IsNonNil is readily implemented using SNEZ on riscv64, removing over 8,000
instructions from the go binary. Other rules will improve on this sequence,
however in this case it makes sense to use a direct simplification.
Change-Id: Ib4068599532398afcd05f51d160673ef5fb5e5a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/299230
Trust: Joel Sing <joel@sing.id.au> Reviewed-by: Michael Munday <mike.munday@lowrisc.org> Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>