[llvm] [RISCV][CodeGen] Add initial vzip codegen support (PR #194548)

[Craig Topper via llvm-commits]

topperc wrote:

> > > @lukel97 do we need to do anything to disable this instruction the VLOptimizer? This instruction reads VL elements from the sources but writes 2*VL results.
> > 
> > 
> > Nevermind, I think the default value of ElementsDependOn being EltDepsVLMask protects this.
> 
> Yeah it should be disabled by default, I switched over the TSFlags to be opt-in a while ago

I know that prevents the instruction from having its VL reduced. Does it also prevent propagating the VL from the instruction to its inputs?

https://github.com/llvm/llvm-project/pull/194548