This is not correct, need to be careful with mapping!

MapDirtyDirtyInIn takes care to NOT load the first two registers, unless they clash with the other ones. This works fine for MULTU where they are pure outputs, but in case of SMLAL and UMLAL they are also inputs!

Need to make a new MapLDirtyLDirtyInIn or something that considers them inputs too. Right now, depending on the instructions before, the output of these two is unpredictable.