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gh-148871: Add CONSTANT_EMPTY_TUPLE to LOAD_COMMON_CONSTANT (GH-149688)

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Pieter Eendebak 2026-05-21 16:54:46 +02:00 • committed by GitHub
parent c35b0f2b62
commit f2fa291db8
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8 changed files with 20 additions and 9 deletions
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3
Include/internal/pycore_magic_number.h
View file

@ -298,6 +298,7 @@ Known values:
Python 3.15a8 3665 (Add FOR_ITER_VIRTUAL and GET_ITER specializations)
Python 3.15b1 3666 (Add SEND_VIRTUAL and SEND_ASYNC_GEN specializations)
Python 3.16a0 3700 (Initial version)
Python 3.16a0 3701 (Add CONSTANT_EMPTY_TUPLE to LOAD_COMMON_CONSTANT)
Python 3.17 will start with 3750
@ -311,7 +312,7 @@ PC/launcher.c must also be updated.
*/
#define PYC_MAGIC_NUMBER 3700
#define PYC_MAGIC_NUMBER 3701
/* This is equivalent to converting PYC_MAGIC_NUMBER to 2 bytes
(little-endian) and then appending b'\r\n'. */
#define PYC_MAGIC_NUMBER_TOKEN \

3
Include/internal/pycore_opcode_utils.h
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@ -81,7 +81,8 @@ extern "C" {
#define CONSTANT_FALSE 10
#define CONSTANT_MINUS_ONE 11
#define CONSTANT_BUILTIN_FROZENSET 12
#define NUM_COMMON_CONSTANTS 13
#define CONSTANT_EMPTY_TUPLE 13
#define NUM_COMMON_CONSTANTS 14
/* Values used in the oparg for RESUME */
#define RESUME_AT_FUNC_START 0

4
Lib/dis.py
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@ -698,8 +698,8 @@ def _get_const_value(op, arg, co_consts):
if op == LOAD_SMALL_INT:
return arg
if op == LOAD_COMMON_CONSTANT:
# Opargs 0-6 are callables; 7-11 are literal values.
if 7 <= arg <= 11:
# Opargs 0-6 and 12 are callables; 7-11 and 13 are literal values.
if 7 <= arg <= 11 or arg == 13:
return _common_constants[arg]
return UNKNOWN
argval = UNKNOWN

2
Lib/opcode.py
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@ -44,7 +44,7 @@
builtins.set,
# Append-only — must match CONSTANT_* in
# Include/internal/pycore_opcode_utils.h.
None, "", True, False, -1, builtins.frozenset]
None, "", True, False, -1, builtins.frozenset, ()]
_nb_ops = _opcode.get_nb_ops()
hascompare = [opmap["COMPARE_OP"]]

8
Lib/test/test_peepholer.py
View file

@ -1307,10 +1307,10 @@ def test_build_empty_tuple(self):
('RETURN_VALUE', None, 0),
]
after = [
('LOAD_CONST', 0, 0),
('LOAD_COMMON_CONSTANT', opcode._common_constants.index(()), 0),
('RETURN_VALUE', None, 0),
]
self.cfg_optimization_test(before, after, consts=[], expected_consts=[()])
self.cfg_optimization_test(before, after, consts=[], expected_consts=[])
def test_fold_tuple_of_constants(self):
before = [
@ -1365,10 +1365,10 @@ def test_fold_constant_intrinsic_list_to_tuple(self):
('RETURN_VALUE', None, 0)
]
after = [
('LOAD_CONST', 0, 0),
('LOAD_COMMON_CONSTANT', opcode._common_constants.index(()), 0),
('RETURN_VALUE', None, 0)
]
self.cfg_optimization_test(before, after, consts=[], expected_consts=[()])
self.cfg_optimization_test(before, after, consts=[], expected_consts=[])
# multiple BUILD_LIST 0: ([], 1, [], 2)
same = [

3
Misc/NEWS.d/next/Core_and_Builtins/2026-05-11-18-20-41.gh-issue-148871.AeCbq7.rst Normal file
View file

@ -0,0 +1,3 @@
The empty tuple ``()`` is now loaded via :opcode:`LOAD_COMMON_CONSTANT`
instead of :opcode:`LOAD_CONST`, removing it from per-code-object
:attr:`~codeobject.co_consts` tuples.

4
Python/flowgraph.c
View file

@ -1468,6 +1468,10 @@ maybe_instr_make_load_common_const(cfg_instr *instr, PyObject *newconst)
&& PyUnicode_GET_LENGTH(newconst) == 0) {
oparg = CONSTANT_EMPTY_STR;
}
else if (PyTuple_CheckExact(newconst)
&& PyTuple_GET_SIZE(newconst) == 0) {
oparg = CONSTANT_EMPTY_TUPLE;
}
else if (PyLong_CheckExact(newconst)) {
int overflow;
long val = PyLong_AsLongAndOverflow(newconst, &overflow);

2
Python/pylifecycle.c
View file

@ -893,6 +893,8 @@ pycore_init_builtins(PyThreadState *tstate)
interp->common_consts[CONSTANT_MINUS_ONE] =
(PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS - 1];
interp->common_consts[CONSTANT_BUILTIN_FROZENSET] = (PyObject *)&PyFrozenSet_Type;
interp->common_consts[CONSTANT_EMPTY_TUPLE] =
Py_GetConstantBorrowed(Py_CONSTANT_EMPTY_TUPLE);
for (int i = 0; i < NUM_COMMON_CONSTANTS; i++) {
assert(interp->common_consts[i] != NULL);
}