[llvm] [SCCP] Add support for trunc nuw range. (PR #152990)

[Andreas Jonson via llvm-commits]

andjo403 wrote:

will look at this latter but a bit confused what you mean with 
> where %j.03 is first -20 and then -19

as the trunc is nuw the variable %j.03 can not have negative values as the trunc will result in poison then see https://llvm.org/docs/LangRef.html#trunc-to-instruction 

https://github.com/llvm/llvm-project/pull/152990