type metricReader func() uint64

func (f metricReader) compute(_ *statAggregate, out *metricValue) {
	out.kind = metricKindUint64
	out.scalar = f()
}

//go:linkname godebug_registerMetric internal/godebug.registerMetric
func godebug_registerMetric(name string, read func() uint64) {
	metricsLock()
	initMetrics()
	d, ok := metrics[name]
	if !ok {
		throw("runtime: unexpected metric registration for " + name)
	}