clang bug affecting greenfly

[new subject]

On Sat, Mar 28, 2026 at 3:22 AM Greg Burd <greg(at)burd(dot)me> wrote:

> 0001 - This is a bug fix for DES/RISC-V/Clang DES initialization.
>
> ------> Join me in "the rabbit hole" on this issue if you care to...
>
> The existing software DES (as shown by the build-farm animal "greenfly" [1]) fails because Clang 20 has an auto-vectorization bug that we trigger in the DES initialization code (des_init() function), not the DES encryption algorithm itself.

> [disable vectorization entirely]
> While that might also fix the other intermittent bug we'd been seeing on greenfly (not tested) disablnig all RVV optimizations seems to heavy handed to me.

The first thing I notice is that not very long ago the buildfarm had 3
gcc RISC-V members, but not anymore. If you care about having coverage
for this hardware, I'd suggest picking up gcc again if that's still
working, and wait and see about clang. Clang has shipped broken code
generation for obscure platforms in the past, and it seems here we're
not even sure of the extent of the breakage.

--
John Naylor
Amazon Web Services