[PATCH] D99142: [RISCV] Add basic cost modelling for fixed vector gather/scatter.

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D99142#2644239 <https://reviews.llvm.org/D99142#2644239>, @frasercrmck wrote:

> I've not done much in this area of RISC-V, but I take it the non-vector costs are suitably higher than the vector costs? We'd still prefer to vectorize these?

The non-vector cost I think is just the same getMemoryOpCost call we're using here multiplied by VF. X86 adds a gather/scatter overhead cost on top of the element*getMemoryOpCost. It doesn't look like AArch64 adds any extra cost and they only support scalable vectors.

I think we'll compute the same cost for scalar loads/stores and gather/scatter with this patch. Hopefully vectorizing the GEP is accounted for separately.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99142/new/

https://reviews.llvm.org/D99142