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Thread-Topic: RETURN micro optimization
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Date: Tue, 5 Apr 2016 07:59:06 +0000
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Subject: RETURN micro optimization
From: dmitry@zend.com (Dmitry Stogov)

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Hi,


I propose a micro optimization for RETURN statement.

Currently "return $x" increments reference counter of $x, then in zend_leav=
e_helper() we perform zval_ptr_dtor() on the same $x.

The patch sets the original value of $x to null in first place, so zval_ptr=
_dtor() is not going to be called.


https://gist.github.com/dstogov/36f68b206242a39691ac539c2fc85d40


the performance impact is invisible (0.1% less instruction retired on Wordp=
ress).


It breaks sapi/phpdbg/tests/breakpoints_005.phpt, but this is probably not =
a big deal.

BTW: this change may affect debuggers in some other way.


Let me know, if you see any problems (I'll delay commit for 2-3 days).


Thanks. Dmitry.

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