GH-118093: Make `CALL_ALLOC_AND_ENTER_INIT` suitable for tier 2. (GH-123140)

* Convert CALL_ALLOC_AND_ENTER_INIT to micro-ops such that tier 2 supports it

* Allow inexact arguments for CALL_ALLOC_AND_ENTER_INIT.

17 files changed, 464 insertions, 299 deletions

diff --git a/Include/internal/pycore_code.h b/Include/internal/pycore_code.h
index 2e76e9f..a722a2e 100644
--- a/Include/internal/pycore_code.h
+++ b/Include/internal/pycore_code.h
@@ -593,6 +593,10 @@ extern _Py_CODEUNIT _Py_GetBaseCodeUnit(PyCodeObject *code, int offset);
 
 extern int _PyInstruction_GetLength(PyCodeObject *code, int offset);
 
+struct _PyCode8 _PyCode_DEF(8);
+
+PyAPI_DATA(const struct _PyCode8) _Py_InitCleanup;
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/Include/internal/pycore_frame.h b/Include/internal/pycore_frame.h
index d3d7455..a6f7c17 100644
--- a/Include/internal/pycore_frame.h
+++ b/Include/internal/pycore_frame.h
@@ -144,8 +144,9 @@ static inline void _PyFrame_Copy(_PyInterpreterFrame *src, _PyInterpreterFrame *
 static inline void
 _PyFrame_Initialize(
     _PyInterpreterFrame *frame, PyFunctionObject *func,
-    PyObject *locals, PyCodeObject *code, int null_locals_from)
+    PyObject *locals, PyCodeObject *code, int null_locals_from, _PyInterpreterFrame *previous)
 {
+    frame->previous = previous;
     frame->f_funcobj = (PyObject *)func;
     frame->f_executable = Py_NewRef(code);
     frame->f_builtins = func->func_builtins;
@@ -298,26 +299,27 @@ PyAPI_FUNC(void) _PyThreadState_PopFrame(PyThreadState *tstate, _PyInterpreterFr
  * Must be guarded by _PyThreadState_HasStackSpace()
  * Consumes reference to func. */
 static inline _PyInterpreterFrame *
-_PyFrame_PushUnchecked(PyThreadState *tstate, PyFunctionObject *func, int null_locals_from)
+_PyFrame_PushUnchecked(PyThreadState *tstate, PyFunctionObject *func, int null_locals_from, _PyInterpreterFrame * previous)
 {
     CALL_STAT_INC(frames_pushed);
     PyCodeObject *code = (PyCodeObject *)func->func_code;
     _PyInterpreterFrame *new_frame = (_PyInterpreterFrame *)tstate->datastack_top;
     tstate->datastack_top += code->co_framesize;
     assert(tstate->datastack_top < tstate->datastack_limit);
-    _PyFrame_Initialize(new_frame, func, NULL, code, null_locals_from);
+    _PyFrame_Initialize(new_frame, func, NULL, code, null_locals_from, previous);
     return new_frame;
 }
 
 /* Pushes a trampoline frame without checking for space.
  * Must be guarded by _PyThreadState_HasStackSpace() */
 static inline _PyInterpreterFrame *
-_PyFrame_PushTrampolineUnchecked(PyThreadState *tstate, PyCodeObject *code, int stackdepth)
+_PyFrame_PushTrampolineUnchecked(PyThreadState *tstate, PyCodeObject *code, int stackdepth, _PyInterpreterFrame * previous)
 {
     CALL_STAT_INC(frames_pushed);
     _PyInterpreterFrame *frame = (_PyInterpreterFrame *)tstate->datastack_top;
     tstate->datastack_top += code->co_framesize;
     assert(tstate->datastack_top < tstate->datastack_limit);
+    frame->previous = previous;
     frame->f_funcobj = Py_None;
     frame->f_executable = Py_NewRef(code);
 #ifdef Py_DEBUG
@@ -344,7 +346,8 @@ _PyFrame_PushTrampolineUnchecked(PyThreadState *tstate, PyCodeObject *code, int
 PyAPI_FUNC(_PyInterpreterFrame *)
 _PyEvalFramePushAndInit(PyThreadState *tstate, PyFunctionObject *func,
                         PyObject *locals, _PyStackRef const* args,
-                        size_t argcount, PyObject *kwnames);
+                        size_t argcount, PyObject *kwnames,
+                        _PyInterpreterFrame *previous);
 
 #ifdef __cplusplus
 }
diff --git a/Include/internal/pycore_object.h b/Include/internal/pycore_object.h
index 2e0b5fa..ee33da7 100644
--- a/Include/internal/pycore_object.h
+++ b/Include/internal/pycore_object.h
@@ -761,7 +761,7 @@ static inline int _PyType_SUPPORTS_WEAKREFS(PyTypeObject *type) {
 }
 
 extern PyObject* _PyType_AllocNoTrack(PyTypeObject *type, Py_ssize_t nitems);
-extern PyObject *_PyType_NewManagedObject(PyTypeObject *type);
+PyAPI_FUNC(PyObject *) _PyType_NewManagedObject(PyTypeObject *type);
 
 extern PyTypeObject* _PyType_CalculateMetaclass(PyTypeObject *, PyObject *);
 extern PyObject* _PyType_GetDocFromInternalDoc(const char *, const char *);
diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
index 8e38855..236e6b4 100644
--- a/Include/internal/pycore_opcode_metadata.h
+++ b/Include/internal/pycore_opcode_metadata.h
@@ -537,7 +537,7 @@ int _PyOpcode_num_pushed(int opcode, int oparg)  {
         case CALL:
             return 1;
         case CALL_ALLOC_AND_ENTER_INIT:
-            return 1;
+            return 0;
         case CALL_BOUND_METHOD_EXACT_ARGS:
             return 0;
         case CALL_BOUND_METHOD_GENERAL:
@@ -1261,6 +1261,7 @@ _PyOpcode_macro_expansion[256] = {
     [BUILD_SLICE] = { .nuops = 1, .uops = { { _BUILD_SLICE, 0, 0 } } },
     [BUILD_STRING] = { .nuops = 1, .uops = { { _BUILD_STRING, 0, 0 } } },
     [BUILD_TUPLE] = { .nuops = 1, .uops = { { _BUILD_TUPLE, 0, 0 } } },
+    [CALL_ALLOC_AND_ENTER_INIT] = { .nuops = 4, .uops = { { _CHECK_PEP_523, 0, 0 }, { _CHECK_AND_ALLOCATE_OBJECT, 2, 1 }, { _CREATE_INIT_FRAME, 0, 0 }, { _PUSH_FRAME, 0, 0 } } },
     [CALL_BOUND_METHOD_EXACT_ARGS] = { .nuops = 9, .uops = { { _CHECK_PEP_523, 0, 0 }, { _CHECK_CALL_BOUND_METHOD_EXACT_ARGS, 0, 0 }, { _INIT_CALL_BOUND_METHOD_EXACT_ARGS, 0, 0 }, { _CHECK_FUNCTION_VERSION, 2, 1 }, { _CHECK_FUNCTION_EXACT_ARGS, 0, 0 }, { _CHECK_STACK_SPACE, 0, 0 }, { _INIT_CALL_PY_EXACT_ARGS, 0, 0 }, { _SAVE_RETURN_OFFSET, 7, 3 }, { _PUSH_FRAME, 0, 0 } } },
     [CALL_BOUND_METHOD_GENERAL] = { .nuops = 6, .uops = { { _CHECK_PEP_523, 0, 0 }, { _CHECK_METHOD_VERSION, 2, 1 }, { _EXPAND_METHOD, 0, 0 }, { _PY_FRAME_GENERAL, 0, 0 }, { _SAVE_RETURN_OFFSET, 7, 3 }, { _PUSH_FRAME, 0, 0 } } },
     [CALL_BUILTIN_CLASS] = { .nuops = 2, .uops = { { _CALL_BUILTIN_CLASS, 0, 0 }, { _CHECK_PERIODIC, 0, 0 } } },
diff --git a/Include/internal/pycore_uop_ids.h b/Include/internal/pycore_uop_ids.h
index 2a25514..226f4a6 100644
--- a/Include/internal/pycore_uop_ids.h
+++ b/Include/internal/pycore_uop_ids.h
@@ -34,7 +34,6 @@ extern "C" {
 #define _BUILD_SLICE BUILD_SLICE
 #define _BUILD_STRING BUILD_STRING
 #define _BUILD_TUPLE BUILD_TUPLE
-#define _CALL_ALLOC_AND_ENTER_INIT CALL_ALLOC_AND_ENTER_INIT
 #define _CALL_BUILTIN_CLASS 314
 #define _CALL_BUILTIN_FAST 315
 #define _CALL_BUILTIN_FAST_WITH_KEYWORDS 316
@@ -53,97 +52,99 @@ extern "C" {
 #define _CALL_STR_1 324
 #define _CALL_TUPLE_1 325
 #define _CALL_TYPE_1 CALL_TYPE_1
-#define _CHECK_ATTR_CLASS 326
-#define _CHECK_ATTR_METHOD_LAZY_DICT 327
-#define _CHECK_ATTR_MODULE 328
-#define _CHECK_ATTR_WITH_HINT 329
-#define _CHECK_CALL_BOUND_METHOD_EXACT_ARGS 330
+#define _CHECK_AND_ALLOCATE_OBJECT 326
+#define _CHECK_ATTR_CLASS 327
+#define _CHECK_ATTR_METHOD_LAZY_DICT 328
+#define _CHECK_ATTR_MODULE 329
+#define _CHECK_ATTR_WITH_HINT 330
+#define _CHECK_CALL_BOUND_METHOD_EXACT_ARGS 331
 #define _CHECK_EG_MATCH CHECK_EG_MATCH
 #define _CHECK_EXC_MATCH CHECK_EXC_MATCH
-#define _CHECK_FUNCTION 331
-#define _CHECK_FUNCTION_EXACT_ARGS 332
-#define _CHECK_FUNCTION_VERSION 333
-#define _CHECK_FUNCTION_VERSION_KW 334
-#define _CHECK_IS_NOT_PY_CALLABLE 335
-#define _CHECK_IS_NOT_PY_CALLABLE_KW 336
-#define _CHECK_MANAGED_OBJECT_HAS_VALUES 337
-#define _CHECK_METHOD_VERSION 338
-#define _CHECK_METHOD_VERSION_KW 339
-#define _CHECK_PEP_523 340
-#define _CHECK_PERIODIC 341
-#define _CHECK_PERIODIC_IF_NOT_YIELD_FROM 342
-#define _CHECK_STACK_SPACE 343
-#define _CHECK_STACK_SPACE_OPERAND 344
-#define _CHECK_VALIDITY 345
-#define _CHECK_VALIDITY_AND_SET_IP 346
-#define _COMPARE_OP 347
-#define _COMPARE_OP_FLOAT 348
-#define _COMPARE_OP_INT 349
-#define _COMPARE_OP_STR 350
-#define _CONTAINS_OP 351
+#define _CHECK_FUNCTION 332
+#define _CHECK_FUNCTION_EXACT_ARGS 333
+#define _CHECK_FUNCTION_VERSION 334
+#define _CHECK_FUNCTION_VERSION_KW 335
+#define _CHECK_IS_NOT_PY_CALLABLE 336
+#define _CHECK_IS_NOT_PY_CALLABLE_KW 337
+#define _CHECK_MANAGED_OBJECT_HAS_VALUES 338
+#define _CHECK_METHOD_VERSION 339
+#define _CHECK_METHOD_VERSION_KW 340
+#define _CHECK_PEP_523 341
+#define _CHECK_PERIODIC 342
+#define _CHECK_PERIODIC_IF_NOT_YIELD_FROM 343
+#define _CHECK_STACK_SPACE 344
+#define _CHECK_STACK_SPACE_OPERAND 345
+#define _CHECK_VALIDITY 346
+#define _CHECK_VALIDITY_AND_SET_IP 347
+#define _COMPARE_OP 348
+#define _COMPARE_OP_FLOAT 349
+#define _COMPARE_OP_INT 350
+#define _COMPARE_OP_STR 351
+#define _CONTAINS_OP 352
 #define _CONTAINS_OP_DICT CONTAINS_OP_DICT
 #define _CONTAINS_OP_SET CONTAINS_OP_SET
 #define _CONVERT_VALUE CONVERT_VALUE
 #define _COPY COPY
 #define _COPY_FREE_VARS COPY_FREE_VARS
+#define _CREATE_INIT_FRAME 353
 #define _DELETE_ATTR DELETE_ATTR
 #define _DELETE_DEREF DELETE_DEREF
 #define _DELETE_FAST DELETE_FAST
 #define _DELETE_GLOBAL DELETE_GLOBAL
 #define _DELETE_NAME DELETE_NAME
 #define _DELETE_SUBSCR DELETE_SUBSCR
-#define _DEOPT 352
+#define _DEOPT 354
 #define _DICT_MERGE DICT_MERGE
 #define _DICT_UPDATE DICT_UPDATE
-#define _DO_CALL 353
-#define _DO_CALL_KW 354
-#define _DYNAMIC_EXIT 355
+#define _DO_CALL 355
+#define _DO_CALL_KW 356
+#define _DYNAMIC_EXIT 357
 #define _END_SEND END_SEND
-#define _ERROR_POP_N 356
+#define _ERROR_POP_N 358
 #define _EXIT_INIT_CHECK EXIT_INIT_CHECK
-#define _EXPAND_METHOD 357
-#define _EXPAND_METHOD_KW 358
-#define _FATAL_ERROR 359
+#define _EXPAND_METHOD 359
+#define _EXPAND_METHOD_KW 360
+#define _FATAL_ERROR 361
 #define _FORMAT_SIMPLE FORMAT_SIMPLE
 #define _FORMAT_WITH_SPEC FORMAT_WITH_SPEC
-#define _FOR_ITER 360
-#define _FOR_ITER_GEN_FRAME 361
-#define _FOR_ITER_TIER_TWO 362
+#define _FOR_ITER 362
+#define _FOR_ITER_GEN_FRAME 363
+#define _FOR_ITER_TIER_TWO 364
 #define _GET_AITER GET_AITER
 #define _GET_ANEXT GET_ANEXT
 #define _GET_AWAITABLE GET_AWAITABLE
 #define _GET_ITER GET_ITER
 #define _GET_LEN GET_LEN
 #define _GET_YIELD_FROM_ITER GET_YIELD_FROM_ITER
-#define _GUARD_BOTH_FLOAT 363
-#define _GUARD_BOTH_INT 364
-#define _GUARD_BOTH_UNICODE 365
-#define _GUARD_BUILTINS_VERSION 366
-#define _GUARD_DORV_NO_DICT 367
-#define _GUARD_DORV_VALUES_INST_ATTR_FROM_DICT 368
-#define _GUARD_GLOBALS_VERSION 369
-#define _GUARD_IS_FALSE_POP 370
-#define _GUARD_IS_NONE_POP 371
-#define _GUARD_IS_NOT_NONE_POP 372
-#define _GUARD_IS_TRUE_POP 373
-#define _GUARD_KEYS_VERSION 374
-#define _GUARD_NOS_FLOAT 375
-#define _GUARD_NOS_INT 376
-#define _GUARD_NOT_EXHAUSTED_LIST 377
-#define _GUARD_NOT_EXHAUSTED_RANGE 378
-#define _GUARD_NOT_EXHAUSTED_TUPLE 379
-#define _GUARD_TOS_FLOAT 380
-#define _GUARD_TOS_INT 381
-#define _GUARD_TYPE_VERSION 382
+#define _GUARD_BOTH_FLOAT 365
+#define _GUARD_BOTH_INT 366
+#define _GUARD_BOTH_UNICODE 367
+#define _GUARD_BUILTINS_VERSION 368
+#define _GUARD_DORV_NO_DICT 369
+#define _GUARD_DORV_VALUES_INST_ATTR_FROM_DICT 370
+#define _GUARD_GLOBALS_VERSION 371
+#define _GUARD_IS_FALSE_POP 372
+#define _GUARD_IS_NONE_POP 373
+#define _GUARD_IS_NOT_NONE_POP 374
+#define _GUARD_IS_TRUE_POP 375
+#define _GUARD_KEYS_VERSION 376
+#define _GUARD_NOS_FLOAT 377
+#define _GUARD_NOS_INT 378
+#define _GUARD_NOT_EXHAUSTED_LIST 379
+#define _GUARD_NOT_EXHAUSTED_RANGE 380
+#define _GUARD_NOT_EXHAUSTED_TUPLE 381
+#define _GUARD_TOS_FLOAT 382
+#define _GUARD_TOS_INT 383
+#define _GUARD_TYPE_VERSION 384
 #define _IMPORT_FROM IMPORT_FROM
 #define _IMPORT_NAME IMPORT_NAME
-#define _INIT_CALL_BOUND_METHOD_EXACT_ARGS 383
-#define _INIT_CALL_PY_EXACT_ARGS 384
-#define _INIT_CALL_PY_EXACT_ARGS_0 385
-#define _INIT_CALL_PY_EXACT_ARGS_1 386
-#define _INIT_CALL_PY_EXACT_ARGS_2 387
-#define _INIT_CALL_PY_EXACT_ARGS_3 388
-#define _INIT_CALL_PY_EXACT_ARGS_4 389
+#define _INIT_CALL_BOUND_METHOD_EXACT_ARGS 385
+#define _INIT_CALL_PY_EXACT_ARGS 386
+#define _INIT_CALL_PY_EXACT_ARGS_0 387
+#define _INIT_CALL_PY_EXACT_ARGS_1 388
+#define _INIT_CALL_PY_EXACT_ARGS_2 389
+#define _INIT_CALL_PY_EXACT_ARGS_3 390
+#define _INIT_CALL_PY_EXACT_ARGS_4 391
 #define _INSTRUMENTED_CALL_FUNCTION_EX INSTRUMENTED_CALL_FUNCTION_EX
 #define _INSTRUMENTED_CALL_KW INSTRUMENTED_CALL_KW
 #define _INSTRUMENTED_FOR_ITER INSTRUMENTED_FOR_ITER
@@ -155,65 +156,65 @@ extern "C" {
 #define _INSTRUMENTED_POP_JUMP_IF_NONE INSTRUMENTED_POP_JUMP_IF_NONE
 #define _INSTRUMENTED_POP_JUMP_IF_NOT_NONE INSTRUMENTED_POP_JUMP_IF_NOT_NONE
 #define _INSTRUMENTED_POP_JUMP_IF_TRUE INSTRUMENTED_POP_JUMP_IF_TRUE
-#define _INTERNAL_INCREMENT_OPT_COUNTER 390
-#define _IS_NONE 391
+#define _INTERNAL_INCREMENT_OPT_COUNTER 392
+#define _IS_NONE 393
 #define _IS_OP IS_OP
-#define _ITER_CHECK_LIST 392
-#define _ITER_CHECK_RANGE 393
-#define _ITER_CHECK_TUPLE 394
-#define _ITER_JUMP_LIST 395
-#define _ITER_JUMP_RANGE 396
-#define _ITER_JUMP_TUPLE 397
-#define _ITER_NEXT_LIST 398
-#define _ITER_NEXT_RANGE 399
-#define _ITER_NEXT_TUPLE 400
-#define _JUMP_TO_TOP 401
+#define _ITER_CHECK_LIST 394
+#define _ITER_CHECK_RANGE 395
+#define _ITER_CHECK_TUPLE 396
+#define _ITER_JUMP_LIST 397
+#define _ITER_JUMP_RANGE 398
+#define _ITER_JUMP_TUPLE 399
+#define _ITER_NEXT_LIST 400
+#define _ITER_NEXT_RANGE 401
+#define _ITER_NEXT_TUPLE 402
+#define _JUMP_TO_TOP 403
 #define _LIST_APPEND LIST_APPEND
 #define _LIST_EXTEND LIST_EXTEND
-#define _LOAD_ATTR 402
-#define _LOAD_ATTR_CLASS 403
-#define _LOAD_ATTR_CLASS_0 404
-#define _LOAD_ATTR_CLASS_1 405
+#define _LOAD_ATTR 404
+#define _LOAD_ATTR_CLASS 405
+#define _LOAD_ATTR_CLASS_0 406
+#define _LOAD_ATTR_CLASS_1 407
 #define _LOAD_ATTR_GETATTRIBUTE_OVERRIDDEN LOAD_ATTR_GETATTRIBUTE_OVERRIDDEN
-#define _LOAD_ATTR_INSTANCE_VALUE 406
-#define _LOAD_ATTR_INSTANCE_VALUE_0 407
-#define _LOAD_ATTR_INSTANCE_VALUE_1 408
-#define _LOAD_ATTR_METHOD_LAZY_DICT 409
-#define _LOAD_ATTR_METHOD_NO_DICT 410
-#define _LOAD_ATTR_METHOD_WITH_VALUES 411
-#define _LOAD_ATTR_MODULE 412
-#define _LOAD_ATTR_NONDESCRIPTOR_NO_DICT 413
-#define _LOAD_ATTR_NONDESCRIPTOR_WITH_VALUES 414
-#define _LOAD_ATTR_PROPERTY_FRAME 415
-#define _LOAD_ATTR_SLOT 416
-#define _LOAD_ATTR_SLOT_0 417
-#define _LOAD_ATTR_SLOT_1 418
-#define _LOAD_ATTR_WITH_HINT 419
+#define _LOAD_ATTR_INSTANCE_VALUE 408
+#define _LOAD_ATTR_INSTANCE_VALUE_0 409
+#define _LOAD_ATTR_INSTANCE_VALUE_1 410
+#define _LOAD_ATTR_METHOD_LAZY_DICT 411
+#define _LOAD_ATTR_METHOD_NO_DICT 412
+#define _LOAD_ATTR_METHOD_WITH_VALUES 413
+#define _LOAD_ATTR_MODULE 414
+#define _LOAD_ATTR_NONDESCRIPTOR_NO_DICT 415
+#define _LOAD_ATTR_NONDESCRIPTOR_WITH_VALUES 416
+#define _LOAD_ATTR_PROPERTY_FRAME 417
+#define _LOAD_ATTR_SLOT 418
+#define _LOAD_ATTR_SLOT_0 419
+#define _LOAD_ATTR_SLOT_1 420
+#define _LOAD_ATTR_WITH_HINT 421
 #define _LOAD_BUILD_CLASS LOAD_BUILD_CLASS
 #define _LOAD_COMMON_CONSTANT LOAD_COMMON_CONSTANT
 #define _LOAD_CONST LOAD_CONST
-#define _LOAD_CONST_INLINE 420
-#define _LOAD_CONST_INLINE_BORROW 421
-#define _LOAD_CONST_INLINE_BORROW_WITH_NULL 422
-#define _LOAD_CONST_INLINE_WITH_NULL 423
+#define _LOAD_CONST_INLINE 422
+#define _LOAD_CONST_INLINE_BORROW 423
+#define _LOAD_CONST_INLINE_BORROW_WITH_NULL 424
+#define _LOAD_CONST_INLINE_WITH_NULL 425
 #define _LOAD_DEREF LOAD_DEREF
-#define _LOAD_FAST 424
-#define _LOAD_FAST_0 425
-#define _LOAD_FAST_1 426
-#define _LOAD_FAST_2 427
-#define _LOAD_FAST_3 428
-#define _LOAD_FAST_4 429
-#define _LOAD_FAST_5 430
-#define _LOAD_FAST_6 431
-#define _LOAD_FAST_7 432
+#define _LOAD_FAST 426
+#define _LOAD_FAST_0 427
+#define _LOAD_FAST_1 428
+#define _LOAD_FAST_2 429
+#define _LOAD_FAST_3 430
+#define _LOAD_FAST_4 431
+#define _LOAD_FAST_5 432
+#define _LOAD_FAST_6 433
+#define _LOAD_FAST_7 434
 #define _LOAD_FAST_AND_CLEAR LOAD_FAST_AND_CLEAR
 #define _LOAD_FAST_CHECK LOAD_FAST_CHECK
 #define _LOAD_FAST_LOAD_FAST LOAD_FAST_LOAD_FAST
 #define _LOAD_FROM_DICT_OR_DEREF LOAD_FROM_DICT_OR_DEREF
 #define _LOAD_FROM_DICT_OR_GLOBALS LOAD_FROM_DICT_OR_GLOBALS
-#define _LOAD_GLOBAL 433
-#define _LOAD_GLOBAL_BUILTINS 434
-#define _LOAD_GLOBAL_MODULE 435
+#define _LOAD_GLOBAL 435
+#define _LOAD_GLOBAL_BUILTINS 436
+#define _LOAD_GLOBAL_MODULE 437
 #define _LOAD_LOCALS LOAD_LOCALS
 #define _LOAD_NAME LOAD_NAME
 #define _LOAD_SPECIAL LOAD_SPECIAL
@@ -226,59 +227,59 @@ extern "C" {
 #define _MATCH_KEYS MATCH_KEYS
 #define _MATCH_MAPPING MATCH_MAPPING
 #define _MATCH_SEQUENCE MATCH_SEQUENCE
-#define _MAYBE_EXPAND_METHOD 436
-#define _MONITOR_CALL 437
-#define _MONITOR_JUMP_BACKWARD 438
-#define _MONITOR_RESUME 439
+#define _MAYBE_EXPAND_METHOD 438
+#define _MONITOR_CALL 439
+#define _MONITOR_JUMP_BACKWARD 440
+#define _MONITOR_RESUME 441
 #define _NOP NOP
 #define _POP_EXCEPT POP_EXCEPT
-#define _POP_JUMP_IF_FALSE 440
-#define _POP_JUMP_IF_TRUE 441
+#define _POP_JUMP_IF_FALSE 442
+#define _POP_JUMP_IF_TRUE 443
 #define _POP_TOP POP_TOP
-#define _POP_TOP_LOAD_CONST_INLINE_BORROW 442
+#define _POP_TOP_LOAD_CONST_INLINE_BORROW 444
 #define _PUSH_EXC_INFO PUSH_EXC_INFO
-#define _PUSH_FRAME 443
+#define _PUSH_FRAME 445
 #define _PUSH_NULL PUSH_NULL
-#define _PY_FRAME_GENERAL 444
-#define _PY_FRAME_KW 445
-#define _QUICKEN_RESUME 446
-#define _REPLACE_WITH_TRUE 447
+#define _PY_FRAME_GENERAL 446
+#define _PY_FRAME_KW 447
+#define _QUICKEN_RESUME 448
+#define _REPLACE_WITH_TRUE 449
 #define _RESUME_CHECK RESUME_CHECK
 #define _RETURN_GENERATOR RETURN_GENERATOR
 #define _RETURN_VALUE RETURN_VALUE
-#define _SAVE_RETURN_OFFSET 448
-#define _SEND 449
-#define _SEND_GEN_FRAME 450
+#define _SAVE_RETURN_OFFSET 450
+#define _SEND 451
+#define _SEND_GEN_FRAME 452
 #define _SETUP_ANNOTATIONS SETUP_ANNOTATIONS
 #define _SET_ADD SET_ADD
 #define _SET_FUNCTION_ATTRIBUTE SET_FUNCTION_ATTRIBUTE
 #define _SET_UPDATE SET_UPDATE
-#define _START_EXECUTOR 451
-#define _STORE_ATTR 452
-#define _STORE_ATTR_INSTANCE_VALUE 453
-#define _STORE_ATTR_SLOT 454
-#define _STORE_ATTR_WITH_HINT 455
+#define _START_EXECUTOR 453
+#define _STORE_ATTR 454
+#define _STORE_ATTR_INSTANCE_VALUE 455
+#define _STORE_ATTR_SLOT 456
+#define _STORE_ATTR_WITH_HINT 457
 #define _STORE_DEREF STORE_DEREF
-#define _STORE_FAST 456
-#define _STORE_FAST_0 457
-#define _STORE_FAST_1 458
-#define _STORE_FAST_2 459
-#define _STORE_FAST_3 460
-#define _STORE_FAST_4 461
-#define _STORE_FAST_5 462
-#define _STORE_FAST_6 463
-#define _STORE_FAST_7 464
+#define _STORE_FAST 458
+#define _STORE_FAST_0 459
+#define _STORE_FAST_1 460
+#define _STORE_FAST_2 461
+#define _STORE_FAST_3 462
+#define _STORE_FAST_4 463
+#define _STORE_FAST_5 464
+#define _STORE_FAST_6 465
+#define _STORE_FAST_7 466
 #define _STORE_FAST_LOAD_FAST STORE_FAST_LOAD_FAST
 #define _STORE_FAST_STORE_FAST STORE_FAST_STORE_FAST
 #define _STORE_GLOBAL STORE_GLOBAL
 #define _STORE_NAME STORE_NAME
 #define _STORE_SLICE STORE_SLICE
-#define _STORE_SUBSCR 465
+#define _STORE_SUBSCR 467
 #define _STORE_SUBSCR_DICT STORE_SUBSCR_DICT
 #define _STORE_SUBSCR_LIST_INT STORE_SUBSCR_LIST_INT
 #define _SWAP SWAP
-#define _TIER2_RESUME_CHECK 466
-#define _TO_BOOL 467
+#define _TIER2_RESUME_CHECK 468
+#define _TO_BOOL 469
 #define _TO_BOOL_BOOL TO_BOOL_BOOL
 #define _TO_BOOL_INT TO_BOOL_INT
 #define _TO_BOOL_LIST TO_BOOL_LIST
@@ -288,14 +289,14 @@ extern "C" {
 #define _UNARY_NEGATIVE UNARY_NEGATIVE
 #define _UNARY_NOT UNARY_NOT
 #define _UNPACK_EX UNPACK_EX
-#define _UNPACK_SEQUENCE 468
+#define _UNPACK_SEQUENCE 470
 #define _UNPACK_SEQUENCE_LIST UNPACK_SEQUENCE_LIST
 #define _UNPACK_SEQUENCE_TUPLE UNPACK_SEQUENCE_TUPLE
 #define _UNPACK_SEQUENCE_TWO_TUPLE UNPACK_SEQUENCE_TWO_TUPLE
 #define _WITH_EXCEPT_START WITH_EXCEPT_START
 #define _YIELD_VALUE YIELD_VALUE
 #define __DO_CALL_FUNCTION_EX _DO_CALL_FUNCTION_EX
-#define MAX_UOP_ID 468
+#define MAX_UOP_ID 470
 
 #ifdef __cplusplus
 }
diff --git a/Include/internal/pycore_uop_metadata.h b/Include/internal/pycore_uop_metadata.h
index 98757b6..15c0ac1 100644
--- a/Include/internal/pycore_uop_metadata.h
+++ b/Include/internal/pycore_uop_metadata.h
@@ -225,6 +225,8 @@ const uint16_t _PyUop_Flags[MAX_UOP_ID+1] = {
     [_CALL_TYPE_1] = HAS_ARG_FLAG | HAS_DEOPT_FLAG,
     [_CALL_STR_1] = HAS_ARG_FLAG | HAS_DEOPT_FLAG | HAS_ERROR_FLAG | HAS_ESCAPES_FLAG,
     [_CALL_TUPLE_1] = HAS_ARG_FLAG | HAS_DEOPT_FLAG | HAS_ERROR_FLAG | HAS_ESCAPES_FLAG,
+    [_CHECK_AND_ALLOCATE_OBJECT] = HAS_ARG_FLAG | HAS_DEOPT_FLAG | HAS_ERROR_FLAG | HAS_ERROR_NO_POP_FLAG | HAS_ESCAPES_FLAG,
+    [_CREATE_INIT_FRAME] = HAS_ARG_FLAG | HAS_ESCAPES_FLAG,
     [_EXIT_INIT_CHECK] = HAS_ERROR_FLAG | HAS_ERROR_NO_POP_FLAG | HAS_ESCAPES_FLAG,
     [_CALL_BUILTIN_CLASS] = HAS_ARG_FLAG | HAS_DEOPT_FLAG | HAS_ERROR_FLAG | HAS_ESCAPES_FLAG,
     [_CALL_BUILTIN_O] = HAS_ARG_FLAG | HAS_EXIT_FLAG | HAS_ERROR_FLAG | HAS_ESCAPES_FLAG,
@@ -327,6 +329,7 @@ const char *const _PyOpcode_uop_name[MAX_UOP_ID+1] = {
     [_CALL_STR_1] = "_CALL_STR_1",
     [_CALL_TUPLE_1] = "_CALL_TUPLE_1",
     [_CALL_TYPE_1] = "_CALL_TYPE_1",
+    [_CHECK_AND_ALLOCATE_OBJECT] = "_CHECK_AND_ALLOCATE_OBJECT",
     [_CHECK_ATTR_CLASS] = "_CHECK_ATTR_CLASS",
     [_CHECK_ATTR_METHOD_LAZY_DICT] = "_CHECK_ATTR_METHOD_LAZY_DICT",
     [_CHECK_ATTR_MODULE] = "_CHECK_ATTR_MODULE",
@@ -360,6 +363,7 @@ const char *const _PyOpcode_uop_name[MAX_UOP_ID+1] = {
     [_CONVERT_VALUE] = "_CONVERT_VALUE",
     [_COPY] = "_COPY",
     [_COPY_FREE_VARS] = "_COPY_FREE_VARS",
+    [_CREATE_INIT_FRAME] = "_CREATE_INIT_FRAME",
     [_DELETE_ATTR] = "_DELETE_ATTR",
     [_DELETE_DEREF] = "_DELETE_DEREF",
     [_DELETE_FAST] = "_DELETE_FAST",
@@ -960,6 +964,10 @@ int _PyUop_num_popped(int opcode, int oparg)
             return 3;
         case _CALL_TUPLE_1:
             return 3;
+        case _CHECK_AND_ALLOCATE_OBJECT:
+            return 2 + oparg;
+        case _CREATE_INIT_FRAME:
+            return 2 + oparg;
         case _EXIT_INIT_CHECK:
             return 1;
         case _CALL_BUILTIN_CLASS:
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2024-08-19-15-13-13.gh-issue-118093.dLZ8qS.rst b/Misc/NEWS.d/next/Core_and_Builtins/2024-08-19-15-13-13.gh-issue-118093.dLZ8qS.rst
new file mode 100644
index 0000000..d8127d8
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2024-08-19-15-13-13.gh-issue-118093.dLZ8qS.rst
@@ -0,0 +1,3 @@
+Break up ``CALL_ALLOC_AND_ENTER_INIT`` into micro-ops and relax
+requirement for exact args, in order to increase the amount of code
+supported by tier 2.
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 621f899..85c2455 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -1796,8 +1796,7 @@ init_frame(_PyInterpreterFrame *frame, PyFunctionObject *func, PyObject *locals)
 {
     PyCodeObject *code = (PyCodeObject *)func->func_code;
     _PyFrame_Initialize(frame, (PyFunctionObject*)Py_NewRef(func),
-                        Py_XNewRef(locals), code, 0);
-    frame->previous = NULL;
+                        Py_XNewRef(locals), code, 0, NULL);
 }
 
 PyFrameObject*
diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index ec57c07..ec0f6ab 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -797,7 +797,7 @@ dummy_func(
             PyTypeObject *tp = Py_TYPE(PyStackRef_AsPyObjectBorrow(container));
             PyHeapTypeObject *ht = (PyHeapTypeObject *)tp;
             PyObject *getitem = ht->_spec_cache.getitem;
-            new_frame = _PyFrame_PushUnchecked(tstate, (PyFunctionObject *)getitem, 2);
+            new_frame = _PyFrame_PushUnchecked(tstate, (PyFunctionObject *)getitem, 2, frame);
             SYNC_SP();
             new_frame->localsplus[0] = container;
             new_frame->localsplus[1] = sub;
@@ -1071,6 +1071,8 @@ dummy_func(
                 tstate->exc_info = &gen->gi_exc_state;
                 assert(next_instr - this_instr + oparg <= UINT16_MAX);
                 frame->return_offset = (uint16_t)(next_instr - this_instr + oparg);
+                assert(gen_frame->previous == NULL);
+                gen_frame->previous = frame;
                 DISPATCH_INLINED(gen_frame);
             }
             if (PyStackRef_Is(v, PyStackRef_None) && PyIter_Check(receiver_o)) {
@@ -1113,6 +1115,7 @@ dummy_func(
             tstate->exc_info = &gen->gi_exc_state;
             assert(1 + INLINE_CACHE_ENTRIES_SEND + oparg <= UINT16_MAX);
             frame->return_offset = (uint16_t)(1 + INLINE_CACHE_ENTRIES_SEND + oparg);
+            gen_frame->previous = frame;
         }
 
         macro(SEND_GEN) =
@@ -2143,7 +2146,7 @@ dummy_func(
             DEOPT_IF(!_PyThreadState_HasStackSpace(tstate, code->co_framesize));
             STAT_INC(LOAD_ATTR, hit);
             Py_INCREF(fget);
-            new_frame = _PyFrame_PushUnchecked(tstate, f, 1);
+            new_frame = _PyFrame_PushUnchecked(tstate, f, 1, frame);
             new_frame->localsplus[0] = owner;
         }
 
@@ -2175,7 +2178,7 @@ dummy_func(
 
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg >> 1);
             Py_INCREF(f);
-            _PyInterpreterFrame *new_frame = _PyFrame_PushUnchecked(tstate, f, 2);
+            _PyInterpreterFrame *new_frame = _PyFrame_PushUnchecked(tstate, f, 2, frame);
             // Manipulate stack directly because we exit with DISPATCH_INLINED().
             STACK_SHRINK(1);
             new_frame->localsplus[0] = owner;
@@ -2956,6 +2959,7 @@ dummy_func(
             gen->gi_frame_state = FRAME_EXECUTING;
             gen->gi_exc_state.previous_item = tstate->exc_info;
             tstate->exc_info = &gen->gi_exc_state;
+            gen_frame->previous = frame;
             // oparg is the return offset from the next instruction.
             frame->return_offset = (uint16_t)(1 + INLINE_CACHE_ENTRIES_FOR_ITER + oparg);
         }
@@ -3225,7 +3229,7 @@ dummy_func(
                 PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                 _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit(
                     tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                    args, total_args, NULL
+                    args, total_args, NULL, frame
                 );
                 // Manipulate stack directly since we leave using DISPATCH_INLINED().
                 STACK_SHRINK(oparg + 2);
@@ -3315,7 +3319,7 @@ dummy_func(
             PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
             new_frame = _PyEvalFramePushAndInit(
                 tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                args, total_args, NULL
+                args, total_args, NULL, frame
             );
             // The frame has stolen all the arguments from the stack,
             // so there is no need to clean them up.
@@ -3454,7 +3458,7 @@ dummy_func(
             int has_self = !PyStackRef_IsNull(self_or_null);
             STAT_INC(CALL, hit);
             PyFunctionObject *func = (PyFunctionObject *)callable_o;
-            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
             _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
             new_frame->localsplus[0] = self_or_null;
             for (int i = 0; i < oparg; i++) {
@@ -3468,7 +3472,7 @@ dummy_func(
             assert(tstate->interp->eval_frame == NULL);
             SYNC_SP();
             _PyFrame_SetStackPointer(frame, stack_pointer);
-            new_frame->previous = frame;
+            assert(new_frame->previous == frame || new_frame->previous->previous == frame);
             CALL_STAT_INC(inlined_py_calls);
             frame = tstate->current_frame = new_frame;
             tstate->py_recursion_remaining--;
@@ -3550,58 +3554,51 @@ dummy_func(
             _CALL_TUPLE_1 +
             _CHECK_PERIODIC;
 
-        inst(CALL_ALLOC_AND_ENTER_INIT, (unused/1, unused/2, callable, null, args[oparg] -- unused)) {
+        op(_CHECK_AND_ALLOCATE_OBJECT, (type_version/2, callable, null, args[oparg] -- self, init, args[oparg])) {
             PyObject *callable_o = PyStackRef_AsPyObjectBorrow(callable);
-            /* This instruction does the following:
-             * 1. Creates the object (by calling ``object.__new__``)
-             * 2. Pushes a shim frame to the frame stack (to cleanup after ``__init__``)
-             * 3. Pushes the frame for ``__init__`` to the frame stack
-             * */
-            _PyCallCache *cache = (_PyCallCache *)&this_instr[1];
             DEOPT_IF(!PyStackRef_IsNull(null));
             DEOPT_IF(!PyType_Check(callable_o));
             PyTypeObject *tp = (PyTypeObject *)callable_o;
-            DEOPT_IF(tp->tp_version_tag != read_u32(cache->func_version));
+            DEOPT_IF(tp->tp_version_tag != type_version);
             assert(tp->tp_flags & Py_TPFLAGS_INLINE_VALUES);
             PyHeapTypeObject *cls = (PyHeapTypeObject *)callable_o;
-            PyFunctionObject *init = (PyFunctionObject *)cls->_spec_cache.init;
-            PyCodeObject *code = (PyCodeObject *)init->func_code;
-            DEOPT_IF(code->co_argcount != oparg+1);
+            PyFunctionObject *init_func = (PyFunctionObject *)cls->_spec_cache.init;
+            PyCodeObject *code = (PyCodeObject *)init_func->func_code;
             DEOPT_IF(!_PyThreadState_HasStackSpace(tstate, code->co_framesize + _Py_InitCleanup.co_framesize));
             STAT_INC(CALL, hit);
-            PyObject *self = _PyType_NewManagedObject(tp);
-            if (self == NULL) {
+            self = PyStackRef_FromPyObjectSteal(_PyType_NewManagedObject(tp));
+            if (PyStackRef_IsNull(self)) {
                 ERROR_NO_POP();
             }
             PyStackRef_CLOSE(callable);
+            init = PyStackRef_FromPyObjectNew(init_func);
+        }
+
+        op(_CREATE_INIT_FRAME, (self, init, args[oparg] -- init_frame: _PyInterpreterFrame *)) {
             _PyInterpreterFrame *shim = _PyFrame_PushTrampolineUnchecked(
-                tstate, (PyCodeObject *)&_Py_InitCleanup, 1);
+                tstate, (PyCodeObject *)&_Py_InitCleanup, 1, frame);
             assert(_PyCode_CODE((PyCodeObject *)shim->f_executable)[0].op.code == EXIT_INIT_CHECK);
             /* Push self onto stack of shim */
-            Py_INCREF(self);
-            shim->localsplus[0] = PyStackRef_FromPyObjectSteal(self);
-            Py_INCREF(init);
-            _PyInterpreterFrame *init_frame = _PyFrame_PushUnchecked(tstate, init, oparg+1);
-            /* Copy self followed by args to __init__ frame */
-            init_frame->localsplus[0] = PyStackRef_FromPyObjectSteal(self);
-            for (int i = 0; i < oparg; i++) {
-                init_frame->localsplus[i+1] = args[i];
-            }
-            frame->return_offset = (uint16_t)(next_instr - this_instr);
-            STACK_SHRINK(oparg+2);
-            _PyFrame_SetStackPointer(frame, stack_pointer);
-            /* Link frames */
-            init_frame->previous = shim;
-            shim->previous = frame;
-            frame = tstate->current_frame = init_frame;
-            CALL_STAT_INC(inlined_py_calls);
+            shim->localsplus[0] = PyStackRef_DUP(self);
+            PyFunctionObject *init_func = (PyFunctionObject *)PyStackRef_AsPyObjectSteal(init);
+            args[-1] = self;
+            init_frame = _PyEvalFramePushAndInit(
+                tstate, init_func, NULL, args-1, oparg+1, NULL, shim);
+            frame->return_offset = 1 + INLINE_CACHE_ENTRIES_CALL;
+            SYNC_SP();
             /* Account for pushing the extra frame.
              * We don't check recursion depth here,
              * as it will be checked after start_frame */
             tstate->py_recursion_remaining--;
-            goto start_frame;
         }
 
+        macro(CALL_ALLOC_AND_ENTER_INIT) =
+            unused/1 +
+            _CHECK_PEP_523 +
+            _CHECK_AND_ALLOCATE_OBJECT +
+            _CREATE_INIT_FRAME +
+            _PUSH_FRAME;
+
         inst(EXIT_INIT_CHECK, (should_be_none -- )) {
             assert(STACK_LEVEL() == 2);
             if (!PyStackRef_Is(should_be_none, PyStackRef_None)) {
@@ -4060,7 +4057,7 @@ dummy_func(
                 PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                 _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit(
                     tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                    args, positional_args, kwnames_o
+                    args, positional_args, kwnames_o, frame
                 );
                 PyStackRef_CLOSE(kwnames);
                 // Manipulate stack directly since we leave using DISPATCH_INLINED().
@@ -4129,7 +4126,7 @@ dummy_func(
             PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
             new_frame = _PyEvalFramePushAndInit(
                 tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                args, positional_args, kwnames_o
+                args, positional_args, kwnames_o, frame
             );
             PyStackRef_CLOSE(kwnames);
             // The frame has stolen all the arguments from the stack,
@@ -4315,7 +4312,7 @@ dummy_func(
 
                     _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit_Ex(tstate,
                                                                                 (PyFunctionObject *)PyStackRef_AsPyObjectSteal(func_st), locals,
-                                                                                nargs, callargs, kwargs);
+                                                                                nargs, callargs, kwargs, frame);
                     // Need to manually shrink the stack since we exit with DISPATCH_INLINED.
                     STACK_SHRINK(oparg + 3);
                     if (new_frame == NULL) {
diff --git a/Python/ceval.c b/Python/ceval.c
index c685a95..b615dee 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -246,7 +246,7 @@ static int check_args_iterable(PyThreadState *, PyObject *func, PyObject *vararg
 static int get_exception_handler(PyCodeObject *, int, int*, int*, int*);
 static  _PyInterpreterFrame *
 _PyEvalFramePushAndInit_Ex(PyThreadState *tstate, PyFunctionObject *func,
-    PyObject *locals, Py_ssize_t nargs, PyObject *callargs, PyObject *kwargs);
+    PyObject *locals, Py_ssize_t nargs, PyObject *callargs, PyObject *kwargs, _PyInterpreterFrame *previous);
 
 #ifdef HAVE_ERRNO_H
 #include <errno.h>
@@ -671,8 +671,6 @@ static const _Py_CODEUNIT _Py_INTERPRETER_TRAMPOLINE_INSTRUCTIONS[] = {
     { .op.code = RESUME, .op.arg = RESUME_OPARG_DEPTH1_MASK | RESUME_AT_FUNC_START }
 };
 
-extern const struct _PyCode_DEF(8) _Py_InitCleanup;
-
 #ifdef Py_DEBUG
 extern void _PyUOpPrint(const _PyUOpInstruction *uop);
 #endif
@@ -1691,7 +1689,7 @@ _PyEval_FrameClearAndPop(PyThreadState *tstate, _PyInterpreterFrame * frame)
 _PyInterpreterFrame *
 _PyEvalFramePushAndInit(PyThreadState *tstate, PyFunctionObject *func,
                         PyObject *locals, _PyStackRef const* args,
-                        size_t argcount, PyObject *kwnames)
+                        size_t argcount, PyObject *kwnames, _PyInterpreterFrame *previous)
 {
     PyCodeObject * code = (PyCodeObject *)func->func_code;
     CALL_STAT_INC(frames_pushed);
@@ -1699,7 +1697,7 @@ _PyEvalFramePushAndInit(PyThreadState *tstate, PyFunctionObject *func,
     if (frame == NULL) {
         goto fail;
     }
-    _PyFrame_Initialize(frame, func, locals, code, 0);
+    _PyFrame_Initialize(frame, func, locals, code, 0, previous);
     if (initialize_locals(tstate, func, frame->localsplus, args, argcount, kwnames)) {
         assert(frame->owner == FRAME_OWNED_BY_THREAD);
         clear_thread_frame(tstate, frame);
@@ -1726,7 +1724,7 @@ fail:
 static _PyInterpreterFrame *
 _PyEvalFramePushAndInit_UnTagged(PyThreadState *tstate, PyFunctionObject *func,
                         PyObject *locals, PyObject *const* args,
-                        size_t argcount, PyObject *kwnames)
+                        size_t argcount, PyObject *kwnames, _PyInterpreterFrame *previous)
 {
 #if defined(Py_GIL_DISABLED)
     size_t kw_count = kwnames == NULL ? 0 : PyTuple_GET_SIZE(kwnames);
@@ -1742,11 +1740,11 @@ _PyEvalFramePushAndInit_UnTagged(PyThreadState *tstate, PyFunctionObject *func,
     for (size_t i = 0; i < kw_count; i++) {
         tagged_args_buffer[argcount + i] = PyStackRef_FromPyObjectSteal(args[argcount + i]);
     }
-    _PyInterpreterFrame *res = _PyEvalFramePushAndInit(tstate, func, locals, (_PyStackRef const *)tagged_args_buffer, argcount, kwnames);
+    _PyInterpreterFrame *res = _PyEvalFramePushAndInit(tstate, func, locals, (_PyStackRef const *)tagged_args_buffer, argcount, kwnames, previous);
     PyMem_Free(tagged_args_buffer);
     return res;
 #else
-    return _PyEvalFramePushAndInit(tstate, func, locals, (_PyStackRef const *)args, argcount, kwnames);
+    return _PyEvalFramePushAndInit(tstate, func, locals, (_PyStackRef const *)args, argcount, kwnames, previous);
 #endif
 }
 
@@ -1755,7 +1753,7 @@ _PyEvalFramePushAndInit_UnTagged(PyThreadState *tstate, PyFunctionObject *func,
 */
 static _PyInterpreterFrame *
 _PyEvalFramePushAndInit_Ex(PyThreadState *tstate, PyFunctionObject *func,
-    PyObject *locals, Py_ssize_t nargs, PyObject *callargs, PyObject *kwargs)
+    PyObject *locals, Py_ssize_t nargs, PyObject *callargs, PyObject *kwargs, _PyInterpreterFrame *previous)
 {
     bool has_dict = (kwargs != NULL && PyDict_GET_SIZE(kwargs) > 0);
     PyObject *kwnames = NULL;
@@ -1776,7 +1774,7 @@ _PyEvalFramePushAndInit_Ex(PyThreadState *tstate, PyFunctionObject *func,
     }
     _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit_UnTagged(
         tstate, (PyFunctionObject *)func, locals,
-        newargs, nargs, kwnames
+        newargs, nargs, kwnames, previous
     );
     if (has_dict) {
         _PyStack_UnpackDict_FreeNoDecRef(newargs, kwnames);
@@ -1813,7 +1811,7 @@ _PyEval_Vector(PyThreadState *tstate, PyFunctionObject *func,
         }
     }
     _PyInterpreterFrame *frame = _PyEvalFramePushAndInit_UnTagged(
-        tstate, func, locals, args, argcount, kwnames);
+        tstate, func, locals, args, argcount, kwnames, NULL);
     if (frame == NULL) {
         return NULL;
     }
diff --git a/Python/ceval_macros.h b/Python/ceval_macros.h
index ed146a1..9e15406 100644
--- a/Python/ceval_macros.h
+++ b/Python/ceval_macros.h
@@ -124,7 +124,7 @@ do { \
     do {                                                \
         assert(tstate->interp->eval_frame == NULL);     \
         _PyFrame_SetStackPointer(frame, stack_pointer); \
-        (NEW_FRAME)->previous = frame;                  \
+        assert((NEW_FRAME)->previous == frame);         \
         frame = tstate->current_frame = (NEW_FRAME);     \
         CALL_STAT_INC(inlined_py_calls);                \
         goto start_frame;                               \
diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
index d699e8d..9226b7a 100644
--- a/Python/executor_cases.c.h
+++ b/Python/executor_cases.c.h
@@ -1031,7 +1031,7 @@
             PyTypeObject *tp = Py_TYPE(PyStackRef_AsPyObjectBorrow(container));
             PyHeapTypeObject *ht = (PyHeapTypeObject *)tp;
             PyObject *getitem = ht->_spec_cache.getitem;
-            new_frame = _PyFrame_PushUnchecked(tstate, (PyFunctionObject *)getitem, 2);
+            new_frame = _PyFrame_PushUnchecked(tstate, (PyFunctionObject *)getitem, 2, frame);
             stack_pointer += -2;
             assert(WITHIN_STACK_BOUNDS());
             new_frame->localsplus[0] = container;
@@ -1319,6 +1319,7 @@
             tstate->exc_info = &gen->gi_exc_state;
             assert(1 + INLINE_CACHE_ENTRIES_SEND + oparg <= UINT16_MAX);
             frame->return_offset = (uint16_t)(1 + INLINE_CACHE_ENTRIES_SEND + oparg);
+            gen_frame->previous = frame;
             stack_pointer[-1].bits = (uintptr_t)gen_frame;
             break;
         }
@@ -2552,7 +2553,7 @@
             }
             STAT_INC(LOAD_ATTR, hit);
             Py_INCREF(fget);
-            new_frame = _PyFrame_PushUnchecked(tstate, f, 1);
+            new_frame = _PyFrame_PushUnchecked(tstate, f, 1, frame);
             new_frame->localsplus[0] = owner;
             stack_pointer[-1].bits = (uintptr_t)new_frame;
             break;
@@ -3316,6 +3317,7 @@
             gen->gi_frame_state = FRAME_EXECUTING;
             gen->gi_exc_state.previous_item = tstate->exc_info;
             tstate->exc_info = &gen->gi_exc_state;
+            gen_frame->previous = frame;
             // oparg is the return offset from the next instruction.
             frame->return_offset = (uint16_t)(1 + INLINE_CACHE_ENTRIES_FOR_ITER + oparg);
             stack_pointer[0].bits = (uintptr_t)gen_frame;
@@ -3604,7 +3606,7 @@
             PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
             new_frame = _PyEvalFramePushAndInit(
                 tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                args, total_args, NULL
+                args, total_args, NULL, frame
             );
             // The frame has stolen all the arguments from the stack,
             // so there is no need to clean them up.
@@ -3838,7 +3840,7 @@
             int has_self = !PyStackRef_IsNull(self_or_null);
             STAT_INC(CALL, hit);
             PyFunctionObject *func = (PyFunctionObject *)callable_o;
-            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
             _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
             new_frame->localsplus[0] = self_or_null;
             for (int i = 0; i < oparg; i++) {
@@ -3864,7 +3866,7 @@
             int has_self = !PyStackRef_IsNull(self_or_null);
             STAT_INC(CALL, hit);
             PyFunctionObject *func = (PyFunctionObject *)callable_o;
-            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
             _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
             new_frame->localsplus[0] = self_or_null;
             for (int i = 0; i < oparg; i++) {
@@ -3890,7 +3892,7 @@
             int has_self = !PyStackRef_IsNull(self_or_null);
             STAT_INC(CALL, hit);
             PyFunctionObject *func = (PyFunctionObject *)callable_o;
-            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
             _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
             new_frame->localsplus[0] = self_or_null;
             for (int i = 0; i < oparg; i++) {
@@ -3916,7 +3918,7 @@
             int has_self = !PyStackRef_IsNull(self_or_null);
             STAT_INC(CALL, hit);
             PyFunctionObject *func = (PyFunctionObject *)callable_o;
-            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
             _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
             new_frame->localsplus[0] = self_or_null;
             for (int i = 0; i < oparg; i++) {
@@ -3942,7 +3944,7 @@
             int has_self = !PyStackRef_IsNull(self_or_null);
             STAT_INC(CALL, hit);
             PyFunctionObject *func = (PyFunctionObject *)callable_o;
-            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
             _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
             new_frame->localsplus[0] = self_or_null;
             for (int i = 0; i < oparg; i++) {
@@ -3967,7 +3969,7 @@
             int has_self = !PyStackRef_IsNull(self_or_null);
             STAT_INC(CALL, hit);
             PyFunctionObject *func = (PyFunctionObject *)callable_o;
-            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+            new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
             _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
             new_frame->localsplus[0] = self_or_null;
             for (int i = 0; i < oparg; i++) {
@@ -3988,7 +3990,7 @@
             stack_pointer += -1;
             assert(WITHIN_STACK_BOUNDS());
             _PyFrame_SetStackPointer(frame, stack_pointer);
-            new_frame->previous = frame;
+            assert(new_frame->previous == frame || new_frame->previous->previous == frame);
             CALL_STAT_INC(inlined_py_calls);
             frame = tstate->current_frame = new_frame;
             tstate->py_recursion_remaining--;
@@ -4087,7 +4089,81 @@
             break;
         }
 
-        /* _CALL_ALLOC_AND_ENTER_INIT is not a viable micro-op for tier 2 because it uses the 'this_instr' variable */
+        case _CHECK_AND_ALLOCATE_OBJECT: {
+            _PyStackRef *args;
+            _PyStackRef null;
+            _PyStackRef callable;
+            _PyStackRef self;
+            _PyStackRef init;
+            oparg = CURRENT_OPARG();
+            args = &stack_pointer[-oparg];
+            null = stack_pointer[-1 - oparg];
+            callable = stack_pointer[-2 - oparg];
+            uint32_t type_version = (uint32_t)CURRENT_OPERAND();
+            PyObject *callable_o = PyStackRef_AsPyObjectBorrow(callable);
+            if (!PyStackRef_IsNull(null)) {
+                UOP_STAT_INC(uopcode, miss);
+                JUMP_TO_JUMP_TARGET();
+            }
+            if (!PyType_Check(callable_o)) {
+                UOP_STAT_INC(uopcode, miss);
+                JUMP_TO_JUMP_TARGET();
+            }
+            PyTypeObject *tp = (PyTypeObject *)callable_o;
+            if (tp->tp_version_tag != type_version) {
+                UOP_STAT_INC(uopcode, miss);
+                JUMP_TO_JUMP_TARGET();
+            }
+            assert(tp->tp_flags & Py_TPFLAGS_INLINE_VALUES);
+            PyHeapTypeObject *cls = (PyHeapTypeObject *)callable_o;
+            PyFunctionObject *init_func = (PyFunctionObject *)cls->_spec_cache.init;
+            PyCodeObject *code = (PyCodeObject *)init_func->func_code;
+            if (!_PyThreadState_HasStackSpace(tstate, code->co_framesize + _Py_InitCleanup.co_framesize)) {
+                UOP_STAT_INC(uopcode, miss);
+                JUMP_TO_JUMP_TARGET();
+            }
+            STAT_INC(CALL, hit);
+            self = PyStackRef_FromPyObjectSteal(_PyType_NewManagedObject(tp));
+            if (PyStackRef_IsNull(self)) {
+                JUMP_TO_ERROR();
+            }
+            PyStackRef_CLOSE(callable);
+            init = PyStackRef_FromPyObjectNew(init_func);
+            stack_pointer[-1 - oparg] = init;
+            stack_pointer[-2 - oparg] = self;
+            break;
+        }
+
+        case _CREATE_INIT_FRAME: {
+            _PyStackRef *args;
+            _PyStackRef init;
+            _PyStackRef self;
+            _PyInterpreterFrame *init_frame;
+            oparg = CURRENT_OPARG();
+            args = &stack_pointer[-oparg];
+            init = stack_pointer[-1 - oparg];
+            self = stack_pointer[-2 - oparg];
+            _PyInterpreterFrame *shim = _PyFrame_PushTrampolineUnchecked(
+                tstate, (PyCodeObject *)&_Py_InitCleanup, 1, frame);
+            assert(_PyCode_CODE((PyCodeObject *)shim->f_executable)[0].op.code == EXIT_INIT_CHECK);
+            /* Push self onto stack of shim */
+            shim->localsplus[0] = PyStackRef_DUP(self);
+            PyFunctionObject *init_func = (PyFunctionObject *)PyStackRef_AsPyObjectSteal(init);
+            args[-1] = self;
+            init_frame = _PyEvalFramePushAndInit(
+                tstate, init_func, NULL, args-1, oparg+1, NULL, shim);
+            frame->return_offset = 1 + INLINE_CACHE_ENTRIES_CALL;
+            stack_pointer += -2 - oparg;
+            assert(WITHIN_STACK_BOUNDS());
+            /* Account for pushing the extra frame.
+             * We don't check recursion depth here,
+             * as it will be checked after start_frame */
+            tstate->py_recursion_remaining--;
+            stack_pointer[0].bits = (uintptr_t)init_frame;
+            stack_pointer += 1;
+            assert(WITHIN_STACK_BOUNDS());
+            break;
+        }
 
         case _EXIT_INIT_CHECK: {
             _PyStackRef should_be_none;
@@ -4705,7 +4781,7 @@
             PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
             new_frame = _PyEvalFramePushAndInit(
                 tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                args, positional_args, kwnames_o
+                args, positional_args, kwnames_o, frame
             );
             PyStackRef_CLOSE(kwnames);
             // The frame has stolen all the arguments from the stack,
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index 486d356..27971ce 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -504,7 +504,7 @@
                 PyTypeObject *tp = Py_TYPE(PyStackRef_AsPyObjectBorrow(container));
                 PyHeapTypeObject *ht = (PyHeapTypeObject *)tp;
                 PyObject *getitem = ht->_spec_cache.getitem;
-                new_frame = _PyFrame_PushUnchecked(tstate, (PyFunctionObject *)getitem, 2);
+                new_frame = _PyFrame_PushUnchecked(tstate, (PyFunctionObject *)getitem, 2, frame);
                 stack_pointer += -2;
                 assert(WITHIN_STACK_BOUNDS());
                 new_frame->localsplus[0] = container;
@@ -517,7 +517,7 @@
                 // Eventually this should be the only occurrence of this code.
                 assert(tstate->interp->eval_frame == NULL);
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -888,7 +888,7 @@
                     PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                     _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit(
                         tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                        args, total_args, NULL
+                        args, total_args, NULL, frame
                     );
                     // Manipulate stack directly since we leave using DISPATCH_INLINED().
                     STACK_SHRINK(oparg + 2);
@@ -975,60 +975,75 @@
             _PyStackRef callable;
             _PyStackRef null;
             _PyStackRef *args;
+            _PyStackRef self;
+            _PyStackRef init;
+            _PyInterpreterFrame *init_frame;
+            _PyInterpreterFrame *new_frame;
             /* Skip 1 cache entry */
-            /* Skip 2 cache entries */
+            // _CHECK_PEP_523
+            {
+                DEOPT_IF(tstate->interp->eval_frame, CALL);
+            }
+            // _CHECK_AND_ALLOCATE_OBJECT
             args = &stack_pointer[-oparg];
             null = stack_pointer[-1 - oparg];
             callable = stack_pointer[-2 - oparg];
-            PyObject *callable_o = PyStackRef_AsPyObjectBorrow(callable);
-            /* This instruction does the following:
-             * 1. Creates the object (by calling ``object.__new__``)
-             * 2. Pushes a shim frame to the frame stack (to cleanup after ``__init__``)
-             * 3. Pushes the frame for ``__init__`` to the frame stack
-             * */
-            _PyCallCache *cache = (_PyCallCache *)&this_instr[1];
-            DEOPT_IF(!PyStackRef_IsNull(null), CALL);
-            DEOPT_IF(!PyType_Check(callable_o), CALL);
-            PyTypeObject *tp = (PyTypeObject *)callable_o;
-            DEOPT_IF(tp->tp_version_tag != read_u32(cache->func_version), CALL);
-            assert(tp->tp_flags & Py_TPFLAGS_INLINE_VALUES);
-            PyHeapTypeObject *cls = (PyHeapTypeObject *)callable_o;
-            PyFunctionObject *init = (PyFunctionObject *)cls->_spec_cache.init;
-            PyCodeObject *code = (PyCodeObject *)init->func_code;
-            DEOPT_IF(code->co_argcount != oparg+1, CALL);
-            DEOPT_IF(!_PyThreadState_HasStackSpace(tstate, code->co_framesize + _Py_InitCleanup.co_framesize), CALL);
-            STAT_INC(CALL, hit);
-            PyObject *self = _PyType_NewManagedObject(tp);
-            if (self == NULL) {
-                goto error;
+            {
+                uint32_t type_version = read_u32(&this_instr[2].cache);
+                PyObject *callable_o = PyStackRef_AsPyObjectBorrow(callable);
+                DEOPT_IF(!PyStackRef_IsNull(null), CALL);
+                DEOPT_IF(!PyType_Check(callable_o), CALL);
+                PyTypeObject *tp = (PyTypeObject *)callable_o;
+                DEOPT_IF(tp->tp_version_tag != type_version, CALL);
+                assert(tp->tp_flags & Py_TPFLAGS_INLINE_VALUES);
+                PyHeapTypeObject *cls = (PyHeapTypeObject *)callable_o;
+                PyFunctionObject *init_func = (PyFunctionObject *)cls->_spec_cache.init;
+                PyCodeObject *code = (PyCodeObject *)init_func->func_code;
+                DEOPT_IF(!_PyThreadState_HasStackSpace(tstate, code->co_framesize + _Py_InitCleanup.co_framesize), CALL);
+                STAT_INC(CALL, hit);
+                self = PyStackRef_FromPyObjectSteal(_PyType_NewManagedObject(tp));
+                if (PyStackRef_IsNull(self)) {
+                    goto error;
+                }
+                PyStackRef_CLOSE(callable);
+                init = PyStackRef_FromPyObjectNew(init_func);
+                stack_pointer[-1 - oparg] = init;
+            }
+            // _CREATE_INIT_FRAME
+            {
+                _PyInterpreterFrame *shim = _PyFrame_PushTrampolineUnchecked(
+                    tstate, (PyCodeObject *)&_Py_InitCleanup, 1, frame);
+                assert(_PyCode_CODE((PyCodeObject *)shim->f_executable)[0].op.code == EXIT_INIT_CHECK);
+                /* Push self onto stack of shim */
+                shim->localsplus[0] = PyStackRef_DUP(self);
+                PyFunctionObject *init_func = (PyFunctionObject *)PyStackRef_AsPyObjectSteal(init);
+                args[-1] = self;
+                init_frame = _PyEvalFramePushAndInit(
+                    tstate, init_func, NULL, args-1, oparg+1, NULL, shim);
+                frame->return_offset = 1 + INLINE_CACHE_ENTRIES_CALL;
+                stack_pointer += -2 - oparg;
+                assert(WITHIN_STACK_BOUNDS());
+                /* Account for pushing the extra frame.
+                 * We don't check recursion depth here,
+                 * as it will be checked after start_frame */
+                tstate->py_recursion_remaining--;
             }
-            PyStackRef_CLOSE(callable);
-            _PyInterpreterFrame *shim = _PyFrame_PushTrampolineUnchecked(
-                tstate, (PyCodeObject *)&_Py_InitCleanup, 1);
-            assert(_PyCode_CODE((PyCodeObject *)shim->f_executable)[0].op.code == EXIT_INIT_CHECK);
-            /* Push self onto stack of shim */
-            Py_INCREF(self);
-            shim->localsplus[0] = PyStackRef_FromPyObjectSteal(self);
-            Py_INCREF(init);
-            _PyInterpreterFrame *init_frame = _PyFrame_PushUnchecked(tstate, init, oparg+1);
-            /* Copy self followed by args to __init__ frame */
-            init_frame->localsplus[0] = PyStackRef_FromPyObjectSteal(self);
-            for (int i = 0; i < oparg; i++) {
-                init_frame->localsplus[i+1] = args[i];
+            // _PUSH_FRAME
+            new_frame = init_frame;
+            {
+                // Write it out explicitly because it's subtly different.
+                // Eventually this should be the only occurrence of this code.
+                assert(tstate->interp->eval_frame == NULL);
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
+                CALL_STAT_INC(inlined_py_calls);
+                frame = tstate->current_frame = new_frame;
+                tstate->py_recursion_remaining--;
+                LOAD_SP();
+                LOAD_IP(0);
+                LLTRACE_RESUME_FRAME();
             }
-            frame->return_offset = (uint16_t)(next_instr - this_instr);
-            STACK_SHRINK(oparg+2);
-            _PyFrame_SetStackPointer(frame, stack_pointer);
-            /* Link frames */
-            init_frame->previous = shim;
-            shim->previous = frame;
-            frame = tstate->current_frame = init_frame;
-            CALL_STAT_INC(inlined_py_calls);
-            /* Account for pushing the extra frame.
-             * We don't check recursion depth here,
-             * as it will be checked after start_frame */
-            tstate->py_recursion_remaining--;
-            goto start_frame;
+            DISPATCH();
         }
 
         TARGET(CALL_BOUND_METHOD_EXACT_ARGS) {
@@ -1099,7 +1114,7 @@
                 int has_self = !PyStackRef_IsNull(self_or_null);
                 STAT_INC(CALL, hit);
                 PyFunctionObject *func = (PyFunctionObject *)callable_o;
-                new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+                new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
                 _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
                 new_frame->localsplus[0] = self_or_null;
                 for (int i = 0; i < oparg; i++) {
@@ -1123,7 +1138,7 @@
                 stack_pointer += -2 - oparg;
                 assert(WITHIN_STACK_BOUNDS());
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -1194,7 +1209,7 @@
                 PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                 new_frame = _PyEvalFramePushAndInit(
                     tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                    args, total_args, NULL
+                    args, total_args, NULL, frame
                 );
                 // The frame has stolen all the arguments from the stack,
                 // so there is no need to clean them up.
@@ -1219,7 +1234,7 @@
                 // Eventually this should be the only occurrence of this code.
                 assert(tstate->interp->eval_frame == NULL);
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -1595,7 +1610,7 @@
                         PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(func));
                         _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit_Ex(tstate,
                             (PyFunctionObject *)PyStackRef_AsPyObjectSteal(func_st), locals,
-                            nargs, callargs, kwargs);
+                            nargs, callargs, kwargs, frame);
                         // Need to manually shrink the stack since we exit with DISPATCH_INLINED.
                         STACK_SHRINK(oparg + 3);
                         if (new_frame == NULL) {
@@ -1781,7 +1796,7 @@
                     PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                     _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit(
                         tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                        args, positional_args, kwnames_o
+                        args, positional_args, kwnames_o, frame
                     );
                     PyStackRef_CLOSE(kwnames);
                     // Manipulate stack directly since we leave using DISPATCH_INLINED().
@@ -1916,7 +1931,7 @@
                 PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                 new_frame = _PyEvalFramePushAndInit(
                     tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                    args, positional_args, kwnames_o
+                    args, positional_args, kwnames_o, frame
                 );
                 PyStackRef_CLOSE(kwnames);
                 // The frame has stolen all the arguments from the stack,
@@ -1942,7 +1957,7 @@
                 // Eventually this should be the only occurrence of this code.
                 assert(tstate->interp->eval_frame == NULL);
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -2086,7 +2101,7 @@
                 PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                 new_frame = _PyEvalFramePushAndInit(
                     tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                    args, positional_args, kwnames_o
+                    args, positional_args, kwnames_o, frame
                 );
                 PyStackRef_CLOSE(kwnames);
                 // The frame has stolen all the arguments from the stack,
@@ -2112,7 +2127,7 @@
                 // Eventually this should be the only occurrence of this code.
                 assert(tstate->interp->eval_frame == NULL);
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -2635,7 +2650,7 @@
                 int has_self = !PyStackRef_IsNull(self_or_null);
                 STAT_INC(CALL, hit);
                 PyFunctionObject *func = (PyFunctionObject *)callable_o;
-                new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self);
+                new_frame = _PyFrame_PushUnchecked(tstate, func, oparg + has_self, frame);
                 _PyStackRef *first_non_self_local = new_frame->localsplus + has_self;
                 new_frame->localsplus[0] = self_or_null;
                 for (int i = 0; i < oparg; i++) {
@@ -2659,7 +2674,7 @@
                 stack_pointer += -2 - oparg;
                 assert(WITHIN_STACK_BOUNDS());
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -2710,7 +2725,7 @@
                 PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                 new_frame = _PyEvalFramePushAndInit(
                     tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                    args, total_args, NULL
+                    args, total_args, NULL, frame
                 );
                 // The frame has stolen all the arguments from the stack,
                 // so there is no need to clean them up.
@@ -2735,7 +2750,7 @@
                 // Eventually this should be the only occurrence of this code.
                 assert(tstate->interp->eval_frame == NULL);
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -3667,6 +3682,7 @@
                 gen->gi_frame_state = FRAME_EXECUTING;
                 gen->gi_exc_state.previous_item = tstate->exc_info;
                 tstate->exc_info = &gen->gi_exc_state;
+                gen_frame->previous = frame;
                 // oparg is the return offset from the next instruction.
                 frame->return_offset = (uint16_t)(1 + INLINE_CACHE_ENTRIES_FOR_ITER + oparg);
             }
@@ -3677,7 +3693,7 @@
                 // Eventually this should be the only occurrence of this code.
                 assert(tstate->interp->eval_frame == NULL);
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -4090,7 +4106,7 @@
                     PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(callable_o));
                     _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit(
                         tstate, (PyFunctionObject *)PyStackRef_AsPyObjectSteal(callable), locals,
-                        args, total_args, NULL
+                        args, total_args, NULL, frame
                     );
                     // Manipulate stack directly since we leave using DISPATCH_INLINED().
                     STACK_SHRINK(oparg + 2);
@@ -4944,7 +4960,7 @@
             STAT_INC(LOAD_ATTR, hit);
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg >> 1);
             Py_INCREF(f);
-            _PyInterpreterFrame *new_frame = _PyFrame_PushUnchecked(tstate, f, 2);
+            _PyInterpreterFrame *new_frame = _PyFrame_PushUnchecked(tstate, f, 2, frame);
             // Manipulate stack directly because we exit with DISPATCH_INLINED().
             STACK_SHRINK(1);
             new_frame->localsplus[0] = owner;
@@ -5274,7 +5290,7 @@
                 DEOPT_IF(!_PyThreadState_HasStackSpace(tstate, code->co_framesize), LOAD_ATTR);
                 STAT_INC(LOAD_ATTR, hit);
                 Py_INCREF(fget);
-                new_frame = _PyFrame_PushUnchecked(tstate, f, 1);
+                new_frame = _PyFrame_PushUnchecked(tstate, f, 1, frame);
                 new_frame->localsplus[0] = owner;
             }
             // _SAVE_RETURN_OFFSET
@@ -5294,7 +5310,7 @@
                 stack_pointer += -1;
                 assert(WITHIN_STACK_BOUNDS());
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -6551,6 +6567,8 @@
                     tstate->exc_info = &gen->gi_exc_state;
                     assert(next_instr - this_instr + oparg <= UINT16_MAX);
                     frame->return_offset = (uint16_t)(next_instr - this_instr + oparg);
+                    assert(gen_frame->previous == NULL);
+                    gen_frame->previous = frame;
                     DISPATCH_INLINED(gen_frame);
                 }
                 if (PyStackRef_Is(v, PyStackRef_None) && PyIter_Check(receiver_o)) {
@@ -6611,6 +6629,7 @@
                 tstate->exc_info = &gen->gi_exc_state;
                 assert(1 + INLINE_CACHE_ENTRIES_SEND + oparg <= UINT16_MAX);
                 frame->return_offset = (uint16_t)(1 + INLINE_CACHE_ENTRIES_SEND + oparg);
+                gen_frame->previous = frame;
             }
             // _PUSH_FRAME
             new_frame = gen_frame;
@@ -6621,7 +6640,7 @@
                 stack_pointer += -1;
                 assert(WITHIN_STACK_BOUNDS());
                 _PyFrame_SetStackPointer(frame, stack_pointer);
-                new_frame->previous = frame;
+                assert(new_frame->previous == frame || new_frame->previous->previous == frame);
                 CALL_STAT_INC(inlined_py_calls);
                 frame = tstate->current_frame = new_frame;
                 tstate->py_recursion_remaining--;
@@ -7650,7 +7669,7 @@
                     PyObject *locals = code_flags & CO_OPTIMIZED ? NULL : Py_NewRef(PyFunction_GET_GLOBALS(func));
                     _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit_Ex(tstate,
                         (PyFunctionObject *)PyStackRef_AsPyObjectSteal(func_st), locals,
-                        nargs, callargs, kwargs);
+                        nargs, callargs, kwargs, frame);
                     // Need to manually shrink the stack since we exit with DISPATCH_INLINED.
                     STACK_SHRINK(oparg + 3);
                     if (new_frame == NULL) {
diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index 97e4c64..6e46d9b 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -627,7 +627,7 @@ dummy_func(void) {
         ctx->done = true;
     }
 
-    op(_PY_FRAME_KW, (callable, self_or_null, args[oparg], kwnames -- new_frame: _Py_UOpsAbstractFrame*)) {
+    op(_PY_FRAME_KW, (callable, self_or_null, args[oparg], kwnames -- new_frame: _Py_UOpsAbstractFrame *)) {
         (void)callable;
         (void)self_or_null;
         (void)args;
@@ -636,6 +636,23 @@ dummy_func(void) {
         ctx->done = true;
     }
 
+    op(_CHECK_AND_ALLOCATE_OBJECT, (type_version/2, callable, null, args[oparg] -- self, init, args[oparg])) {
+        (void)type_version;
+        (void)callable;
+        (void)null;
+        (void)args;
+        self = sym_new_not_null(ctx);
+        init = sym_new_not_null(ctx);
+    }
+
+    op(_CREATE_INIT_FRAME, (self, init, args[oparg] -- init_frame: _Py_UOpsAbstractFrame *)) {
+        (void)self;
+        (void)init;
+        (void)args;
+        init_frame = NULL;
+        ctx->done = true;
+    }
+
     op(_RETURN_VALUE, (retval -- res)) {
         SYNC_SP();
         ctx->frame->stack_pointer = stack_pointer;
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index 3ec2e69..e5be9d0 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -1866,7 +1866,46 @@
             break;
         }
 
-        /* _CALL_ALLOC_AND_ENTER_INIT is not a viable micro-op for tier 2 */
+        case _CHECK_AND_ALLOCATE_OBJECT: {
+            _Py_UopsSymbol **args;
+            _Py_UopsSymbol *null;
+            _Py_UopsSymbol *callable;
+            _Py_UopsSymbol *self;
+            _Py_UopsSymbol *init;
+            args = &stack_pointer[-oparg];
+            null = stack_pointer[-1 - oparg];
+            callable = stack_pointer[-2 - oparg];
+            args = &stack_pointer[-oparg];
+            uint32_t type_version = (uint32_t)this_instr->operand;
+            (void)type_version;
+            (void)callable;
+            (void)null;
+            (void)args;
+            self = sym_new_not_null(ctx);
+            init = sym_new_not_null(ctx);
+            stack_pointer[-2 - oparg] = self;
+            stack_pointer[-1 - oparg] = init;
+            break;
+        }
+
+        case _CREATE_INIT_FRAME: {
+            _Py_UopsSymbol **args;
+            _Py_UopsSymbol *init;
+            _Py_UopsSymbol *self;
+            _Py_UOpsAbstractFrame *init_frame;
+            args = &stack_pointer[-oparg];
+            init = stack_pointer[-1 - oparg];
+            self = stack_pointer[-2 - oparg];
+            (void)self;
+            (void)init;
+            (void)args;
+            init_frame = NULL;
+            ctx->done = true;
+            stack_pointer[-2 - oparg] = (_Py_UopsSymbol *)init_frame;
+            stack_pointer += -1 - oparg;
+            assert(WITHIN_STACK_BOUNDS());
+            break;
+        }
 
         case _EXIT_INIT_CHECK: {
             stack_pointer += -1;
diff --git a/Python/specialize.c b/Python/specialize.c
index 4fec5a3..b3a2e07 100644
--- a/Python/specialize.c
+++ b/Python/specialize.c
@@ -1809,10 +1809,6 @@ specialize_class_call(PyObject *callable, _Py_CODEUNIT *instr, int nargs)
             return -1;
         }
         if (init != NULL) {
-            if (((PyCodeObject *)init->func_code)->co_argcount != nargs+1) {
-                SPECIALIZATION_FAIL(CALL, SPEC_FAIL_WRONG_NUMBER_ARGUMENTS);
-                return -1;
-            }
             _PyCallCache *cache = (_PyCallCache *)(instr + 1);
             write_u32(cache->func_version, tp->tp_version_tag);
             _Py_SET_OPCODE(*instr, CALL_ALLOC_AND_ENTER_INIT);
@@ -2654,7 +2650,7 @@ static const PyBytesObject no_location = {
     .ob_sval = { NO_LOC_4 }
 };
 
-const struct _PyCode_DEF(8) _Py_InitCleanup = {
+const struct _PyCode8 _Py_InitCleanup = {
     _PyVarObject_HEAD_INIT(&PyCode_Type, 3),
     .co_consts = (PyObject *)&_Py_SINGLETON(tuple_empty),
     .co_names = (PyObject *)&_Py_SINGLETON(tuple_empty),
diff --git a/Tools/c-analyzer/cpython/ignored.tsv b/Tools/c-analyzer/cpython/ignored.tsv
index 63b640e..b91b117 100644
--- a/Tools/c-analyzer/cpython/ignored.tsv
+++ b/Tools/c-analyzer/cpython/ignored.tsv
@@ -742,3 +742,7 @@ Modules/clinic/md5module.c.h	_md5_md5	_keywords	-
 Modules/clinic/grpmodule.c.h	grp_getgrgid	_keywords	-
 Modules/clinic/grpmodule.c.h	grp_getgrnam	_keywords	-
 Objects/object.c	-	constants	static PyObject*[]
+
+
+## False positives
+Python/specialize.c	-	_Py_InitCleanup	-