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Date: Mon, 3 Aug 2020 19:44:46 +0200
Message-ID: <CAEPJdumwKEZymxXGmv-_-NadixnbzyHPVn87NjXzeoGHACtpwQ@mail.gmail.com>
To: PHP Internals <internals@lists.php.net>, Dmitry Stogov <dmitry@zend.com>, 
	Nikita Popov <nikita.ppv@gmail.com>
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Subject: @@Jit Attribute Considerations
From: kontakt@beberlei.de (Benjamin Eberlei)

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Hi,

I am going to pick up a discussion from
https://github.com/php/php-src/pull/5915 about the @@Jit attribute.

Nikita mentioned he is still not 100% clear what the usecase is for @@Jit
attribute and asked to discuss here.

The reason is that the default tracing JIT is clever to decide itself when
to JIT or not, better not interfere with that. In case you run the tracing
JIT, only @@Jit("off") has an effect the others @@Jit("tracing") and
@@Jit("function") get ignored.

Only the trigger mode 4 (attributes) is actually using @@Jit("tracing") and
"function". This trigger mode feels like micro-management for developers
and since it has virtually no spotlight in discussions and blog posts about
the JIT at the moment, we don't know if it brings benefits.

Maybe for now it would be better to remove docblock / attribute support for
the JIT, and take a new attempt at it in 8.1? That prevents us from rolling
something we regret having to maintain later.

greetings
Benjamin

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