[LLVMdev] A new project proposal for LLVM and calling help from a chinese student

Star tanmingxing at mprc.pku.edu.cn
Wed Oct 29 22:39:46 PDT 2008

Hi, Benoit,
Thanks very much for your advice.
You see the algorithm greatly improve the performance of liveness analysis.
However, it seems still not efficient.
First, it is inefficient in space. You have to pre-compute all Tq for every
Tq and save them, even though only the highest nodes of Tq are needed for a
given query(q,v); Second, it is inefficient in time. Given any query(q,v),
you have to  traverse all Tq to find the highest nodes. When the Tq is
large, it maybe will cost a lot. To conquer this problem, you first order
nodes according to dominance, and then the "highest node" will be the first
node. However, when many nodes are not dominated by each other, you have to
traverse them.
In fact, I think the highest node proposed in your new slice is very similar
to the entry of SCC if the node is a loop entry. So, maybe I could use this
information to improve this algorithm, even though I don't know clearly how
to improve it now.
Thanks again, I will try to implement it in LLVM, and further more, try my
best to improve it.

Best wishes,

-----Original Message-----
From: Benoit Boissinot [mailto:bboissin at gmail.com] 
Sent: Wednesday, October 29, 2008 10:06 PM
To: LLVM Developers Mailing List
Cc: 谭明星
Subject: Re: [LLVMdev] A new project proposal for LLVM and calling help from
a chinese student


> On Oct 28, 2008, at 10:10 AM, 谭明星 wrote:
>> PS: The following are links about this paper:
>> http://portal.acm.org/citation.cfm?id=1356064

I've put the slides from CGO online:
They should be much better than the one from my presentation at EmSoC.



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