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References: <A4BF27E9DF4D4E64AB2164332B12410D@carla> <155749706.20090117211737@marcus-boerger.de> 
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Date: Mon, 11 May 2009 22:17:16 +0100
Message-ID: <af54caaf0905111417t40d486bcg1f710ed157091f9e@mail.gmail.com>
To: Guilherme Blanco <guilhermeblanco@gmail.com>
Cc: Dmitry Stogov <dmitry@zend.com>, Marcus Boerger <helly@php.net>, Timm Friebe <thekid@thekid.de>, 
	internals@lists.php.net
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Subject: Re: [PHP-DEV] Method call improvements
From: paul.biggar@gmail.com (Paul Biggar)

On Mon, May 11, 2009 at 7:47 PM, Guilherme Blanco
<guilhermeblanco@gmail.com> wrote:
> What's the status on this one?!

I think it died from neglect. But it was a really good idea.


One question that was raised was:

> On Thu, Jan 22, 2009 at 10:20 AM, Dmitry Stogov <dmitry@zend.com> wrote:
>> However we can introduce some indirect table associated with op_array, which
>> can be used to implement inline caches without direct opcode modification
>> (in the same way as IS_CV variables work). There are a lot of papers about
>> polymorphic inline caches (e.g.
>> http://research.sun.com/self/papers/pics.html) which we probably should use
>> to not to invite bicycle.

You can't actually use PICs or even ICs with the Zend engine, because
you can't insert code into the callee method's header (you would need
a JIT). You also wouldn't want to, since PHP can't use the
recompilation techniques that Self had. You can use lookup caches,
which is exactly what the original patch was.

FWIW, since PHP has a static inheritence chain, the best approach
seems to be to build a virtual dispatch table, instead of a hashtable
for functions. However, there might be some esoteric extensions which
make this difficult.



Paul

-- 
Paul Biggar
paul.biggar@gmail.com