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GeezerVison is showing github.com — gh-131798: JIT: Narrow the return type of `_GET_LEN` to int by Zheaoli · Pull Request #133345 · python/cpython

gh-131798: JIT: Narrow the return type of `_GET_LEN` to int #133345

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Merged

brandtbucher merged 23 commits into python:main from Zheaoli:manjusaka/get-len

May 20, 2025

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gh-131798: JIT: Narrow the return type of `_GET_LEN` to int #133345

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gh-131798: JIT: Narrow the return type of _GET_LEN to int

Merge branch 'main' into manjusaka/get-len

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44 changes: 44 additions & 0 deletions 44 Lib/test/test_capi/test_opt.py

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -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)
Comment thread Zheaoli marked this conversation as resolved. Resolved Uh oh! There was an error while loading. Please reload this page.
		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
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2 changes: 2 additions & 0 deletions 2 Misc/NEWS.d/next/Core_and_Builtins/2025-05-03-22-31-53.gh-issue-131798.fQ0ato.rst

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Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Allow the JIT to remove int guards after ``_GET_LEN`` by setting the return
		type to int.

19 changes: 19 additions & 0 deletions 19 Python/optimizer_bytecodes.c

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -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);
Comment thread Zheaoli marked this conversation as resolved. Resolved Uh oh! There was an error while loading. Please reload this page.
		}
		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);
Comment thread Zheaoli marked this conversation as resolved. Resolved Uh oh! There was an error while loading. Please reload this page.
		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) {
Expand Down

23 changes: 22 additions & 1 deletion 23 Python/optimizer_cases.c.h

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gh-131798: JIT: Narrow the return type of _GET_LEN to int #133345

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gh-131798: JIT: Narrow the return type of `_GET_LEN` to int #133345

gh-131798: JIT: Narrow the return type of `_GET_LEN` to int #133345