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

[Elvis Wang via llvm-commits]

ElvisWang123 wrote:

> Would be good to combine #137745 & #137746, so the recipes are used already, sorry if that wasn't clearer from the previous comment

Ah it is fine, I misunderstood the previous comment :smiley:. Combined all the changes into #137746. 

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