GH-131296: fix clang-cl warning on Windows in sre.c

[chris-eibl]

I think this is a skip news?

• Issue: clang-cl issues many warnings when building on Windows #131296

[chris-eibl]

Fix warning : unexpected argument 'agtw' to '#pragma optimize'; expected "" [-Wignored-pragmas]

[chris-eibl]

agtw has been used in PY_LOCAL_AGGRESSIVE until #87332. Quote from @gvanrossum#87332 (comment)

A coworker happened to look at our use of #pragma optimize() for Windows (VS 2017) and noticed:

unless there’s something I’m missing, the ‘a’ and ‘w’ portions of the string being passed to the optimize pragma are not doing anything; I’m pretty sure they’ve been useless for 10+ years. The ‘g’ means turn on global optimizations and the ‘t’ means optimize for “time” (i.e. speed). See the documentation at https://docs.microsoft.com/en-us/cpp/preprocessor/optimize?view=msvc-160

It was then changed to gt (https://github.com/python/cpython/pull/24485/files) and entirely removed in https://github.com/python/cpython/pull/32023/files.

[chris-eibl]

@zooba Again a very Windows (MSVC) specific one. Back then, you've changed PY_LOCAL_AGGRESSIVE from agtw to gt - agtw is really dusty.

OTOH, even though the comment says /* doesn't seem to make much difference... */ - I think it does, because this is also done for debug builds. But since /Ob1 is now used for debug builds (AFAIR by Victor), maybe this is not needed anymore at all?

[zooba]

I expect @mdboom will have looked more closely at this one.

Chances are we just want a !__clang__ condition and to do nothing at all in ClangCL.

[chris-eibl]

Sure, that's the easiest thing to do in case we do not want to care about

unless there’s something I’m missing, the ‘a’ and ‘w’ portions of the string being passed to the optimize pragma are not doing anything; I’m pretty sure they’ve been useless for 10+ years.

[mdboom]

I expect @mdboom will have looked more closely at this one.

Chances are we just want a !__clang__ condition and to do nothing at all in ClangCL.

Yeah, I agree.

[chris-eibl]

Ups - I wanted to update the PR, but the PR is closed - do you want me to create a new PR instead of addressing the suggested fix:
#if defined(_MSC_VER) && !defined(__clang__)

[mdboom]

Ups - I wanted to update the PR, but the PR is closed - do you want me to create a new PR instead of addressing the suggested fix: #if defined(_MSC_VER) && !defined(__clang__)

No, sorry. Just human error (I pressed the wrong button).

[chris-eibl]

Much simpler - just ignore __clang__ and keep agtw for MSVC.