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Date: Tue, 5 Apr 2016 14:44:32 +0300
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Subject: Re: [PHP-DEV] RETURN micro optimization
From: dmitry@zend.com (Dmitry Stogov)

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But somehow it broke one phpdbg test, so it's better to check.

Thanks. Dmitry.

On 04/05/2016 12:15 PM, Joe Watkins wrote:
> Morning Derick,
>
>     I don't think it does make anything impossible, it's just a more 
> efficient copying method in the EXPECTED branch is all.
>
> Cheers
> Joe
>
> On Tue, Apr 5, 2016 at 10:04 AM, Derick Rethans <derick@php.net 
> <mailto:derick@php.net>> wrote:
>
>     On Tue, 5 Apr 2016, Dmitry Stogov wrote:
>
>     > I propose a micro optimization for RETURN statement.
>     >
>     > Currently "return $x" increments reference counter of $x, then in
>     > zend_leave_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
>     > Wordpress).
>     >
>     > 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.
>
>     I'd like to know why this breaks before saying something. It'd be
>     a PITA
>     if this micro optimisation wouldn't actually do a lot performance
>     wise,
>     but makes some debugging not possible.
>
>     cheers,
>     Derick
>
>     --
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>


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