gh-134584: Optimize `_BINARY_OP_SUBSCR_LIST_SLICE` (GH-144659)

diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
index 98d9c2b51a78348cb0b0c236467fc8b387ff08ac..4c1e7aebd0d29140cc90d0c5498df464624bbb2a 100644 (file)
--- a/Include/internal/pycore_opcode_metadata.h
+++ b/Include/internal/pycore_opcode_metadata.h
@@ -1103,7 +1103,7 @@ const struct opcode_metadata _PyOpcode_opcode_metadata[267] = {
     [BINARY_OP_SUBSCR_DICT] = { true, INSTR_FMT_IXC0000, HAS_EXIT_FLAG | HAS_ERROR_FLAG | HAS_ERROR_NO_POP_FLAG | HAS_ESCAPES_FLAG },
     [BINARY_OP_SUBSCR_GETITEM] = { true, INSTR_FMT_IXC0000, HAS_DEOPT_FLAG | HAS_SYNC_SP_FLAG | HAS_NEEDS_GUARD_IP_FLAG | HAS_RECORDS_VALUE_FLAG },
     [BINARY_OP_SUBSCR_LIST_INT] = { true, INSTR_FMT_IXC0000, HAS_DEOPT_FLAG | HAS_EXIT_FLAG | HAS_ESCAPES_FLAG },
-    [BINARY_OP_SUBSCR_LIST_SLICE] = { true, INSTR_FMT_IXC0000, HAS_EXIT_FLAG | HAS_ERROR_FLAG | HAS_ESCAPES_FLAG },
+    [BINARY_OP_SUBSCR_LIST_SLICE] = { true, INSTR_FMT_IXC0000, HAS_EXIT_FLAG | HAS_ERROR_FLAG | HAS_ERROR_NO_POP_FLAG | HAS_ESCAPES_FLAG },
     [BINARY_OP_SUBSCR_STR_INT] = { true, INSTR_FMT_IXC0000, HAS_DEOPT_FLAG | HAS_EXIT_FLAG },
     [BINARY_OP_SUBSCR_TUPLE_INT] = { true, INSTR_FMT_IXC0000, HAS_DEOPT_FLAG | HAS_EXIT_FLAG | HAS_ESCAPES_FLAG },
     [BINARY_OP_SUBSCR_USTR_INT] = { true, INSTR_FMT_IXC0000, HAS_DEOPT_FLAG | HAS_EXIT_FLAG },
@@ -1356,7 +1356,7 @@ _PyOpcode_macro_expansion[256] = {
     [BINARY_OP_SUBSCR_DICT] = { .nuops = 4, .uops = { { _GUARD_NOS_DICT, OPARG_SIMPLE, 0 }, { _BINARY_OP_SUBSCR_DICT, OPARG_SIMPLE, 5 }, { _POP_TOP, OPARG_SIMPLE, 5 }, { _POP_TOP, OPARG_SIMPLE, 5 } } },
     [BINARY_OP_SUBSCR_GETITEM] = { .nuops = 5, .uops = { { _RECORD_NOS, OPARG_SIMPLE, 0 }, { _CHECK_PEP_523, OPARG_SIMPLE, 5 }, { _BINARY_OP_SUBSCR_CHECK_FUNC, OPARG_SIMPLE, 5 }, { _BINARY_OP_SUBSCR_INIT_CALL, OPARG_SIMPLE, 5 }, { _PUSH_FRAME, OPARG_SIMPLE, 5 } } },
     [BINARY_OP_SUBSCR_LIST_INT] = { .nuops = 5, .uops = { { _GUARD_TOS_INT, OPARG_SIMPLE, 0 }, { _GUARD_NOS_LIST, OPARG_SIMPLE, 0 }, { _BINARY_OP_SUBSCR_LIST_INT, OPARG_SIMPLE, 5 }, { _POP_TOP_INT, OPARG_SIMPLE, 5 }, { _POP_TOP, OPARG_SIMPLE, 5 } } },
-    [BINARY_OP_SUBSCR_LIST_SLICE] = { .nuops = 3, .uops = { { _GUARD_TOS_SLICE, OPARG_SIMPLE, 0 }, { _GUARD_NOS_LIST, OPARG_SIMPLE, 0 }, { _BINARY_OP_SUBSCR_LIST_SLICE, OPARG_SIMPLE, 5 } } },
+    [BINARY_OP_SUBSCR_LIST_SLICE] = { .nuops = 5, .uops = { { _GUARD_TOS_SLICE, OPARG_SIMPLE, 0 }, { _GUARD_NOS_LIST, OPARG_SIMPLE, 0 }, { _BINARY_OP_SUBSCR_LIST_SLICE, OPARG_SIMPLE, 5 }, { _POP_TOP, OPARG_SIMPLE, 5 }, { _POP_TOP, OPARG_SIMPLE, 5 } } },
     [BINARY_OP_SUBSCR_STR_INT] = { .nuops = 5, .uops = { { _GUARD_TOS_INT, OPARG_SIMPLE, 0 }, { _GUARD_NOS_COMPACT_ASCII, OPARG_SIMPLE, 0 }, { _BINARY_OP_SUBSCR_STR_INT, OPARG_SIMPLE, 5 }, { _POP_TOP_INT, OPARG_SIMPLE, 5 }, { _POP_TOP_UNICODE, OPARG_SIMPLE, 5 } } },
     [BINARY_OP_SUBSCR_TUPLE_INT] = { .nuops = 6, .uops = { { _GUARD_TOS_INT, OPARG_SIMPLE, 0 }, { _GUARD_NOS_TUPLE, OPARG_SIMPLE, 0 }, { _GUARD_BINARY_OP_SUBSCR_TUPLE_INT_BOUNDS, OPARG_SIMPLE, 0 }, { _BINARY_OP_SUBSCR_TUPLE_INT, OPARG_SIMPLE, 5 }, { _POP_TOP_INT, OPARG_SIMPLE, 5 }, { _POP_TOP, OPARG_SIMPLE, 5 } } },
     [BINARY_OP_SUBSCR_USTR_INT] = { .nuops = 5, .uops = { { _GUARD_TOS_INT, OPARG_SIMPLE, 0 }, { _GUARD_NOS_UNICODE, OPARG_SIMPLE, 0 }, { _BINARY_OP_SUBSCR_USTR_INT, OPARG_SIMPLE, 5 }, { _POP_TOP_INT, OPARG_SIMPLE, 5 }, { _POP_TOP_UNICODE, OPARG_SIMPLE, 5 } } },

diff --git a/Include/internal/pycore_uop_ids.h b/Include/internal/pycore_uop_ids.h
index f9313621756b45832a4d093e9f6a938526645971..94b05b736ed2771c54934c8eaeb528c84ecdb05b 100644 (file)
--- a/Include/internal/pycore_uop_ids.h
+++ b/Include/internal/pycore_uop_ids.h
@@ -414,7 +414,7 @@ extern "C" {
 #define _BINARY_OP_SUBSCR_INIT_CALL_r21 611
 #define _BINARY_OP_SUBSCR_INIT_CALL_r31 612
 #define _BINARY_OP_SUBSCR_LIST_INT_r23 613
-#define _BINARY_OP_SUBSCR_LIST_SLICE_r21 614
+#define _BINARY_OP_SUBSCR_LIST_SLICE_r23 614
 #define _BINARY_OP_SUBSCR_STR_INT_r23 615
 #define _BINARY_OP_SUBSCR_TUPLE_INT_r03 616
 #define _BINARY_OP_SUBSCR_TUPLE_INT_r13 617

diff --git a/Include/internal/pycore_uop_metadata.h b/Include/internal/pycore_uop_metadata.h
index 0835ee5c9499d1d1ac54e76579826a1029377287..5a47eae7a9abb15a1863eea8211d6da7e5650fa2 100644 (file)
--- a/Include/internal/pycore_uop_metadata.h
+++ b/Include/internal/pycore_uop_metadata.h
@@ -119,7 +119,7 @@ const uint32_t _PyUop_Flags[MAX_UOP_ID+1] = {
     [_BINARY_SLICE] = HAS_ERROR_FLAG | HAS_ESCAPES_FLAG,
     [_STORE_SLICE] = HAS_ERROR_FLAG | HAS_ESCAPES_FLAG,
     [_BINARY_OP_SUBSCR_LIST_INT] = HAS_DEOPT_FLAG | HAS_ESCAPES_FLAG,
-    [_BINARY_OP_SUBSCR_LIST_SLICE] = HAS_ERROR_FLAG | HAS_ESCAPES_FLAG,
+    [_BINARY_OP_SUBSCR_LIST_SLICE] = HAS_ERROR_FLAG | HAS_ERROR_NO_POP_FLAG | HAS_ESCAPES_FLAG,
     [_BINARY_OP_SUBSCR_STR_INT] = HAS_DEOPT_FLAG,
     [_BINARY_OP_SUBSCR_USTR_INT] = HAS_DEOPT_FLAG,
     [_GUARD_NOS_TUPLE] = HAS_EXIT_FLAG,
@@ -1159,7 +1159,7 @@ const _PyUopCachingInfo _PyUop_Caching[MAX_UOP_ID+1] = {
         .entries = {
             { -1, -1, -1 },
             { -1, -1, -1 },
-            { 1, 2, _BINARY_OP_SUBSCR_LIST_SLICE_r21 },
+            { 3, 2, _BINARY_OP_SUBSCR_LIST_SLICE_r23 },
             { -1, -1, -1 },
         },
     },
@@ -3702,7 +3702,7 @@ const uint16_t _PyUop_Uncached[MAX_UOP_REGS_ID+1] = {
     [_BINARY_SLICE_r31] = _BINARY_SLICE,
     [_STORE_SLICE_r30] = _STORE_SLICE,
     [_BINARY_OP_SUBSCR_LIST_INT_r23] = _BINARY_OP_SUBSCR_LIST_INT,
-    [_BINARY_OP_SUBSCR_LIST_SLICE_r21] = _BINARY_OP_SUBSCR_LIST_SLICE,
+    [_BINARY_OP_SUBSCR_LIST_SLICE_r23] = _BINARY_OP_SUBSCR_LIST_SLICE,
     [_BINARY_OP_SUBSCR_STR_INT_r23] = _BINARY_OP_SUBSCR_STR_INT,
     [_BINARY_OP_SUBSCR_USTR_INT_r23] = _BINARY_OP_SUBSCR_USTR_INT,
     [_GUARD_NOS_TUPLE_r02] = _GUARD_NOS_TUPLE,
@@ -4297,7 +4297,7 @@ const char *const _PyOpcode_uop_name[MAX_UOP_REGS_ID+1] = {
     [_BINARY_OP_SUBSCR_LIST_INT] = "_BINARY_OP_SUBSCR_LIST_INT",
     [_BINARY_OP_SUBSCR_LIST_INT_r23] = "_BINARY_OP_SUBSCR_LIST_INT_r23",
     [_BINARY_OP_SUBSCR_LIST_SLICE] = "_BINARY_OP_SUBSCR_LIST_SLICE",
-    [_BINARY_OP_SUBSCR_LIST_SLICE_r21] = "_BINARY_OP_SUBSCR_LIST_SLICE_r21",
+    [_BINARY_OP_SUBSCR_LIST_SLICE_r23] = "_BINARY_OP_SUBSCR_LIST_SLICE_r23",
     [_BINARY_OP_SUBSCR_STR_INT] = "_BINARY_OP_SUBSCR_STR_INT",
     [_BINARY_OP_SUBSCR_STR_INT_r23] = "_BINARY_OP_SUBSCR_STR_INT_r23",
     [_BINARY_OP_SUBSCR_TUPLE_INT] = "_BINARY_OP_SUBSCR_TUPLE_INT",

diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
index 765cb69dc04df18a599565afd486b7d39c93c395..2cad53d9c0728b6ab0bd363f6c7856ba6bb90dee 100644 (file)
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -3660,6 +3660,23 @@ class TestUopsOptimization(unittest.TestCase):
         self.assertLessEqual(count_ops(ex, "_POP_TOP_INT"), 1)
         self.assertIn("_POP_TOP_NOP", uops)
 
+    def test_binary_subscr_list_slice(self):
+        def testfunc(n):
+            x = 0
+            for _ in range(n):
+                l = [1, 2, 3]
+                x += l[0:1][0]
+            return x
+
+        res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+        self.assertEqual(res, TIER2_THRESHOLD)
+        uops = get_opnames(ex)
+
+        self.assertIn("_BINARY_OP_SUBSCR_LIST_SLICE", uops)
+        self.assertNotIn("_GUARD_TOS_LIST", uops)
+        self.assertEqual(count_ops(ex, "_POP_TOP"), 3)
+        self.assertEqual(count_ops(ex, "_POP_TOP_NOP"), 4)
+
     def test_is_op(self):
         def test_is_false(n):
             a = object()

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-02-10-12-08-58.gh-issue-134584.P9LDy5.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-02-10-12-08-58.gh-issue-134584.P9LDy5.rst
new file mode 100644 (file)
index 0000000..fab5018
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-02-10-12-08-58.gh-issue-134584.P9LDy5.rst
@@ -0,0 +1 @@
+Optimize and eliminate ref-counting in ``_BINARY_OP_SUBSCR_LIST_SLICE``

diff --git a/Modules/_testinternalcapi/test_cases.c.h b/Modules/_testinternalcapi/test_cases.c.h
index dda3bc53dc5e0dfc5e1c0e02861765f6052e2af9..35b1bc4e17c5d509566fb477125ed86b6fdf3af4 100644 (file)
--- a/Modules/_testinternalcapi/test_cases.c.h
+++ b/Modules/_testinternalcapi/test_cases.c.h
@@ -892,6 +892,9 @@
             _PyStackRef list_st;
             _PyStackRef sub_st;
             _PyStackRef res;
+            _PyStackRef ls;
+            _PyStackRef ss;
+            _PyStackRef value;
             // _GUARD_TOS_SLICE
             {
                 tos = stack_pointer[-1];
@@ -925,26 +928,31 @@
                 PyObject *res_o = _PyList_SliceSubscript(list, sub);
                 stack_pointer = _PyFrame_GetStackPointer(frame);
                 STAT_INC(BINARY_OP, hit);
-                _PyFrame_SetStackPointer(frame, stack_pointer);
-                _PyStackRef tmp = sub_st;
-                sub_st = PyStackRef_NULL;
-                stack_pointer[-1] = sub_st;
-                PyStackRef_CLOSE(tmp);
-                tmp = list_st;
-                list_st = PyStackRef_NULL;
-                stack_pointer[-2] = list_st;
-                PyStackRef_CLOSE(tmp);
-                stack_pointer = _PyFrame_GetStackPointer(frame);
-                stack_pointer += -2;
-                ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
                 if (res_o == NULL) {
                     JUMP_TO_LABEL(error);
                 }
                 res = PyStackRef_FromPyObjectSteal(res_o);
+                ls = list_st;
+                ss = sub_st;
+            }
+            // _POP_TOP
+            {
+                value = ss;
+                stack_pointer[-2] = res;
+                stack_pointer[-1] = ls;
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                PyStackRef_XCLOSE(value);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            }
+            // _POP_TOP
+            {
+                value = ls;
+                stack_pointer += -1;
+                ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                PyStackRef_XCLOSE(value);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
             }
-            stack_pointer[0] = res;
-            stack_pointer += 1;
-            ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
             DISPATCH();
         }
 

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index bd22599aef725dfe473758a858578911f4043881..e1884ac38c016dbdd6d6523b18ea5b4a0d3a40dd 100644 (file)
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -938,9 +938,9 @@ dummy_func(
         }
 
         macro(BINARY_OP_SUBSCR_LIST_SLICE) =
-            _GUARD_TOS_SLICE + _GUARD_NOS_LIST + unused/5 + _BINARY_OP_SUBSCR_LIST_SLICE;
+            _GUARD_TOS_SLICE + _GUARD_NOS_LIST + unused/5 + _BINARY_OP_SUBSCR_LIST_SLICE + POP_TOP + POP_TOP;
 
-        op(_BINARY_OP_SUBSCR_LIST_SLICE, (list_st, sub_st -- res)) {
+        op(_BINARY_OP_SUBSCR_LIST_SLICE, (list_st, sub_st -- res, ls, ss)) {
             PyObject *sub = PyStackRef_AsPyObjectBorrow(sub_st);
             PyObject *list = PyStackRef_AsPyObjectBorrow(list_st);
 
@@ -949,9 +949,13 @@ dummy_func(
 
             PyObject *res_o = _PyList_SliceSubscript(list, sub);
             STAT_INC(BINARY_OP, hit);
-            DECREF_INPUTS();
-            ERROR_IF(res_o == NULL);
+            if (res_o == NULL) {
+                ERROR_NO_POP();
+            }
             res = PyStackRef_FromPyObjectSteal(res_o);
+            ls = list_st;
+            ss = sub_st;
+            INPUTS_DEAD();
         }
 
         macro(BINARY_OP_SUBSCR_STR_INT) =

diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
index f8de66cbce3a9f76872d6afa5a82f58c5f6d4c8f..f976e150451d4996b8eea02161f954d276425981 100644 (file)
--- a/Python/executor_cases.c.h
+++ b/Python/executor_cases.c.h
@@ -5368,12 +5368,14 @@
             break;
         }
 
-        case _BINARY_OP_SUBSCR_LIST_SLICE_r21: {
+        case _BINARY_OP_SUBSCR_LIST_SLICE_r23: {
             CHECK_CURRENT_CACHED_VALUES(2);
             assert(WITHIN_STACK_BOUNDS_IGNORING_CACHE());
             _PyStackRef sub_st;
             _PyStackRef list_st;
             _PyStackRef res;
+            _PyStackRef ls;
+            _PyStackRef ss;
             _PyStackRef _stack_item_0 = _tos_cache0;
             _PyStackRef _stack_item_1 = _tos_cache1;
             sub_st = _stack_item_1;
@@ -5390,27 +5392,19 @@
             PyObject *res_o = _PyList_SliceSubscript(list, sub);
             stack_pointer = _PyFrame_GetStackPointer(frame);
             STAT_INC(BINARY_OP, hit);
-            _PyFrame_SetStackPointer(frame, stack_pointer);
-            _PyStackRef tmp = sub_st;
-            sub_st = PyStackRef_NULL;
-            stack_pointer[-1] = sub_st;
-            PyStackRef_CLOSE(tmp);
-            tmp = list_st;
-            list_st = PyStackRef_NULL;
-            stack_pointer[-2] = list_st;
-            PyStackRef_CLOSE(tmp);
-            stack_pointer = _PyFrame_GetStackPointer(frame);
-            stack_pointer += -2;
-            ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
             if (res_o == NULL) {
                 SET_CURRENT_CACHED_VALUES(0);
                 JUMP_TO_ERROR();
             }
             res = PyStackRef_FromPyObjectSteal(res_o);
+            ls = list_st;
+            ss = sub_st;
+            _tos_cache2 = ss;
+            _tos_cache1 = ls;
             _tos_cache0 = res;
-            _tos_cache1 = PyStackRef_ZERO_BITS;
-            _tos_cache2 = PyStackRef_ZERO_BITS;
-            SET_CURRENT_CACHED_VALUES(1);
+            SET_CURRENT_CACHED_VALUES(3);
+            stack_pointer += -2;
+            ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
             assert(WITHIN_STACK_BOUNDS_IGNORING_CACHE());
             break;
         }

diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index 4cc9d9e03a545dd7928aa8f96ed523c81aed4573..202bf5edcf09df5ae0e8c9aae2baf6eba063b11d 100644 (file)
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -892,6 +892,9 @@
             _PyStackRef list_st;
             _PyStackRef sub_st;
             _PyStackRef res;
+            _PyStackRef ls;
+            _PyStackRef ss;
+            _PyStackRef value;
             // _GUARD_TOS_SLICE
             {
                 tos = stack_pointer[-1];
@@ -925,26 +928,31 @@
                 PyObject *res_o = _PyList_SliceSubscript(list, sub);
                 stack_pointer = _PyFrame_GetStackPointer(frame);
                 STAT_INC(BINARY_OP, hit);
-                _PyFrame_SetStackPointer(frame, stack_pointer);
-                _PyStackRef tmp = sub_st;
-                sub_st = PyStackRef_NULL;
-                stack_pointer[-1] = sub_st;
-                PyStackRef_CLOSE(tmp);
-                tmp = list_st;
-                list_st = PyStackRef_NULL;
-                stack_pointer[-2] = list_st;
-                PyStackRef_CLOSE(tmp);
-                stack_pointer = _PyFrame_GetStackPointer(frame);
-                stack_pointer += -2;
-                ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
                 if (res_o == NULL) {
                     JUMP_TO_LABEL(error);
                 }
                 res = PyStackRef_FromPyObjectSteal(res_o);
+                ls = list_st;
+                ss = sub_st;
+            }
+            // _POP_TOP
+            {
+                value = ss;
+                stack_pointer[-2] = res;
+                stack_pointer[-1] = ls;
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                PyStackRef_XCLOSE(value);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
+            }
+            // _POP_TOP
+            {
+                value = ls;
+                stack_pointer += -1;
+                ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
+                _PyFrame_SetStackPointer(frame, stack_pointer);
+                PyStackRef_XCLOSE(value);
+                stack_pointer = _PyFrame_GetStackPointer(frame);
             }
-            stack_pointer[0] = res;
-            stack_pointer += 1;
-            ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
             DISPATCH();
         }
 

diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index e82770742a356c4c3be4b73b73b1b1d3c485c071..7c928e6502a412ded07b6fdc00164b09ae1406f9 100644 (file)
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -422,6 +422,12 @@ dummy_func(void) {
         ss = sub_st;
     }
 
+    op(_BINARY_OP_SUBSCR_LIST_SLICE, (list_st, sub_st -- res, ls, ss)) {
+        res = sym_new_type(ctx, &PyList_Type);
+        ls = list_st;
+        ss = sub_st;
+    }
+
     op(_TO_BOOL, (value -- res)) {
         int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
         if (!already_bool) {

diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index cc1d28f49442b406f3eec11a981d0a6f7f4f0f28..24ae511ebcde317a30023f78e20260fdba436019 100644 (file)
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -957,11 +957,21 @@
         }
 
         case _BINARY_OP_SUBSCR_LIST_SLICE: {
+            JitOptRef sub_st;
+            JitOptRef list_st;
             JitOptRef res;
-            res = sym_new_not_null(ctx);
-            CHECK_STACK_BOUNDS(-1);
+            JitOptRef ls;
+            JitOptRef ss;
+            sub_st = stack_pointer[-1];
+            list_st = stack_pointer[-2];
+            res = sym_new_type(ctx, &PyList_Type);
+            ls = list_st;
+            ss = sub_st;
+            CHECK_STACK_BOUNDS(1);
             stack_pointer[-2] = res;
-            stack_pointer += -1;
+            stack_pointer[-1] = ls;
+            stack_pointer[0] = ss;
+            stack_pointer += 1;
             ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
             break;
         }