gh-126835: Move constant tuple folding from ast_opt to CFG (#130769)

9 files changed, 264 insertions, 172 deletions

diff --git a/Lib/test/test_ast/test_ast.py b/Lib/test/test_ast/test_ast.py
index e63ddb7..1b108ce 100644
--- a/Lib/test/test_ast/test_ast.py
+++ b/Lib/test/test_ast/test_ast.py
@@ -153,22 +153,6 @@ class AST_Tests(unittest.TestCase):
                         self.assertIsInstance(res.body[0].value, ast.Name)
                         self.assertEqual(res.body[0].value.id, expected)
 
-    def test_optimization_levels_const_folding(self):
-        folded = ('Expr', (1, 0, 1, 6), ('Constant', (1, 0, 1, 6), (1, 2), None))
-        not_folded = ('Expr', (1, 0, 1, 6),
-                         ('Tuple', (1, 0, 1, 6),
-                             [('Constant', (1, 1, 1, 2), 1, None),
-                             ('Constant', (1, 4, 1, 5), 2, None)], ('Load',)))
-
-        cases = [(-1, not_folded), (0, not_folded), (1, folded), (2, folded)]
-        for (optval, expected) in cases:
-            with self.subTest(optval=optval):
-                tree1 = ast.parse("(1, 2)", optimize=optval)
-                tree2 = ast.parse(ast.parse("(1, 2)"), optimize=optval)
-                for tree in [tree1, tree2]:
-                    res = to_tuple(tree.body[0])
-                    self.assertEqual(res, expected)
-
     def test_invalid_position_information(self):
         invalid_linenos = [
             (10, 1), (-10, -11), (10, -11), (-5, -2), (-5, 1)
@@ -3193,101 +3177,6 @@ class ASTOptimiziationTests(unittest.TestCase):
 
         self.assert_ast(code, non_optimized_target, optimized_target)
 
-
-    def test_folding_tuple(self):
-        code = "(1,)"
-
-        non_optimized_target = self.wrap_expr(ast.Tuple(elts=[ast.Constant(1)]))
-        optimized_target = self.wrap_expr(ast.Constant(value=(1,)))
-
-        self.assert_ast(code, non_optimized_target, optimized_target)
-
-    def test_folding_type_param_in_function_def(self):
-        code = "def foo[%s = (1, 2)](): pass"
-
-        unoptimized_tuple = ast.Tuple(elts=[ast.Constant(1), ast.Constant(2)])
-        unoptimized_type_params = [
-            ("T", "T", ast.TypeVar),
-            ("**P", "P", ast.ParamSpec),
-            ("*Ts", "Ts", ast.TypeVarTuple),
-        ]
-
-        for type, name, type_param in unoptimized_type_params:
-            result_code = code % type
-            optimized_target = self.wrap_statement(
-                ast.FunctionDef(
-                    name='foo',
-                    args=ast.arguments(),
-                    body=[ast.Pass()],
-                    type_params=[type_param(name=name, default_value=ast.Constant((1, 2)))]
-                )
-            )
-            non_optimized_target = self.wrap_statement(
-                ast.FunctionDef(
-                    name='foo',
-                    args=ast.arguments(),
-                    body=[ast.Pass()],
-                    type_params=[type_param(name=name, default_value=unoptimized_tuple)]
-                )
-            )
-            self.assert_ast(result_code, non_optimized_target, optimized_target)
-
-    def test_folding_type_param_in_class_def(self):
-        code = "class foo[%s = (1, 2)]: pass"
-
-        unoptimized_tuple = ast.Tuple(elts=[ast.Constant(1), ast.Constant(2)])
-        unoptimized_type_params = [
-            ("T", "T", ast.TypeVar),
-            ("**P", "P", ast.ParamSpec),
-            ("*Ts", "Ts", ast.TypeVarTuple),
-        ]
-
-        for type, name, type_param in unoptimized_type_params:
-            result_code = code % type
-            optimized_target = self.wrap_statement(
-                ast.ClassDef(
-                    name='foo',
-                    body=[ast.Pass()],
-                    type_params=[type_param(name=name, default_value=ast.Constant((1, 2)))]
-                )
-            )
-            non_optimized_target = self.wrap_statement(
-                ast.ClassDef(
-                    name='foo',
-                    body=[ast.Pass()],
-                    type_params=[type_param(name=name, default_value=unoptimized_tuple)]
-                )
-            )
-            self.assert_ast(result_code, non_optimized_target, optimized_target)
-
-    def test_folding_type_param_in_type_alias(self):
-        code = "type foo[%s = (1, 2)] = 1"
-
-        unoptimized_tuple = ast.Tuple(elts=[ast.Constant(1), ast.Constant(2)])
-        unoptimized_type_params = [
-            ("T", "T", ast.TypeVar),
-            ("**P", "P", ast.ParamSpec),
-            ("*Ts", "Ts", ast.TypeVarTuple),
-        ]
-
-        for type, name, type_param in unoptimized_type_params:
-            result_code = code % type
-            optimized_target = self.wrap_statement(
-                ast.TypeAlias(
-                    name=ast.Name(id='foo', ctx=ast.Store()),
-                    type_params=[type_param(name=name, default_value=ast.Constant((1, 2)))],
-                    value=ast.Constant(value=1),
-                )
-            )
-            non_optimized_target = self.wrap_statement(
-                ast.TypeAlias(
-                    name=ast.Name(id='foo', ctx=ast.Store()),
-                    type_params=[type_param(name=name, default_value=unoptimized_tuple)],
-                    value=ast.Constant(value=1),
-                )
-            )
-            self.assert_ast(result_code, non_optimized_target, optimized_target)
-
     def test_folding_match_case_allowed_expressions(self):
         def get_match_case_values(node):
             result = []
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 90998ff..0cc172c 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -554,7 +554,7 @@ class BuiltinTest(ComplexesAreIdenticalMixin, unittest.TestCase):
         self.assertEqual(type(glob['ticker']()), AsyncGeneratorType)
 
     def test_compile_ast(self):
-        args = ("a*(1,2)", "f.py", "exec")
+        args = ("a*__debug__", "f.py", "exec")
         raw = compile(*args, flags = ast.PyCF_ONLY_AST).body[0]
         opt1 = compile(*args, flags = ast.PyCF_OPTIMIZED_AST).body[0]
         opt2 = compile(ast.parse(args[0]), *args[1:], flags = ast.PyCF_OPTIMIZED_AST).body[0]
@@ -565,14 +565,14 @@ class BuiltinTest(ComplexesAreIdenticalMixin, unittest.TestCase):
             self.assertIsInstance(tree.value.left, ast.Name)
             self.assertEqual(tree.value.left.id, 'a')
 
-        raw_right = raw.value.right  # expect Tuple((1, 2))
-        self.assertIsInstance(raw_right, ast.Tuple)
-        self.assertListEqual([elt.value for elt in raw_right.elts], [1, 2])
+        raw_right = raw.value.right
+        self.assertIsInstance(raw_right, ast.Name)
+        self.assertEqual(raw_right.id, "__debug__")
 
         for opt in [opt1, opt2]:
-            opt_right = opt.value.right  # expect Constant((1,2))
+            opt_right = opt.value.right
             self.assertIsInstance(opt_right, ast.Constant)
-            self.assertEqual(opt_right.value, (1, 2))
+            self.assertEqual(opt_right.value, True)
 
     def test_delattr(self):
         sys.spam = 1
diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index b1dc770..ce9c060 100644
--- a/Lib/test/test_compile.py
+++ b/Lib/test/test_compile.py
@@ -793,9 +793,9 @@ class TestSpecifics(unittest.TestCase):
         f1, f2 = lambda: "not a name", lambda: ("not a name",)
         f3 = lambda x: x in {("not a name",)}
         self.assertIs(f1.__code__.co_consts[0],
-                      f2.__code__.co_consts[0][0])
+                      f2.__code__.co_consts[1][0])
         self.assertIs(next(iter(f3.__code__.co_consts[1])),
-                      f2.__code__.co_consts[0])
+                      f2.__code__.co_consts[1])
 
         # {0} is converted to a constant frozenset({0}) by the peephole
         # optimizer
@@ -1129,6 +1129,31 @@ class TestSpecifics(unittest.TestCase):
                 self.assertIn('LOAD_ATTR', instructions)
                 self.assertIn('CALL', instructions)
 
+    def test_folding_type_param(self):
+        get_code_fn_cls = lambda x: x.co_consts[0].co_consts[2]
+        get_code_type_alias = lambda x: x.co_consts[0].co_consts[3]
+        snippets = [
+            ("def foo[T = 40 + 5](): pass", get_code_fn_cls),
+            ("def foo[**P = 40 + 5](): pass", get_code_fn_cls),
+            ("def foo[*Ts = 40 + 5](): pass", get_code_fn_cls),
+            ("class foo[T = 40 + 5]: pass", get_code_fn_cls),
+            ("class foo[**P = 40 + 5]: pass", get_code_fn_cls),
+            ("class foo[*Ts = 40 + 5]: pass", get_code_fn_cls),
+            ("type foo[T = 40 + 5] = 1", get_code_type_alias),
+            ("type foo[**P = 40 + 5] = 1", get_code_type_alias),
+            ("type foo[*Ts = 40 + 5] = 1", get_code_type_alias),
+        ]
+        for snippet, get_code in snippets:
+            c = compile(snippet, "<dummy>", "exec")
+            code = get_code(c)
+            opcodes = list(dis.get_instructions(code))
+            instructions = [opcode.opname for opcode in opcodes]
+            args = [opcode.oparg for opcode in opcodes]
+            self.assertNotIn(40, args)
+            self.assertNotIn(5, args)
+            self.assertIn('LOAD_SMALL_INT', instructions)
+            self.assertIn(45, args)
+
     def test_lineno_procedure_call(self):
         def call():
             (
diff --git a/Lib/test/test_opcache.py b/Lib/test/test_opcache.py
index ce9c489..ac13246 100644
--- a/Lib/test/test_opcache.py
+++ b/Lib/test/test_opcache.py
@@ -1666,7 +1666,8 @@ class TestSpecializer(TestBase):
     def test_unpack_sequence(self):
         def unpack_sequence_two_tuple():
             for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
-                a, b = 1, 2
+                t = 1, 2
+                a, b = t
                 self.assertEqual(a, 1)
                 self.assertEqual(b, 2)
 
@@ -1677,8 +1678,11 @@ class TestSpecializer(TestBase):
 
         def unpack_sequence_tuple():
             for _ in range(_testinternalcapi.SPECIALIZATION_THRESHOLD):
-                a, = 1,
+                a, b, c, d = 1, 2, 3, 4
                 self.assertEqual(a, 1)
+                self.assertEqual(b, 2)
+                self.assertEqual(c, 3)
+                self.assertEqual(d, 4)
 
         unpack_sequence_tuple()
         self.assert_specialized(unpack_sequence_tuple, "UNPACK_SEQUENCE_TUPLE")
diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
index 4644641..6de89c4 100644
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -154,7 +154,7 @@ class TestTranforms(BytecodeTestCase):
         for line, elem in (
             ('a = 1,2,3', (1, 2, 3)),
             ('("a","b","c")', ('a', 'b', 'c')),
-            ('a,b,c = 1,2,3', (1, 2, 3)),
+            ('a,b,c,d = 1,2,3,4', (1, 2, 3, 4)),
             ('(None, 1, None)', (None, 1, None)),
             ('((1, 2), 3, 4)', ((1, 2), 3, 4)),
             ):
@@ -1349,6 +1349,111 @@ class DirectCfgOptimizerTests(CfgOptimizationTestCase):
         ]
         self.cfg_optimization_test(same, same, consts=[])
 
+    def test_fold_constant_intrinsic_list_to_tuple(self):
+        INTRINSIC_LIST_TO_TUPLE = 6
+
+        # long tuple
+        consts = 1000
+        before = (
+            [('BUILD_LIST', 0, 0)] +
+            [('LOAD_CONST', 0, 0), ('LIST_APPEND', 1, 0)] * consts +
+            [('CALL_INTRINSIC_1', INTRINSIC_LIST_TO_TUPLE, 0), ('RETURN_VALUE', None, 0)]
+        )
+        after = [
+            ('LOAD_CONST', 1, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        result_const = tuple(["test"] * consts)
+        self.cfg_optimization_test(before, after, consts=["test"], expected_consts=["test", result_const])
+
+        # empty list
+        before = [
+            ('BUILD_LIST', 0, 0),
+            ('CALL_INTRINSIC_1', INTRINSIC_LIST_TO_TUPLE, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        after = [
+            ('LOAD_CONST', 0, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        self.cfg_optimization_test(before, after, consts=[], expected_consts=[()])
+
+        # multiple BUILD_LIST 0: ([], 1, [], 2)
+        same = [
+            ('BUILD_LIST', 0, 0),
+            ('BUILD_LIST', 0, 0),
+            ('LIST_APPEND', 1, 0),
+            ('LOAD_SMALL_INT', 1, 0),
+            ('LIST_APPEND', 1, 0),
+            ('BUILD_LIST', 0, 0),
+            ('LIST_APPEND', 1, 0),
+            ('LOAD_SMALL_INT', 2, 0),
+            ('LIST_APPEND', 1, 0),
+            ('CALL_INTRINSIC_1', INTRINSIC_LIST_TO_TUPLE, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        self.cfg_optimization_test(same, same, consts=[])
+
+        # nested folding: (1, 1+1, 3)
+        before = [
+            ('BUILD_LIST', 0, 0),
+            ('LOAD_SMALL_INT', 1, 0),
+            ('LIST_APPEND', 1, 0),
+            ('LOAD_SMALL_INT', 1, 0),
+            ('LOAD_SMALL_INT', 1, 0),
+            ('BINARY_OP', get_binop_argval('NB_ADD'), 0),
+            ('LIST_APPEND', 1, 0),
+            ('LOAD_SMALL_INT', 3, 0),
+            ('LIST_APPEND', 1, 0),
+            ('CALL_INTRINSIC_1', INTRINSIC_LIST_TO_TUPLE, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        after = [
+            ('LOAD_CONST', 0, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        self.cfg_optimization_test(before, after, consts=[], expected_consts=[(1, 2, 3)])
+
+        # NOP's in between: (1, 2, 3)
+        before = [
+            ('BUILD_LIST', 0, 0),
+            ('NOP', None, 0),
+            ('LOAD_SMALL_INT', 1, 0),
+            ('NOP', None, 0),
+            ('NOP', None, 0),
+            ('LIST_APPEND', 1, 0),
+            ('NOP', None, 0),
+            ('LOAD_SMALL_INT', 2, 0),
+            ('NOP', None, 0),
+            ('NOP', None, 0),
+            ('LIST_APPEND', 1, 0),
+            ('NOP', None, 0),
+            ('LOAD_SMALL_INT', 3, 0),
+            ('NOP', None, 0),
+            ('LIST_APPEND', 1, 0),
+            ('NOP', None, 0),
+            ('CALL_INTRINSIC_1', INTRINSIC_LIST_TO_TUPLE, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        after = [
+            ('LOAD_CONST', 0, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        self.cfg_optimization_test(before, after, consts=[], expected_consts=[(1, 2, 3)])
+
+        # no sequence start
+        same = [
+            ('LOAD_SMALL_INT', 1, 0),
+            ('LIST_APPEND', 1, 0),
+            ('LOAD_SMALL_INT', 2, 0),
+            ('LIST_APPEND', 1, 0),
+            ('LOAD_SMALL_INT', 3, 0),
+            ('LIST_APPEND', 1, 0),
+            ('CALL_INTRINSIC_1', INTRINSIC_LIST_TO_TUPLE, 0),
+            ('RETURN_VALUE', None, 0)
+        ]
+        self.cfg_optimization_test(same, same, consts=[])
+
     def test_optimize_if_const_list(self):
         before = [
             ('NOP', None, 0),
diff --git a/Programs/test_frozenmain.h b/Programs/test_frozenmain.h
index 1c7f74c..281cf1c 100644
--- a/Programs/test_frozenmain.h
+++ b/Programs/test_frozenmain.h
@@ -9,19 +9,19 @@ unsigned char M_test_frozenmain[] = {
     30,0,89,1,78,8,0,0,0,0,0,0,0,0,0,0,
     0,0,0,0,0,0,0,0,32,0,50,0,0,0,0,0,
     0,0,80,4,43,26,0,0,0,0,0,0,0,0,0,0,
-    112,5,80,5,15,0,68,24,0,0,112,6,89,2,32,0,
-    80,6,89,6,11,0,80,7,89,5,89,6,43,26,0,0,
+    112,5,80,7,15,0,68,24,0,0,112,6,89,2,32,0,
+    80,5,89,6,11,0,80,6,89,5,89,6,43,26,0,0,
     0,0,0,0,0,0,0,0,11,0,48,4,50,1,0,0,
     0,0,0,0,30,0,73,26,0,0,8,0,29,0,80,1,
     34,0,41,8,233,0,0,0,0,78,122,18,70,114,111,122,
     101,110,32,72,101,108,108,111,32,87,111,114,108,100,122,8,
     115,121,115,46,97,114,103,118,218,6,99,111,110,102,105,103,
-    41,5,218,12,112,114,111,103,114,97,109,95,110,97,109,101,
-    218,10,101,120,101,99,117,116,97,98,108,101,218,15,117,115,
-    101,95,101,110,118,105,114,111,110,109,101,110,116,218,17,99,
-    111,110,102,105,103,117,114,101,95,99,95,115,116,100,105,111,
-    218,14,98,117,102,102,101,114,101,100,95,115,116,100,105,111,
-    122,7,99,111,110,102,105,103,32,122,2,58,32,41,7,218,
+    122,7,99,111,110,102,105,103,32,122,2,58,32,41,5,218,
+    12,112,114,111,103,114,97,109,95,110,97,109,101,218,10,101,
+    120,101,99,117,116,97,98,108,101,218,15,117,115,101,95,101,
+    110,118,105,114,111,110,109,101,110,116,218,17,99,111,110,102,
+    105,103,117,114,101,95,99,95,115,116,100,105,111,218,14,98,
+    117,102,102,101,114,101,100,95,115,116,100,105,111,41,7,218,
     3,115,121,115,218,17,95,116,101,115,116,105,110,116,101,114,
     110,97,108,99,97,112,105,218,5,112,114,105,110,116,218,4,
     97,114,103,118,218,11,103,101,116,95,99,111,110,102,105,103,
diff --git a/Python/ast_opt.c b/Python/ast_opt.c
index 4a191e9..8ee322f 100644
--- a/Python/ast_opt.c
+++ b/Python/ast_opt.c
@@ -390,44 +390,6 @@ fold_binop(expr_ty node, PyArena *arena, _PyASTOptimizeState *state)
     return 1;
 }
 
-static PyObject*
-make_const_tuple(asdl_expr_seq *elts)
-{
-    for (Py_ssize_t i = 0; i < asdl_seq_LEN(elts); i++) {
-        expr_ty e = (expr_ty)asdl_seq_GET(elts, i);
-        if (e->kind != Constant_kind) {
-            return NULL;
-        }
-    }
-
-    PyObject *newval = PyTuple_New(asdl_seq_LEN(elts));
-    if (newval == NULL) {
-        return NULL;
-    }
-
-    for (Py_ssize_t i = 0; i < asdl_seq_LEN(elts); i++) {
-        expr_ty e = (expr_ty)asdl_seq_GET(elts, i);
-        PyObject *v = e->v.Constant.value;
-        PyTuple_SET_ITEM(newval, i, Py_NewRef(v));
-    }
-    return newval;
-}
-
-static int
-fold_tuple(expr_ty node, PyArena *arena, _PyASTOptimizeState *state)
-{
-    if (state->syntax_check_only) {
-        return 1;
-    }
-    PyObject *newval;
-
-    if (node->v.Tuple.ctx != Load)
-        return 1;
-
-    newval = make_const_tuple(node->v.Tuple.elts);
-    return make_const(node, newval, arena);
-}
-
 static int astfold_mod(mod_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
 static int astfold_stmt(stmt_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
 static int astfold_expr(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
@@ -620,7 +582,6 @@ astfold_expr(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
         break;
     case Tuple_kind:
         CALL_SEQ(astfold_expr, expr, node_->v.Tuple.elts);
-        CALL(fold_tuple, expr_ty, node_);
         break;
     case Name_kind:
         if (state->syntax_check_only) {
diff --git a/Python/codegen.c b/Python/codegen.c
index e1f6474..44d23ca 100644
--- a/Python/codegen.c
+++ b/Python/codegen.c
@@ -1688,11 +1688,26 @@ codegen_typealias(compiler *c, stmt_ty s)
     return SUCCESS;
 }
 
+static bool
+is_const_tuple(asdl_expr_seq *elts)
+{
+    for (Py_ssize_t i = 0; i < asdl_seq_LEN(elts); i++) {
+        expr_ty e = (expr_ty)asdl_seq_GET(elts, i);
+        if (e->kind != Constant_kind) {
+            return false;
+        }
+    }
+    return true;
+}
+
 /* Return false if the expression is a constant value except named singletons.
    Return true otherwise. */
 static bool
 check_is_arg(expr_ty e)
 {
+    if (e->kind == Tuple_kind) {
+        return !is_const_tuple(e->v.Tuple.elts);
+    }
     if (e->kind != Constant_kind) {
         return true;
     }
diff --git a/Python/flowgraph.c b/Python/flowgraph.c
index 8154129..cf3e740 100644
--- a/Python/flowgraph.c
+++ b/Python/flowgraph.c
@@ -1482,6 +1482,95 @@ fold_tuple_of_constants(basicblock *bb, int i, PyObject *consts, PyObject *const
     return instr_make_load_const(instr, const_tuple, consts, const_cache);
 }
 
+/* Replace:
+    BUILD_LIST 0
+    LOAD_CONST c1
+    LIST_APPEND 1
+    LOAD_CONST c2
+    LIST_APPEND 1
+    ...
+    LOAD_CONST cN
+    LIST_APPEND 1
+    CALL_INTRINSIC_1 INTRINSIC_LIST_TO_TUPLE
+   with:
+    LOAD_CONST (c1, c2, ... cN)
+*/
+static int
+fold_constant_intrinsic_list_to_tuple(basicblock *bb, int i,
+                                      PyObject *consts, PyObject *const_cache)
+{
+    assert(PyDict_CheckExact(const_cache));
+    assert(PyList_CheckExact(consts));
+    assert(i >= 0);
+    assert(i < bb->b_iused);
+
+    cfg_instr *intrinsic = &bb->b_instr[i];
+    assert(intrinsic->i_opcode == CALL_INTRINSIC_1);
+    assert(intrinsic->i_oparg == INTRINSIC_LIST_TO_TUPLE);
+
+    int consts_found = 0;
+    bool expect_append = true;
+
+    for (int pos = i - 1; pos >= 0; pos--) {
+        cfg_instr *instr = &bb->b_instr[pos];
+        int opcode = instr->i_opcode;
+        int oparg = instr->i_oparg;
+
+        if (opcode == NOP) {
+            continue;
+        }
+
+        if (opcode == BUILD_LIST && oparg == 0) {
+            if (!expect_append) {
+                /* Not a sequence start. */
+                return SUCCESS;
+            }
+
+            /* Sequence start, we are done. */
+            PyObject *newconst = PyTuple_New((Py_ssize_t)consts_found);
+            if (newconst == NULL) {
+                return ERROR;
+            }
+
+            for (int newpos = i - 1; newpos >= pos; newpos--) {
+                instr = &bb->b_instr[newpos];
+                if (instr->i_opcode == NOP) {
+                    continue;
+                }
+                if (loads_const(instr->i_opcode)) {
+                    PyObject *constant = get_const_value(instr->i_opcode, instr->i_oparg, consts);
+                    if (constant == NULL) {
+                        Py_DECREF(newconst);
+                        return ERROR;
+                    }
+                    assert(consts_found > 0);
+                    PyTuple_SET_ITEM(newconst, --consts_found, constant);
+                }
+                nop_out(&instr, 1);
+            }
+            assert(consts_found == 0);
+            return instr_make_load_const(intrinsic, newconst, consts, const_cache);
+        }
+
+        if (expect_append) {
+            if (opcode != LIST_APPEND || oparg != 1) {
+                return SUCCESS;
+            }
+        }
+        else {
+            if (!loads_const(opcode)) {
+                return SUCCESS;
+            }
+            consts_found++;
+        }
+
+        expect_append = !expect_append;
+    }
+
+    /* Did not find sequence start. */
+    return SUCCESS;
+}
+
 #define MIN_CONST_SEQUENCE_SIZE 3
 /*
 Optimize lists and sets for:
@@ -2378,9 +2467,13 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts)
                 RETURN_IF_ERROR(fold_const_unaryop(bb, i, consts, const_cache));
                 break;
             case CALL_INTRINSIC_1:
-                // for _ in (*foo, *bar) -> for _ in [*foo, *bar]
-                if (oparg == INTRINSIC_LIST_TO_TUPLE && nextop == GET_ITER) {
-                    INSTR_SET_OP0(inst, NOP);
+                if (oparg == INTRINSIC_LIST_TO_TUPLE) {
+                    if (nextop == GET_ITER) {
+                        INSTR_SET_OP0(inst, NOP);
+                    }
+                    else {
+                        RETURN_IF_ERROR(fold_constant_intrinsic_list_to_tuple(bb, i, consts, const_cache));
+                    }
                 }
                 else if (oparg == INTRINSIC_UNARY_POSITIVE) {
                     RETURN_IF_ERROR(fold_const_unaryop(bb, i, consts, const_cache));