switch width {
		case 21:
			if (v<<11)>>11 != v {
				c.ctxt.Diag("21 bit-width, short branch too far\n%v", p)
			}
			o1 = OP_16IR_5I(c.opirr(as), uint32(v), uint32(rj))
		case 16:
			if (v<<16)>>16 != v {
				c.ctxt.Diag("16 bit-width, short branch too far\n%v", p)
			}
			o1 = OP_16IRR(c.opirr(as), uint32(v), uint32(rj), uint32(rd))
		default:
			c.ctxt.Diag("unexpected branch encoding\n%v", p)
		}

ProcStart dt=147800 p=2 p_seq=16
ProcStop dt=29
ProcStart dt=3880 p=1 p_seq=28
ProcStop dt=30
ProcStart dt=801175 p=5 p_seq=3
ProcStop dt=19
ProcStart dt=47961 p=6 p_seq=4
ProcStop dt=15
ProcStart dt=16716 p=6 p_seq=5
GoUnblock dt=60 g=6 g_seq=2 stack=0
GoStart dt=90 g=6 g_seq=3
HeapAlloc dt=193 heapalloc_value=26453304
GoBlock dt=29 reason_string=12 stack=15
ProcStop dt=12
ProcStart dt=704555 p=7 p_seq=10