Circuitry and method

Circuitry comprises memory access circuitry to control memory access by mapping virtual memory addresses in a virtual memory address space to physical memory addresses in a physical memory address space, the memory access circuitry being configured to provide a sparse mapping in which a mapped subset of the virtual memory address space is mapped to physical memory while an unmapped subset of the virtual memory address space is unmapped, the memory access circuitry being configured to discard write operations to virtual memory addresses in the unmapped subset of the virtual memory address space and processing circuitry to execute program code defining a processing operation to generate processed data and to store the processed data in a memory region of the virtual memory address space applicable to that processing operation; detector circuitry to detect whether the memory region is entirely within the unmapped subset of the virtual memory address space.