Patent ID: 6055629
Filing Date: 2000-04-25
Classification: D06F,G06F

Abstract:
A method of updating a history register comprising a plurality of bits, each having a first value and a second value, to maintain the conditional branch history of one of a plurality of bunches of instructions comprising a plurality of instructions, at least one bunch of instructions including at least one conditional branch instruction, each conditional branch instruction having an actual taken state being selectable from a first state and a second state, the method comprising:determining the presence of at least one of the conditional branch instructions in the bunch of instructions having an actual taken state of the first state;responsive to the presence of at least one of the conditional branch instructions in the bunch of instructions having an actual taken state of the first state, shifting the first value into the history register;responsive to the absence of at least one conditional branch instructions in the bunch of instructions having an actual taken state of the first state, shifting the second value into the history register; andmaking branch predictions for all conditional branch instructions in the bunch of instructions based upon contents of the history register.