legalize-ext-csedebug-output.mir fails in a reverse iteration build because the OpcodeHitTable is a DenseMap and is iterated to print CSEInfo. We could have copied OpcodeHitTable to a vector and sorted it before iteration. Maybe that would be an overkill. I saw this comment in the test that we could regex the opcodes. Do we care about the order of the CSEInfo opcodes?