https://github.com/python/cpython/commit/1efd9939c8742a251f232f09ccd0c1def7fda66e
commit: 1efd9939c8742a251f232f09ccd0c1def7fda66e
branch: main
author: Sacul <[email protected]>
committer: Fidget-Spinner <[email protected]>
date: 2026-03-17T22:07:17+08:00
summary:
gh-131798: Optimize `_ITER_CHECK_RANGE` and `_ITER_CHECK_LIST` in the JIT
(GH-144583)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-02-08-01-19-50.gh-issue-131798.PaWDNH.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 1385a7f840d7be..2a126a7b29cc73 100644
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -3981,6 +3981,22 @@ def testfunc(n):
self.assertIn("_POP_TOP_NOP", uops)
self.assertLessEqual(count_ops(ex, "_POP_TOP"), 2)
+ def test_iter_check_list(self):
+ def testfunc(n):
+ x = 0
+ for _ in range(n):
+ l = [1]
+ for num in l: # unguarded
+ x += num
+ return x
+
+ res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+ self.assertEqual(res, TIER2_THRESHOLD)
+ uops = get_opnames(ex)
+
+ self.assertIn("_BUILD_LIST", uops)
+ self.assertNotIn("_ITER_CHECK_LIST", uops)
+
def test_match_class(self):
def testfunc(n):
class A:
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-02-08-01-19-50.gh-issue-131798.PaWDNH.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-02-08-01-19-50.gh-issue-131798.PaWDNH.rst
new file mode 100644
index 00000000000000..fe80c2d911b6ee
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-02-08-01-19-50.gh-issue-131798.PaWDNH.rst
@@ -0,0 +1 @@
+Optimize ``_ITER_CHECK_RANGE`` and ``_ITER_CHECK_LIST`` in the JIT
diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index f3a391b2e37ef9..9b77fd0c32d9d9 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -1091,6 +1091,24 @@ dummy_func(void) {
sym_set_type(iter, &PyTuple_Type);
}
+ op(_ITER_CHECK_LIST, (iter, null_or_index -- iter, null_or_index)) {
+ if (sym_matches_type(iter, &PyList_Type)) {
+ ADD_OP(_NOP, 0, 0);
+ }
+ else {
+ sym_set_type(iter, &PyList_Type);
+ }
+ }
+
+ op(_ITER_CHECK_RANGE, (iter, null_or_index -- iter, null_or_index)) {
+ if (sym_matches_type(iter, &PyRange_Type)) {
+ ADD_OP(_NOP, 0, 0);
+ }
+ else {
+ sym_set_type(iter, &PyRange_Type);
+ }
+ }
+
op(_ITER_NEXT_RANGE, (iter, null_or_index -- iter, null_or_index, next)) {
next = sym_new_type(ctx, &PyLong_Type);
}
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index 52a0c08ac677b7..eef07cedaf38e2 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -2752,6 +2752,14 @@
/* _INSTRUMENTED_FOR_ITER is not a viable micro-op for tier 2 */
case _ITER_CHECK_LIST: {
+ JitOptRef iter;
+ iter = stack_pointer[-2];
+ if (sym_matches_type(iter, &PyList_Type)) {
+ ADD_OP(_NOP, 0, 0);
+ }
+ else {
+ sym_set_type(iter, &PyList_Type);
+ }
break;
}
@@ -2800,6 +2808,14 @@
}
case _ITER_CHECK_RANGE: {
+ JitOptRef iter;
+ iter = stack_pointer[-2];
+ if (sym_matches_type(iter, &PyRange_Type)) {
+ ADD_OP(_NOP, 0, 0);
+ }
+ else {
+ sym_set_type(iter, &PyRange_Type);
+ }
break;
}
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