[llvm] [RISCV][GlobalISel] Legalize G_ADD, G_SUB, G_AND, G_OR, G_XOR on RISC-V Vector Extension (PR #71400)

[Michael Maitland via llvm-commits]

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