[llvm] [IRSim] Fix overlap() (PR #92988)

[Justin Fargnoli via llvm-commits]

justinfargnoli wrote:

Saved work [here](https://github.com/justinfargnoli/llvm-project/tree/origin/overlap).

Closing to focus on other priorities. 

Marking as a good first issue for another contributor to write up a test case. 

https://github.com/llvm/llvm-project/pull/92988