Hints in a data processing apparatus

Abstract

An apparatus has processing circuitry to perform processing operations specified by program instructions and loop control circuitry to identify a program loop specified by the program instructions. On identification of a program loop, the loop control circuitry stores loop control data that indicates a program loop body, excluding any program flow control instructions that specify the program loop. The loop control circuitry controls the processing circuitry to carry out loop iterations of the program loop body indicated by the loop control data. The processing circuitry is responsive to a hint instruction occurring at the beginning of a given program loop body to cause loop control data for the given program loop to exclude the hint instruction from a modified program loop body and to perform a performance modifying operating procedure specified by the hint instruction when carrying out loop iterations of the modified program loop body. The omission of the hint instruction avoids needless repeated execution of the instruction on subsequent loop iterations.

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