Re: [RFT PATCH 5/7] gpio: exar: unduplicate address and offset computation

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Mon, Oct 26, 2020 at 3:51 PM Andy Shevchenko
<andy.shevchenko@xxxxxxxxx> wrote:
>
> On Mon, Oct 26, 2020 at 4:23 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
> >
> > From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> >
> > Provide and use helpers for calculating the register address and bit
> > offset instead of hand coding it in every function.
>
> Can you check code generation on x86, for example?
>
> Sometimes compilers are eager to use idiv assembly instruction which
> does simultaneously / and %.
> I dunno if a) it's used for / 8 and % 8 since 8 is 2^3, b) splitting
> to functions makes the above optimisation impossible.
>

Is this optimization really needed though? It's not like it's a hot
path if it's protected by a mutex anyway. I prefer cleaner code here.

Bartosz