[llvm] [InstCombine] Update the `select` operand when the `cond` is `trunc` and has the `nuw` or `nsw` property. (PR #105914)

[Nikita Popov via llvm-commits]

nikic wrote:

> Would it be better to place this transformation at
> 
> https://github.com/llvm/llvm-project/blob/99b85cae628c1cc5641944290712cd84ccf1f6c8/llvm/lib/Analysis/InstructionSimplify.cpp#L4812
> ? If yes, I'd like to relocate the implementation there.

The transform can't go into InstSimplify because it modifies/creates an instruction.

https://github.com/llvm/llvm-project/pull/105914