[llvm] [RISCV][GlobalISel] Vector Extension vadd Legalizer (PR #71400)

[via llvm-commits]

tschuett wrote:

My main pet peeve with scalable vectors is that the binops only take two parameters and there is no space for masks resp. predicates today.
https://github.com/llvm/llvm-project/blob/521ac12a251e7cf88d3b304186081de31a7503be/llvm/include/llvm/Target/GenericOpcodes.td#L262

https://github.com/llvm/llvm-project/pull/71400