Hi,

Basically, it compares how precise we are w.r.t to alias classification. We 
measured the fraction of alias queries in BE for which we do not alias. As you 
can see, for C++ benchmarks we are not performing that well. There are several 
reasons for this -

1)      Alias classification is done after inlining and since we aren't 
context-sensitive yet we tend to be less precise.

2)      Alias classification is called multiple times in BE and therefore is 
more up-to-date. We do not have this luxury since solving the constraint graph 
is more expensive. Moreover to make it worse, there are still a number of cases 
(after VHO/PreOpt) where after the transformation we no longer have the WN to 
AliasTag (point-to sets) mapping, and we end up being conservative. This is 
something we are currently looking at.

3)      We still have scalability issues in 483.xalancbmk. We have managed to 
address this by selectively "collapsing" objects - thus losing 
field-sensitivity. But more tuning is required.

4)      Moreover, I believe this provides a better infrastructure to accurately 
compute mod/ref sets as well as improve the precision on memory SSA which can 
hopefully lead to better performance. So far we are only seeing minor 
improvements as shown in the same slide. Fortunately, we aren't degrading the 
performance :)


Thanks
Rajiv


From: Tianwei [mailto:tianwei.sh...@gmail.com]
Sent: Friday, December 03, 2010 5:10 PM
To: Ravindran, Rajiv
Cc: open64-devel@lists.sourceforge.net
Subject: Re: [Open64-devel] nextgen alias analysis review request

Hi, Ravindran,
     Do you mind to explain a bit more for the page 18 of the slides?  what's 
the two bar? and what's the performance result?   If they are real running time 
improvement at IPA, since you can pass 483(especially with your 
field-sensitivity), that is really exciting.

     I will try to look at all your files later.

Tianwei
On Sat, Dec 4, 2010 at 5:51 AM, Ravindran, Rajiv 
<ravind...@hp.com<mailto:ravind...@hp.com>> wrote:
Hi folks,

Attached is a high-level design document describing our implementation of a new 
alias analysis infrastructure in Open64. Also included is the presentation we 
made of the same at the recent developer's forum. A patch containing the 
changes to the existing files is included in nextgenalias.diff, while the new 
files have been directly attached.

We plan to initially check this in disabled. Any comments or suggestions is 
greatly appreciated.

Thanks
Rajiv


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--
Sheng, Tianwei
Inst. of High Performance Computing
Dept. of Computer Sci. & Tech.
Tsinghua Univ.
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