[llvm] [BasicAA] Scalable offset with scalable typesize. (PR #80818)

[David Green via llvm-commits]

davemgreen wrote:

> > We essentially divide each side by vscale and are left needing to check that the offset >= typesize.
> 
> Is that correct without the IsNSW flag?

Hmm. Yeah maybe. I was thinking of offsets similar to typesizes, and it would be a strange access than might wrap around depending on the vscale. I'll add a IsNSW check if you think that's better - it looks like a few cases in the tests get a little worse, but we might be able to improve it in the future with vscale_range to show the extreme would not overflow.

https://github.com/llvm/llvm-project/pull/80818