[llvm] [InstCombine] Simplify with.overflow intrinsics with assumption information (PR #84016)

[Quentin Dian via llvm-commits]

DianQK wrote:

> @DianQK Should I close this PR since [rust-lang/rust#122975](https://github.com/rust-lang/rust/pull/122975) landed?

I believe it will take at least two more PRs to resolve this issue. The first one is https://github.com/rust-lang/rust/pull/123256#issuecomment-2029075872.

Given the differences in inlining rules between Rust and LLVM, there are likely some edge cases that still cannot be resolved.

https://github.com/llvm/llvm-project/pull/84016