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To: <internals@lists.php.net>, "Dmitry Stogov" <dmitry@zend.com>
References: <00ea01c8a160$2edd8160$0201a8c0@pc1> <016c01c8eccd$e28cfac0$0201a8c0@pc1> <488835D0.1040005@zend.com> <00e501c8ed77$3498cf20$0201a8c0@pc1> <48889901.8000008@zend.com>
Date: Thu, 31 Jul 2008 07:08:54 -0500
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Subject: Re: [PHP-DEV] [PATCH] No runtime fetching of built-in global constants
From: php_lists@realplain.com ("Matt Wilmas")

Hi Dmitry,

For the behavior change that I mentioned in the other thread, with this
code:

function foo() {
    static $a = -PHP_INT_MAX;
}

Which could work sometimes, and sometimes not (if in a namespace or
ZEND_COMPILE_NO_CONSTANT_SUBSTITUTION is set).  I changed things so that
there is no substitution of constants (except with CT_SUBST flag, like
always) for compile time constants (ZEND_CT mode).  They don't create a
FETCH_CONSTANT opcode anyway. :-)

Another thing I realized wasn't getting optimized (runtime constants), which
can be, is with:

namespace foo;
$a = ::PHP_INT_MAX;  // :: for global scope

So the patch allows substitution there as well.

http://realplain.com/php/ct_const_fixes.diff
http://realplain.com/php/ct_const_fixes_5_3.diff


- Matt


----- Original Message -----
From: "Dmitry Stogov"
Sent: Thursday, July 24, 2008

> I would propose the attached patch for this optimization.
>
> Opcode caches and encoders will have to disable this optimization with
> ZEND_COMPILE_NO_CONSTANT_SUBSTITUTION
>
> Any objections?
>
> Thanks. Dmitry.
>