ci := CallersFrames(pcs)
	for {
		f, more := ci.Next()
		frames = append(frames, makeTraceFrame(gen, f))
		if !more {
			return frames
		}
	}
}

type traceFrame struct {
	PC     uintptr
	funcID uint64
	fileID uint64
	line   uint64
}

// makeTraceFrame sets up a traceFrame for a frame.
func makeTraceFrame(gen uintptr, f Frame) traceFrame {
	var frame traceFrame
	frame.PC = f.PC

// stack ID for it.
//
// It then returns a traceArg representing that stack which may be
// passed to write.
func (tl traceLocker) startPC(pc uintptr) traceArg {
	// +PCQuantum because makeTraceFrame expects return PCs and subtracts PCQuantum.
	return traceArg(trace.stackTab[tl.gen%2].put([]uintptr{
		logicalStackSentinel,
		startPCForTrace(pc) + sys.PCQuantum,
	}))
}