Hey there 🤗, Welcome to my GSoC Journey

This is a series of blogs that I am writing to share my amazing GSoC 22 (Google Summer of Code 2022) Journey with you all.

Supporting Multi-Dimensional Arrays and WASM Testing at CI

During this week, I worked on adding support for Mult-Dimensional Arrays in the WebAssembly Backend. I also worked on supporting integration tests testing for WASM at the CI.

One of the challeges in this week was to figure out passing of the dimensional information of arrays during function/subroutine calls. It seems, one of the possible ways to do so is to use/implement array descriptor support in the WebAssembly Backend. I tried supporting the array descriptor idea in WASM: Initial Support for Array Descriptor #98, but could not figure out a good/acceptable implementation for it.

Currently, as suggested by Ondřej, we are trying to pass array dimensions explicitly as function parameters. There is an ASR->ASR pass under implementation at Add ASR pass for supporting passing array arguments by data pointer #87, which would hopefully/possibly transform the following

subroutine f(a, b)
integer :: a(:,:)
real :: b(:,:,:)
end subroutine

into

subroutine f(na1, na2, a, nb1, nb2, nb3, b)
integer, intent(in) :: na1, na2, nb1, nb2, nb3
integer :: a(na1, na2)
real :: b(nb1, nb2, nb3)
end subroutine

and also update the respective function/subroutine calls as follows:

call f(x, y)

to

call f(size(x,1), size(x, 2), x, size(y, 1), size(y, 2), size(y, 3), y)

This suggested approach (which looks good and beautiful) can enable the wasm backend to support passing arrays (along with their dimensional information) to functions/subroutines. I submitted a PR at WASM: Supporting array passing with explicit shapes #99 which supports this approach in the wasm backend.

This phase was mostly/approximately from 30-07-2022 to 05-08-2022.

The MRs during this phase are as follows:

That’s all for this blog. Thank you for your time. We continue this series in the next blog.