cmd/internal/obj/riscv: add support for vector mask instructions
Add support for vector mask instructions to the RISC-V assembler.
These allow manipulation of vector masks and include mask register
logical instructions, population count and find-first bit set
instructions.
Change-Id: I3ab3aa0f918338aee9b37ac5a2b2fdc407875072
Reviewed-on: https://go-review.googlesource.com/c/go/+/646779 Reviewed-by: Carlos Amedee <carlos@golang.org> Reviewed-by: Meng Zhuo <mengzhuo1203@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Mark Ryan <markdryan@rivosinc.com> Reviewed-by: Junyang Shao <shaojunyang@google.com>