Method and apparatus for recovering from branch misprediction

An apparatus for executing a branch instruction, comprising:

• a processor;
• a branch prediction unit on the processor;
• a fetch unit on the processor;
• wherein during execution of the branch instruction by the processor, the fetch unit fetches subsequent instructions for execution based on a stored prediction of a resolution of the branch instruction provided to the fetch unit by the branch prediction unit;
• if an actual resolution of the branch instruction is different from the predicted resolution, the processor
• updates the stored prediction of the resolution of the branch instruction to the actual resolution of the branch instruction;
• and
• re-executes the branch instruction, wherein when re-executing the branch instruction, the fetch unit fetches subsequent instructions for execution based on the updated stored prediction for the resolution of the branch instruction provided to the fetch unit by the branch prediction unit.

A computer system for executing a branch instruction, comprising:

• a processor;
• a memory coupled to the processor, wherein the memory stores data for the processor;
• a branch prediction unit on the processor;
• a fetch unit on the processor;
• wherein during execution of the branch instruction by the processor, the fetch unit fetches subsequent instructions for execution from the memory based on a stored prediction of a resolution of the branch instruction provided to the fetch unit by the branch prediction unit;
• if an actual resolution of the branch instruction is different from the predicted resolution, the processor
• updates the stored prediction of the resolution of the branch instruction to the actual resolution of the branch instruction;
• and
• re-executes the branch instruction, wherein when re-executing the branch instruction, the fetch unit fetches subsequent instructions for execution from the memory based on the updated stored prediction for the resolution of the branch instruction provided to the fetch unit by the branch prediction unit.