Make instruction selection easier to parameterize.
Make instruction selection easier to parameterize.

Add stubbed version of generate_device_io. Causes assertion currently, need to debug.

jbush001/NyuziProcessor,FulcronZ/NyuziProcessor,hoangt/NyuziProcessor,FulcronZ/NyuziProcessor,FulcronZ/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor,hoangt/NyuziProcessor,hoangt/NyuziProcessor,jbush001/NyuziProcessor,hoangt/NyuziProcessor,jbush001/NyuziProcessor,FulcronZ/NyuziProcessor,jbush001/NyuziProcessor