[llvm] [X86] Combine LRINT/LLRINT and TRUNC when TRUNC has nsw flag (PR #126217)

[Phoebe Wang via llvm-commits]

phoebewang wrote:

> @phoebewang have you looked into compiling `(int)rintf(x)` to `cvtss2si`?

Do you mean the FE proposes I posted before? No, it's not in my priority list. But I don't think we need to wait for it, there are many nsw/nuw trunc transformations if you search in the tests.

https://github.com/llvm/llvm-project/pull/126217