llvm-project

248be984 - Reapply "[RISCV][TTI] Add shuffle costing for masked slide lowering (#128537)"

Reapply "[RISCV][TTI] Add shuffle costing for masked slide lowering (#128537)" With a fix for fully undef masks. These can't reach the lowering code, but can reach the costing code via e.g. SLP. This change adds the TTI costing corresponding to the recently added isMaskedSlidePair lowering for vector shuffles. However, since the existing costing code hadn't covered either slideup, slidedown, or the (now removed) isElementRotate, the impact is larger in scope than just that new lowering. --------- Co-authored-by: Alexey Bataev <a.bataev@gmx.com> Co-authored-by: Luke Lau <luke_lau@icloud.com>