// Handle syscalls.
	if to == trace.GoSyscall {
		start := ev.Time()
		if from == trace.GoUndetermined {
			// Back-date the event to the start of the trace.
			start = ctx.startTime
		}
		// Write down that we've entered a syscall. Note: we might have no G or P here
		// if we're in a cgo callback or this is a transition from GoUndetermined
		// (i.e. the G has been blocked in a syscall).
		gs.syscallBegin(start, goID, ev.Stack())

	// Handle syscalls.
	if to == trace.GoSyscall {
		start := ev.Time()
		if from == trace.GoUndetermined {
			// Back-date the event to the start of the trace.
			start = ctx.startTime
		}
		// Write down that we've entered a syscall. Note: we might have no P here
		// if we're in a cgo callback or this is a transition from GoUndetermined
		// (i.e. the G has been blocked in a syscall).
		gs.syscallBegin(start, ev.Thread(), ev.Stack())

			// Basic state transition validation.
			id := tr.Resource.Goroutine()
			old, new := tr.Goroutine()
			if new == trace.GoUndetermined {
				e.Errorf("transition to undetermined state for goroutine %d", id)
			}
			if v.seenSync && old == trace.GoUndetermined {
				e.Errorf("undetermined goroutine %d after first global sync", id)
			}
			if new == trace.GoNotExist && v.hasAnyRange(trace.MakeResourceID(id)) {

	if to == trace.GoSyscall && ev.Proc() != trace.NoProc {
		start := ev.Time()
		if from == trace.GoUndetermined {
			// Back-date the event to the start of the trace.
			start = ctx.startTime
		}
		// Write down that we've entered a syscall. Note: we might have no P here
		// if we're in a cgo callback or this is a transition from GoUndetermined
		// (i.e. the G has been blocked in a syscall).
		gs.syscallBegin(start, ev.Proc(), ev.Stack())

			File: f.File,
			Line: int(f.Line),
		})
		return true
	})
	return frames
}

func viewerGState(state trace.GoState, inMarkAssist bool) traceviewer.GState {
	switch state {
	case trace.GoUndetermined:
		return traceviewer.GDead
	case trace.GoNotExist:
		return traceviewer.GDead
	case trace.GoRunnable:
		return traceviewer.GRunnable
	case trace.GoRunning:
		return traceviewer.GRunning
	case trace.GoWaiting:

const NoGoroutine = GoID(-1)

// GoState represents the state of a goroutine.
//
// New GoStates may be added in the future. Users of this type must be robust
// to that possibility.
type GoState uint8

const (
	GoUndetermined GoState = iota // No information is known about the goroutine.
	GoNotExist                    // Goroutine does not exist.
	GoRunnable                    // Goroutine is runnable but not running.

				t.Errorf("found region start event for the wrong resource: wanted goroutine %d, got %s", goid, st.Resource)
			}
			if old, _ := st.Goroutine(); old != trace.GoNotExist && old != trace.GoUndetermined {
				t.Errorf("expected transition from GoNotExist or GoUndetermined, got transition from %s instead", old)
			}
		}
	default:
		t.Errorf("unexpected want start event type: %s", wantStart)
	}

	switch wantEnd {
	case trace.EventBad:

				break
			}

			// Handle transition out.
			g := s.gs[id]
			switch old {
			case GoUndetermined, GoNotExist:
				g = &GoroutineSummary{ID: id, goroutineSummary: &goroutineSummary{}}
				// If we're coming out of GoUndetermined, then the creation time is the
				// time of the last sync.
				if old == GoUndetermined {
					g.CreationTime = s.syncTs
				} else {
					g.CreationTime = ev.Time()
				}

		}
		s.seq = makeSeq(gen, 0) // Reset seq.
	} else if gen == o.initialGen {
		// Set the state.
		o.gStates[gid] = &gState{id: gid, status: status, seq: makeSeq(gen, 0)}
		oldState = GoUndetermined
	} else {
		return curCtx, false, fmt.Errorf("found goroutine status for new goroutine after the first generation: id=%v status=%v", gid, status)
	}