[llvm] [DAG] Fold add(mul(add(A, CA), CM), CB) -> add(mul(A, CM), CM*CA+CB) (PR #90860)

[David Green via llvm-commits]

davemgreen wrote:

Also, as I think it might come up - there is no change in vector code because isLegalAddImmediate can't handle the immediates (and the examples I tried looked a little worse overall).

https://github.com/llvm/llvm-project/pull/90860