Patent ID: 7844806
Filing Date: 2010-11-30
Classification: G06F

Abstract:
1. In a microprocessor system using pipelined instruction processing, a method for updating a global history prediction record, the method comprising: accepting a first microprocessor instruction of consecutive operations, including a first conditional branch operation with an associated first branch address, at a first stage in a pipelined microprocessor execution process; accessing a current value from a global history record (GHR) of conditional branch resolutions and predictions; hashing the current global history record value with the first branch address, creating a first hash result; using the first hash result to access an indexed branch history table (BHT) of branch direction counts; using the BHT, making a first branch prediction; only in response to the first branch prediction being “taken”, left-shifting the current GHR value; hashing the left-shifted GHR with the first branch address, creating a second hash result; and, supplying the second hash result from a register to the GHR as an updated GHR value.