[llvm] [CGP] Drop poison-generating flags after hoisting (PR #90382)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM, but is it possible to add these tests in llvm/test/Transforms/CodeGenPrepare/ARM/branch-on-zero.ll, which has the other tests for this transform?

https://github.com/llvm/llvm-project/pull/90382