https://github.com/python/cpython/commit/4c20f46fa011df57190cc19b21bafde1f65e73a7
commit: 4c20f46fa011df57190cc19b21bafde1f65e73a7
branch: main
author: Diego Russo <diego.ru...@arm.com>
committer: Fidget-Spinner <kenjin4...@gmail.com>
date: 2025-04-26T02:57:42+08:00
summary:
gh-131798: JIT: Narrow the return type of _CALL_LEN to int (#132940)
Reduce unnecessary guards whenever `len()` is called and used
after.
Co-authored-by: Max Bernstein <tekknol...@gmail.com>
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-04-25-14-56-45.gh-issue-131798.NpcKub.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 0fb2d78a87ecf1..0047306ae422db 100644
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -1911,6 +1911,18 @@ def testfunc(n):
self.assertNotIn("_COMPARE_OP_INT", uops)
self.assertNotIn("_GUARD_IS_TRUE_POP", uops)
+ def test_call_len(self):
+ def testfunc(n):
+ a = [1, 2, 3, 4]
+ for _ in range(n):
+ _ = len(a) - 1
+
+ _, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+ uops = get_opnames(ex)
+ self.assertNotIn("_GUARD_NOS_INT", uops)
+ self.assertNotIn("_GUARD_TOS_INT", uops)
+ self.assertIn("_CALL_LEN", uops)
+
def global_identity(x):
return x
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-04-25-14-56-45.gh-issue-131798.NpcKub.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-04-25-14-56-45.gh-issue-131798.NpcKub.rst
new file mode 100644
index 00000000000000..8214870284ed93
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-04-25-14-56-45.gh-issue-131798.NpcKub.rst
@@ -0,0 +1 @@
+Allow the JIT to remove int guards after ``_CALL_LEN`` by setting the return
type to int. Patch by Diego Russo
diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index ff2830d3003c61..040e54479b722a 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -1055,6 +1055,10 @@ dummy_func(void) {
sym_set_const(callable, (PyObject *)&PyUnicode_Type);
}
+ op(_CALL_LEN, (callable[1], self_or_null[1], args[oparg] -- res)) {
+ res = sym_new_type(ctx, &PyLong_Type);
+ }
+
// END BYTECODES //
}
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index 303e402b759530..9a5a362ec199a9 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -2014,7 +2014,7 @@
case _CALL_LEN: {
JitOptSymbol *res;
- res = sym_new_not_null(ctx);
+ res = sym_new_type(ctx, &PyLong_Type);
stack_pointer[-2 - oparg] = res;
stack_pointer += -1 - oparg;
assert(WITHIN_STACK_BOUNDS());
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