[llvm] [DA] Add option to run only SIV routines (PR #157084)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

> I don't mind a debugging option, but just wanted to check: the hierarchy of checks is that it performs SIV first before doing the others. So, does it matter for testing that some other checks might be running afterwards?

Yes. The issue arises because SIVs run first. The problems are:

- Almost all functions now fail to handle overflows correctly, leading to incorrect results.
- Even if we only fix the SIV functions, subsequent checks can still return incorrect results, in which case the overall outcome does not change.
- As a result, currently it's difficult (or even impossible) to verify through regression tests whether the fix for SIV functions is correct or not.

Therefore, this option is useful to ensure that at least the SIV functions work correctly, even if other checks might produce incorrect results.

https://github.com/llvm/llvm-project/pull/157084