Re: port-sparc/58352: ld: /usr/lib/libubsan.so: undefined reference to `__sync_val_compare_and_swap_8'

[Rin Okuyama <rokuyama.rk%gmail.com@localhost>]

On 2024/06/19 23:55, Martin Husemann wrote:
> The following reply was made to PR port-sparc/58352; it has been noted by GNATS.
>
> From: Martin Husemann <martin%duskware.de@localhost>
> To: gnats-bugs%netbsd.org@localhost
> Cc:
> Subject: Re: port-sparc/58352: ld: /usr/lib/libubsan.so: undefined reference
>   to `__sync_val_compare_and_swap_8'
> Date: Wed, 19 Jun 2024 16:51:37 +0200
>
>   On Wed, Jun 19, 2024 at 02:45:02PM +0000, Rin Okuyama wrote:
>   >  (3) Earliest CPU model satisfy (2) seems `ultrasparc3`, IIUC:
>   >  (I'm not familiar to sparc although...)
>   
>   All ultrasparc CPUs support VIS and can do 64bit atomic ops.
>   
>   The ultrasparc3 introduced "VIS 2" with additional instructions.

Hmm, I tried `-mcpu=ultrasparc`, but generated library has reference to
__sync_val_compare_and_swap_8. I've not figured out why, at the moment.

>   However, for 32bit sparc CPUs we can not assume support (and it is pretty
>   lame of ubsan to use it). Can we patch the ubsan code to only require 64bit
>   atomics #ifdef _LP64 ?

Yeah, this is just what I tried. It works at least on i386, but
diff is *really* large:

https://gist.github.com/rokuyama/24d0ed7e537fffc07e2975c3880817f1

I wonder whether we can ship atomic64 runtime routines with
lib*san as, e.g., hidden symbols...

Thanks,
rin