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

[via llvm-commits]

https://github.com/ayalz commented:

Post-approval review comments (potentially to be continued).

Should the block diagram of https://llvm.org/docs/Vectorizers.html#epilogue-vectorization be updated?

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