[llvm] [IR] Add nowrap flags for trunc instruction (PR #85592)

[via llvm-commits]

elhewaty wrote:

@dtcxzyw, I am thinking of filing a meta issue (task), and work on tasks related to this patch:

- [ ] Add nowrap flags
- [ ] Fix unexpected crashes
- [ ] Lower it to the nowrap flags to SDAG
- [ ] Infer nsw/nuw flags in instCombine
- [ ]  Implement zext(trunc nuw) and sext(trunc nsw) fold
- [ ] Emit trunc nuw/nsw in SimplifyIndVars IV widening
- [ ] Look for opportunities in the code to use trunc nuw/nsw

but I am busy these days, I will continue working on these tasks, but if you need them, and they are urgent you can work on them.

what do you think?

https://github.com/llvm/llvm-project/pull/85592