These tests covers mulf, ori, and subi.
NFC
Note: I plan to add more tests to cover the other operators as well (div, add, xor, etc.) but I wanted to double check that the direction was okay first.
BTW, I may have found a bug in the sparsification pass. I found a case where it crashes, but maybe it's because my hand-generated IR is somehow invalid. See https://github.com/llvm/llvm-project/issues/59394 for more details.
can we make this CHECK-ON/CHECK-OFF to make it more consistent with style in this dir?