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To: <internals@lists.php.net>, "Dmitry Stogov" <dmitry@zend.com>
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Date: Thu, 28 Aug 2008 09:18:45 -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,

Well, it's been awhile since Alpha 1 :-), so I wanted to finally resend this
before Alpha 2!  I agree that the additional optimization probably wouldn't
happen often, as there won't be that much namespace usage right away, I
assume.  But I think it makes sense to handle :: prefix constants, since
they're known to have global scope, and I can see the future [online]
optimization tip: "When using namespaces, use :: for global constants to get
compile-time substitution." ;-)

The code is the same as before, just updated the patch.  It doesn't really
seem less clear, to me, than the current code.  In zend_do_fetch_constant(),
the "check_namespace" variable may be better named something like
"from_namespace" according to my changes, to be more clear, but I left that
out to make the patch as simple as possible.

http://realplain.com/php/ct_const_fixes.diff
http://realplain.com/php/ct_const_fixes_5_3.diff


Thanks,
Matt


----- Original Message -----
From: "Dmitry Stogov"
Sent: Thursday, July 31, 2008

> Hi Matt,
>
> Now I know. :)
> Anyway, I don't think this optimization will work often.
>
> Send me the patch after Alpha1 release.
>
> Thanks. Dmitry.
>
>
> Matt Wilmas wrote:
> > Hi Dmitry,
> >
> > Do you know that with your changes, no substitution will happen in a
> > namespace even when using :: prefix? :-/  (That's what I would do when I
> > know it's global, for optimization.)  Or is that what you meant by "not
so
> > optimal?"
> >
> >
> > - Matt
> >
> >
> > ----- Original Message -----
> > From: "Dmitry Stogov"
> > Sent: Thursday, July 31, 2008
> >
> >> Thanks Matt. I committed near the same patch.
> >> It's not so optimal, but little bit more clear.
> >>
> >> Thanks. Dmitry.
> >>
> >> Matt Wilmas wrote:
> >>> 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
> >