Avoidance of Address Generation Interlock Delays on Branch Instructions
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
A decode history table is a device that predicts the outcome of conditional branches using the past history of the branch. The prediction accuracy of the table is in the range of 80 percent - 95 percent depending upon table size and sophistication. A significant number of conditional branches branmcare interlocked for address generation with earlier instructions. The interlocked address is significant in the decode/address generation phase only for the hedging fetches for the branch target instructions.If the interlock is on a conditional branch that eventually proves to be not taken, then waiting until address generation is complete for successful completion of the branch decode is an unnecessary delay.