Address manipulation using indices and tags

A computer program product embodied in a non-transitory computer readable medium for address manipulation, the computer program product comprising code which causes one or more processors to perform operations of:

• generating a first index from one or more bits of a processor program counter, wherein the first index is used to access a branch predictor bimodal table;
• providing a first branch prediction from the bimodal table, based on the first index;
• matching the first branch prediction against N tables, wherein N is three or more, wherein the tables contain prior branch histories, and wherein:
• the branch history in table T(N) is of greater length than the branch history of table T(N−1);
• and
• the branch history in table T(N−1) is of greater length than the branch history of table T(N−2);
• manipulating a processor address using a greatest length of hits of branch prediction matches from the N tables, based on one or more hits occurring;
• and
• manipulating the branch predictor address using the first branch prediction from the bimodal table, based on zero hits occurring.

A computer system for address manipulation comprising:

• a memory which stores instructions;
• one or more processors attached to the memory wherein the one or more processors, when executing the instructions which are stored, are configured to:
• generate a first index from one or more bits of a processor program counter, wherein the first index is used to access a branch predictor bimodal table;
• provide a first branch prediction from the bimodal table, based on the first index;
• match the first branch prediction against N tables, wherein N is three or more, wherein the tables contain prior branch histories, and wherein:
• the branch history in table T(N) is of greater length than the branch history of table T(N−1);
• and
• the branch history in table T(N−1) is of greater length than the branch history of table T(N−2);
• manipulate a processor address using a greatest length of hits of branch prediction matches from the N tables, based on one or more hits occurring;
• and
• manipulate the branch predictor address using the first branch prediction from the bimodal table, based on zero hits occurring.