https://github.com/python/cpython/commit/409fa8e1f3cfaae35fa4d12f6ac6d564c07ec6be
commit: 409fa8e1f3cfaae35fa4d12f6ac6d564c07ec6be
branch: main
author: Peter Bierma <[email protected]>
committer: ZeroIntensity <[email protected]>
date: 2026-05-19T13:57:37-04:00
summary:
gh-150027: Avoid copying during construction of `frozenset` objects (GH-150028)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-05-18-17-16-51.gh-issue-150027.sJgLvd.rst
M Include/internal/pycore_intrinsics.h
M Include/internal/pycore_opcode_utils.h
M Include/internal/pycore_setobject.h
M Lib/opcode.py
M Lib/test/test_builtin.py
M Lib/test/test_compiler_codegen.py
M Objects/setobject.c
M Python/codegen.c
M Python/intrinsics.c
M Python/pylifecycle.c
diff --git a/Include/internal/pycore_intrinsics.h
b/Include/internal/pycore_intrinsics.h
index 39c2a30f6e979d..59a7b16073f886 100644
--- a/Include/internal/pycore_intrinsics.h
+++ b/Include/internal/pycore_intrinsics.h
@@ -18,8 +18,9 @@
#define INTRINSIC_TYPEVARTUPLE 9
#define INTRINSIC_SUBSCRIPT_GENERIC 10
#define INTRINSIC_TYPEALIAS 11
+#define INTRINSIC_BUILD_FROZENSET 12
-#define MAX_INTRINSIC_1 11
+#define MAX_INTRINSIC_1 12
/* Binary Functions: */
diff --git a/Include/internal/pycore_opcode_utils.h
b/Include/internal/pycore_opcode_utils.h
index 3e2c4ae411c925..b20718344b3998 100644
--- a/Include/internal/pycore_opcode_utils.h
+++ b/Include/internal/pycore_opcode_utils.h
@@ -80,7 +80,8 @@ extern "C" {
#define CONSTANT_TRUE 9
#define CONSTANT_FALSE 10
#define CONSTANT_MINUS_ONE 11
-#define NUM_COMMON_CONSTANTS 12
+#define CONSTANT_BUILTIN_FROZENSET 12
+#define NUM_COMMON_CONSTANTS 13
/* Values used in the oparg for RESUME */
#define RESUME_AT_FUNC_START 0
diff --git a/Include/internal/pycore_setobject.h
b/Include/internal/pycore_setobject.h
index 24d0135ed1aeca..92d1a15177f79e 100644
--- a/Include/internal/pycore_setobject.h
+++ b/Include/internal/pycore_setobject.h
@@ -35,6 +35,9 @@ extern void _PySet_ClearInternal(PySetObject *so);
PyAPI_FUNC(int) _PySet_AddTakeRef(PySetObject *so, PyObject *key);
+PyObject *
+_PySet_Freeze(PyObject *set);
+
#ifdef __cplusplus
}
#endif
diff --git a/Lib/opcode.py b/Lib/opcode.py
index 4e60fb5af34f22..bb7824da70e8e5 100644
--- a/Lib/opcode.py
+++ b/Lib/opcode.py
@@ -44,7 +44,7 @@
builtins.set,
# Append-only — must match CONSTANT_* in
# Include/internal/pycore_opcode_utils.h.
- None, "", True, False, -1]
+ None, "", True, False, -1, builtins.frozenset]
_nb_ops = _opcode.get_nb_ops()
hascompare = [opmap["COMPARE_OP"]]
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index d62a3a4f17f85e..1f52b16948c703 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -268,7 +268,10 @@ def f_list():
def f_set():
return set(2*x for x in [1,2,3])
- funcs = [f_all, f_any, f_tuple, f_list, f_set]
+ def f_frozenset():
+ return frozenset(2*x for x in [1,2,3])
+
+ funcs = [f_all, f_any, f_tuple, f_list, f_set, f_frozenset]
for f in funcs:
# check that generator code object is not duplicated
@@ -278,35 +281,37 @@ def f_set():
# check the overriding the builtins works
- global all, any, tuple, list, set
- saved = all, any, tuple, list, set
+ global all, any, tuple, list, set, frozenset
+ saved = all, any, tuple, list, set, frozenset
try:
all = lambda x : "all"
any = lambda x : "any"
tuple = lambda x : "tuple"
list = lambda x : "list"
set = lambda x : "set"
+ frozenset = lambda x : "frozenset"
overridden_outputs = [f() for f in funcs]
finally:
- all, any, tuple, list, set = saved
+ all, any, tuple, list, set, frozenset = saved
- self.assertEqual(overridden_outputs, ['all', 'any', 'tuple', 'list',
'set'])
+ self.assertEqual(overridden_outputs, ['all', 'any', 'tuple', 'list',
'set', 'frozenset'])
# Now repeat, overriding the builtins module as well
- saved = all, any, tuple, list, set
+ saved = all, any, tuple, list, set, frozenset
try:
builtins.all = all = lambda x : "all"
builtins.any = any = lambda x : "any"
builtins.tuple = tuple = lambda x : "tuple"
builtins.list = list = lambda x : "list"
builtins.set = set = lambda x : "set"
+ builtins.frozenset = frozenset = lambda x : "frozenset"
overridden_outputs = [f() for f in funcs]
finally:
- all, any, tuple, list, set = saved
- builtins.all, builtins.any, builtins.tuple, builtins.list,
builtins.set = saved
+ all, any, tuple, list, set, frozenset = saved
+ builtins.all, builtins.any, builtins.tuple, builtins.list,
builtins.set, builtins.frozenset = saved
- self.assertEqual(overridden_outputs, ['all', 'any', 'tuple', 'list',
'set'])
+ self.assertEqual(overridden_outputs, ['all', 'any', 'tuple', 'list',
'set', 'frozenset'])
def test_builtin_call_async_genexpr_no_crash(self):
async def f_all():
diff --git a/Lib/test/test_compiler_codegen.py
b/Lib/test/test_compiler_codegen.py
index d02937c84d9534..36058854a41d63 100644
--- a/Lib/test/test_compiler_codegen.py
+++ b/Lib/test/test_compiler_codegen.py
@@ -161,3 +161,34 @@ def test_syntax_error__return_not_in_function(self):
self.assertIsNone(cm.exception.text)
self.assertEqual(cm.exception.offset, 1)
self.assertEqual(cm.exception.end_offset, 10)
+
+ def test_frozenset_optimization(self):
+ l1 = self.Label()
+ snippet = "frozenset({1, 2, 3})"
+ expected = [
+ ('RESUME', 0),
+ ('ANNOTATIONS_PLACEHOLDER', None),
+ ('LOAD_NAME', 0),
+ ('COPY', 1),
+ ('LOAD_COMMON_CONSTANT', 12),
+ ('IS_OP', 0),
+ ('POP_JUMP_IF_FALSE', l1),
+ ('POP_TOP', None),
+ ('LOAD_CONST', 1),
+ ('LOAD_CONST', 2),
+ ('LOAD_CONST', 3),
+ ('BUILD_SET', 3),
+ ('CALL_INTRINSIC_1', 12),
+ ('JUMP', 0),
+ l1,
+ ('PUSH_NULL', None),
+ ('LOAD_CONST', 1),
+ ('LOAD_CONST', 2),
+ ('LOAD_CONST', 3),
+ ('BUILD_SET', 3),
+ ('CALL', 1),
+ ('POP_TOP', None),
+ ('LOAD_CONST', 0),
+ ('RETURN_VALUE', None)
+ ]
+ self.codegen_test(snippet, expected)
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-05-18-17-16-51.gh-issue-150027.sJgLvd.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-05-18-17-16-51.gh-issue-150027.sJgLvd.rst
new file mode 100644
index 00000000000000..66446105da3fba
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-05-18-17-16-51.gh-issue-150027.sJgLvd.rst
@@ -0,0 +1,2 @@
+Improve performance of :class:`frozenset` objects by avoiding copies during
+construction.
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 1e630563604552..a1f654f0715bf3 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -1545,6 +1545,16 @@ set_swap_bodies(PySetObject *a, PySetObject *b)
FT_ATOMIC_STORE_PTR_RELEASE(b->table, b_table);
}
+PyObject *
+_PySet_Freeze(PyObject *set)
+{
+ assert(set != NULL);
+ assert(PySet_CheckExact(set));
+ assert(_PyObject_IsUniquelyReferenced(set));
+ set->ob_type = &PyFrozenSet_Type;
+ return Py_NewRef(set);
+}
+
/*[clinic input]
@critical_section
set.copy
diff --git a/Python/codegen.c b/Python/codegen.c
index 529c1733598e38..205c49cff1827c 100644
--- a/Python/codegen.c
+++ b/Python/codegen.c
@@ -3953,22 +3953,45 @@ maybe_optimize_function_call(compiler *c, expr_ty e,
jump_target_label end)
if (! (func->kind == Name_kind &&
asdl_seq_LEN(args) == 1 &&
- asdl_seq_LEN(kwds) == 0 &&
- asdl_seq_GET(args, 0)->kind == GeneratorExp_kind))
+ asdl_seq_LEN(kwds) == 0))
{
return 0;
}
- expr_ty generator_exp = asdl_seq_GET(args, 0);
- PySTEntryObject *generator_entry = _PySymtable_Lookup(SYMTABLE(c), (void
*)generator_exp);
+ location loc = LOC(func);
+
+ expr_ty arg_expr = asdl_seq_GET(args, 0);
+
+ if (_PyUnicode_EqualToASCIIString(func->v.Name.id, "frozenset")
+ && (arg_expr->kind == Set_kind || arg_expr->kind == SetComp_kind)) {
+ NEW_JUMP_TARGET_LABEL(c, skip_optimization);
+
+ ADDOP_I(c, loc, COPY, 1);
+ ADDOP_I(c, loc, LOAD_COMMON_CONSTANT, CONSTANT_BUILTIN_FROZENSET);
+ ADDOP_COMPARE(c, loc, Is);
+ ADDOP_JUMP(c, loc, POP_JUMP_IF_FALSE, skip_optimization);
+ ADDOP(c, loc, POP_TOP);
+
+ VISIT(c, expr, arg_expr);
+ ADDOP_I(c, loc, CALL_INTRINSIC_1, INTRINSIC_BUILD_FROZENSET);
+
+ ADDOP_JUMP(c, loc, JUMP, end);
+
+ USE_LABEL(c, skip_optimization);
+ return 1;
+ }
+
+ if (arg_expr->kind != GeneratorExp_kind) {
+ return 0;
+ }
+
+ PySTEntryObject *generator_entry = _PySymtable_Lookup(SYMTABLE(c), (void
*)arg_expr);
if (generator_entry->ste_coroutine) {
Py_DECREF(generator_entry);
return 0;
}
Py_DECREF(generator_entry);
- location loc = LOC(func);
-
int optimized = 0;
NEW_JUMP_TARGET_LABEL(c, skip_optimization);
@@ -3994,6 +4017,9 @@ maybe_optimize_function_call(compiler *c, expr_ty e,
jump_target_label end)
else if (_PyUnicode_EqualToASCIIString(func->v.Name.id, "set")) {
const_oparg = CONSTANT_BUILTIN_SET;
}
+ else if (_PyUnicode_EqualToASCIIString(func->v.Name.id, "frozenset")) {
+ const_oparg = CONSTANT_BUILTIN_FROZENSET;
+ }
if (const_oparg != -1) {
ADDOP_I(c, loc, COPY, 1); // the function
ADDOP_I(c, loc, LOAD_COMMON_CONSTANT, const_oparg);
@@ -4003,10 +4029,10 @@ maybe_optimize_function_call(compiler *c, expr_ty e,
jump_target_label end)
if (const_oparg == CONSTANT_BUILTIN_TUPLE || const_oparg ==
CONSTANT_BUILTIN_LIST) {
ADDOP_I(c, loc, BUILD_LIST, 0);
- } else if (const_oparg == CONSTANT_BUILTIN_SET) {
+ } else if (const_oparg == CONSTANT_BUILTIN_SET || const_oparg ==
CONSTANT_BUILTIN_FROZENSET) {
ADDOP_I(c, loc, BUILD_SET, 0);
}
- VISIT(c, expr, generator_exp);
+ VISIT(c, expr, arg_expr);
NEW_JUMP_TARGET_LABEL(c, loop);
NEW_JUMP_TARGET_LABEL(c, cleanup);
@@ -4017,7 +4043,7 @@ maybe_optimize_function_call(compiler *c, expr_ty e,
jump_target_label end)
if (const_oparg == CONSTANT_BUILTIN_TUPLE || const_oparg ==
CONSTANT_BUILTIN_LIST) {
ADDOP_I(c, loc, LIST_APPEND, 3);
ADDOP_JUMP(c, loc, JUMP, loop);
- } else if (const_oparg == CONSTANT_BUILTIN_SET) {
+ } else if (const_oparg == CONSTANT_BUILTIN_SET || const_oparg ==
CONSTANT_BUILTIN_FROZENSET) {
ADDOP_I(c, loc, SET_ADD, 3);
ADDOP_JUMP(c, loc, JUMP, loop);
}
@@ -4029,7 +4055,8 @@ maybe_optimize_function_call(compiler *c, expr_ty e,
jump_target_label end)
ADDOP(c, NO_LOCATION, POP_ITER);
if (const_oparg != CONSTANT_BUILTIN_TUPLE &&
const_oparg != CONSTANT_BUILTIN_LIST &&
- const_oparg != CONSTANT_BUILTIN_SET) {
+ const_oparg != CONSTANT_BUILTIN_SET &&
+ const_oparg != CONSTANT_BUILTIN_FROZENSET) {
ADDOP_LOAD_CONST(c, loc, initial_res == Py_True ? Py_False :
Py_True);
}
ADDOP_JUMP(c, loc, JUMP, end);
@@ -4044,6 +4071,9 @@ maybe_optimize_function_call(compiler *c, expr_ty e,
jump_target_label end)
} else if (const_oparg == CONSTANT_BUILTIN_SET) {
// result is already a set
}
+ else if (const_oparg == CONSTANT_BUILTIN_FROZENSET) {
+ ADDOP_I(c, loc, CALL_INTRINSIC_1, INTRINSIC_BUILD_FROZENSET);
+ }
else {
ADDOP_LOAD_CONST(c, loc, initial_res);
}
diff --git a/Python/intrinsics.c b/Python/intrinsics.c
index 9f994950f2721d..f081f33cc83b88 100644
--- a/Python/intrinsics.c
+++ b/Python/intrinsics.c
@@ -9,6 +9,7 @@
#include "pycore_intrinsics.h" // INTRINSIC_PRINT
#include "pycore_list.h" // _PyList_AsTupleAndClear()
#include "pycore_object.h" // _PyObject_IsUniquelyReferenced()
+#include "pycore_setobject.h" // _PySet_Freeze()
#include "pycore_pyerrors.h" // _PyErr_SetString()
#include "pycore_runtime.h" // _Py_ID()
#include "pycore_typevarobject.h" // _Py_make_typevar()
@@ -207,6 +208,14 @@ make_typevar(PyThreadState* Py_UNUSED(ignored), PyObject
*v)
return _Py_make_typevar(v, NULL, NULL);
}
+static PyObject *
+make_frozenset(PyThreadState* Py_UNUSED(ignored), PyObject *set)
+{
+ assert(PySet_CheckExact(set));
+ assert(_PyObject_IsUniquelyReferenced(set));
+ return _PySet_Freeze(set);
+}
+
#define INTRINSIC_FUNC_ENTRY(N, F) \
[N] = {F, #N},
@@ -225,6 +234,7 @@ _PyIntrinsics_UnaryFunctions[] = {
INTRINSIC_FUNC_ENTRY(INTRINSIC_TYPEVARTUPLE, _Py_make_typevartuple)
INTRINSIC_FUNC_ENTRY(INTRINSIC_SUBSCRIPT_GENERIC, _Py_subscript_generic)
INTRINSIC_FUNC_ENTRY(INTRINSIC_TYPEALIAS, _Py_make_typealias)
+ INTRINSIC_FUNC_ENTRY(INTRINSIC_BUILD_FROZENSET, make_frozenset)
};
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 46579a45f4cc39..cc29a832fc7549 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -892,6 +892,7 @@ pycore_init_builtins(PyThreadState *tstate)
interp->common_consts[CONSTANT_FALSE] = Py_False;
interp->common_consts[CONSTANT_MINUS_ONE] =
(PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS - 1];
+ interp->common_consts[CONSTANT_BUILTIN_FROZENSET] = (PyObject
*)&PyFrozenSet_Type;
for (int i = 0; i < NUM_COMMON_CONSTANTS; i++) {
assert(interp->common_consts[i] != NULL);
}
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