[llvm] [DA] Fix overflow in symbolic RDIV test (PR #185805)

[Ryotaro Kasuga via llvm-commits]

https://github.com/kasuga-fj commented:

Nit: Overflow checks are also necessary for the calculations of `C2_C1` and `C1_C2`.

This approach is the same one I had considered before but eventually decided not to pursue. If you have not checked yet, you may want to observe how the test results change when updating them with `utils/update_analyze_test_checks.py`. You will probably find that the Symbolic RDIV test can prove almost nothing in most cases. I think the Symbolic RDIV test has almost no analytical capability, and it might be better to remove it.
 
So, I think this change is "correct", but not very meaningful. I'm planning to propose to remove the Symbolic RDIV test in the following steps:
- A dependence test using `ConstantRange` was recently added in the Strong SIV test. Add the same test to all other SIV tests.
- Extract the logic into a single function. I believe the function will have roughly the same analysis capability as the "safe" Symbolic RDIV test.
- Replace the Symbolic RDIV test with the new function in some way.

Of course, this is just my plan, and I’m not sure whether others will agree with it.

https://github.com/llvm/llvm-project/pull/185805