[llvm] [VPlan] Move recording of Inst->VPValue to VPRecipeBuilder (NFCI). (PR #84464)

[via llvm-commits]

ayalz wrote:

> > Independent of this patch: should VPRecipeBuilder (or some other sub/class thereof) be confined to initial VPlan construction from LLVM-IR, excluding construction of recipes during VPlan-to-VPlan transformations?
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> Yes, `VPRecipeBuilder` ( not to be confused with `VPBuilder`) is only used for initial construction. We should split of the logic to create the initial VPlan to a separate helper, and only instantiate `VPRecipeBuilder` there

Agreed. Would also be good to clarify the distinction between the two builders, possibly using more accurate names. May also be interesting to consider the analogous TransformState, used to maintain the temporary state during translation from VPlan to LLVM-IR.

https://github.com/llvm/llvm-project/pull/84464