[llvm-dev] Building and Invoking DSA or Pool Alloc

John Criswell via llvm-dev llvm-dev at lists.llvm.org
Thu Apr 28 06:18:51 PDT 2016


On 4/28/16 4:55 AM, Mani, Suresh wrote:
>
> Hi Criswell,
>
> Thanks a lot for the immediate and detailed response on this.
>
> Sure I will try using the ported version 
> https://github.com/jtcriswell/llvm-dsa and check.
>

To be clear, the DSA code has been ported to LLVM 3.7.  The Poolalloc 
APA transform has not.

Also, if you're using DSA, you will probably get more accurate results 
if you analyze unoptimized code.  LLVM's optimizations now do some 
really funky things to the IR that make it more difficult for DSA to do 
its type-inference.  With less precise type inference, DSA provides less 
precise points-to analysis results (the type-inference gives DSA its 
field sensitivity feature).

I think DSA can be fixed to deal with those issues, and there are 
multiple ways to fix it.  However, no one's stepped up to the plate to 
do it yet.

Regards,

John Criswell

> Thanks
>
> M Suresh
>
> *From:*John Criswell [mailto:jtcriswel at gmail.com]
> *Sent:* Wednesday, April 27, 2016 6:47 PM
> *To:* Mani, Suresh; llvm-dev at lists.llvm.org
> *Subject:* Re: [llvm-dev] Building and Invoking DSA or Pool Alloc
>
> Dear Suresh,
>
> First, may I ask why you're using automatic pool allocation (APA)?  
> The APA transforms have probably suffered significant bitrot; I 
> haven't used them much in recent years.  APA's current algorithms for 
> deciding when and where to make pools are a bit complicated.  
> Depending on your needs, it may make more sense to morph the current 
> APA code into something that is simpler and easier to maintain (e.g., 
> a transform that creates global, context-insensitive pools) than to 
> use it for doing context-sensitive pool allocation (which requires 
> changing function signatures which becomes tricky when the program 
> uses external libraries).
>
> We've used DSA recently (Fall 2014), so it's in much better shape.  We 
> even have a version of it ported to LLVM 3.7 
> (https://github.com/jtcriswell/llvm-dsa).
>
> Second, to answer your question, the reason why you're seeing this 
> error is because you haven't loaded the DSA libraries into opt.  You 
> need to include additional -load options to opt to load DSA.  I 
> believe the libraries you need to load (in order) are libAssistDS.so 
> and libLLVMDataStructure.so:
>
> opt -load AssistDS.so -load LLVMDataStructucture.so -load poolalloc.so ...
>
> An alternative to running opt is to build a simple tool which links in 
> these libraries and runs the needed passes over the bitcode file 
> (essentially, writing a specialized opt tool just for running these 
> passes).  The pa programs (poolalloc/tools/Pa) is an outdated example 
> of such a tool.
>
> Regards,
>
> John Criswell
>
> On 4/27/16 2:06 AM, Mani, Suresh via llvm-dev wrote:
>
>     Hi ,
>
>     This Is ‘Suresh M’ from AMD compiler team.
>
>     1)      I obtained the source code of llvm and pool-alloc
>      (relase_32 versions ) using the following commands,
>
>     svn co http://llvm.org/svn/llvm-project/llvm/branches/release_32 llvm
>
>     cd llvm/projects
>
>     svn co
>     http://llvm.org/svn/llvm-project/poolalloc/branches/release_32
>     poolalloc
>
>     2)      Was able to build the binaries and libraries
>
>                 ../rel_32/build_rel/projects/poolalloc/Release+Asserts/lib
>
>     -rw-rw-r-- 1 sumani sumani  987956 Apr 15 15:56 AssistDS.a
>
>     -rwxrwxr-x 1 sumani sumani  508376 Apr 15 15:56 AssistDS.so
>
>     -rw-rw-r-- 1 sumani sumani    2648 Apr 15 15:56 libcount.a
>
>     -rwxrwxr-x 1 sumani sumani    8539 Apr 15 15:56 libcount.so
>
>     -rw-rw-r-- 1 sumani sumani    6514 Apr 15 15:56 libpa_pre_rt.a
>
>     -rw-rw-r-- 1 sumani sumani   13526 Apr 15 15:56 libpoolalloc_fl_rt.a
>
>     -rw-rw-r-- 1 sumani sumani   26048 Apr 15 15:56 libpoolalloc_rt.a
>
>     -rwxrwxr-x 1 sumani sumani   28731 Apr 15 15:56 libpoolalloc_rt.so
>
>     -rw-rw-r-- 1 sumani sumani 1656724 Apr 15 15:56 LLVMDataStructure.a
>
>     -rwxrwxr-x 1 sumani sumani  809363 Apr 15 15:56 LLVMDataStructure.so
>
>     -rw-rw-r-- 1 sumani sumani 1255556 Apr 15 15:56 poolalloc.a
>
>     -rwxrwxr-x 1 sumani sumani  609417 Apr 15 15:56 poolalloc.so
>
>     -rwxrwxr-x 1 sumani sumani   23861 Apr 15 15:56 typechecks_rt.so
>
>     ../rel_32/build_rel/Release+Asserts/bin          // Contains the
>     llvm binaries
>
>     ../rel_32/build_rel/Release+Asserts/lib           // Contains the
>     llvm libraries
>
>     3)      Invoking opt as follows,
>
>     ../rel_32/build_rel/Release+Asserts/bin/opt -load
>     ../rel_32/build_rel/projects/poolalloc/Release+Asserts/lib/poolalloc.so
>     --help
>
>                       Error opening
>     ../rel_32/build_rel/projects/poolalloc/Release+Asserts/lib/poolalloc.so:
>     ../rel_32/build_rel/projects/poolalloc/Release+Asserts/lib/poolalloc.so:
>     *undefined symbol: _ZN4llvm21EquivBUDataStructures2IDE*
>
>                      -load request ignored.
>
>                       OVERVIEW: llvm .bc -> .bc modular optimizer and
>     analysis printer
>
>                       USAGE: opt [options] <input bitcode file>
>
>                       OPTIONS:
>
>       -O1                                          - Optimization
>     level 1. Similar to clang -O1
>
>       -O2                                          - Optimization
>     level 2. Similar to clang -O2
>
>       -O3                                          - Optimization
>     level 3. Similar to clang -O3
>
>                              :
>
>                              :
>
>     Can anyone please do let me know how this could be resolved.
>
>     Thanks
>
>     M Suresh
>
>
>
>
>     _______________________________________________
>
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>
>     llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
>
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>
>
>
>
> -- 
> John Criswell
> Assistant Professor
> Department of Computer Science, University of Rochester
> http://www.cs.rochester.edu/u/criswell


-- 
John Criswell
Assistant Professor
Department of Computer Science, University of Rochester
http://www.cs.rochester.edu/u/criswell

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