seenSync := false

	// Helpers.
	handleSTW := func(r Range) bool {
		return flags&UtilSTW != 0 && isGCSTW(r)
	}
	handleMarkAssist := func(r Range) bool {
		return flags&UtilAssist != 0 && isGCMarkAssist(r)
	}
	handleSweep := func(r Range) bool {
		return flags&UtilSweep != 0 && isGCSweep(r)
	}

	// Iterate through the trace, tracking mutator utilization.
	var lastEv *Event
	for i := range events {