The loop buffer is similar in principle to a cache dedicated to instructions. The differences are that the loop buffer only retains instructions in sequence and is much smaller in size and hence lower in cost.

Branch Prediction :

Various techniques can be used to predict whether a branch will be taken or not. The most common techniques are:

• Predict never taken


• Predict always taken


• Predict by opcode


• Taken/not taken switch


• Branch history table.

The first three approaches are static; they do not depend on the execution history upto the time of the contitional branch instructions.

The later two approaches are dynamic- they depend on the execution history.