Branch prediction circuit selector with instruction context related condition type determining

摘要

A processor having improved branch prediction accuracy includes at least one execution unit that executes sequential instructions and branch processing circuitry that processes branch instructions. The branch processing circuitry includes a number of branch prediction circuits that are each capable of providing a branch prediction for a conditional branch instruction and a selector that selects a branch prediction of a branch prediction circuit based upon the type of condition upon which the conditional branch instruction depends. The selector preferably includes hardware that determines the type of condition upon which the conditional branch instruction depends by reference to an instruction context defined by one or more instructions adjacent the conditional branch instruction in programmed sequence. The branch processing circuitry further includes path address logic that determines a path address of the selected branch prediction. Thus, branch prediction accuracy can be improved by considering the type of condition upon which a conditional branch instruction depends, rather than just branch history.