[llvm] [VPlan] Make VPInstruction::AnyOf poison-safe. (PR #154156)

[via llvm-commits]

ayalz wrote:

> AnyOf reduces multiple input vectors to a single boolean value. When used for early-exit vectorization, we need to consider any lane after the early exit being poison. Any poison lane would result in poison after the AnyOf reduction. To prevent this, freeze all inputs to AnyOf.
> 
> Fixes #153946.
> 
> https://alive2.llvm.org/ce/z/FD-XxA

Good catch! Is the freezing required only in early-exit cases?

https://github.com/llvm/llvm-project/pull/154156