    NON_DESCRIPTOR, /* Is not a descriptor, and is an instance of an immutable class */
+    MUTABLE,   /* Instance of a mutable class; might, or might not, be a descriptor */
+    ABSENT, /* Attribute is not present on the class */
+    DUNDER_CLASS, /* __class__ attribute */
+    GETSET_OVERRIDDEN, /* __getattribute__ or __setattr__ has been overridden */
+    GETATTRIBUTE_IS_PYTHON_FUNCTION  /* Descriptor requires calling a Python __getattribute__ */
+} DescriptorClassification;
+
+
+static DescriptorClassification
+analyze_descriptor(PyTypeObject *type, PyObject *name, PyObject **descr, int store)
+{
+    bool has_getattr = false;
+    if (store) {
+        if (type->tp_setattro != PyObject_GenericSetAttr) {
+            *descr = NULL;
+            return GETSET_OVERRIDDEN;
+        }
+    }
+    else {
+        getattrofunc getattro_slot = type->tp_getattro;
+        if (getattro_slot == PyObject_GenericGetAttr) {
+            /* Normal attribute lookup; */
+            has_getattr = false;
+        }
+        else if (getattro_slot == _Py_slot_tp_getattr_hook ||
+            getattro_slot == _Py_slot_tp_getattro) {
+            /* One or both of __getattribute__ or __getattr__ may have been
+             overridden See typeobject.c for why these functions are special. */
+            PyObject *getattribute = _PyType_Lookup(type,
+                &_Py_ID(__getattribute__));
+            PyInterpreterState *interp = _PyInterpreterState_GET();
+            bool has_custom_getattribute = getattribute != NULL &&
+                getattribute != interp->callable_cache.object__getattribute__;
+            has_getattr = _PyType_Lookup(type, &_Py_ID(__getattr__)) != NULL;
+            if (has_custom_getattribute) {
+                if (getattro_slot == _Py_slot_tp_getattro &&
+                    !has_getattr &&
+                    Py_IS_TYPE(getattribute, &PyFunction_Type)) {
+                    *descr = getattribute;
+                    return GETATTRIBUTE_IS_PYTHON_FUNCTION;
+                }
+                /* Potentially both __getattr__ and __getattribute__ are set.
+                   Too complicated */
+                *descr = NULL;
+                return GETSET_OVERRIDDEN;
+            }
+            /* Potentially has __getattr__ but no custom __getattribute__.
+               Fall through to usual descriptor analysis.
+               Usual attribute lookup should only be allowed at runtime
+               if we can guarantee that there is no way an exception can be
+               raised. This means some specializations, e.g. specializing
+               for property() isn't safe.
+            */
+        }
+        else {
+            *descr = NULL;
+            return GETSET_OVERRIDDEN;
+        }
+    }
+    PyObject *descriptor = _PyType_Lookup(type, name);
+    *descr = descriptor;
+    if (descriptor == NULL) {
+        return ABSENT;
+    }
+    PyTypeObject *desc_cls = Py_TYPE(descriptor);
+    if (!(desc_cls->tp_flags & Py_TPFLAGS_IMMUTABLETYPE)) {
+        return MUTABLE;
+    }
+    if (desc_cls->tp_descr_set) {
+        if (desc_cls == &PyMemberDescr_Type) {
+            PyMemberDescrObject *member = (PyMemberDescrObject *)descriptor;
+            struct PyMemberDef *dmem = member->d_member;
+            if (dmem->type == T_OBJECT_EX) {
+                return OBJECT_SLOT;
+            }
+            return OTHER_SLOT;
+        }
+        if (desc_cls == &PyProperty_Type) {
+            /* We can't detect at runtime whether an attribute exists
+               with property. So that means we may have to call
+               __getattr__. */
+            return has_getattr ? GETSET_OVERRIDDEN : PROPERTY;
+        }
+        if (PyUnicode_CompareWithASCIIString(name, "__class__") == 0) {
+            if (descriptor == _PyType_Lookup(&PyBaseObject_Type, name)) {
+                return DUNDER_CLASS;
+            }
+        }
+        if (store) {
+            return OVERRIDING;
+        }
+    }
+    if (desc_cls->tp_descr_get) {
+        if (desc_cls->tp_flags & Py_TPFLAGS_METHOD_DESCRIPTOR) {
+            return METHOD;
+        }
+        if (Py_IS_TYPE(descriptor, &PyClassMethodDescr_Type)) {
+            return BUILTIN_CLASSMETHOD;
+        }
+        if (Py_IS_TYPE(descriptor, &PyClassMethod_Type)) {
+            return PYTHON_CLASSMETHOD;
+        }
+        return NON_OVERRIDING;
+    }
+    return NON_DESCRIPTOR;
+}
+
+static int
+specialize_dict_access(
+    PyObject *owner, _Py_CODEUNIT *instr, PyTypeObject *type,
+    DescriptorClassification kind, PyObject *name,
+    int base_op, int values_op, int hint_op)
+{
+    assert(kind == NON_OVERRIDING || kind == NON_DESCRIPTOR || kind == ABSENT ||
+        kind == BUILTIN_CLASSMETHOD || kind == PYTHON_CLASSMETHOD);
+    // No descriptor, or non overriding.
+    if ((type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0) {
+        SPECIALIZATION_FAIL(base_op, SPEC_FAIL_ATTR_NOT_MANAGED_DICT);
+        return 0;
+    }
+    _PyAttrCache *cache = (_PyAttrCache *)(instr + 1);
+    PyDictOrValues dorv = *_PyObject_DictOrValuesPointer(owner);
+    if (_PyDictOrValues_IsValues(dorv)) {
+        // Virtual dictionary
+        PyDictKeysObject *keys = ((PyHeapTypeObject *)type)->ht_cached_keys;
+        assert(PyUnicode_CheckExact(name));
+        Py_ssize_t index = _PyDictKeys_StringLookup(keys, name);
+        assert (index != DKIX_ERROR);
+        if (index != (uint16_t)index) {
+            SPECIALIZATION_FAIL(base_op,
+                                index == DKIX_EMPTY ?
+                                SPEC_FAIL_ATTR_NOT_IN_KEYS :
+                                SPEC_FAIL_OUT_OF_RANGE);
+            return 0;
+        }
+        write_u32(cache->version, type->tp_version_tag);
+        cache->index = (uint16_t)index;
+        instr->op.code = values_op;
+    }
+    else {
+        PyDictObject *dict = (PyDictObject *)_PyDictOrValues_GetDict(dorv);
+        if (dict == NULL || !PyDict_CheckExact(dict)) {
+            SPECIALIZATION_FAIL(base_op, SPEC_FAIL_NO_DICT);
+            return 0;
+        }
+        // We found an instance with a __dict__.
+        Py_ssize_t index =
+            _PyDict_LookupIndex(dict, name);
+        if (index != (uint16_t)index) {
+            SPECIALIZATION_FAIL(base_op,
+                                index == DKIX_EMPTY ?
+                                SPEC_FAIL_ATTR_NOT_IN_DICT :
+                                SPEC_FAIL_OUT_OF_RANGE);
+            return 0;
+        }
+        cache->index = (uint16_t)index;
+        write_u32(cache->version, type->tp_version_tag);
+        instr->op.code = hint_op;
+    }
+    return 1;
+}
+
+static int specialize_attr_loadmethod(PyObject* owner, _Py_CODEUNIT* instr, PyObject* name,
+    PyObject* descr, DescriptorClassification kind);
+static int specialize_class_load_attr(PyObject* owner, _Py_CODEUNIT* instr, PyObject* name);
+
+void
+_Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[LOAD_ATTR] == INLINE_CACHE_ENTRIES_LOAD_ATTR);
+    _PyAttrCache *cache = (_PyAttrCache *)(instr + 1);
+    PyTypeObject *type = Py_TYPE(owner);
+    if (!_PyType_IsReady(type)) {
+        // We *might* not really need this check, but we inherited it from
+        // PyObject_GenericGetAttr and friends... and this way we still do the
+        // right thing if someone forgets to call PyType_Ready(type):
+        SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OTHER);
+        goto fail;
+    }
+    if (PyModule_CheckExact(owner)) {
+        if (specialize_module_load_attr(owner, instr, name))
+        {
+            goto fail;
+        }
+        goto success;
+    }
+    if (PyType_Check(owner)) {
+        if (specialize_class_load_attr(owner, instr, name)) {
+            goto fail;
+        }
+        goto success;
+    }
+    PyObject *descr = NULL;
+    DescriptorClassification kind = analyze_descriptor(type, name, &descr, 0);
+    assert(descr != NULL || kind == ABSENT || kind == GETSET_OVERRIDDEN);
+    if (type_get_version(type, LOAD_ATTR) == 0) {
+        goto fail;
+    }
+    switch(kind) {
+        case OVERRIDING:
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_OVERRIDING_DESCRIPTOR);
+            goto fail;
+        case METHOD:
+        {
+            int oparg = instr->op.arg;
+            if (oparg & 1) {
+                if (specialize_attr_loadmethod(owner, instr, name, descr, kind)) {
+                    goto success;
+                }
+            }
+            else {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_METHOD);
+            }
+            goto fail;
+        }
+        case PROPERTY:
+        {
+            _PyLoadMethodCache *lm_cache = (_PyLoadMethodCache *)(instr + 1);
+            assert(Py_TYPE(descr) == &PyProperty_Type);
+            PyObject *fget = ((_PyPropertyObject *)descr)->prop_get;
+            if (fget == NULL) {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_EXPECTED_ERROR);
+                goto fail;
+            }
+            if (!Py_IS_TYPE(fget, &PyFunction_Type)) {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_PROPERTY_NOT_PY_FUNCTION);
+                goto fail;
+            }
+            if (!function_check_args(fget, 1, LOAD_ATTR)) {
+                goto fail;
+            }
+            uint32_t version = function_get_version(fget, LOAD_ATTR);
+            if (version == 0) {
+                goto fail;
+            }
+            if (_PyInterpreterState_GET()->eval_frame) {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OTHER);
+                goto fail;
+            }
+            write_u32(lm_cache->keys_version, version);
+            assert(type->tp_version_tag != 0);
+            write_u32(lm_cache->type_version, type->tp_version_tag);
+            /* borrowed */
+            write_obj(lm_cache->descr, fget);
+            instr->op.code = LOAD_ATTR_PROPERTY;
+            goto success;
+        }
+        case OBJECT_SLOT:
+        {
+            PyMemberDescrObject *member = (PyMemberDescrObject *)descr;
+            struct PyMemberDef *dmem = member->d_member;
+            Py_ssize_t offset = dmem->offset;
+            if (!PyObject_TypeCheck(owner, member->d_common.d_type)) {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_EXPECTED_ERROR);
+                goto fail;
+            }
+            if (dmem->flags & PY_AUDIT_READ) {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_AUDITED_SLOT);
+                goto fail;
+            }
+            if (offset != (uint16_t)offset) {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OUT_OF_RANGE);
+                goto fail;
+            }
+            assert(dmem->type == T_OBJECT_EX);
+            assert(offset > 0);
+            cache->index = (uint16_t)offset;
+            write_u32(cache->version, type->tp_version_tag);
+            instr->op.code = LOAD_ATTR_SLOT;
+            goto success;
+        }
+        case DUNDER_CLASS:
+        {
+            Py_ssize_t offset = offsetof(PyObject, ob_type);
+            assert(offset == (uint16_t)offset);
+            cache->index = (uint16_t)offset;
+            write_u32(cache->version, type->tp_version_tag);
+            instr->op.code = LOAD_ATTR_SLOT;
+            goto success;
+        }
+        case OTHER_SLOT:
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_NON_OBJECT_SLOT);
+            goto fail;
+        case MUTABLE:
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_MUTABLE_CLASS);
+            goto fail;
+        case GETSET_OVERRIDDEN:
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OVERRIDDEN);
+            goto fail;
+        case GETATTRIBUTE_IS_PYTHON_FUNCTION:
+        {
+            assert(type->tp_getattro == _Py_slot_tp_getattro);
+            assert(Py_IS_TYPE(descr, &PyFunction_Type));
+            _PyLoadMethodCache *lm_cache = (_PyLoadMethodCache *)(instr + 1);
+            if (!function_check_args(descr, 2, LOAD_ATTR)) {
+                goto fail;
+            }
+            uint32_t version = function_get_version(descr, LOAD_ATTR);
+            if (version == 0) {
+                goto fail;
+            }
+            if (_PyInterpreterState_GET()->eval_frame) {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OTHER);
+                goto fail;
+            }
+            write_u32(lm_cache->keys_version, version);
+            /* borrowed */
+            write_obj(lm_cache->descr, descr);
+            write_u32(lm_cache->type_version, type->tp_version_tag);
+            instr->op.code = LOAD_ATTR_GETATTRIBUTE_OVERRIDDEN;
+            goto success;
+        }
+        case BUILTIN_CLASSMETHOD:
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_BUILTIN_CLASS_METHOD_OBJ);
+            goto fail;
+        case PYTHON_CLASSMETHOD:
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_CLASS_METHOD_OBJ);
+            goto fail;
+        case NON_OVERRIDING:
+            SPECIALIZATION_FAIL(LOAD_ATTR,
+                                (type->tp_flags & Py_TPFLAGS_MANAGED_DICT) ?
+                                SPEC_FAIL_ATTR_CLASS_ATTR_DESCRIPTOR :
+                                SPEC_FAIL_ATTR_NOT_MANAGED_DICT);
+            goto fail;
+        case NON_DESCRIPTOR:
+            SPECIALIZATION_FAIL(LOAD_ATTR,
+                                (type->tp_flags & Py_TPFLAGS_MANAGED_DICT) ?
+                                SPEC_FAIL_ATTR_CLASS_ATTR_SIMPLE :
+                                SPEC_FAIL_ATTR_NOT_MANAGED_DICT);
+            goto fail;
+        case ABSENT:
+            if (specialize_dict_access(owner, instr, type, kind, name, LOAD_ATTR,
+                                    LOAD_ATTR_INSTANCE_VALUE, LOAD_ATTR_WITH_HINT))
+            {
+                goto success;
+            }
+    }
+fail:
+    STAT_INC(LOAD_ATTR, failure);
+    assert(!PyErr_Occurred());
+    instr->op.code = LOAD_ATTR;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(LOAD_ATTR, success);
+    assert(!PyErr_Occurred());
+    cache->counter = adaptive_counter_cooldown();
+}
+
+void
+_Py_Specialize_StoreAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[STORE_ATTR] == INLINE_CACHE_ENTRIES_STORE_ATTR);
+    _PyAttrCache *cache = (_PyAttrCache *)(instr + 1);
+    PyTypeObject *type = Py_TYPE(owner);
+    if (!_PyType_IsReady(type)) {
+        // We *might* not really need this check, but we inherited it from
+        // PyObject_GenericSetAttr and friends... and this way we still do the
+        // right thing if someone forgets to call PyType_Ready(type):
+        SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_OTHER);
+        goto fail;
+    }
+    if (PyModule_CheckExact(owner)) {
+        SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_OVERRIDDEN);
+        goto fail;
+    }
+    PyObject *descr;
+    DescriptorClassification kind = analyze_descriptor(type, name, &descr, 1);
+    if (type_get_version(type, STORE_ATTR) == 0) {
+        goto fail;
+    }
+    switch(kind) {
+        case OVERRIDING:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_OVERRIDING_DESCRIPTOR);
+            goto fail;
+        case METHOD:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_METHOD);
+            goto fail;
+        case PROPERTY:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_PROPERTY);
+            goto fail;
+        case OBJECT_SLOT:
+        {
+            PyMemberDescrObject *member = (PyMemberDescrObject *)descr;
+            struct PyMemberDef *dmem = member->d_member;
+            Py_ssize_t offset = dmem->offset;
+            if (!PyObject_TypeCheck(owner, member->d_common.d_type)) {
+                SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_EXPECTED_ERROR);
+                goto fail;
+            }
+            if (dmem->flags & READONLY) {
+                SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_READ_ONLY);
+                goto fail;
+            }
+            if (offset != (uint16_t)offset) {
+                SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_OUT_OF_RANGE);
+                goto fail;
+            }
+            assert(dmem->type == T_OBJECT_EX);
+            assert(offset > 0);
+            cache->index = (uint16_t)offset;
+            write_u32(cache->version, type->tp_version_tag);
+            instr->op.code = STORE_ATTR_SLOT;
+            goto success;
+        }
+        case DUNDER_CLASS:
+        case OTHER_SLOT:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_NON_OBJECT_SLOT);
+            goto fail;
+        case MUTABLE:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_MUTABLE_CLASS);
+            goto fail;
+        case GETATTRIBUTE_IS_PYTHON_FUNCTION:
+        case GETSET_OVERRIDDEN:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_OVERRIDDEN);
+            goto fail;
+        case BUILTIN_CLASSMETHOD:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_BUILTIN_CLASS_METHOD_OBJ);
+            goto fail;
+        case PYTHON_CLASSMETHOD:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_CLASS_METHOD_OBJ);
+            goto fail;
+        case NON_OVERRIDING:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_CLASS_ATTR_DESCRIPTOR);
+            goto fail;
+        case NON_DESCRIPTOR:
+            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_CLASS_ATTR_SIMPLE);
+            goto fail;
+        case ABSENT:
+            if (specialize_dict_access(owner, instr, type, kind, name, STORE_ATTR,
+                                    STORE_ATTR_INSTANCE_VALUE, STORE_ATTR_WITH_HINT))
+            {
+                goto success;
+            }
+    }
+fail:
+    STAT_INC(STORE_ATTR, failure);
+    assert(!PyErr_Occurred());
+    instr->op.code = STORE_ATTR;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(STORE_ATTR, success);
+    assert(!PyErr_Occurred());
+    cache->counter = adaptive_counter_cooldown();
+}
+
+
+#ifdef Py_STATS
+static int
+load_attr_fail_kind(DescriptorClassification kind)
+{
+    switch (kind) {
+        case OVERRIDING:
+            return SPEC_FAIL_ATTR_OVERRIDING_DESCRIPTOR;
+        case METHOD:
+            return SPEC_FAIL_ATTR_METHOD;
+        case PROPERTY:
+            return SPEC_FAIL_ATTR_PROPERTY;
+        case OBJECT_SLOT:
+            return SPEC_FAIL_ATTR_OBJECT_SLOT;
+        case OTHER_SLOT:
+            return SPEC_FAIL_ATTR_NON_OBJECT_SLOT;
+        case DUNDER_CLASS:
+            return SPEC_FAIL_OTHER;
+        case MUTABLE:
+            return SPEC_FAIL_ATTR_MUTABLE_CLASS;
+        case GETSET_OVERRIDDEN:
+        case GETATTRIBUTE_IS_PYTHON_FUNCTION:
+            return SPEC_FAIL_OVERRIDDEN;
+        case BUILTIN_CLASSMETHOD:
+            return SPEC_FAIL_ATTR_BUILTIN_CLASS_METHOD;
+        case PYTHON_CLASSMETHOD:
+            return SPEC_FAIL_ATTR_CLASS_METHOD_OBJ;
+        case NON_OVERRIDING:
+            return SPEC_FAIL_ATTR_NON_OVERRIDING_DESCRIPTOR;
+        case NON_DESCRIPTOR:
+            return SPEC_FAIL_ATTR_NOT_DESCRIPTOR;
+        case ABSENT:
+            return SPEC_FAIL_ATTR_INSTANCE_ATTRIBUTE;
+    }
+    Py_UNREACHABLE();
+}
+#endif
+
+static int
+specialize_class_load_attr(PyObject *owner, _Py_CODEUNIT *instr,
+                             PyObject *name)
+{
+    _PyLoadMethodCache *cache = (_PyLoadMethodCache *)(instr + 1);
+    if (!PyType_CheckExact(owner) || _PyType_Lookup(Py_TYPE(owner), name)) {
+        SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_METACLASS_ATTRIBUTE);
+        return -1;
+    }
+    PyObject *descr = NULL;
+    DescriptorClassification kind = 0;
+    kind = analyze_descriptor((PyTypeObject *)owner, name, &descr, 0);
+    if (type_get_version((PyTypeObject *)owner, LOAD_ATTR) == 0) {
+        return -1;
+    }
+    switch (kind) {
+        case METHOD:
+        case NON_DESCRIPTOR:
+            write_u32(cache->type_version, ((PyTypeObject *)owner)->tp_version_tag);
+            write_obj(cache->descr, descr);
+            instr->op.code = LOAD_ATTR_CLASS;
+            return 0;
+#ifdef Py_STATS
+        case ABSENT:
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_EXPECTED_ERROR);
+            return -1;
+#endif
+        default:
+            SPECIALIZATION_FAIL(LOAD_ATTR, load_attr_fail_kind(kind));
+            return -1;
+    }
+}
+
+// Please collect stats carefully before and after modifying. A subtle change
+// can cause a significant drop in cache hits. A possible test is
+// python.exe -m test_typing test_re test_dis test_zlib.
+static int
+specialize_attr_loadmethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
+PyObject *descr, DescriptorClassification kind)
+{
+    _PyLoadMethodCache *cache = (_PyLoadMethodCache *)(instr + 1);
+    PyTypeObject *owner_cls = Py_TYPE(owner);
+
+    assert(kind == METHOD && descr != NULL);
+    if (owner_cls->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
+        PyDictOrValues dorv = *_PyObject_DictOrValuesPointer(owner);
+        PyDictKeysObject *keys = ((PyHeapTypeObject *)owner_cls)->ht_cached_keys;
+        if (!_PyDictOrValues_IsValues(dorv)) {
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_HAS_MANAGED_DICT);
+            return 0;
+        }
+        Py_ssize_t index = _PyDictKeys_StringLookup(keys, name);
+        if (index != DKIX_EMPTY) {
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_SHADOWED);
+            return 0;
+        }
+        uint32_t keys_version = _PyDictKeys_GetVersionForCurrentState(
+                _PyInterpreterState_GET(), keys);
+        if (keys_version == 0) {
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OUT_OF_VERSIONS);
+            return 0;
+        }
+        write_u32(cache->keys_version, keys_version);
+        instr->op.code = LOAD_ATTR_METHOD_WITH_VALUES;
+    }
+    else {
+        Py_ssize_t dictoffset = owner_cls->tp_dictoffset;
+        if (dictoffset < 0 || dictoffset > INT16_MAX) {
+            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OUT_OF_RANGE);
+            return 0;
+        }
+        if (dictoffset == 0) {
+            instr->op.code = LOAD_ATTR_METHOD_NO_DICT;
+        }
+        else {
+            PyObject *dict = *(PyObject **) ((char *)owner + dictoffset);
+            if (dict) {
+                SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_NOT_MANAGED_DICT);
+                return 0;
+            }
+            assert(owner_cls->tp_dictoffset > 0);
+            assert(owner_cls->tp_dictoffset <= INT16_MAX);
+            instr->op.code = LOAD_ATTR_METHOD_LAZY_DICT;
+        }
+    }
+    /* `descr` is borrowed. This is safe for methods (even inherited ones from
+    *  super classes!) as long as tp_version_tag is validated for two main reasons:
+    *
+    *  1. The class will always hold a reference to the method so it will
+    *  usually not be GC-ed. Should it be deleted in Python, e.g.
+    *  `del obj.meth`, tp_version_tag will be invalidated, because of reason 2.
+    *
+    *  2. The pre-existing type method cache (MCACHE) uses the same principles
+    *  of caching a borrowed descriptor. The MCACHE infrastructure does all the
+    *  heavy lifting for us. E.g. it invalidates tp_version_tag on any MRO
+    *  modification, on any type object change along said MRO, etc. (see
+    *  PyType_Modified usages in typeobject.c). The MCACHE has been
+    *  working since Python 2.6 and it's battle-tested.
+    */
+    write_u32(cache->type_version, owner_cls->tp_version_tag);
+    write_obj(cache->descr, descr);
+    return 1;
+}
+
+void
+_Py_Specialize_LoadGlobal(
+    PyObject *globals, PyObject *builtins,
+    _Py_CODEUNIT *instr, PyObject *name)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[LOAD_GLOBAL] == INLINE_CACHE_ENTRIES_LOAD_GLOBAL);
+    /* Use inline cache */
+    _PyLoadGlobalCache *cache = (_PyLoadGlobalCache *)(instr + 1);
+    assert(PyUnicode_CheckExact(name));
+    if (!PyDict_CheckExact(globals)) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_LOAD_GLOBAL_NON_DICT);
+        goto fail;
+    }
+    PyDictKeysObject * globals_keys = ((PyDictObject *)globals)->ma_keys;
+    if (!DK_IS_UNICODE(globals_keys)) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_LOAD_GLOBAL_NON_STRING_OR_SPLIT);
+        goto fail;
+    }
+    Py_ssize_t index = _PyDictKeys_StringLookup(globals_keys, name);
+    if (index == DKIX_ERROR) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_EXPECTED_ERROR);
+        goto fail;
+    }
+    PyInterpreterState *interp = _PyInterpreterState_GET();
+    if (index != DKIX_EMPTY) {
+        if (index != (uint16_t)index) {
+            SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_OUT_OF_RANGE);
+            goto fail;
+        }
+        uint32_t keys_version = _PyDictKeys_GetVersionForCurrentState(
+                interp, globals_keys);
+        if (keys_version == 0) {
+            SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_OUT_OF_VERSIONS);
+            goto fail;
+        }
+        if (keys_version != (uint16_t)keys_version) {
+            SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_OUT_OF_RANGE);
+            goto fail;
+        }
+        cache->index = (uint16_t)index;
+        cache->module_keys_version = (uint16_t)keys_version;
+        instr->op.code = LOAD_GLOBAL_MODULE;
+        goto success;
+    }
+    if (!PyDict_CheckExact(builtins)) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_LOAD_GLOBAL_NON_DICT);
+        goto fail;
+    }
+    PyDictKeysObject * builtin_keys = ((PyDictObject *)builtins)->ma_keys;
+    if (!DK_IS_UNICODE(builtin_keys)) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_LOAD_GLOBAL_NON_STRING_OR_SPLIT);
+        goto fail;
+    }
+    index = _PyDictKeys_StringLookup(builtin_keys, name);
+    if (index == DKIX_ERROR) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_EXPECTED_ERROR);
+        goto fail;
+    }
+    if (index != (uint16_t)index) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_OUT_OF_RANGE);
+        goto fail;
+    }
+    uint32_t globals_version = _PyDictKeys_GetVersionForCurrentState(
+            interp, globals_keys);
+    if (globals_version == 0) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_OUT_OF_VERSIONS);
+        goto fail;
+    }
+    if (globals_version != (uint16_t)globals_version) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_OUT_OF_RANGE);
+        goto fail;
+    }
+    uint32_t builtins_version = _PyDictKeys_GetVersionForCurrentState(
+            interp, builtin_keys);
+    if (builtins_version == 0) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_OUT_OF_VERSIONS);
+        goto fail;
+    }
+    if (builtins_version > UINT16_MAX) {
+        SPECIALIZATION_FAIL(LOAD_GLOBAL, SPEC_FAIL_OUT_OF_RANGE);
+        goto fail;
+    }
+    cache->index = (uint16_t)index;
+    cache->module_keys_version = (uint16_t)globals_version;
+    cache->builtin_keys_version = (uint16_t)builtins_version;
+    instr->op.code = LOAD_GLOBAL_BUILTIN;
+    goto success;
+fail:
+    STAT_INC(LOAD_GLOBAL, failure);
+    assert(!PyErr_Occurred());
+    instr->op.code = LOAD_GLOBAL;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(LOAD_GLOBAL, success);
+    assert(!PyErr_Occurred());
+    cache->counter = adaptive_counter_cooldown();
+}
+
+#ifdef Py_STATS
+static int
+binary_subscr_fail_kind(PyTypeObject *container_type, PyObject *sub)
+{
+    if (container_type == &PyUnicode_Type) {
+        if (PyLong_CheckExact(sub)) {
+            return SPEC_FAIL_SUBSCR_STRING_INT;
+        }
+        if (PySlice_Check(sub)) {
+            return SPEC_FAIL_SUBSCR_STRING_SLICE;
+        }
+        return SPEC_FAIL_OTHER;
+    }
+    else if (strcmp(container_type->tp_name, "array.array") == 0) {
+        if (PyLong_CheckExact(sub)) {
+            return SPEC_FAIL_SUBSCR_ARRAY_INT;
+        }
+        if (PySlice_Check(sub)) {
+            return SPEC_FAIL_SUBSCR_ARRAY_SLICE;
+        }
+        return SPEC_FAIL_OTHER;
+    }
+    else if (container_type->tp_as_buffer) {
+        if (PyLong_CheckExact(sub)) {
+            return SPEC_FAIL_SUBSCR_BUFFER_INT;
+        }
+        if (PySlice_Check(sub)) {
+            return SPEC_FAIL_SUBSCR_BUFFER_SLICE;
+        }
+        return SPEC_FAIL_OTHER;
+    }
+    else if (container_type->tp_as_sequence) {
+        if (PyLong_CheckExact(sub) && container_type->tp_as_sequence->sq_item) {
+            return SPEC_FAIL_SUBSCR_SEQUENCE_INT;
+        }
+    }
+    return SPEC_FAIL_OTHER;
+}
+#endif
+
+static int
+function_kind(PyCodeObject *code) {
+    int flags = code->co_flags;
+    if ((flags & (CO_VARKEYWORDS | CO_VARARGS)) || code->co_kwonlyargcount) {
+        return SPEC_FAIL_CODE_COMPLEX_PARAMETERS;
+    }
+    if ((flags & CO_OPTIMIZED) == 0) {
+        return SPEC_FAIL_CODE_NOT_OPTIMIZED;
+    }
+    return SIMPLE_FUNCTION;
+}
+
+/* Returning false indicates a failure. */
+static bool
+function_check_args(PyObject *o, int expected_argcount, int opcode)
+{
+    assert(Py_IS_TYPE(o, &PyFunction_Type));
+    PyFunctionObject *func = (PyFunctionObject *)o;
+    PyCodeObject *fcode = (PyCodeObject *)func->func_code;
+    int kind = function_kind(fcode);
+    if (kind != SIMPLE_FUNCTION) {
+        SPECIALIZATION_FAIL(opcode, kind);
+        return false;
+    }
+    if (fcode->co_argcount != expected_argcount) {
+        SPECIALIZATION_FAIL(opcode, SPEC_FAIL_WRONG_NUMBER_ARGUMENTS);
+        return false;
+    }
+    return true;
+}
+
+/* Returning 0 indicates a failure. */
+static uint32_t
+function_get_version(PyObject *o, int opcode)
+{
+    assert(Py_IS_TYPE(o, &PyFunction_Type));
+    PyFunctionObject *func = (PyFunctionObject *)o;
+    uint32_t version = _PyFunction_GetVersionForCurrentState(func);
+    if (version == 0) {
+        SPECIALIZATION_FAIL(opcode, SPEC_FAIL_OUT_OF_VERSIONS);
+        return 0;
+    }
+    return version;
+}
+
+/* Returning 0 indicates a failure. */
+static uint32_t
+type_get_version(PyTypeObject *t, int opcode)
+{
+    uint32_t version = t->tp_version_tag;
+    if (version == 0) {
+        SPECIALIZATION_FAIL(opcode, SPEC_FAIL_OUT_OF_VERSIONS);
+        return 0;
+    }
+    return version;
+}
+
+void
+_Py_Specialize_BinarySubscr(
+     PyObject *container, PyObject *sub, _Py_CODEUNIT *instr)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[BINARY_SUBSCR] ==
+           INLINE_CACHE_ENTRIES_BINARY_SUBSCR);
+    _PyBinarySubscrCache *cache = (_PyBinarySubscrCache *)(instr + 1);
+    PyTypeObject *container_type = Py_TYPE(container);
+    if (container_type == &PyList_Type) {
+        if (PyLong_CheckExact(sub)) {
+            if (_PyLong_IsNonNegativeCompact((PyLongObject *)sub)) {
+                instr->op.code = BINARY_SUBSCR_LIST_INT;
+                goto success;
+            }
+            SPECIALIZATION_FAIL(BINARY_SUBSCR, SPEC_FAIL_OUT_OF_RANGE);
+            goto fail;
+        }
+        SPECIALIZATION_FAIL(BINARY_SUBSCR,
+            PySlice_Check(sub) ? SPEC_FAIL_SUBSCR_LIST_SLICE : SPEC_FAIL_OTHER);
+        goto fail;
+    }
+    if (container_type == &PyTuple_Type) {
+        if (PyLong_CheckExact(sub)) {
+            if (_PyLong_IsNonNegativeCompact((PyLongObject *)sub)) {
+                instr->op.code = BINARY_SUBSCR_TUPLE_INT;
+                goto success;
+            }
+            SPECIALIZATION_FAIL(BINARY_SUBSCR, SPEC_FAIL_OUT_OF_RANGE);
+            goto fail;
+        }
+        SPECIALIZATION_FAIL(BINARY_SUBSCR,
+            PySlice_Check(sub) ? SPEC_FAIL_SUBSCR_TUPLE_SLICE : SPEC_FAIL_OTHER);
+        goto fail;
+    }
+    if (container_type == &PyDict_Type) {
+        instr->op.code = BINARY_SUBSCR_DICT;
+        goto success;
+    }
+    PyTypeObject *cls = Py_TYPE(container);
+    PyObject *descriptor = _PyType_Lookup(cls, &_Py_ID(__getitem__));
+    if (descriptor && Py_TYPE(descriptor) == &PyFunction_Type) {
+        if (!(container_type->tp_flags & Py_TPFLAGS_HEAPTYPE)) {
+            SPECIALIZATION_FAIL(BINARY_SUBSCR, SPEC_FAIL_SUBSCR_NOT_HEAP_TYPE);
+            goto fail;
+        }
+        PyFunctionObject *func = (PyFunctionObject *)descriptor;
+        PyCodeObject *fcode = (PyCodeObject *)func->func_code;
+        int kind = function_kind(fcode);
+        if (kind != SIMPLE_FUNCTION) {
+            SPECIALIZATION_FAIL(BINARY_SUBSCR, kind);
+            goto fail;
+        }
+        if (fcode->co_argcount != 2) {
+            SPECIALIZATION_FAIL(BINARY_SUBSCR, SPEC_FAIL_WRONG_NUMBER_ARGUMENTS);
+            goto fail;
+        }
+        uint32_t version = _PyFunction_GetVersionForCurrentState(func);
+        if (version == 0) {
+            SPECIALIZATION_FAIL(BINARY_SUBSCR, SPEC_FAIL_OUT_OF_VERSIONS);
+            goto fail;
+        }
+        if (_PyInterpreterState_GET()->eval_frame) {
+            SPECIALIZATION_FAIL(BINARY_SUBSCR, SPEC_FAIL_OTHER);
+            goto fail;
+        }
+        PyHeapTypeObject *ht = (PyHeapTypeObject *)container_type;
+        // This pointer is invalidated by PyType_Modified (see the comment on
+        // struct _specialization_cache):
+        ht->_spec_cache.getitem = descriptor;
+        ht->_spec_cache.getitem_version = version;
+        instr->op.code = BINARY_SUBSCR_GETITEM;
+        goto success;
+    }
+    SPECIALIZATION_FAIL(BINARY_SUBSCR,
+                        binary_subscr_fail_kind(container_type, sub));
+fail:
+    STAT_INC(BINARY_SUBSCR, failure);
+    assert(!PyErr_Occurred());
+    instr->op.code = BINARY_SUBSCR;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(BINARY_SUBSCR, success);
+    assert(!PyErr_Occurred());
+    cache->counter = adaptive_counter_cooldown();
+}
+
+void
+_Py_Specialize_StoreSubscr(PyObject *container, PyObject *sub, _Py_CODEUNIT *instr)
+{
+    assert(ENABLE_SPECIALIZATION);
+    _PyStoreSubscrCache *cache = (_PyStoreSubscrCache *)(instr + 1);
+    PyTypeObject *container_type = Py_TYPE(container);
+    if (container_type == &PyList_Type) {
+        if (PyLong_CheckExact(sub)) {
+            if (_PyLong_IsNonNegativeCompact((PyLongObject *)sub)
+                && ((PyLongObject *)sub)->long_value.ob_digit[0] < (size_t)PyList_GET_SIZE(container))
+            {
+                instr->op.code = STORE_SUBSCR_LIST_INT;
+                goto success;
+            }
+            else {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_OUT_OF_RANGE);
+                goto fail;
+            }
+        }
+        else if (PySlice_Check(sub)) {
+            SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_LIST_SLICE);
+            goto fail;
+        }
+        else {
+            SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_OTHER);
+            goto fail;
+        }
+    }
+    if (container_type == &PyDict_Type) {
+        instr->op.code = STORE_SUBSCR_DICT;
+        goto success;
+    }
+#ifdef Py_STATS
+    PyMappingMethods *as_mapping = container_type->tp_as_mapping;
+    if (as_mapping && (as_mapping->mp_ass_subscript
+                       == PyDict_Type.tp_as_mapping->mp_ass_subscript)) {
+        SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_DICT_SUBCLASS_NO_OVERRIDE);
+        goto fail;
+    }
+    if (PyObject_CheckBuffer(container)) {
+        if (PyLong_CheckExact(sub) && (!_PyLong_IsNonNegativeCompact((PyLongObject *)sub))) {
+            SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_OUT_OF_RANGE);
+        }
+        else if (strcmp(container_type->tp_name, "array.array") == 0) {
+            if (PyLong_CheckExact(sub)) {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_ARRAY_INT);
+            }
+            else if (PySlice_Check(sub)) {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_ARRAY_SLICE);
+            }
+            else {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_OTHER);
+            }
+        }
+        else if (PyByteArray_CheckExact(container)) {
+            if (PyLong_CheckExact(sub)) {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_BYTEARRAY_INT);
+            }
+            else if (PySlice_Check(sub)) {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_BYTEARRAY_SLICE);
+            }
+            else {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_OTHER);
+            }
+        }
+        else {
+            if (PyLong_CheckExact(sub)) {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_BUFFER_INT);
+            }
+            else if (PySlice_Check(sub)) {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_BUFFER_SLICE);
+            }
+            else {
+                SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_OTHER);
+            }
+        }
+        goto fail;
+    }
+    PyObject *descriptor = _PyType_Lookup(container_type, &_Py_ID(__setitem__));
+    if (descriptor && Py_TYPE(descriptor) == &PyFunction_Type) {
+        PyFunctionObject *func = (PyFunctionObject *)descriptor;
+        PyCodeObject *code = (PyCodeObject *)func->func_code;
+        int kind = function_kind(code);
+        if (kind == SIMPLE_FUNCTION) {
+            SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_PY_SIMPLE);
+        }
+        else {
+            SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_SUBSCR_PY_OTHER);
+        }
+        goto fail;
+    }
+#endif
+    SPECIALIZATION_FAIL(STORE_SUBSCR, SPEC_FAIL_OTHER);
+fail:
+    STAT_INC(STORE_SUBSCR, failure);
+    assert(!PyErr_Occurred());
+    instr->op.code = STORE_SUBSCR;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(STORE_SUBSCR, success);
+    assert(!PyErr_Occurred());
+    cache->counter = adaptive_counter_cooldown();
+}
+
+static int
+specialize_class_call(PyObject *callable, _Py_CODEUNIT *instr, int nargs,
+                      PyObject *kwnames)
+{
+    PyTypeObject *tp = _PyType_CAST(callable);
+    if (tp->tp_new == PyBaseObject_Type.tp_new) {
+        SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_PYTHON_CLASS);
+        return -1;
+    }
+    if (tp->tp_flags & Py_TPFLAGS_IMMUTABLETYPE) {
+        int oparg = instr->op.arg;
+        if (nargs == 1 && kwnames == NULL && oparg == 1) {
+            if (tp == &PyUnicode_Type) {
+                instr->op.code = CALL_NO_KW_STR_1;
+                return 0;
+            }
+            else if (tp == &PyType_Type) {
+                instr->op.code = CALL_NO_KW_TYPE_1;
+                return 0;
+            }
+            else if (tp == &PyTuple_Type) {
+                instr->op.code = CALL_NO_KW_TUPLE_1;
+                return 0;
+            }
+        }
+        if (tp->tp_vectorcall != NULL) {
+            instr->op.code = CALL_BUILTIN_CLASS;
+            return 0;
+        }
+        SPECIALIZATION_FAIL(CALL, tp == &PyUnicode_Type ?
+            SPEC_FAIL_CALL_STR : SPEC_FAIL_CALL_CLASS_NO_VECTORCALL);
+        return -1;
+    }
+    SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_CLASS_MUTABLE);
+    return -1;
+}
+
+#ifdef Py_STATS
+static int
+builtin_call_fail_kind(int ml_flags)
+{
+    switch (ml_flags & (METH_VARARGS | METH_FASTCALL | METH_NOARGS | METH_O |
+        METH_KEYWORDS | METH_METHOD)) {
+        case METH_VARARGS:
+            return SPEC_FAIL_CALL_CFUNC_VARARGS;
+        case METH_VARARGS | METH_KEYWORDS:
+            return SPEC_FAIL_CALL_CFUNC_VARARGS_KEYWORDS;
+        case METH_NOARGS:
+            return SPEC_FAIL_CALL_CFUNC_NOARGS;
+        case METH_METHOD | METH_FASTCALL | METH_KEYWORDS:
+            return SPEC_FAIL_CALL_CFUNC_METHOD_FASTCALL_KEYWORDS;
+        /* These cases should be optimized, but return "other" just in case */
+        case METH_O:
+        case METH_FASTCALL:
+        case METH_FASTCALL | METH_KEYWORDS:
+            return SPEC_FAIL_OTHER;
+        default:
+            return SPEC_FAIL_CALL_BAD_CALL_FLAGS;
+    }
+}
+
+static int
+meth_descr_call_fail_kind(int ml_flags)
+{
+    switch (ml_flags & (METH_VARARGS | METH_FASTCALL | METH_NOARGS | METH_O |
+                        METH_KEYWORDS | METH_METHOD)) {
+        case METH_VARARGS:
+            return SPEC_FAIL_CALL_METH_DESCR_VARARGS;
+        case METH_VARARGS | METH_KEYWORDS:
+            return SPEC_FAIL_CALL_METH_DESCR_VARARGS_KEYWORDS;
+        case METH_METHOD | METH_FASTCALL | METH_KEYWORDS:
+            return SPEC_FAIL_CALL_METH_DESCR_METHOD_FASTCALL_KEYWORDS;
+            /* These cases should be optimized, but return "other" just in case */
+        case METH_NOARGS:
+        case METH_O:
+        case METH_FASTCALL:
+        case METH_FASTCALL | METH_KEYWORDS:
+            return SPEC_FAIL_OTHER;
+        default:
+            return SPEC_FAIL_CALL_BAD_CALL_FLAGS;
+    }
+}
+#endif
+
+static int
+specialize_method_descriptor(PyMethodDescrObject *descr, _Py_CODEUNIT *instr,
+                             int nargs, PyObject *kwnames)
+{
+    if (kwnames) {
+        SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_KWNAMES);
+        return -1;
+    }
+
+    switch (descr->d_method->ml_flags &
+        (METH_VARARGS | METH_FASTCALL | METH_NOARGS | METH_O |
+        METH_KEYWORDS | METH_METHOD)) {
+        case METH_NOARGS: {
+            if (nargs != 1) {
+                SPECIALIZATION_FAIL(CALL, SPEC_FAIL_WRONG_NUMBER_ARGUMENTS);
+                return -1;
+            }
+            instr->op.code = CALL_NO_KW_METHOD_DESCRIPTOR_NOARGS;
+            return 0;
+        }
+        case METH_O: {
+            if (nargs != 2) {
+                SPECIALIZATION_FAIL(CALL, SPEC_FAIL_WRONG_NUMBER_ARGUMENTS);
+                return -1;
+            }
+            PyInterpreterState *interp = _PyInterpreterState_GET();
+            PyObject *list_append = interp->callable_cache.list_append;
+            _Py_CODEUNIT next = instr[INLINE_CACHE_ENTRIES_CALL + 1];
+            bool pop = (next.op.code == POP_TOP);
+            int oparg = instr->op.arg;
+            if ((PyObject *)descr == list_append && oparg == 1 && pop) {
+                instr->op.code = CALL_NO_KW_LIST_APPEND;
+                return 0;
+            }
+            instr->op.code = CALL_NO_KW_METHOD_DESCRIPTOR_O;
+            return 0;
+        }
+        case METH_FASTCALL: {
+            instr->op.code = CALL_NO_KW_METHOD_DESCRIPTOR_FAST;
+            return 0;
+        }
+        case METH_FASTCALL | METH_KEYWORDS: {
+            instr->op.code = CALL_METHOD_DESCRIPTOR_FAST_WITH_KEYWORDS;
+            return 0;
+        }
+    }
+    SPECIALIZATION_FAIL(CALL, meth_descr_call_fail_kind(descr->d_method->ml_flags));
+    return -1;
+}
+
+static int
+specialize_py_call(PyFunctionObject *func, _Py_CODEUNIT *instr, int nargs,
+                   PyObject *kwnames, bool bound_method)
+{
+    _PyCallCache *cache = (_PyCallCache *)(instr + 1);
+    PyCodeObject *code = (PyCodeObject *)func->func_code;
+    int kind = function_kind(code);
+    /* Don't specialize if PEP 523 is active */
+    if (_PyInterpreterState_GET()->eval_frame) {
+        SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_PEP_523);
+        return -1;
+    }
+    if (kwnames) {
+        SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_KWNAMES);
+        return -1;
+    }
+    if (kind != SIMPLE_FUNCTION) {
+        SPECIALIZATION_FAIL(CALL, kind);
+        return -1;
+    }
+    int argcount = code->co_argcount;
+    int defcount = func->func_defaults == NULL ? 0 : (int)PyTuple_GET_SIZE(func->func_defaults);
+    int min_args = argcount-defcount;
+    // GH-105840: min_args is negative when somebody sets too many __defaults__!
+    if (min_args < 0 || nargs > argcount || nargs < min_args) {
+        SPECIALIZATION_FAIL(CALL, SPEC_FAIL_WRONG_NUMBER_ARGUMENTS);
+        return -1;
+    }
+    assert(nargs <= argcount && nargs >= min_args);
+    assert(min_args >= 0 && defcount >= 0);
+    assert(defcount == 0 || func->func_defaults != NULL);
+    int version = _PyFunction_GetVersionForCurrentState(func);
+    if (version == 0) {
+        SPECIALIZATION_FAIL(CALL, SPEC_FAIL_OUT_OF_VERSIONS);
+        return -1;
+    }
+    write_u32(cache->func_version, version);
+    if (argcount == nargs) {
+        instr->op.code = bound_method ? CALL_BOUND_METHOD_EXACT_ARGS : CALL_PY_EXACT_ARGS;
+    }
+    else if (bound_method) {
+        SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_BOUND_METHOD);
+        return -1;
+    }
+    else {
+        instr->op.code = CALL_PY_WITH_DEFAULTS;
+    }
+    return 0;
+}
+
+static int
+specialize_c_call(PyObject *callable, _Py_CODEUNIT *instr, int nargs,
+                  PyObject *kwnames)
+{
+    if (PyCFunction_GET_FUNCTION(callable) == NULL) {
+        return 1;
+    }
+    switch (PyCFunction_GET_FLAGS(callable) &
+        (METH_VARARGS | METH_FASTCALL | METH_NOARGS | METH_O |
+        METH_KEYWORDS | METH_METHOD)) {
+        case METH_O: {
+            if (kwnames) {
+                SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_KWNAMES);
+                return -1;
+            }
+            if (nargs != 1) {
+                SPECIALIZATION_FAIL(CALL, SPEC_FAIL_WRONG_NUMBER_ARGUMENTS);
+                return 1;
+            }
+            /* len(o) */
+            PyInterpreterState *interp = _PyInterpreterState_GET();
+            if (callable == interp->callable_cache.len) {
+                instr->op.code = CALL_NO_KW_LEN;
+                return 0;
+            }
+            instr->op.code = CALL_NO_KW_BUILTIN_O;
+            return 0;
+        }
+        case METH_FASTCALL: {
+            if (kwnames) {
+                SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_KWNAMES);
+                return -1;
+            }
+            if (nargs == 2) {
+                /* isinstance(o1, o2) */
+                PyInterpreterState *interp = _PyInterpreterState_GET();
+                if (callable == interp->callable_cache.isinstance) {
+                    instr->op.code = CALL_NO_KW_ISINSTANCE;
+                    return 0;
+                }
+            }
+            instr->op.code = CALL_NO_KW_BUILTIN_FAST;
+            return 0;
+        }
+        case METH_FASTCALL | METH_KEYWORDS: {
+            instr->op.code = CALL_BUILTIN_FAST_WITH_KEYWORDS;
+            return 0;
+        }
+        default:
+            SPECIALIZATION_FAIL(CALL,
+                builtin_call_fail_kind(PyCFunction_GET_FLAGS(callable)));
+            return 1;
+    }
+}
+
+#ifdef Py_STATS
+static int
+call_fail_kind(PyObject *callable)
+{
+    assert(!PyCFunction_CheckExact(callable));
+    assert(!PyFunction_Check(callable));
+    assert(!PyType_Check(callable));
+    assert(!Py_IS_TYPE(callable, &PyMethodDescr_Type));
+    assert(!PyMethod_Check(callable));
+    if (PyInstanceMethod_Check(callable)) {
+        return SPEC_FAIL_CALL_INSTANCE_METHOD;
+    }
+    // builtin method
+    else if (PyCMethod_Check(callable)) {
+        return SPEC_FAIL_CALL_CMETHOD;
+    }
+    else if (Py_TYPE(callable) == &PyWrapperDescr_Type) {
+        return SPEC_FAIL_CALL_OPERATOR_WRAPPER;
+    }
+    else if (Py_TYPE(callable) == &_PyMethodWrapper_Type) {
+        return SPEC_FAIL_CALL_METHOD_WRAPPER;
+    }
+    return SPEC_FAIL_OTHER;
+}
+#endif
+
+
+/* TODO:
+    - Specialize calling classes.
+*/
+void
+_Py_Specialize_Call(PyObject *callable, _Py_CODEUNIT *instr, int nargs,
+                    PyObject *kwnames)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[CALL] == INLINE_CACHE_ENTRIES_CALL);
+    assert(_Py_OPCODE(*instr) != INSTRUMENTED_CALL);
+    _PyCallCache *cache = (_PyCallCache *)(instr + 1);
+    int fail;
+    if (PyCFunction_CheckExact(callable)) {
+        fail = specialize_c_call(callable, instr, nargs, kwnames);
+    }
+    else if (PyFunction_Check(callable)) {
+        fail = specialize_py_call((PyFunctionObject *)callable, instr, nargs,
+                                  kwnames, false);
+    }
+    else if (PyType_Check(callable)) {
+        fail = specialize_class_call(callable, instr, nargs, kwnames);
+    }
+    else if (Py_IS_TYPE(callable, &PyMethodDescr_Type)) {
+        fail = specialize_method_descriptor((PyMethodDescrObject *)callable,
+                                            instr, nargs, kwnames);
+    }
+    else if (PyMethod_Check(callable)) {
+        PyObject *func = ((PyMethodObject *)callable)->im_func;
+        if (PyFunction_Check(func)) {
+            fail = specialize_py_call((PyFunctionObject *)func,
+                                      instr, nargs+1, kwnames, true);
+        } else {
+            SPECIALIZATION_FAIL(CALL, SPEC_FAIL_CALL_BOUND_METHOD);
+            fail = -1;
+        }
+    }
+    else {
+        SPECIALIZATION_FAIL(CALL, call_fail_kind(callable));
+        fail = -1;
+    }
+    if (fail) {
+        STAT_INC(CALL, failure);
+        assert(!PyErr_Occurred());
+        instr->op.code = CALL;
+        cache->counter = adaptive_counter_backoff(cache->counter);
+    }
+    else {
+        STAT_INC(CALL, success);
+        assert(!PyErr_Occurred());
+        cache->counter = adaptive_counter_cooldown();
+    }
+}
+
+#ifdef Py_STATS
+static int
+binary_op_fail_kind(int oparg, PyObject *lhs, PyObject *rhs)
+{
+    switch (oparg) {
+        case NB_ADD:
+        case NB_INPLACE_ADD:
+            if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
+                return SPEC_FAIL_BINARY_OP_ADD_DIFFERENT_TYPES;
+            }
+            return SPEC_FAIL_BINARY_OP_ADD_OTHER;
+        case NB_AND:
+        case NB_INPLACE_AND:
+            if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
+                return SPEC_FAIL_BINARY_OP_AND_DIFFERENT_TYPES;
+            }
+            if (PyLong_CheckExact(lhs)) {
+                return SPEC_FAIL_BINARY_OP_AND_INT;
+            }
+            return SPEC_FAIL_BINARY_OP_AND_OTHER;
+        case NB_FLOOR_DIVIDE:
+        case NB_INPLACE_FLOOR_DIVIDE:
+            return SPEC_FAIL_BINARY_OP_FLOOR_DIVIDE;
+        case NB_LSHIFT:
+        case NB_INPLACE_LSHIFT:
+            return SPEC_FAIL_BINARY_OP_LSHIFT;
+        case NB_MATRIX_MULTIPLY:
+        case NB_INPLACE_MATRIX_MULTIPLY:
+            return SPEC_FAIL_BINARY_OP_MATRIX_MULTIPLY;
+        case NB_MULTIPLY:
+        case NB_INPLACE_MULTIPLY:
+            if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
+                return SPEC_FAIL_BINARY_OP_MULTIPLY_DIFFERENT_TYPES;
+            }
+            return SPEC_FAIL_BINARY_OP_MULTIPLY_OTHER;
+        case NB_OR:
+        case NB_INPLACE_OR:
+            return SPEC_FAIL_BINARY_OP_OR;
+        case NB_POWER:
+        case NB_INPLACE_POWER:
+            return SPEC_FAIL_BINARY_OP_POWER;
+        case NB_REMAINDER:
+        case NB_INPLACE_REMAINDER:
+            return SPEC_FAIL_BINARY_OP_REMAINDER;
+        case NB_RSHIFT:
+        case NB_INPLACE_RSHIFT:
+            return SPEC_FAIL_BINARY_OP_RSHIFT;
+        case NB_SUBTRACT:
+        case NB_INPLACE_SUBTRACT:
+            if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
+                return SPEC_FAIL_BINARY_OP_SUBTRACT_DIFFERENT_TYPES;
+            }
+            return SPEC_FAIL_BINARY_OP_SUBTRACT_OTHER;
+        case NB_TRUE_DIVIDE:
+        case NB_INPLACE_TRUE_DIVIDE:
+            if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
+                return SPEC_FAIL_BINARY_OP_TRUE_DIVIDE_DIFFERENT_TYPES;
+            }
+            if (PyFloat_CheckExact(lhs)) {
+                return SPEC_FAIL_BINARY_OP_TRUE_DIVIDE_FLOAT;
+            }
+            return SPEC_FAIL_BINARY_OP_TRUE_DIVIDE_OTHER;
+        case NB_XOR:
+        case NB_INPLACE_XOR:
+            return SPEC_FAIL_BINARY_OP_XOR;
+    }
+    Py_UNREACHABLE();
+}
+#endif
+
+void
+_Py_Specialize_BinaryOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
+                        int oparg, PyObject **locals)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[BINARY_OP] == INLINE_CACHE_ENTRIES_BINARY_OP);
+    _PyBinaryOpCache *cache = (_PyBinaryOpCache *)(instr + 1);
+    switch (oparg) {
+        case NB_ADD:
+        case NB_INPLACE_ADD:
+            if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
+                break;
+            }
+            if (PyUnicode_CheckExact(lhs)) {
+                _Py_CODEUNIT next = instr[INLINE_CACHE_ENTRIES_BINARY_OP + 1];
+                bool to_store = (next.op.code == STORE_FAST ||
+                                 next.op.code == STORE_FAST__LOAD_FAST);
+                if (to_store && locals[next.op.arg] == lhs) {
+                    instr->op.code = BINARY_OP_INPLACE_ADD_UNICODE;
+                    goto success;
+                }
+                instr->op.code = BINARY_OP_ADD_UNICODE;
+                goto success;
+            }
+            if (PyLong_CheckExact(lhs)) {
+                instr->op.code = BINARY_OP_ADD_INT;
+                goto success;
+            }
+            if (PyFloat_CheckExact(lhs)) {
+                instr->op.code = BINARY_OP_ADD_FLOAT;
+                goto success;
+            }
+            break;
+        case NB_MULTIPLY:
+        case NB_INPLACE_MULTIPLY:
+            if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
+                break;
+            }
+            if (PyLong_CheckExact(lhs)) {
+                instr->op.code = BINARY_OP_MULTIPLY_INT;
+                goto success;
+            }
+            if (PyFloat_CheckExact(lhs)) {
+                instr->op.code = BINARY_OP_MULTIPLY_FLOAT;
+                goto success;
+            }
+            break;
+        case NB_SUBTRACT:
+        case NB_INPLACE_SUBTRACT:
+            if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
+                break;
+            }
+            if (PyLong_CheckExact(lhs)) {
+                instr->op.code = BINARY_OP_SUBTRACT_INT;
+                goto success;
+            }
+            if (PyFloat_CheckExact(lhs)) {
+                instr->op.code = BINARY_OP_SUBTRACT_FLOAT;
+                goto success;
+            }
+            break;
+    }
+    SPECIALIZATION_FAIL(BINARY_OP, binary_op_fail_kind(oparg, lhs, rhs));
+    STAT_INC(BINARY_OP, failure);
+    instr->op.code = BINARY_OP;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(BINARY_OP, success);
+    cache->counter = adaptive_counter_cooldown();
+}
+
+
+#ifdef Py_STATS
+static int
+compare_op_fail_kind(PyObject *lhs, PyObject *rhs)
+{
+    if (Py_TYPE(lhs) != Py_TYPE(rhs)) {
+        if (PyFloat_CheckExact(lhs) && PyLong_CheckExact(rhs)) {
+            return SPEC_FAIL_COMPARE_OP_FLOAT_LONG;
+        }
+        if (PyLong_CheckExact(lhs) && PyFloat_CheckExact(rhs)) {
+            return SPEC_FAIL_COMPARE_OP_LONG_FLOAT;
+        }
+        return SPEC_FAIL_COMPARE_OP_DIFFERENT_TYPES;
+    }
+    if (PyBytes_CheckExact(lhs)) {
+        return SPEC_FAIL_COMPARE_OP_BYTES;
+    }
+    if (PyTuple_CheckExact(lhs)) {
+        return SPEC_FAIL_COMPARE_OP_TUPLE;
+    }
+    if (PyList_CheckExact(lhs)) {
+        return SPEC_FAIL_COMPARE_OP_LIST;
+    }
+    if (PySet_CheckExact(lhs) || PyFrozenSet_CheckExact(lhs)) {
+        return SPEC_FAIL_COMPARE_OP_SET;
+    }
+    if (PyBool_Check(lhs)) {
+        return SPEC_FAIL_COMPARE_OP_BOOL;
+    }
+    if (Py_TYPE(lhs)->tp_richcompare == PyBaseObject_Type.tp_richcompare) {
+        return SPEC_FAIL_COMPARE_OP_BASEOBJECT;
+    }
+    return SPEC_FAIL_OTHER;
+}
+#endif
+
+void
+_Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
+                         int oparg)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[COMPARE_OP] == INLINE_CACHE_ENTRIES_COMPARE_OP);
+    _PyCompareOpCache *cache = (_PyCompareOpCache *)(instr + 1);
+    if (Py_TYPE(lhs) != Py_TYPE(rhs)) {
+        SPECIALIZATION_FAIL(COMPARE_OP, compare_op_fail_kind(lhs, rhs));
+        goto failure;
+    }
+    if (PyFloat_CheckExact(lhs)) {
+        instr->op.code = COMPARE_OP_FLOAT;
+        goto success;
+    }
+    if (PyLong_CheckExact(lhs)) {
+        if (_PyLong_IsCompact((PyLongObject *)lhs) && _PyLong_IsCompact((PyLongObject *)rhs)) {
+            instr->op.code = COMPARE_OP_INT;
+            goto success;
+        }
+        else {
+            SPECIALIZATION_FAIL(COMPARE_OP, SPEC_FAIL_COMPARE_OP_BIG_INT);
+            goto failure;
+        }
+    }
+    if (PyUnicode_CheckExact(lhs)) {
+        int cmp = oparg >> 4;
+        if (cmp != Py_EQ && cmp != Py_NE) {
+            SPECIALIZATION_FAIL(COMPARE_OP, SPEC_FAIL_COMPARE_OP_STRING);
+            goto failure;
+        }
+        else {
+            instr->op.code = COMPARE_OP_STR;
+            goto success;
+        }
+    }
+    SPECIALIZATION_FAIL(COMPARE_OP, compare_op_fail_kind(lhs, rhs));
+failure:
+    STAT_INC(COMPARE_OP, failure);
+    instr->op.code = COMPARE_OP;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(COMPARE_OP, success);
+    cache->counter = adaptive_counter_cooldown();
+}
+
+#ifdef Py_STATS
+static int
+unpack_sequence_fail_kind(PyObject *seq)
+{
+    if (PySequence_Check(seq)) {
+        return SPEC_FAIL_UNPACK_SEQUENCE_SEQUENCE;
+    }
+    if (PyIter_Check(seq)) {
+        return SPEC_FAIL_UNPACK_SEQUENCE_ITERATOR;
+    }
+    return SPEC_FAIL_OTHER;
+}
+#endif
+
+void
+_Py_Specialize_UnpackSequence(PyObject *seq, _Py_CODEUNIT *instr, int oparg)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[UNPACK_SEQUENCE] ==
+           INLINE_CACHE_ENTRIES_UNPACK_SEQUENCE);
+    _PyUnpackSequenceCache *cache = (_PyUnpackSequenceCache *)(instr + 1);
+    if (PyTuple_CheckExact(seq)) {
+        if (PyTuple_GET_SIZE(seq) != oparg) {
+            SPECIALIZATION_FAIL(UNPACK_SEQUENCE, SPEC_FAIL_EXPECTED_ERROR);
+            goto failure;
+        }
+        if (PyTuple_GET_SIZE(seq) == 2) {
+            instr->op.code = UNPACK_SEQUENCE_TWO_TUPLE;
+            goto success;
+        }
+        instr->op.code = UNPACK_SEQUENCE_TUPLE;
+        goto success;
+    }
+    if (PyList_CheckExact(seq)) {
+        if (PyList_GET_SIZE(seq) != oparg) {
+            SPECIALIZATION_FAIL(UNPACK_SEQUENCE, SPEC_FAIL_EXPECTED_ERROR);
+            goto failure;
+        }
+        instr->op.code = UNPACK_SEQUENCE_LIST;
+        goto success;
+    }
+    SPECIALIZATION_FAIL(UNPACK_SEQUENCE, unpack_sequence_fail_kind(seq));
+failure:
+    STAT_INC(UNPACK_SEQUENCE, failure);
+    instr->op.code = UNPACK_SEQUENCE;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(UNPACK_SEQUENCE, success);
+    cache->counter = adaptive_counter_cooldown();
+}
+
+#ifdef Py_STATS
+
+int
+ _PySpecialization_ClassifyIterator(PyObject *iter)
+{
+    if (PyGen_CheckExact(iter)) {
+        return SPEC_FAIL_ITER_GENERATOR;
+    }
+    if (PyCoro_CheckExact(iter)) {
+        return SPEC_FAIL_ITER_COROUTINE;
+    }
+    if (PyAsyncGen_CheckExact(iter)) {
+        return SPEC_FAIL_ITER_ASYNC_GENERATOR;
+    }
+    if (PyAsyncGenASend_CheckExact(iter)) {
+        return SPEC_FAIL_ITER_ASYNC_GENERATOR_SEND;
+    }
+    PyTypeObject *t = Py_TYPE(iter);
+    if (t == &PyListIter_Type) {
+        return SPEC_FAIL_ITER_LIST;
+    }
+    if (t == &PyTupleIter_Type) {
+        return SPEC_FAIL_ITER_TUPLE;
+    }
+    if (t == &PyDictIterKey_Type) {
+        return SPEC_FAIL_ITER_DICT_KEYS;
+    }
+    if (t == &PyDictIterValue_Type) {
+        return SPEC_FAIL_ITER_DICT_VALUES;
+    }
+    if (t == &PyDictIterItem_Type) {
+        return SPEC_FAIL_ITER_DICT_ITEMS;
+    }
+    if (t == &PySetIter_Type) {
+        return SPEC_FAIL_ITER_SET;
+    }
+    if (t == &PyUnicodeIter_Type) {
+        return SPEC_FAIL_ITER_STRING;
+    }
+    if (t == &PyBytesIter_Type) {
+        return SPEC_FAIL_ITER_BYTES;
+    }
+    if (t == &PyRangeIter_Type) {
+        return SPEC_FAIL_ITER_RANGE;
+    }
+    if (t == &PyEnum_Type) {
+        return SPEC_FAIL_ITER_ENUMERATE;
+    }
+    if (t == &PyMap_Type) {
+        return SPEC_FAIL_ITER_MAP;
+    }
+    if (t == &PyZip_Type) {
+        return SPEC_FAIL_ITER_ZIP;
+    }
+    if (t == &PySeqIter_Type) {
+        return SPEC_FAIL_ITER_SEQ_ITER;
+    }
+    if (t == &PyListRevIter_Type) {
+        return SPEC_FAIL_ITER_REVERSED_LIST;
+    }
+    if (t == &_PyUnicodeASCIIIter_Type) {
+        return SPEC_FAIL_ITER_ASCII_STRING;
+    }
+    const char *name = t->tp_name;
+    if (strncmp(name, "itertools", 9) == 0) {
+        return SPEC_FAIL_ITER_ITERTOOLS;
+    }
+    if (strncmp(name, "callable_iterator", 17) == 0) {
+        return SPEC_FAIL_ITER_CALLABLE;
+    }
+    return SPEC_FAIL_OTHER;
+}
+
+#endif
+
+void
+_Py_Specialize_ForIter(PyObject *iter, _Py_CODEUNIT *instr, int oparg)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[FOR_ITER] == INLINE_CACHE_ENTRIES_FOR_ITER);
+    _PyForIterCache *cache = (_PyForIterCache *)(instr + 1);
+    PyTypeObject *tp = Py_TYPE(iter);
+    if (tp == &PyListIter_Type) {
+        instr->op.code = FOR_ITER_LIST;
+        goto success;
+    }
+    else if (tp == &PyTupleIter_Type) {
+        instr->op.code = FOR_ITER_TUPLE;
+        goto success;
+    }
+    else if (tp == &PyRangeIter_Type) {
+        instr->op.code = FOR_ITER_RANGE;
+        goto success;
+    }
+    else if (tp == &PyGen_Type && oparg <= SHRT_MAX) {
+        assert(instr[oparg + INLINE_CACHE_ENTRIES_FOR_ITER + 1].op.code == END_FOR  ||
+            instr[oparg + INLINE_CACHE_ENTRIES_FOR_ITER + 1].op.code == INSTRUMENTED_END_FOR
+        );
+        if (_PyInterpreterState_GET()->eval_frame) {
+            SPECIALIZATION_FAIL(FOR_ITER, SPEC_FAIL_OTHER);
+            goto failure;
+        }
+        instr->op.code = FOR_ITER_GEN;
+        goto success;
+    }
+    SPECIALIZATION_FAIL(FOR_ITER,
+                        _PySpecialization_ClassifyIterator(iter));
+failure:
+    STAT_INC(FOR_ITER, failure);
+    instr->op.code = FOR_ITER;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(FOR_ITER, success);
+    cache->counter = adaptive_counter_cooldown();
+}
+
+void
+_Py_Specialize_Send(PyObject *receiver, _Py_CODEUNIT *instr)
+{
+    assert(ENABLE_SPECIALIZATION);
+    assert(_PyOpcode_Caches[SEND] == INLINE_CACHE_ENTRIES_SEND);
+    _PySendCache *cache = (_PySendCache *)(instr + 1);
+    PyTypeObject *tp = Py_TYPE(receiver);
+    if (tp == &PyGen_Type || tp == &PyCoro_Type) {
+        if (_PyInterpreterState_GET()->eval_frame) {
+            SPECIALIZATION_FAIL(SEND, SPEC_FAIL_OTHER);
+            goto failure;
+        }
+        instr->op.code = SEND_GEN;
+        goto success;
+    }
+    SPECIALIZATION_FAIL(SEND,
+                        _PySpecialization_ClassifyIterator(receiver));
+failure:
+    STAT_INC(SEND, failure);
+    instr->op.code = SEND;
+    cache->counter = adaptive_counter_backoff(cache->counter);
+    return;
+success:
+    STAT_INC(SEND, success);
+    cache->counter = adaptive_counter_cooldown();
+}