Re: [PHP-DEV] RETURN micro optimization

2016-04-05 Thread Joe Watkins 
Dmitry,

No worries ... I had just found out it wasn't particular to phpdbg ...



Cheers
Joe

On Tue, Apr 5, 2016 at 1:14 PM, Dmitry Stogov  wrote:

>
>
> On 04/05/2016 12:04 PM, Derick Rethans 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.
>>
> Actually, the patch has a bug.
> It doesn't take into account that "return $x;" might be used in global
> scope.
> Setting $x to NULL in this case isn't right, of course.
>
> Introducing another check would probably negate the effect of
> micro-optimization.
>
> So, ignore this for now, and sorry for noise.
>
> Thanks. Dmitry.
>
>
>
>
>> cheers,
>> Derick
>>
>
>
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>
>

Re: [PHP-DEV] RETURN micro optimization

2016-04-05 Thread Dmitry Stogov 



On 04/05/2016 12:04 PM, Derick Rethans 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.

Actually, the patch has a bug.
It doesn't take into account that "return $x;" might be used in global 
scope.

Setting $x to NULL in this case isn't right, of course.

Introducing another check would probably negate the effect of 
micro-optimization.


So, ignore this for now, and sorry for noise.

Thanks. Dmitry.




cheers,
Derick



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Re: [PHP-DEV] RETURN micro optimization

2016-04-05 Thread Dmitry Stogov 

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 > 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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Re: [PHP-DEV] RETURN micro optimization

2016-04-05 Thread Joe Watkins 
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  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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> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>

Re: [PHP-DEV] RETURN micro optimization

2016-04-05 Thread Derick Rethans 
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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Re: [PHP-DEV] RETURN micro optimization

2016-04-05 Thread Pierre Joye 
On Tue, Apr 5, 2016 at 2:59 PM, Dmitry Stogov  wrote:
> Hi,
>
>
> 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 suppose it is for 7.1 anyway, right? so debugger will have to be
ported but it would be nice to know exactly how this change will
affect them to make sure that users can migrate to 7.1 smoothly and
still use their tools.

Cheers,
-- 
Pierre

@pierrejoye | http://www.libgd.org

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[PHP-DEV] RETURN micro optimization

2016-04-05 Thread Dmitry Stogov 
Hi,


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.


Let me know, if you see any problems (I'll delay commit for 2-3 days).


Thanks. Dmitry.