[llvm] [RISCV][AsmParser] Allow parsing vset{i}vli omitting LMUL parameter (PR #115277)

[Craig Topper via llvm-commits]

topperc wrote:

I think the examples weren't updated when the spec was changed to make all fields required here https://github.com/riscv/riscv-isa-manual/pull/1489

https://github.com/llvm/llvm-project/pull/115277