https://github.com/python/cpython/commit/e1c0c451a2ff815fc817e71ec15c37bff9cb84d0
commit: e1c0c451a2ff815fc817e71ec15c37bff9cb84d0
branch: main
author: Nadeshiko Manju <[email protected]>
committer: brandtbucher <[email protected]>
date: 2025-05-20T18:02:50-04:00
summary:
GH-131798: Narrow the return type of _GET_LEN to int (GH-133345)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-05-03-22-31-53.gh-issue-131798.fQ0ato.rst
M Lib/test/test_capi/test_opt.py
M Python/optimizer_bytecodes.c
M Python/optimizer_cases.c.h
diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
index f7a4200e1eec0e..50c4f19a1ab55f 100644
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -1925,6 +1925,50 @@ def testfunc(n):
self.assertNotIn("_GUARD_NOS_INT", uops)
self.assertNotIn("_GUARD_TOS_INT", uops)
+ def test_get_len_with_const_tuple(self):
+ def testfunc(n):
+ x = 0.0
+ for _ in range(n):
+ match (1, 2, 3, 4):
+ case [_, _, _, _]:
+ x += 1.0
+ return x
+ res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+ self.assertEqual(int(res), TIER2_THRESHOLD)
+ uops = get_opnames(ex)
+ self.assertNotIn("_GUARD_NOS_INT", uops)
+ self.assertNotIn("_GET_LEN", uops)
+ self.assertIn("_LOAD_CONST_INLINE_BORROW", uops)
+
+ def test_get_len_with_non_const_tuple(self):
+ def testfunc(n):
+ x = 0.0
+ for _ in range(n):
+ match object(), object():
+ case [_, _]:
+ x += 1.0
+ return x
+ res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+ self.assertEqual(int(res), TIER2_THRESHOLD)
+ uops = get_opnames(ex)
+ self.assertNotIn("_GUARD_NOS_INT", uops)
+ self.assertNotIn("_GET_LEN", uops)
+ self.assertIn("_LOAD_CONST_INLINE_BORROW", uops)
+
+ def test_get_len_with_non_tuple(self):
+ def testfunc(n):
+ x = 0.0
+ for _ in range(n):
+ match [1, 2, 3, 4]:
+ case [_, _, _, _]:
+ x += 1.0
+ return x
+ res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+ self.assertEqual(int(res), TIER2_THRESHOLD)
+ uops = get_opnames(ex)
+ self.assertNotIn("_GUARD_NOS_INT", uops)
+ self.assertIn("_GET_LEN", uops)
+
def test_binary_op_subscr_tuple_int(self):
def testfunc(n):
x = 0
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-05-03-22-31-53.gh-issue-131798.fQ0ato.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-05-03-22-31-53.gh-issue-131798.fQ0ato.rst
new file mode 100644
index 00000000000000..f322d43b30a9f3
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-05-03-22-31-53.gh-issue-131798.fQ0ato.rst
@@ -0,0 +1,2 @@
+Allow the JIT to remove int guards after ``_GET_LEN`` by setting the return
+type to int.
diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index 3799f25880d34b..639b4b7af1632c 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -1116,6 +1116,25 @@ dummy_func(void) {
res = sym_new_type(ctx, &PyLong_Type);
}
+ op(_GET_LEN, (obj -- obj, len)) {
+ int tuple_length = sym_tuple_length(obj);
+ if (tuple_length == -1) {
+ len = sym_new_type(ctx, &PyLong_Type);
+ }
+ else {
+ assert(tuple_length >= 0);
+ PyObject *temp = PyLong_FromLong(tuple_length);
+ if (temp == NULL) {
+ goto error;
+ }
+ if (_Py_IsImmortal(temp)) {
+ REPLACE_OP(this_instr, _LOAD_CONST_INLINE_BORROW, 0,
(uintptr_t)temp);
+ }
+ len = sym_new_const(ctx, temp);
+ Py_DECREF(temp);
+ }
+ }
+
op(_GUARD_CALLABLE_LEN, (callable, unused, unused -- callable, unused,
unused)) {
PyObject *len = _PyInterpreterState_GET()->callable_cache.len;
if (sym_get_const(ctx, callable) == len) {
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index a2c68457d8ef4e..0a539b2829e3ba 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -1463,8 +1463,29 @@
}
case _GET_LEN: {
+ JitOptSymbol *obj;
JitOptSymbol *len;
- len = sym_new_not_null(ctx);
+ obj = stack_pointer[-1];
+ int tuple_length = sym_tuple_length(obj);
+ if (tuple_length == -1) {
+ len = sym_new_type(ctx, &PyLong_Type);
+ }
+ else {
+ assert(tuple_length >= 0);
+ PyObject *temp = PyLong_FromLong(tuple_length);
+ if (temp == NULL) {
+ goto error;
+ }
+ if (_Py_IsImmortal(temp)) {
+ REPLACE_OP(this_instr, _LOAD_CONST_INLINE_BORROW, 0,
(uintptr_t)temp);
+ }
+ len = sym_new_const(ctx, temp);
+ stack_pointer[0] = len;
+ stack_pointer += 1;
+ assert(WITHIN_STACK_BOUNDS());
+ Py_DECREF(temp);
+ stack_pointer += -1;
+ }
stack_pointer[0] = len;
stack_pointer += 1;
assert(WITHIN_STACK_BOUNDS());
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