// than regular goroutine switches, so this path is heavily
// optimized to remove unnecessary work.
// The fast path here is three CAS: the one at the top on gp.atomicstatus,
// the one in the middle to choose the next g,
// and the one at the bottom on gnext.atomicstatus.
// It is important not to add more atomic operations or other
// expensive operations to the fast path.
func coroswitch_m(gp *g) {
	c := gp.coroarg

	// TODO(49370): This code is riddled with write barriers, but called from
	// a signal handler. Add the go:nowritebarrierrec annotation and restructure
	// this to avoid write barriers.

	switch h.gp.atomicstatus.Load() {
	case _Grunning:
		if getg().m != h.mp {
			println("trap on wrong M", getg().m, h.mp)
			return false
		}
		// Save the signal context
		h.saveSigContext(ctxt)
		// Set PC to debugCallV2.

	const yieldDelay = 5 * 1000
	var nextYield int64

	// loop if gp->atomicstatus is in a scan state giving
	// GC time to finish and change the state to oldval.
	for i := 0; !gp.atomicstatus.CompareAndSwap(oldval, newval); i++ {
		if oldval == _Gwaiting && gp.atomicstatus.Load() == _Grunnable {
			systemstack(func() {
				// Call on the systemstack to prevent throw from counting

	// 4. When a panic is recovered and control returns to the respective frame,
	//    param may point to a savedOpenDeferState.
	param        unsafe.Pointer
	atomicstatus atomic.Uint32
	stackLock    uint32 // sigprof/scang lock; TODO: fold in to atomicstatus
	goid         uint64
	schedlink    guintptr
	waitsince    int64      // approx time when the g become blocked
	waitreason   waitReason // if status==Gwaiting

	if readgstatus(gp)&_Gscan == 0 {
		print("runtime:scanstack: gp=", gp, ", goid=", gp.goid, ", gp->atomicstatus=", hex(readgstatus(gp)), "\n")
		throw("scanstack - bad status")
	}

	switch readgstatus(gp) &^ _Gscan {
	default:
		print("runtime: gp=", gp, ", goid=", gp.goid, ", gp->atomicstatus=", readgstatus(gp), "\n")
		throw("mark - bad status")
	case _Gdead:
		return 0
	case _Grunning:

	return 1 << s
}

// Called from runtime·morestack when more stack is needed.
// Allocate larger stack and relocate to new stack.
// Stack growth is multiplicative, for constant amortized cost.
//
// g->atomicstatus will be Grunning or Gscanrunning upon entry.
// If the scheduler is trying to stop this g, then it will set preemptStop.
//
// This must be nowritebarrierrec because it can be called as part of