[cfe-dev] Help needed in analyzing liveness of variables with LLVM IR

[Madhur Amilkanthwar via cfe-dev]

+cfe dev

On Fri, Apr 7, 2017 at 5:13 PM, Madhur Amilkanthwar <madhur13490 at gmail.com>
wrote:

> Adding llvm-dev.
>
> I don't know if this is readily available in LLVM but here is what you
> could do something like below.
>
> worklist = NULL
> for each loop L in function {
>   for each block B in L {
>      for each Inst I in B {
>
>         if (I.use_empty())
>            continue;
>
>         for each use of I {
>             B1 = I.getParent();
>
>            if (L.contains(B))
>                 continue;
>
>             worklist.add(I)
>             break;
>         }
>      }
>    }
> }
>
> Similar thing seems to be in Transforms/Utils/LCSSA.cpp
>
>
> On Fri, Apr 7, 2017 at 11:01 AM, Shail Dave via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> Hi,
>>
>> Thank you for your time in reading this. I need help in analyzing the
>> live-in and live-out variables for few loops in the llvm IR. I want to
>> figure out which is a live-variable at the end of the loop and what is
>> live-in variable for the loop. I found that such provisions are available
>> for machine instructions. But, I have to use this at IR level. I found few
>> papers showing algorithms to construct such analysis but, it seems to me
>> that this must be a problem encountered before and there should be at least
>> similar functionalities in some of the analyses passes in the existing LLVM
>> framework. It would be great if I can find some references or someone can
>> give some suggestions.
>>
>> If I cannot find some existing passes, I am also not sure about – how can
>> I make use of Intrinsic::invariant_start or Intrinsic::lifetime_start for
>> aforementioned purpose. Any help is highly appreciated. Thanks!
>>
>> Best,
>> *Shail*
>>
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>>
>
>
> --
> *Disclaimer: Views, concerns, thoughts, questions, ideas expressed in this
> mail are of my own and my employer has no take in it. *
> Thank You.
> Madhur D. Amilkanthwar
>
>


-- 
*Disclaimer: Views, concerns, thoughts, questions, ideas expressed in this
mail are of my own and my employer has no take in it. *
Thank You.
Madhur D. Amilkanthwar
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