Re: [PATCH] [RFC] x86: avoid -mtune=atom with clang

[Miguel Ojeda]

On Tue, Oct 19, 2021 at 7:11 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
>
> +ifdef CONFIG_CC_IS_CLANG
> +        cflags-$(CONFIG_MATOM)         += -march=atom -mtune=generic
> +else
>          cflags-$(CONFIG_MATOM)         += -march=atom
> +endif

Is it possible to factor it out? Also, a comment with the LLVM version
we last checked would be good. Something like...

    cflags-$(CONFIG_MATOM)         += -march=atom

    # Atom optimizations do not seem well exercised in, at least, LLVM <= 13,
    # to the point of getting problems with register allocation.
    ifdef CONFIG_CC_IS_CLANG
            cflags-$(CONFIG_MATOM)         += -mtune=generic
    endif

Cheers,
Miguel