1.BHT (too much hardware)
every branch has a private counter(SN WN WT ST) [N bit] [counter0] [counter1] [counter2].....[counter 2^N]
2.G-Share (good for if()...if()...)
use global branch result to index a counter [g] [counter0] [counter1]
3.P-Share (good for for(...)...)
XOR the pc bit and the BHT to index a counter [pc bits] ^ [BHT] ---> counter
4.Combine G-share and P-share
