SELECTIVE BRANCH TARGET BUFFER (BTB) ALLOCATION

摘要

Information is processed in a data processing system having a branch target buffer (BTB) (31). In one form, an instruction is received and decoded. A determination is made whether the instruction is a taken branch instruction based on a condition code value (33) set by one of a logical operation, an arithmetic operation or a comparison result of the execution of another instruction or execution of the instruction. An instruction specifier (50) associated with the taken branch instruction is used to determine whether to allocate an entry of the branch target buffer for storing a branch target of the taken branch instruction. In one form the instruction specifier is a field of the instruction. Depending upon the value of the branch target buffer allocation specifier, the instruction fetch unit (30) will not allocate an entry in the branch target buffer for unconditional branch instructions.