Return address stack

Beginner

A stack of notes that remembers where to come back to after each helper part of a program finishes.

Novice

A small hardware stack that predicts where a function will return to: a call pushes the address after it, and a return pops it. It is much more accurate for returns than a branch target buffer.

Expert

Typically tens of entries; fails on overflow or mismatched call/return. Its speculative pushes and pops must be repaired after a mispredict.

Explained in Branch prediction and out-of-order execution (Architectures).