func dropm() {
	// Clear m and g, and return m to the extra list.
	// After the call to setg we can only call nosplit functions
	// with no pointer manipulation.
	mp := getg().m

	// Emit a trace event for this syscall -> dead transition.
	//
	// N.B. the tracer can run on a bare M just fine, we just have
	// to make sure to do this before setg(nil) and unminit.
	var trace traceLocker
	if !mp.isExtraInSig {

		x15        = buildReg("X15")
		gpsp       = gp | buildReg("SP")
		gpspsb     = gpsp | buildReg("SB")
		gpspsbg    = gpspsb | g
		callerSave = gp | fp | g // runtime.setg (and anything calling it) may clobber g
	)
	// Common slices of register masks
	var (
		gponly = []regMask{gp}
		fponly = []regMask{fp}
	)

	// Common regInfo
	var (

    (Const64 <typ.Int> [0])
    (Const64 <typ.Int> [0]))

// interface ops
(ConstInterface) =>
  (IMake
    (ConstNil <typ.Uintptr>)
    (ConstNil <typ.BytePtr>))

(NilCheck ptr:(GetG mem) mem) => ptr

(If (Not cond) yes no) => (If cond no yes)
(If (ConstBool [c]) yes no) && c => (First yes no)
(If (ConstBool [c]) yes no) && !c => (First no yes)