re-enable JIT for ZTS builds on Apple Silicon

[realFlowControl]

Fixes#13400

For __APPLE__ && __aarch64__ && ZTS, this PR moves the JIT buffer out of the OPcache shared memory and creates a dedicated mapping.

Background

OPcache JIT is currently disabled for ZTS builds on Apple Silicon. The JIT buffer normally lives at the end of OPcache's MAP_SHARED | MAP_ANON allocation. In ZTS, one thread may generate code while another executes existing code, so the buffer must remain executable while it is writable.

Apple Silicon rejects RWX anonymous mappings with EPERM. Apple's supported solution is MAP_JIT with pthread_jit_write_protect_np(), which provides per-thread write protection, but macOS rejects MAP_JIT | MAP_SHARED with EINVAL. The existing combined OPcache/JIT mapping won't work on Apple Silicon.

[henderkes]

I don't know if this was in response to my mail, but thank you 😄

[realFlowControl]

I don't know if this was in response to my mail, but thank you 😄

Actually yes, haha. I knew that this should work, I just was not working on it and then reading your mail reminded me of it 👍

[arnaud-lb]

Looks good to me otherwise!

[arnaud-lb]

Thank you @realFlowControl!

[iluuu1994]

This change is problematic for CI. I.e. it makes all the tests with an explicit opcache.jit= directive fail. See https://github.com/php/php-src/actions/runs/29793770728/job/88520997977. I'd like to avoid manually implementing SKIPIF for all of these, do you have another idea?

Normally opcache would just log something with ACCEL_LOG_WARNING and ignore the directive, instead of a fatal error. Is that an option?

[realFlowControl]

This change is problematic for CI. I.e. it makes all the tests with an explicit opcache.jit= directive fail. See https://github.com/php/php-src/actions/runs/29793770728/job/88520997977. I'd like to avoid manually implementing SKIPIF for all of these, do you have another idea?

Normally opcache would just log something with ACCEL_LOG_WARNING and ignore the directive, instead of a fatal error. Is that an option?

Ah I see. Yeah I think that should work, I have a look and keep you posted.