[llvm] [DAG] Fold urem(urem(A, BCst), Op1Cst) -> urem(A, Op1Cst) (PR #159517)

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kper wrote:

> The logic looks correct to me. But should it have a "one use" check, like was mentioned in #157644?

I wasn't really sure. We only added it because it showed that we're breaking up the div+rem patterns. Beside that there wasn't a functional reason. So should I add it again?

https://github.com/llvm/llvm-project/pull/159517