[LLVMdev] GC in multithreaded (but with no shared state) environment

Paweł Batko
Mon, 17 Feb 2014 18:42:31 -0000

After reading
http://lists.cs.uiuc.edu/pipermail/llvmdev/2009-November/027391.html, I was
hoping that there exists a way to overwrite the head of LLVM's shadow stack
to make it thread local and that it would magically just work..

> Note that I used per-thread shadow stacks but none of the LLVM GC
support. I used a technique similar to Henderson's accurate garbage
collection in an uncooperative environment.

Thanks, I'll definitely take a look at your work and the paper you
mentioned.

Paweł.




2014-02-17 11:31 GMT+01:00 Jon Harrop <jonathandeanharrop at
googlemail.com>:

> I already did this for HLVM. Check it out:
>
> http://www.ffconsultancy.com/ocaml/hlvm/
>
> Note that I used per-thread shadow stacks but none of the LLVM GC support.
> I used a technique similar to Henderson's accurate garbage collection
in an
> uncooperative environment.
>
> Parallel performance was extremely good:
>
> http://flyingfrogblog.blogspot.com/2010/01/naive-parallelism-with-hlvm.html
>
> HLVM can be faster than Java, Haskell, OCaml, MLton and almost as fast as
> C/C++:
>
>
>
http://flyingfrogblog.blogspot.com/2010/01/hlvm-on-ray-tracer-language-comparison.html
>
> The design of HLVM is very simple. The GC that handles concurrent mutators
> is only 100 lines of code. The entire garbage collected VM is only 2,000
> lines of OCaml code.
>
> Cheers,
> Jon.
>
> On Mon, Feb 17, 2014 at 7:27 AM, Paweł Batko <pawel.batko at
gmail.com>wrote:
>
>> Hi all,
>>
>> I would like to implement GC for a language supporting multiple
threads.
>> There will be no shared state between threads as communication will be
>> based on message passing. I do not care much about performance. The
>> priority for me is to get things working.
>>
>> I have read LLVM guide on writing GC:
>> http://llvm.org/docs/GarbageCollection.html. Shadow stack approach
looks
>> very promising. The problem is, as described in the guide, shadow stack
is
>> single thread solution. It would be ideal if I could get LLVM to create
a
>> shadow stack on per thread basis. How could this be achieved?
>>
>> Thanks,
>> Paweł.
>>
>> _______________________________________________
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>>
>>
>
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