[dev.simd] cmd/compile: reorder operands for some simd operations

This adds support for one ad hoc reordering, which
requires a new intrinsic-to-ssa helper matching the
name that is used in the generator (and this in the
generated code).  In this case, it is opLen{2,3}Imm8_2I
which expects the immediate after the self (0) and
first (1) parameters to the method, and before the
mask if there is one.  I.e., the immediate is arg 2
in the call.

The changes to simdintrinsics and stubs are generated
by simdgen CL 684019.

Change-Id: Ia54aab9825d469a2f3efa6d1fb079242181c0ca6
Reviewed-on: https://go-review.googlesource.com/c/go/+/684776
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

0 files changed, 0 insertions, 0 deletions