Re: [PATCH] target/arm: Remove unnecessary gen_io_end() calls

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> Since commit ba3e7926691ed3 it has been unnecessary for target code
> to call gen_io_end() after an IO instruction in icount mode; it is
> sufficient to call gen_io_start() before it and to force the end of
> the TB.
>
> Many now-unnecessary calls to gen_io_end() were removed in commit
> 9e9b10c6491153b, but some were missed or accidentally added later.
> Remove unneeded calls from the arm target:
>
>  * the call in the handling of exception-return-via-LDM is
>    unnecessary, and the code is already forcing end-of-TB
>  * the call in the VFP access check code is more complicated:
>    we weren't ending the TB, so we need to add the code to
>    force that by setting DISAS_UPDATE

That was the thing I was staring at trying to puzzle out.

I guess going forward we want to base the base DisasContext to
gen_io_start so we can flip a bit and then assert we don't start a new
instruction having already handled an IO instruction which should have
been the last one.

>  * the doc comment for ARM_CP_IO doesn't need to mention
>    gen_io_end() any more
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée