Re: [PATCH 2/2] x86/irqflags: Use ASM_OUTPUT_RM in native_save_fl()

[Linus Torvalds]

On Sun, 21 Dec 2025 at 15:44, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>
> Sigh.
>
> It's just disappointing to see this kind of stuff.

I actually find all these builtins existing in the first place more
disappointing.

Inline asm is the *generic* answer, and the one that works for pretty
much any situation. It's required in the general case, and it's the
thing that works with older compilers.

Having a builtin for things like this - without any appreciable
improvement in code - is just pointless and stupid.

Now, generic cross-architecture builtins are one thing: then you can
use them "portably". So having a builtin for 'ffs()' is not wrong.

But something like __builtin_ia32_readeflags_u64() is just entirely
pointless. What is the supposed advantage over just doing inline
assembly?

                 Linus