[llvm] s390x: pattern match saturated truncation (PR #155377)

[Folkert de Vries via llvm-commits]

folkertdev wrote:

Thank you for guiding me through this! LLVM can be kind of inscrutable, so that help is really useful.

Am I supposed to do something to merge this? 

https://github.com/llvm/llvm-project/pull/155377