cmd/asm: add error check for move constant instructions on arm64
The current Go assembler encodes "MOVK $(0<<16|32|48), Rd" as the
same binary with "MOVK $0, Rd", but for arm64 move constant instructions
MOVK, MOVN and MOVZ, "op $0, Rd" and "op $(0<<16|32|48), Rd" have
different semantics. In order not to change the way the assembler
frontend parses constants, this patch adds a check for the zero shifts.
Change-Id: Ia844c419ce49f63605b549e3a2e98d9075dd1cf1
Reviewed-on: https://go-review.googlesource.com/c/go/+/275812
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: fannie zhang <Fannie.Zhang@arm.com> Reviewed-by: Cherry Mui <cherryyz@google.com>