cmd/asm: remove the incorrect check of LDADDx-like instructions
According to the ARM Architecture Reference Manual, LDADDx-like
instructions can take rt as zr when the encode A bit is 0. They
are used by the alias STADDx-like instructions. The current
assembler adds incorrect constraints for them, which is rt can't
be zr when field.enc A is 0. This patch removes it.
Add test cases.
Reported by Matt Horsnell <matt.horsnell@arm.com>
The reference:
https://developer.arm.com/documentation/ddi0602/2022-12/Base-Instructions
Change-Id: Ia2487a5e3900e32994fc14edaf03deeb245e70c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/462295 Reviewed-by: Matt Horsnell <matthew.horsnell@gmail.com>
Run-TryBot: Joel Sing <joel@sing.id.au> Reviewed-by: Cherry Mui <cherryyz@google.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>