An apparatus comprising processing circuitry is provided, the processing circuitry comprising execution circuitry, commit circuitry, issue circuitry comprising an issue queue and selection circuitry, and a branch predictor. The processing circuitry is configured to identify a speculation barrier instruction in the commit queue. While an entry in the commit queue identifies a speculation barrier instruction, when a branch instruction that follows the speculation barrier instruction in the program order is selected for issue, the processing circuitry performs a first execution of the instruction, inhibiting updating of branch prediction data items associated with the branch instruction and inhibiting the selection circuitry from invalidating the associated issue queue entry. When the speculation barrier instruction completes, the processing circuitry is configured to perform a second execution of the instruction, updating the branch prediction data items associated with the branch instruction and allowing the issue circuitry to invalidate the associated issue queue entry.