search for: ab7d333a

I have a CopyToReg that is moving a 16bit reg to a 32bit reg, it's currently being mapped out as a simple mov (not an ext), I would like to change that to an ext. It seemed that the SelDAG was the easiest and cleanest way to do this. I can change the mov to an extension MI in the .td file; however, I can't tell at that point whether it's a sext or a zext, so it seemed the SelDAG was