[PATCH] compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING

[Ingo Molnar]

* Masahiro Yamada <yamada.masahiro at socionext.com> wrote:

> Commit 60a3cdd06394 ("x86: add optimized inlining") introduced
> CONFIG_OPTIMIZE_INLINING, but it has been available only for x86.
> 
> The idea is obviously arch-agnostic although we need some code fixups.
> This commit moves the config entry from arch/x86/Kconfig.debug to
> lib/Kconfig.debug so that all architectures (except MIPS for now) can
> benefit from it.
> 
> At this moment, I added "depends on !MIPS" because fixing 0day bot reports
> for MIPS was complex to me.
> 
> I tested this patch on my arm/arm64 boards.
> 
> This can make a huge difference in kernel image size especially when
> CONFIG_OPTIMIZE_FOR_SIZE is enabled.
> 
> For example, I got 3.5% smaller arm64 kernel image for v5.1-rc1.
> 
>   dec       file
>   18983424  arch/arm64/boot/Image.before
>   18321920  arch/arm64/boot/Image.after
> 
> This also slightly improves the "Kernel hacking" Kconfig menu.
> Commit e61aca5158a8 ("Merge branch 'kconfig-diet' from Dave Hansen')
> mentioned this config option would be a good fit in the "compiler option"
> menu. I did so.

No objections against moving it from x86 code to generic code.

Thanks,

	Ingo