| SET_TAG -- set TagReg if it exists
| GRAN_FETCH -- for GrAnSim only -- HWL
| GRAN_RESCHEDULE -- for GrAnSim only -- HWL
| GRAN_FETCH_AND_RESCHEDULE -- for GrAnSim only -- HWL
| THREAD_CONTEXT_SWITCH -- for GrAnSim only -- HWL
| GRAN_YIELD -- for GrAnSim only -- HWL
| SET_TAG -- set TagReg if it exists
| GRAN_FETCH -- for GrAnSim only -- HWL
| GRAN_RESCHEDULE -- for GrAnSim only -- HWL
| GRAN_FETCH_AND_RESCHEDULE -- for GrAnSim only -- HWL
| THREAD_CONTEXT_SWITCH -- for GrAnSim only -- HWL
| GRAN_YIELD -- for GrAnSim only -- HWL