On Fri, Oct 23, 2020 at 2:46 PM David Laight <david.lai...@aculab.com> wrote:
>
> From: Greg KH <gre...@linuxfoundation.org>
> > Sent: 22 October 2020 14:51
>
> I've rammed the code into godbolt.
>
> https://godbolt.org/z/9v5PPW
>
> Definitely a clang bug.
>
> Search for [wx]24 in the clang output.
> nr_segs comes in as w2 and the initial bound checks are done on w2.
> w24 is loaded from w2 - I don't believe this changes the high bits.
You believe wrong, "mov w24, w2" is a zero-extending operation.
Arnd
