// hide pointers from the GC. Use with care and sparingly.
// It is safe to use with values not found in the Go heap.
// Prefer CompareAndSwap instead.
//
//go:nosplit
func (p *Pointer[T]) CompareAndSwapNoWB(old, new *T) bool {
	return p.u.CompareAndSwapNoWB(unsafe.Pointer(old), unsafe.Pointer(new))
}

// CompareAndSwap atomically (with respect to other methods)
// compares u's value with old, and if they're equal,

func ReadTrace() []byte {
top:
	var buf []byte
	var park bool
	systemstack(func() {
		buf, park = readTrace0()
	})
	if park {
		gopark(func(gp *g, _ unsafe.Pointer) bool {
			if !trace.reader.CompareAndSwapNoWB(nil, gp) {
				// We're racing with another reader.
				// Wake up and handle this case.
				return false
			}

			if g2 := traceReader(); gp == g2 {
				// New data arrived between unlocking