[llvm] [RISCV] Lower non-power-of-2 vector to nearest power-of-2 vector leng… (PR #106092)

[Philip Reames via llvm-commits]

preames wrote:

The current version appears to be hitting some pretty terrible scalarization, but at a high level this doesn't sound unreasonable.  If we do take this approach for 2^N-1 vectors, I'd want us to be able to move our entire fixed vector lowering to this strategy.  Consistency here is fairly important - for confidence in correctness if nothing else.  

https://github.com/llvm/llvm-project/pull/106092