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gh-153486: Preserve negative indices in compact int subscript specializations #153523

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gh-153486: Preserve negative indices in compact int subscript specializations #153523

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9a4d55e
gh-153486: Factor non-negative compact int subscript guards
KRRT7 Jul 10, 2026
12c8513
gh-153486: Add NEWS entry
KRRT7 Jul 10, 2026
7b711cc
gh-153486: Specialize negative list int subscripts
KRRT7 Jul 10, 2026
ea05f8d
Merge branch 'main' into list-int-compact-guard-main
KRRT7 Jul 10, 2026
410e297
Revert "gh-153486: Specialize negative list int subscripts"
KRRT7 Jul 10, 2026
9205927
gh-153486: Specialize negative list int subscripts
KRRT7 Jul 10, 2026
613223c
gh-153486: Preserve negative compact subscript specializations
KRRT7 Jul 10, 2026
3b1a1a7
gh-153486: Normalize negative tuple indices in JIT optimizer
KRRT7 Jul 10, 2026
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9 changes: 7 additions & 2 deletions Include/internal/pycore_uop_ids.h
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21 changes: 21 additions & 0 deletions Include/internal/pycore_uop_metadata.h
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42 changes: 42 additions & 0 deletions Lib/test/test_opcache.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1890,6 +1890,17 @@ def binary_subscr_tuple_int():
"BINARY_OP_SUBSCR_TUPLE_INT")
self.assert_no_opcode(binary_subscr_tuple_int, "BINARY_OP")

def binary_subscr_tuple_negative_int():
for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
a = (1, 2, 3)
idx = -1
self.assertEqual(a[idx], 3)

binary_subscr_tuple_negative_int()
self.assert_specialized(binary_subscr_tuple_negative_int,
"BINARY_OP_SUBSCR_TUPLE_INT")
self.assert_no_opcode(binary_subscr_tuple_negative_int, "BINARY_OP")

def binary_subscr_dict():
for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
a = {1: 2, 2: 3}
Expand Down Expand Up @@ -1967,6 +1978,16 @@ def binary_subscr_str_int():
self.assert_specialized(binary_subscr_str_int, "BINARY_OP_SUBSCR_STR_INT")
self.assert_no_opcode(binary_subscr_str_int, "BINARY_OP")

def binary_subscr_str_negative_int():
for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
a = "foobar"
idx = -1
self.assertEqual(a[idx], "r")

binary_subscr_str_negative_int()
self.assert_specialized(binary_subscr_str_negative_int, "BINARY_OP_SUBSCR_STR_INT")
self.assert_no_opcode(binary_subscr_str_negative_int, "BINARY_OP")

def binary_subscr_str_int_non_compact():
for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
a = "바이트코드_특수화"
Expand All @@ -1977,6 +1998,16 @@ def binary_subscr_str_int_non_compact():
self.assert_specialized(binary_subscr_str_int_non_compact, "BINARY_OP_SUBSCR_USTR_INT")
self.assert_no_opcode(binary_subscr_str_int_non_compact, "BINARY_OP_SUBSCR_STR_INT")

def binary_subscr_str_negative_int_non_compact():
for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
a = "바이트코드_특수화"
idx = -1
self.assertEqual(a[idx], "화")

binary_subscr_str_negative_int_non_compact()
self.assert_specialized(binary_subscr_str_negative_int_non_compact, "BINARY_OP_SUBSCR_USTR_INT")
self.assert_no_opcode(binary_subscr_str_negative_int_non_compact, "BINARY_OP_SUBSCR_STR_INT")

def binary_subscr_getitems():
class C:
def __init__(self, val):
Expand Down Expand Up @@ -2026,6 +2057,17 @@ def store_subscr_defaultdict():
self.assert_specialized(store_subscr_defaultdict, "STORE_SUBSCR_DICT")
self.assert_no_opcode(store_subscr_defaultdict, "STORE_SUBSCR")

def store_subscr_list_negative_int():
for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
a = [1, 2, 3]
idx = -1
a[idx] = 4
self.assertEqual(a, [1, 2, 4])

store_subscr_list_negative_int()
self.assert_specialized(store_subscr_list_negative_int, "STORE_SUBSCR_LIST_INT")
self.assert_no_opcode(store_subscr_list_negative_int, "STORE_SUBSCR")

def store_subscr_dict_subclass_override():
class MyDict(dict):
def __setitem__(self, key, value):
Expand Down
2 changes: 2 additions & 0 deletions ...t/Core_and_Builtins/2026-07-10-10-05-00.gh-issue-153486.compact-index-guard.rst
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@@ -0,0 +1,2 @@
Improve optimized handling of non-negative integer indices for lists,
tuples, and strings.
38 changes: 19 additions & 19 deletions Modules/_testinternalcapi/test_cases.c.h
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52 changes: 36 additions & 16 deletions Python/bytecodes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1134,7 +1134,8 @@ dummy_func(
macro(STORE_SLICE) = _SPECIALIZE_STORE_SLICE + _STORE_SLICE;

macro(BINARY_OP_SUBSCR_LIST_INT) =
_GUARD_TOS_INT + _GUARD_NOS_LIST + unused/5 + _BINARY_OP_SUBSCR_LIST_INT + _POP_TOP_INT + POP_TOP;
_GUARD_TOS_INT + _GUARD_NOS_LIST + unused/5 +
_BINARY_OP_SUBSCR_LIST_INT + _POP_TOP_INT + POP_TOP;

op(_BINARY_OP_SUBSCR_LIST_INT, (list_st, sub_st -- res, ls, ss)) {
PyObject *sub = PyStackRef_AsPyObjectBorrow(sub_st);
Expand Down Expand Up @@ -1185,17 +1186,21 @@ dummy_func(
}

macro(BINARY_OP_SUBSCR_STR_INT) =
_GUARD_TOS_INT + _GUARD_NOS_COMPACT_ASCII + unused/5 + _BINARY_OP_SUBSCR_STR_INT + _POP_TOP_INT + _POP_TOP_UNICODE;
_GUARD_TOS_INT + _GUARD_NOS_COMPACT_ASCII +
unused/5 + _BINARY_OP_SUBSCR_STR_INT + _POP_TOP_INT + _POP_TOP_UNICODE;

op(_BINARY_OP_SUBSCR_STR_INT, (str_st, sub_st -- res, s, i)) {
PyObject *sub = PyStackRef_AsPyObjectBorrow(sub_st);
PyObject *str = PyStackRef_AsPyObjectBorrow(str_st);

assert(PyLong_CheckExact(sub));
assert(PyUnicode_CheckExact(str));
EXIT_IF(!_PyLong_IsNonNegativeCompact((PyLongObject*)sub));
Py_ssize_t index = ((PyLongObject*)sub)->long_value.ob_digit[0];
EXIT_IF(PyUnicode_GET_LENGTH(str) <= index);
Py_ssize_t index = _PyLong_CompactValue((PyLongObject *)sub);
Py_ssize_t len = PyUnicode_GET_LENGTH(str);
if (index < 0) {
index += len;
}
EXIT_IF(index < 0 || len <= index);
uint8_t c = PyUnicode_1BYTE_DATA(str)[index];
assert(c < 128);
STAT_INC(BINARY_OP, hit);
Expand All @@ -1207,17 +1212,21 @@ dummy_func(
}

macro(BINARY_OP_SUBSCR_USTR_INT) =
_GUARD_TOS_INT + _GUARD_NOS_UNICODE + unused/5 + _BINARY_OP_SUBSCR_USTR_INT + _POP_TOP_INT + _POP_TOP_UNICODE;
_GUARD_TOS_INT + _GUARD_NOS_UNICODE +
unused/5 + _BINARY_OP_SUBSCR_USTR_INT + _POP_TOP_INT + _POP_TOP_UNICODE;

op(_BINARY_OP_SUBSCR_USTR_INT, (str_st, sub_st -- res, s, i)) {
PyObject *sub = PyStackRef_AsPyObjectBorrow(sub_st);
PyObject *str = PyStackRef_AsPyObjectBorrow(str_st);

assert(PyLong_CheckExact(sub));
assert(PyUnicode_CheckExact(str));
EXIT_IF(!_PyLong_IsNonNegativeCompact((PyLongObject*)sub));
Py_ssize_t index = ((PyLongObject*)sub)->long_value.ob_digit[0];
EXIT_IF(PyUnicode_GET_LENGTH(str) <= index);
Py_ssize_t index = _PyLong_CompactValue((PyLongObject *)sub);
Py_ssize_t len = PyUnicode_GET_LENGTH(str);
if (index < 0) {
index += len;
}
EXIT_IF(index < 0 || len <= index);
// Specialize for reading an ASCII character from any string:
Py_UCS4 c = PyUnicode_READ_CHAR(str, index);
EXIT_IF(Py_ARRAY_LENGTH(_Py_SINGLETON(strings).ascii) <= c);
Expand Down Expand Up @@ -1256,10 +1265,12 @@ dummy_func(
assert(PyLong_CheckExact(sub));
assert(PyTuple_CheckExact(tuple));

// Deopt unless 0 <= sub < PyTuple_Size(list)
EXIT_IF(!_PyLong_IsNonNegativeCompact((PyLongObject *)sub));
Py_ssize_t index = ((PyLongObject*)sub)->long_value.ob_digit[0];
EXIT_IF(index >= PyTuple_GET_SIZE(tuple));
Py_ssize_t index = _PyLong_CompactValue((PyLongObject *)sub);
Py_ssize_t len = PyTuple_GET_SIZE(tuple);
if (index < 0) {
index += len;
}
EXIT_IF(index < 0 || index >= len);
}

op(_BINARY_OP_SUBSCR_TUPLE_INT, (tuple_st, sub_st -- res, ts, ss)) {
Expand All @@ -1270,7 +1281,10 @@ dummy_func(
assert(PyTuple_CheckExact(tuple));

STAT_INC(BINARY_OP, hit);
Py_ssize_t index = ((PyLongObject*)sub)->long_value.ob_digit[0];
Py_ssize_t index = _PyLong_CompactValue((PyLongObject *)sub);
if (index < 0) {
index += PyTuple_GET_SIZE(tuple);
}
PyObject *res_o = PyTuple_GET_ITEM(tuple, index);
assert(res_o != NULL);
res = PyStackRef_FromPyObjectNew(res_o);
Expand Down Expand Up @@ -1411,8 +1425,15 @@ dummy_func(

macro(STORE_SUBSCR) = _SPECIALIZE_STORE_SUBSCR + _STORE_SUBSCR;

op(_GUARD_TOS_NON_NEGATIVE_COMPACT_INT, (value -- value)) {
PyObject *value_o = PyStackRef_AsPyObjectBorrow(value);
assert(PyLong_CheckExact(value_o));
EXIT_IF(!_PyLong_IsNonNegativeCompact((PyLongObject *)value_o));
}

macro(STORE_SUBSCR_LIST_INT) =
_GUARD_TOS_INT + _GUARD_NOS_LIST + unused/1 + _STORE_SUBSCR_LIST_INT + _POP_TOP_INT + POP_TOP;
_GUARD_TOS_INT + _GUARD_NOS_LIST + unused/1 +
_STORE_SUBSCR_LIST_INT + _POP_TOP_INT + POP_TOP;

op(_STORE_SUBSCR_LIST_INT, (value, list_st, sub_st -- ls, ss)) {
PyObject *sub = PyStackRef_AsPyObjectBorrow(sub_st);
Expand All @@ -1424,7 +1445,6 @@ dummy_func(
Py_ssize_t index = _PyLong_CompactValue((PyLongObject *)sub);
DEOPT_IF(!LOCK_OBJECT(list));
Py_ssize_t len = PyList_GET_SIZE(list);
// Ensure index < len(list)
if (index < 0) {
index += len;
}
Expand Down
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