Apparatus and method for performing branch prediction

A method of performing branch prediction in an apparatus having processing circuitry to execute instructions, and branch prediction circuitry to make branch outcome predictions in respect of branch instructions, the method comprising:

• providing within the branch prediction circuitry loop minimum iteration prediction circuitry having one or more entries, each entry being associated with a loop controlling branch instruction that controls repeated execution of a loop comprising a number of instructions;
• during a training phase for an entry, seeking to identify a minimum number of iterations of the associated loop;
• and
• when the training phase has successfully identified a minimum number of iterations, employing the loop minimum iteration prediction circuitry to subsequently identify a branch outcome prediction for the associated loop controlling branch instruction for use during each of the minimum number of iterations.

An apparatus comprising:

• processing means for executing instructions;
• and
• branch prediction means for making branch outcome predictions in respect of branch instructions;
• the branch prediction means including loop minimum iteration prediction means having one or more entries, each entry being associated with a loop controlling branch instruction that controls repeated execution of a loop comprising a number of instructions, and being arranged during a training phase to seek to identify a minimum number of iterations of the loop;
• the loop minimum iteration prediction means, when the training phase has successfully identified a minimum number of iterations, for subsequently identifying a branch outcome prediction for the associated loop controlling branch instruction for use during each of the minimum number of iterations.