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gh-139393: fix _CALL_LEN JIT tests for tuples #139394

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Merged
merged 3 commits into from
Sep 28, 2025
Merged

gh-139393: fix _CALL_LEN JIT tests for tuples #139394

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3162b3e
fix `_CALL_LEN` JIT tests for tuples
picnixz Sep 28, 2025
ea1f0e9
remove unused export
picnixz Sep 28, 2025
be5e820
Update Lib/test/test_capi/test_opt.py
picnixz Sep 28, 2025
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14 changes: 11 additions & 3 deletions Lib/test/test_capi/test_opt.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@

_testinternalcapi = import_helper.import_module("_testinternalcapi")

from _testinternalcapi import TIER2_THRESHOLD
from _testinternalcapi import _PY_NSMALLPOSINTS, TIER2_THRESHOLD

#For test of issue 136154
GLOBAL_136154 = 42
Expand Down Expand Up @@ -2093,6 +2093,10 @@ def testfunc(n):
self.assertNotIn("_GUARD_TOS_INT", uops)

def test_call_len_known_length_small_int(self):
# Make sure that len(t) is optimized for a tuple of length 5.
# See https://github.com/python/cpython/issues/139393.
self.assertGreater(_PY_NSMALLPOSINTS, 5)

def testfunc(n):
x = 0
for _ in range(n):
Expand All @@ -2113,13 +2117,17 @@ def testfunc(n):
self.assertNotIn("_POP_TOP_LOAD_CONST_INLINE_BORROW", uops)

def test_call_len_known_length(self):
# Make sure that len(t) is optimized for a tuple of length 2048.
# See https://github.com/python/cpython/issues/139393.
self.assertLess(_PY_NSMALLPOSINTS, 2048)

def testfunc(n):
class C:
t = tuple(range(300))
t = tuple(range(2048))
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Instead of using a hardcoded magic number, it would be nice if we used _PY_NSMALLPOSINTS * 2 or something like that to make sure this test always works, even if we increase _PY_NSMALLPOSINTS in the future.

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@picnixz picnixz Sep 28, 2025 •
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I am actually unsure whether we need hardcoding here actually because of the JIT. I'll check if changing it to a compile-time known value is necessary or not.

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Yeah that's what I feared. While the test still passes, the uops will be different. I don't remember when we have some inlined computations x * y that are then transformed in a single LOAD_CONST.

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Also, I think we should make such change at other places as well. If you want to, let's open a separate issue.


x = 0
for _ in range(n):
if len(C.t) == 300: # comparison + guard removed
if len(C.t) == 2048: # comparison + guard removed
x += 1
return x

Expand Down
9 changes: 9 additions & 0 deletions Modules/_testinternalcapi.c
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Expand Up @@ -34,6 +34,7 @@
#include "pycore_pyerrors.h" // _PyErr_ChainExceptions1()
#include "pycore_pylifecycle.h" // _PyInterpreterConfig_InitFromDict()
#include "pycore_pystate.h" // _PyThreadState_GET()
#include "pycore_runtime_structs.h" // _PY_NSMALLPOSINTS, _PY_NSMALLNEGINTS
#include "pycore_unicodeobject.h" // _PyUnicode_TransformDecimalAndSpaceToASCII()

#include "clinic/_testinternalcapi.c.h"
Expand Down Expand Up @@ -2576,6 +2577,14 @@ module_exec(PyObject *module)
return 1;
}

if (PyModule_AddIntMacro(module, _PY_NSMALLPOSINTS) < 0) {
return 1;
}

if (PyModule_AddIntMacro(module, _PY_NSMALLNEGINTS) < 0) {
return 1;
}
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This isn't used anywhere, is it?

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Mmh, yes, this one isn't used anymore. I wondered whether I needed one but I don't need to. I'll amend this one.

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Side comment: this function should return -1 instead of 1 as it's the case for other Py_mod_exec functions (I got surprised by the "return 1"). It doesn't really matter per se, but I think we should generally document what kind of values we expect for Py_mod_* handlers and tp_* ones (it's not clear what tp_clear should return and when).

Currently, errors in Py_mod_exec functions are indicated by a non-zero return value, but it's not documented. I would advise that we document this.


return 0;
}

Expand Down
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