Re: x86/include/asm/arch_hweight.h:49:15: error: invalid input size for constraint 'D'

Borislav Petkov
2023-02-07T16:44:27Z

On Tue, Feb 07, 2023 at 09:37:37AM -0700, Nathan Chancellor wrote:
> Clang does its semantic analysis before optimization, so it cannot dead
> code eliminate that chunk before it checks the validity of the asm
> constraints, that is just how the pipeline is structured as far as I
> understand it. That is one of the biggest and longest standing
> differences between clang and GCC that we know about, the upstream link
> in the issue below has some more info.
>
> https://github.com/ClangBuiltLinux/linux/issues/3
>
> I am not super familiar with the internal details of LLVM and clang as
> other folks are though so I could be wrong or missing something :)

Thanks and wow, that's issue #3. Like wow that's old. And reading Nick's
text, it sure does sound like that's the one.

Fun.

--
Regards/Gruss,
Boris.