cmd/asm: on PPC64, allow ISEL to accept a CR bit arg
Using the CR bit register arguments makes it more easy to
understand which condition and CR field is being tested when
using ISEL.
Likewise, cleanup optab setup for ISEL. ISEL should only
accept a 5 bit unsigned constant (C_U5CON), and C_ZCON
arguments are accepted by a C_U5CON optab arg.
Change-Id: I2495dbe3595dd3f16c510b3492a88133af9f7e1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/402375 Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Run-TryBot: Paul Murphy <murp@ibm.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>