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Date: Thu, 17 Jul 2008 09:20:18 -0500
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Subject: Re: [PHP-DEV] Optimization for ..._MULTIPLY_LONG on more systems
From: php_lists@realplain.com ("Matt Wilmas")

Hi all,

Replying to this OLD message about the ZEND_SIGNED_MULTIPLY_LONG() change...
It's just a small thing, but it's been on the TODO for a while, so I
attempted to correct the issue with my original patch that used "long long"
type, which wasn't available on the older MSVC versions, etc.  I created a
zend_long64 type (when possible, #if logic copied from snprintf.h's WIDE_INT
definition), hopefully it's mostly correct/OK, and maybe it can be used
elsewhere too.

Since the new memory manager, ..._MULTIPLY_LONG() isn't used for
safe_emalloc() anymore, so I made another safe_address() variation (overflow
safe, I hope).  I noticed ~0.6% slowdown on bench.php, though it seems this
zend_ulong64 version should use fewer cycles than the doubles one for sure,
if someone wants to analyze it more. :-)

Finally, is it even possible to also have a Windows assembly version of
these 2 things, where I left the comments?  There is for
zend_mm_[high|low]_bit(), but they're very simple...

http://realplain.com/php/multiply_long.diff
http://realplain.com/php/multiply_long_5_3.diff


- Matt


----- Original Message -----
From: "Matt Wilmas"
Sent: Wednesday, November 08, 2006

> Hi,
>
> Here's an additional ZEND_SIGNED_MULTIPLY_LONG() for platforms with 32-bit
> longs that don't use the assembly version (so all Windows systems at
> least?).  On my Windows system, mul_function() is 40% faster with this
> version (no overflow), which makes PHP's * operator 20% faster; with
> overflow mul_function() is 20% faster (though I don't see any difference
> with the * operator).  The macro is also used in safe_emalloc()...
>
> Patch just against 5_2 as the file versions are the only difference.
>
>
> Matt