What do LatestWriteMap and GlobalActiveWritesMap do?

[hengxin]

1. How to update GlobalActiveWritesMap?
   • in computing intervals
   • in applying W'WR order
2. How to update LatestWriteMap?
   • in computing intervals
   • in applying W'WR order
3. Does GlobalActiveWritesMap matter?
   • not necessary to keep it accurate?
4. Does LatestWriteMap matter?
   • YES. for cycle detection.