[llvm] [VPlan] Thread plan to VPBuilder (NFC) (PR #125364)

[David Sherwood via llvm-commits]

https://github.com/david-arm commented:

It seems like there is more to this PR than just passing a VPlan object reference to the VPBuilder constructor, since it's also changing VPRecipeBuilder to instantiate a `VPBuilder` object every time a `VPRecipeBuilder` object is constructed. Unless I'm missing something I can't see any reason why they are tied together in the same patch?

Can you explain more what the patch is trying to achieve with the refactoring so we can see the bigger picture? I am actually more concerned about the VPRecipeBuilder changes because it's not immediately obvious to me what the impact of dropping the reference is. Presumably there was a reason why it was a reference, perhaps to keep the insertion point in sync with other uses of the builder outside the class? @fhahn any thoughts?

https://github.com/llvm/llvm-project/pull/125364