llvm dev - May 2017 - SCEV - Non liner induction variable Addrec expression

Hello,

We are students at the Carnegie Mellon university.
We are currently working on a project which needs non linear IV's and their
corresponding increments.

We tried decoding their ADDRecExpr and found ourselves in a puzzle.

so basically we want to use the ADDRec expression(e.g. {k,+,l,+,n,+,m},
k,l,n,m being constants) to compute the increments of the
non linear IV's(e.g. j += A*i*I + B*I + c ), without requiring further
details about I (also an induction variable), A, B and C are constants.

we were hoping if someone has some documentation or already know how to do
this.

Hoping for a reply soon.

Thanks,
Students.

Hi,

On Mon, May 1, 2017 at 6:43 PM, via llvm-dev <llvm-dev at lists.llvm.org>
wrote:
> We tried decoding their ADDRecExpr and found ourselves in a puzzle.
>
> so basically we want to use the ADDRec expression(e.g. {k,+,l,+,n,+,m},
> k,l,n,m being constants) to compute the increments of the
> non linear IV's(e.g. j += A*i*I + B*I + c ), without requiring further
> details about I (also an induction variable), A, B and C are constants.
I'm not sure what you mean by "without requiring further details about
I", but did you take a look at SCEVAddRecExpr::getStepRecurrence ?

-- Sanjoy