[llvm-branch-commits] [llvm] release/21.x: [AArch64, TTI] Disable RealUse check for vector insert/extract costs and Apple CPUs. (#146526) (PR #149815)

[Florian Hahn via llvm-branch-commits]

fhahn wrote:

Hm, happy to include the full change. We evaluated carefully evaluated this for Apple CPUs, where this is a significant improvement, with little risk given the evaluation on Apple platforms.

> Is this mitigating a regression? If not, I don't think we should backport optimization improvements.

It does not mitigate a specific regression introduced recently, but fixes a number of cases of unprofitable SLP vectorization.

>From https://discourse.llvm.org/t/llvm-21-x-release-information-and-branching/87065, my understand was that we will relax what patches we take until RC2 in order to give developers time to finish or cut features, given that the branch was pulled forward with relatively short notice.

https://github.com/llvm/llvm-project/pull/149815