[llvm] KnownBits: refine high-bits of mul in signed case (PR #113051)

[Nikita Popov via llvm-commits]

nikic wrote:

> > For the future, can you please not create separate PRs for test additions and instead include them as a separate commit? Otherwise we cannot test the impact on llvm-opt-benchmark.
> 
> The test addition is included as the first commit in this PR, no?

Oh right, I got confused here. And I see now that your follow-up PR was already tested in https://github.com/dtcxzyw/llvm-opt-benchmark/pull/1591, and does not seem to provide benefit on real code.

https://github.com/llvm/llvm-project/pull/113051