Re: [PATCH 07/10] target/arm: Implement v8.1M low-overhead-loop instructions

[Peter Maydell]

On Tue, 13 Oct 2020 at 18:30, Richard Henderson
<richard.henderson@linaro.org> wrote:
> Well, the only further comment is that, in the followup, only WLS gains the IT
> block check.  While I understand that's required to avoid an abort in QEMU for
> this case, all three of the insns have that case as CONSTRAINED UNPREDICTABLE.
>  It might be worthwhile checking for IT in all of them, just to continue our
> normal "unpredictable raises sigill, when easy" choice.

Maybe, but there are a lot of instructions that are
unpredictable-in-an-IT-block (CPSID, CRC32B, HVC...)
and our general approach seems to have been "don't check unless
it would cause an actual problem". The only place I can find
where we do check for this case is in trans_B_cond_thumb(),
which we do for the same reason as here.

thanks
-- PMM