[llvm] [WIP][SLP] Forest Vectorization for Wide Chains (PR #171917)

[Ryan Buchner via llvm-commits]

bababuck wrote:

> HI @bababuck - I wanted to check if you are still planning to work on landing this upstream? We’re interested in pursuing this to improve the SLP vectorization of the SPEC benchmark namd on AArch64, so we could help out with the reviews and/or upstreaming the NFC changes

Thanks for reaching out! Still planning on pursuing such work, but the changes in this MR are outdated, and I was a little naive with the initial approach here as I was more limited in my understanding of the SLP at the time.

I've also just come across another use case for this so am planning on diving back into this space, would be great to collaborate if you have the bandwidth!

https://github.com/llvm/llvm-project/pull/171917