style question: breaking inline assembly lines

[Joel Sherrill]

On Mon, Jun 12, 2023 at 3:10 PM Gedare Bloom <gedare at rtems.org> wrote:

> We have a mix of ways to write inline assembly. It would be convenient
> to choose one way. The prevailing options are based on breaking around
> the colons (reg/field separators), either to break at colons if the
> line length > 80, or to always break at colons.
>
> I personally find it is easier to read inline assembly that has broken
> at the colons. But we have these options:
> 1. Always break at the colon
> 2. Only break when the line length is exceeded
>

I lean to (1).

>
> With #2, we also can break as usual, or we can force breaks at the
> colons. I have seen examples of both in the source tree. Any strong
> opinions one way or another?
>

There may also be cases of multiple assembly instructions on the
same line or split across multiple with line continuation. I don't know
of one offhand though.

>
> here's a line broken because of line lengths, that has not split the
> arguments at the colons:
>
> https://git.rtems.org/rtems/tree/cpukit/score/cpu/arm/include/rtems/score/aarch32-system-registers.h#n69
>
> Here's a line broken because of line lengths:
>
> https://git.rtems.org/rtems/tree/cpukit/score/cpu/arm/include/rtems/score/cpu.h#n501
>
> Here's a line broken always:
> https://git.rtems.org/rtems/tree/cpukit/score/cpu/aarch64/cpu.c#n153
>
> And for good measure, here's an unbroken line that should be broken:
>
> https://git.rtems.org/rtems/tree/cpukit/score/cpu/microblaze/include/rtems/score/cpu.h#n206
>
> With the newest version of clang-format we will be able to accommodate
> always breaking the lines. It currently is inconsistent with whether
> it puts the first argument on its own line, or keeps it with the
> "__asm__ volatile (" that I could probably make consistent if we
> decide we need it to be.
>
> Gedare
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