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 98d9c2b..4c1e7ae 100644 --- a/Include/internal/pycore_opcode_metadata.h +++ b/Include/internal/pycore_opcode_metadata.h
@@ -1103,7 +1103,7 @@ [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 @@ [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 f931362..94b05b7 100644 --- a/Include/internal/pycore_uop_ids.h +++ b/Include/internal/pycore_uop_ids.h
@@ -414,7 +414,7 @@ #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 0835ee5..5a47eae 100644 --- a/Include/internal/pycore_uop_metadata.h +++ b/Include/internal/pycore_uop_metadata.h
@@ -119,7 +119,7 @@ [_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 @@ .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 @@ [_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 @@ [_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 765cb69..2cad53d 100644 --- a/Lib/test/test_capi/test_opt.py +++ b/Lib/test/test_capi/test_opt.py
@@ -3660,6 +3660,23 @@ def testfunc(n): 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 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 dda3bc5..35b1bc4 100644 --- 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; } - stack_pointer[0] = res; - stack_pointer += 1; - ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__); + // _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); + } DISPATCH(); }
diff --git a/Python/bytecodes.c b/Python/bytecodes.c index bd22599..e1884ac 100644 --- 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 f8de66c..f976e15 100644 --- 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 4cc9d9e..202bf5e 100644 --- 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; } - stack_pointer[0] = res; - stack_pointer += 1; - ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__); + // _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); + } DISPATCH(); }
diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c index e827707..7c928e6 100644 --- 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 cc1d28f..24ae511 100644 --- 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; }