[PATCH u-boot-marvell v2 8/9] arm: mvebu: spl: Use IS_ENABLED() instead of #ifdef where possible

[Marek Behún]

On Thu, 16 Dec 2021 19:16:40 +0100
Pali Rohár <pali at kernel.org> wrote:

> The reason that it currently works is just because
> gcc compiler does not do all checks before doing optimizations and so it
> currently does generate any errors or warnings.

Compiler cannot currently check this, only linker, because the function
is always declared in mvebu's cpu.h.

See https://lore.kernel.org/u-boot/20211214134536.2baeb2a0@thinkpad/
where I also proposed empty static inline implementations for non-A375
platforms, but Stefan thinks it's not an issue currently, because it
does not cause any regressions, I guess. U-Boot's build system
currently does not allow for -O0, you can choose only -O2 or -Os.

We can always add empty static inline implementations into mvebu's
cpu.h when it becomes an issue, or you can send a patch now, if you
want a completely perfect code ASAP.

But note that for that you'll need to check other functions there, as
well. (If you look at
  https://source.denx.de/u-boot/u-boot/-/blob/master/arch/arm/mach-mvebu/include/mach/cpu.h
there are functions declared, without guarding #ifs, for all mvebu
platforms: A3k, A7k, A37x and A38x.)

Marek