[llvm] [VPlan] Use InstSimplifyFolder in tryToConstantFold (PR #141222)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> Can we drop some of the existing simplifications as a result?

No, unfortunately. Those matchers match VPValues, which are values in the VPlan overlay, while the constant-folder requires live-ins, or IR values (Value *).

https://github.com/llvm/llvm-project/pull/141222