[llvm] [VPlan] Dispatch to multiple exit blocks via middle blocks. (PR #112138)

[David Sherwood via llvm-commits]

david-arm wrote:

Hi @fhahn, just for reference here is a branch that contains the changes in this PR as a single initial commit, followed by 3 more commits to add support for early exit auto-vectorisation. It's just a reworking of my original PR #88385, based off this new approach.

https://github.com/david-arm/llvm-project/tree/ee_autovec2

Once this PR lands I'll update PR #88385 accordingly. Hopefully the branch will give you an indication of what direction I'm moving towards and might help to make sense of the comments I left on this PR too!

https://github.com/llvm/llvm-project/pull/112138