gh-117578: Fix inlining regression in PyType_GetModuleByDef()

[neonene]

On main and 3.13, there are cases where the get_module_by_def function in typeobject.c is not inlined in its wrapper functions:

Wrappers	Windows	callee: get_module_by_def()
PyType_GetModuleByDef()	Release	/Ob2:called /Ob3:inlined
	PGO	inlined
_PyType_GetModuleByDef2()	Release	/Ob2:called /Ob3:inlined
	PGO	called

Non-builtin modules can have extra function-call overheads, where the wrappers cannot be inlined.

This PR specifies Py_ALWAYS_INLINE to the callee.

cc @encukou

• Issue: PyType_GetModuleByDef family for binary functions performance #117578

[encukou]

Hm, it doesn't sound right to override profile-guided optimization, especially since test_decimal (the only current caller of _PyType_GetModuleByDef2) is in the PGO test set.
Does this PR have a significant performance impact?

[neonene]

It is mentioned on the faster-cpython repo that the telco test has slowed down a lot.

According to MSVC, the module state access counts were:

Function / breakdown entry-cnt alternative access ----------------------- --------- --------------------------- PyType_GetModuleByDef() 6852643 convert_op 2971848 via context object PyDecType_New 1651188 via context object (partial) dec_addstatus 1651188 via context object (partial) current_context 1486221 via context object (partial) dec_mpd_qquantize 247731 METH_METHOD ctx_mpd_qquantize 165000 METH_METHOD ... _PyType_GetModuleByDef2() 1073193 nm_mpd_qadd 660462 nm_mpd_qmul 412731 

Tested with the /Ob3 option, switching the inlining specifier: f740a5d. My Release/PGO builds on Windows get slower using TLS version of PyThreadState_Get(), which is also observed at #103324 (comment). If *nix OSes are in good health with TLS, I guess I also need to run the telco with a good condition (without TLS):

	sub
GetModuleByDef	call	inline	inline
GetModuleByDef2	call	call	inline
normal 3.14	perf			(the higher, the faster)
	1.00x	(base)	1.01x
	1.03x	1.05x	1.08x	respect alternative
less TLS overhead	perf			(experiment)
	1.05x	1.05x	1.06x
	1.08x	1.08x	1.08x	respect alternative

module state access	normal	TLS-less
current	(base)	1.05x
This PR	1.01x	1.06x
PyThreadState_Get()	1.05x	1.04x	example patches
PR with alternatives	1.08x	1.08x
global state	1.08x	1.11x
static type (GC unused)	1.14x	1.14x	taken from 3.12

This patch would need to be applied if we wanted as much speed as the global state access on Windows, which has little effect alone (1%) for some reason.

[neonene]

Windows PGO:
- telco: 9.21 ms +- 0.12 ms -> 9.02 ms +- 0.09 ms: 1.02x faster

[neonene]

Is it acceptable that test_decimal.py has a test case like below, instead of touching the C code?

@requires_cdecimalclassCArithmeticOperatorsTest(ArithmeticOperatorsTest, unittest.TestCase): ... @unittest.skipIf(nottest.support.PGO, 'PGO training only')deftest_excecise_binop(self): Decimal=self.decimal.Decimald=Decimal('11.1') foriinrange(500000): 1+d# at least 300000 times

[neonene]

I'll try PyType_GetBaseByToken() version.

[neonene]

Closing in favor of proposing the PyType_GetBaseByToken() version, which can supersede _PyType_GetModuleByDef2() on PGO and Relase(/Ob3) builds.