[llvm] [Inline][Cloning] Drop incompatible attributes from `NewFunc` before `instSimplify` (PR #90489)

[Nikita Popov via llvm-commits]

nikic wrote:

I really don't think that this is the right way to fix the problem. The core issue here is not that we have incompatible attributes, but that we have return instructions that are invalid in the new function.

If it's not feasible to fix this by rewriting the returns before we perform the simplification, then I'd prefer to go with the fix from https://github.com/llvm/llvm-project/pull/87482 instead (with some comments to explain why we're doing this).

https://github.com/llvm/llvm-project/pull/90489