[llvm] [VPlan] Impl VPlan-based pattern match for ExtendedRed and MulAccRed (NFCI) (PR #113903)

[Elvis Wang via llvm-commits]

ElvisWang123 wrote:


I think currently we need mul-extend-reduction and extend-reduction recipe to model these reduction pattern in the VPlan.

Yes, generating new recipe is good but using new recipe to model these patterns would duplicate lots of codes in the `execute()` function since we lack of  middle-end IRs for these patterns. The new recipes would still need to generate  all vector instructions for recipes that has been folding into it. 


https://github.com/llvm/llvm-project/pull/113903