gh-148083: Constant-fold _CONTAINS_OP_SET for frozenset (gh-148084)

Author: corona10

Lib/test/test_capi/test_opt.py

@@ -23,6 +23,9 @@
 # For frozendict JIT tests
 FROZEN_DICT_CONST = frozendict(x=1, y=2)
 
+# For frozenset JIT tests
+FROZEN_SET_CONST = frozenset({1, 2, 3})
+
 class _GenericKey:
     pass
 
@@ -2169,7 +2172,8 @@ def f(n):
         self.assertIsNotNone(ex)
         uops = get_opnames(ex)
         self.assertNotIn("_GUARD_TOS_ANY_SET", uops)
-        self.assertIn("_CONTAINS_OP_SET", uops)
+        # _CONTAINS_OP_SET is constant-folded away for frozenset literals
+        self.assertIn("_INSERT_2_LOAD_CONST_INLINE_BORROW", uops)
 
     def test_remove_guard_for_known_type_tuple(self):
         def f(n):
@@ -4399,6 +4403,20 @@ def testfunc(n):
         # lookup result is folded to constant 1, so comparison is optimized away
         self.assertNotIn("_COMPARE_OP_INT", uops)
 
+    def test_contains_op_frozenset_const_fold(self):
+        def testfunc(n):
+            x = 0
+            for _ in range(n):
+                if 1 in FROZEN_SET_CONST:
+                    x += 1
+            return x
+
+        res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+        self.assertEqual(res, TIER2_THRESHOLD)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        self.assertNotIn("_CONTAINS_OP_SET", uops)
+
     def test_binary_subscr_list_slice(self):
         def testfunc(n):
             x = 0

Misc/NEWS.d/next/Core_and_Builtins/2026-04-04-20-59-12.gh-issue-148083.9ZHNBN.rst

@@ -0,0 +1 @@
+Constant-fold ``_CONTAINS_OP_SET`` for :class:`frozenset`. Patch by Donghee Na.

Python/optimizer_analysis.c

@@ -30,6 +30,7 @@
 #include "pycore_unicodeobject.h"
 #include "pycore_ceval.h"
 #include "pycore_floatobject.h"
+#include "pycore_setobject.h"
 
 #include <stdarg.h>
 #include <stdbool.h>

Python/optimizer_bytecodes.c

@@ -706,6 +706,9 @@ dummy_func(void) {
         b = sym_new_type(ctx, &PyBool_Type);
         l = left;
         r = right;
+        if (sym_matches_type(right, &PyFrozenSet_Type)) {
+            REPLACE_OPCODE_IF_EVALUATES_PURE(left, right, b);
+        }
     }
 
     op(_CONTAINS_OP_DICT, (left, right -- b, l, r)) {

Python/optimizer_cases.c.h

@@ -283,7 +283,8 @@ _Py_uop_sym_is_safe_const(JitOptContext *ctx, JitOptRef sym)
            (typ == &PyFloat_Type) ||
            (typ == &_PyNone_Type) ||
            (typ == &PyBool_Type) ||
-           (typ == &PyFrozenDict_Type);
+           (typ == &PyFrozenDict_Type) ||
+           (typ == &PyFrozenSet_Type);
 }
 
 void