[LLVMdev] Question about DSA analysis

John Criswell criswell at illinois.edu
Mon May 20 07:13:36 PDT 2013

On 5/19/13 11:46 AM, Jing Zhou wrote:
> Greeting.
> I am working on one DSA related project. Got several questions about 
> LLVM's DSA analysis:
> 1. I looked through the llvm doc, it seems  "-ds-aa" option is the one 
> I should use. 
> (http://llvm.org/docs/AliasAnalysis.html#the-ds-aa-pass). however 
> based on the poolalloc's svn history, this option was removed on (or 
> before) 2011.   May I know why this one was removed ? and is there any 
> equivalent option (or options combination) in current poolalloc project  ?

We removed ds-aa because it had bit-rotted and very few people were 
using it.  There was a patch to resurrect it, but it didn't apply 
cleanly (I think we moved from LLVM 3.0 to 3.2 between the time the 
patch was submitted and the time I got around to looking at it), and 
there was only 1 user of ds-aa, so making it work was low priority.

How you should use the DSA analysis depends on what you're doing. For 
intra-procedural alias analysis queries, you can use the DSGraph 
straight from the BottomUp or TopDown DSA analysis passes.  For both 
intra- and inter-procedural alias analysis queries, you can use the 
DSNodeEquivs pass.  If you need a shape graph, you can use the DSGraph 
interface directly.

If you could tell me how you want to use DSA, I can explain which 
approach to use and how to make it work.

> 2. I checked the svn history of poolalloc. there is no update to trunk 
> since last Nov.  the release_32 branch was updated this March. I am 
> wondering which one is good to use ? and are they compatible with 
> latest llvm trunk or llvm release_3_3 branch ?

The release_32 branch is the actively maintained branch at the moment.  
When we're ready to to move to LLVM 3.3, we'll merge the release_32 
branch back into trunk and then update the code to compile with LLVM 3.3.

While I don't have a timeline yet for when the update to LLVM 3.3 will 
happen, I think the earliest date that we'd begin an update would be 
July or August.

-- John T.

> thank you in advance
> btw: I am not in the llvmdev email alias, please include my email 
> address in your reply.
> -Jing
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