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	<dmitry@php.net>
Date: Sun, 18 Jun 2006 14:49:47 +0100
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Subject: messing with branch prediction
From: nlopess@php.net ("Nuno Lopes")

Hello,

Yesterday I was playing with branch prediction in the Zend VM executor. 
Although I didn't have any noticeable performance improvement within the 
bench.php script, I've put the patch on-line, because someone else might 
want to mess with it too :) (but with care..)

patch: http://mega.ist.utl.pt/~ncpl/zend_branch_prediction.txt
gcc docs: 
http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-g_t_005f_005fbuiltin_005fexpect-2440

the zend.h part of the patch is based on the similar macros (with the same 
name, too) found in the Linux kernel.

I made & tested the patch in a Centrino laptop with gcc 3.4, so it might be 
the cause of getting no relevant performance increase. On CPUs with longer 
pipelines (like Pentium 4/NetBurst architecture), the performance increase 
might be noticeable.


Happy hacking :)
Nuno