[llvm] [InstCombine] Fold X * (2^N + 1) >> N -> X + X >> N, or directly to X if X >> N is 0 (PR #90295)

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AtariDreams wrote:

> This PR looked sensible the last time I checked it -- now it contains another new random InstSimplify fold and also seems to change some one-use conditions.
> 
> Please learn some patience. Don't keep making random changes to your PR just because nobody is around to hit the merge button right this second. Do not ping PRs more often than once a week.

Not random. It is an alternate folding of the same pattern but if it meets more strict criteria.

https://github.com/llvm/llvm-project/pull/90295