[llvm] [DA] Rewrite the formula in the Strong SIV test (PR #179665)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

@amehsan Could you please clarify whether you intend to block this PR? From my perspective, your objection seems to rely on your proof, which others have not agreed with so far. If you don't intend to block the PR, I would like to proceed with merging once another reviewer approves it, as I believe merging a PR with a single dissenting opinion is not uncommon.

https://github.com/llvm/llvm-project/pull/179665