[llvm] [RISCV] Set a barrier between mask producer and user of V0 (PR #114012)

[Philip Reames via llvm-commits]

https://github.com/preames approved this pull request.

LGTM - Seems like a reasonable workaround for a real issue and a few days have gone by with no other suggestions made.  

https://github.com/llvm/llvm-project/pull/114012