[llvm] [RISCV][GISel] Instruction select for vector G_ADD, G_SUB (PR #74114)

[Michael Maitland via llvm-commits]

michaelmaitland wrote:

> > I checked out your code and I am not seeing early exit before selectImpl for the G_ADD. I only see the COPY and PseudoRET instructions entering into the `if (!MI.isPreISelOpcode() || Opc == TargetOpcode::G_PHI) {...}` block.
> 
> did you pick the vector legalizer commits from my other PR?

Yes

https://github.com/llvm/llvm-project/pull/74114