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RE: [patch] Improve loop array prefetch for IA-64


Canqun,

Nice job getting this ready for the current version of gcc!

Question: does gcc now know the difference between prefetching to cache L1 via "lfetch", as opposed to prefetching only to level L2 via "lfetch.nt1"?  For floating point data, the latter is the only interesting case because float loads only access the L2.  Thus using "lfetch" for floating point arrays will unnecessarily wipe out the contents of L1.  (gcc 3.2.3 only seems to generate "lfetch", which is why I ask...)

Thanks,
Mark 

-----Original Message-----
From: Canqun Yang [mailto:canqun@yahoo.com.cn] 
Sent: Friday, June 02, 2006 5:14 AM
To: gcc@gcc.gnu.org; gcc-patches@gcc.gnu.org
Subject: [patch] Improve loop array prefetch for IA-64

Hi, all

This patch results a performance increase of 4% for SPECfp2000 and 13% for NAS benchmark suite on
Itanium-2 system, respectively. More performance increase is hopeful by further tuning the
parameters and improving the prefetch algorithm at tree level. 


Canqun Yang


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