[LLVMdev] Regarding PRE in LLVM

Chris Lattner sabre at nondot.org
Tue Mar 29 07:29:29 PST 2005

On Tue, 29 Mar 2005, Dheeraj Kumar Arora wrote:
>        While surfing on net I found that LLVM is using sparse version of
> E-path_PRE approach in file PRE.cpp but I could not get what actually code
> is doing and I could not find the name of the developer in the file.
>        Just want to know to because I could not able to find any
> paper on sparse version of this algorithm.

I wrote the code, using Dhamdhere's "E-path PRE---partial redundancy 
elimination made easy" paper as inspiration and starting from first 

The code in LLVM CVS is about 75% done.  In handles a bunch of cases, but 
misses others.  It has not been used in quite some time, so it has 
probably bitrotten some.

If you're interested in sparse PRE, I suggest chasing down references for 
GVN-PRE by Thomas VanDrunen.  His thesis is here: 



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