An information processor for executing a program comprising a plurality of separate program instructions is provided. The processor comprises processing logic operable to individually execute said separate program instructions of said program, an operand store operable to store operand values and an accelerator having a plurality of functional units. The accelerator executes a combined operation corresponding to a computational sub-graph of the separate program instructions by configuring individual ones of said plurality of functional units to perform particular processing operations associated with the combined operation. The accelerator executes the combined operation in dependence upon operand mapping data providing a mapping between operands of the combined operation and storage locations within said operand store and in dependence upon separately specified configuration data providing a mapping between the plurality of functional units and the particular processing operations. The configuration data can be re-used for different operand mappings.