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Date: Fri, 26 Sep 2014 01:45:52 +0400
Message-ID: <CA+9eiLs-WLzJE61uH0UD8v2ed-jt4RApPZyrJQfTu+ebK6_RAA@mail.gmail.com>
To: Nikita Popov <nikita.ppv@gmail.com>
Cc: Leigh <leight@gmail.com>, PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11c2bb1e7f29270503eab966
Subject: Re: [PHP-DEV] [VOTE] Fix list() behavior inconsistency
From: dmitry@zend.com (Dmitry Stogov)

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FETCH_DIM_TMP_VAR is used especiualy for list().
It expects array, don't check for objects and strings.
It doesn't remove the operand and allow it's reuse in next opcode.

FETCH_DIM_R is used for list() only in some cases (when operand IS_VAR).
To work in list() context it has to keep operand not destroyed, and to do
it FETCH_DIM_R has to check for (opline->extended_value &
ZEND_FETCH_ADD_LOCK).
Note that this check has to be executed for each array access operation
unrelated to list() handling.

Thanks. Dmitry.

On Fri, Sep 26, 2014 at 12:32 AM, Nikita Popov <nikita.ppv@gmail.com> wrote:

> On Thu, Sep 25, 2014 at 1:15 PM, Dmitry Stogov <dmitry@zend.com> wrote:
>
>> disabling string handling would allow make operation simpler and would
>> improve regular access to array elements.
>> We won't need to check for (opline->extended_value & ZEND_FETCH_ADD_LOCK)
>> in FETCH_DIM_R handler.
>> However, it's going to be very small improvement, and I don't care a lot.
>> :)
>>
>> enabling string handling would require complication of
>> ZEND_FETCH_DIM_TMP_VAR handler (for strings support).
>> It's going to make list() handling a bit slower, but not significantly.
>>
>> my choice +1 for disabling.
>>
>
> Could you please clarify why removing string support would make the
> operation simpler? I voted for always supporting strings because I thought
> that is the option that simplifies things - in particular it would allow
> use to drop the FETCH_DIM_TMP_VAR opcode and always go through FETCH_DIM_R
> instead. Sample patch here:
> https://github.com/nikic/php-src/compare/stringOffsetsInList Or did I
> miss something and we can't do that?
>
> Nikita
>

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