dfca6c0d3b
After unrolling, there may be additional simplifications that can be applied. One example is removing SCALAR-STEPS for the first part where only the first lane is demanded. This removes redundant adds of 0 from a large number of tests (~200), many which I am still working on updating. In preparation for removing redundant WideIV steps added in https://github.com/llvm/llvm-project/pull/119284. PR: https://github.com/llvm/llvm-project/pull/123655