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gh-139109: Replace _CHECK_STACK_SPACE with _CHECK_STACK_SPACE_OPERAND in JIT optiimizer #144394

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Merged
markshannon merged 3 commits into from
Feb 2, 2026
Merged

gh-139109: Replace _CHECK_STACK_SPACE with _CHECK_STACK_SPACE_OPERAND in JIT optiimizer #144394

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f05c6af
Replace _CHECK_STACK_SPACE with _CHECK_STACK_SPACE_OPERAND in JIT opt…
cocolato Feb 2, 2026
c33f2ab
refact _CHECK_STACK_SPACE && fix tests
cocolato Feb 2, 2026
3ed9164
fix tests
cocolato Feb 2, 2026
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102 changes: 38 additions & 64 deletions Lib/test/test_capi/test_opt.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1022,7 +1022,6 @@ def return_hello():
# Constant narrowing allows constant folding for second comparison
self.assertLessEqual(count_ops(ex, "_COMPARE_OP_STR"), 1)

@unittest.skip("gh-139109 WIP")
def test_combine_stack_space_checks_sequential(self):
def dummy12(x):
return x - 1
Expand All @@ -1046,12 +1045,14 @@ def testfunc(n):
self.assertEqual(uop_names.count("_PUSH_FRAME"), 2)
self.assertEqual(uop_names.count("_RETURN_VALUE"), 2)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE"), 0)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 1)
# sequential calls: max(12, 13) == 13
largest_stack = _testinternalcapi.get_co_framesize(dummy13.__code__)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND", largest_stack), uops_and_operands)
# Each call gets its own _CHECK_STACK_SPACE_OPERAND
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 2)
# Each _CHECK_STACK_SPACE_OPERAND has the framesize of its function
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy12.__code__)), uops_and_operands)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy13.__code__)), uops_and_operands)

@unittest.skip("gh-139109 WIP")
def test_combine_stack_space_checks_nested(self):
def dummy12(x):
return x + 3
Expand All @@ -1074,15 +1075,12 @@ def testfunc(n):
self.assertEqual(uop_names.count("_PUSH_FRAME"), 2)
self.assertEqual(uop_names.count("_RETURN_VALUE"), 2)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE"), 0)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 1)
# nested calls: 15 + 12 == 27
largest_stack = (
_testinternalcapi.get_co_framesize(dummy15.__code__) +
_testinternalcapi.get_co_framesize(dummy12.__code__)
)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND", largest_stack), uops_and_operands)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 2)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy15.__code__)), uops_and_operands)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy12.__code__)), uops_and_operands)

@unittest.skip("gh-139109 WIP")
def test_combine_stack_space_checks_several_calls(self):
def dummy12(x):
return x + 3
Expand Down Expand Up @@ -1110,15 +1108,14 @@ def testfunc(n):
self.assertEqual(uop_names.count("_PUSH_FRAME"), 4)
self.assertEqual(uop_names.count("_RETURN_VALUE"), 4)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE"), 0)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 1)
# max(12, 18 + max(12, 13)) == 31
largest_stack = (
_testinternalcapi.get_co_framesize(dummy18.__code__) +
_testinternalcapi.get_co_framesize(dummy13.__code__)
)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND", largest_stack), uops_and_operands)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 4)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy12.__code__)), uops_and_operands)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy13.__code__)), uops_and_operands)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy18.__code__)), uops_and_operands)

@unittest.skip("gh-139109 WIP")
def test_combine_stack_space_checks_several_calls_different_order(self):
# same as `several_calls` but with top-level calls reversed
def dummy12(x):
Expand Down Expand Up @@ -1147,15 +1144,14 @@ def testfunc(n):
self.assertEqual(uop_names.count("_PUSH_FRAME"), 4)
self.assertEqual(uop_names.count("_RETURN_VALUE"), 4)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE"), 0)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 1)
# max(18 + max(12, 13), 12) == 31
largest_stack = (
_testinternalcapi.get_co_framesize(dummy18.__code__) +
_testinternalcapi.get_co_framesize(dummy13.__code__)
)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND", largest_stack), uops_and_operands)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 4)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy12.__code__)), uops_and_operands)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy13.__code__)), uops_and_operands)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy18.__code__)), uops_and_operands)

@unittest.skip("gh-139109 WIP")
def test_combine_stack_space_complex(self):
def dummy0(x):
return x
Expand Down Expand Up @@ -1193,19 +1189,8 @@ def testfunc(n):
self.assertEqual(uop_names.count("_RETURN_VALUE"), 15)

self.assertEqual(uop_names.count("_CHECK_STACK_SPACE"), 0)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 1)
largest_stack = (
_testinternalcapi.get_co_framesize(dummy6.__code__) +
_testinternalcapi.get_co_framesize(dummy5.__code__) +
_testinternalcapi.get_co_framesize(dummy2.__code__) +
_testinternalcapi.get_co_framesize(dummy1.__code__) +
_testinternalcapi.get_co_framesize(dummy0.__code__)
)
self.assertIn(
("_CHECK_STACK_SPACE_OPERAND", largest_stack), uops_and_operands
)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 15)

@unittest.skip("gh-139109 WIP")
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def test_combine_stack_space_checks_large_framesize(self):
# Create a function with a large framesize. This ensures _CHECK_STACK_SPACE is
# actually doing its job. Note that the resulting trace hits
Expand Down Expand Up @@ -1250,24 +1235,13 @@ def testfunc(n):

uops_and_operands = [(opcode, operand) for opcode, _, _, operand in ex]
uop_names = [uop[0] for uop in uops_and_operands]
self.assertEqual(uop_names.count("_PUSH_FRAME"), 2)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 1)

# this hits a different case during trace projection in refcount test runs only,
# so we need to account for both possibilities
self.assertIn(uop_names.count("_CHECK_STACK_SPACE"), [0, 1])
if uop_names.count("_CHECK_STACK_SPACE") == 0:
largest_stack = (
_testinternalcapi.get_co_framesize(dummy15.__code__) +
_testinternalcapi.get_co_framesize(dummy_large.__code__)
)
else:
largest_stack = _testinternalcapi.get_co_framesize(dummy15.__code__)
self.assertIn(
("_CHECK_STACK_SPACE_OPERAND", largest_stack), uops_and_operands
)
self.assertGreaterEqual(uop_names.count("_PUSH_FRAME"), 1)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE"), 0)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"),
uop_names.count("_PUSH_FRAME"))
self.assertIn(("_CHECK_STACK_SPACE_OPERAND",
_testinternalcapi.get_co_framesize(dummy15.__code__)), uops_and_operands)

@unittest.skip("gh-139109 WIP")
def test_combine_stack_space_checks_recursion(self):
def dummy15(x):
while x > 0:
Expand All @@ -1290,12 +1264,12 @@ def testfunc(n):

uops_and_operands = [(opcode, operand) for opcode, _, _, operand in ex]
uop_names = [uop[0] for uop in uops_and_operands]
self.assertEqual(uop_names.count("_PUSH_FRAME"), 2)
self.assertEqual(uop_names.count("_PUSH_FRAME"), 12)
self.assertEqual(uop_names.count("_RETURN_VALUE"), 0)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE"), 1)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 1)
largest_stack = _testinternalcapi.get_co_framesize(dummy15.__code__)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND", largest_stack), uops_and_operands)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE"), 0)
self.assertEqual(uop_names.count("_CHECK_STACK_SPACE_OPERAND"), 12)
framesize = _testinternalcapi.get_co_framesize(dummy15.__code__)
self.assertIn(("_CHECK_STACK_SPACE_OPERAND", framesize), uops_and_operands)

def test_many_nested(self):
# overflow the trace_stack
Expand Down
12 changes: 9 additions & 3 deletions Python/optimizer_bytecodes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1088,13 +1088,19 @@ dummy_func(void) {
}

op(_CHECK_STACK_SPACE, (unused, unused, unused[oparg] -- unused, unused, unused[oparg])) {
assert((this_instr + 1)->opcode == _CHECK_RECURSION_REMAINING);
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assert((this_instr + 4)->opcode == _PUSH_FRAME);
PyCodeObject *co = get_code_with_logging((this_instr + 4));
if (co == NULL) {
ctx->done = true;
break;
}
ADD_OP(_CHECK_STACK_SPACE_OPERAND, 0, co->co_framesize);
REPLACE_OP((this_instr + 1), _NOP, 0, 0);
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}

op (_CHECK_STACK_SPACE_OPERAND, (framesize/2 -- )) {
(void)framesize;
/* We should never see _CHECK_STACK_SPACE_OPERANDs.
* They are only created at the end of this pass. */
Py_UNREACHABLE();
}

op(_PUSH_FRAME, (new_frame -- )) {
Expand Down
10 changes: 9 additions & 1 deletion Python/optimizer_cases.c.h
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