[llvm-dev] Induction variable identification?

[Ehsan Amiri via llvm-dev]

To be clear, I was suggesting to read the code in simplifyLoopIVs() in
"lib/Transforms/Utils/SimplifyIndVar.cpp" to see how it identifies IVs. (as
opposed to calling the function to change the code).

On Sun, Oct 16, 2016 at 12:48 PM, Ehsan Amiri <ehsanamiri at gmail.com> wrote:

> If you have a canonicalized IV, you can use Loop::
> getCanonicalInductionVariable() declared in "include/llvm/Analysis/
> LoopInfo.h".
>
> Otherwise you probably need to start from  function simplifyLoopIVs() in
> "lib/Transforms/Utils/SimplifyIndVar.cpp". This method looks at all phi
> nodes in the header of the loop, but later on in the process, it skips some
> of them. For example, when we reach SimplifyIndvar::simplifyUsers(), in
> the beginning of this function we check if the IV data type isSCEVable() or
> not. If not, we immediately return.
>
> Hope that helps
> Ehsan
>
>
> On Sun, Oct 16, 2016 at 6:38 AM, Madhur Amilkanthwar via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hi,
>> How does LLVM identify induction variables of a loop?
>> Is the algorithm based on SSA graphs?
>>
>> I have a complicated loop and I need to do some analysis around it.
>> Can anyone please point me to source of identification part?
>>
>>
>>
>> --
>> *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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>>
>
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