[llvm-dev] loop induction variables at IR level

Archa . via llvm-dev llvm-dev at lists.llvm.org
Sat Jul 1 09:27:12 PDT 2017


My understanding of induction variable is that it drives the loop with
fixed increment and by comparing it based on a condition (Hope I understood
it right). I want to extract and print this variable and what it is
compared to.

I have been trying to understand the ScalarEvolution and SCEVexpander
through llvm documentation are there any examples on how it is used,
because I have not been able to understand its usage properly.

Thanks and Regards
On 01-Jul-2017 3:54 pm, "Hal Finkel" <hfinkel at anl.gov> wrote:

> Hi, Archa,
> What do you want to do with the induction variable? For most uses cases,
> you can use the ScalarEvolution analysis (and, if necessary, the
> ScalarEvolutionExpander).
>  -Hal
> On 07/01/2017 03:56 AM, Archa . via llvm-dev wrote:
> Hi,
> I was looking at trying to get loop induction variable at IR level. LLVM
> documentation mentioned indvars pass and getCanonicalInductionVariable()
> to get them, I tried running the indvars pass and then a custom pass which
> iterates through loops and uses the function to obtain variable for a
> simple loop program. But the API returns null. I also read in similar posts
> that the indvars pass is not available in the current version but
> documentation still mentions them.
> Is there something I am missing in my method , or is there an alternative
> method to get the induction variable in the latest version.
> Thanks in advance
> Regards
> Archa
> _______________________________________________
> LLVM Developers mailing listllvm-dev at lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> --
> Hal Finkel
> Lead, Compiler Technology and Programming Languages
> Leadership Computing Facility
> Argonne National Laboratory
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170701/b8e41855/attachment.html>

More information about the llvm-dev mailing list