[llvm] [InstCombine] Fold logic of zero-checks to multiplication for MinSize (PR #171805)

[via llvm-commits]

TelGome wrote:

> Should the title say [DAGCombine]?

Yes, that makes sense. The issue is labeled `llvm:instcombine`, so I named it accordingly. But I'm fine with updating the title to `[DAGCombine]` if that's more appropriate.

https://github.com/llvm/llvm-project/pull/171805