Data processing apparatus and method for processing a received workload in order to generate result data

A data processing apparatus and method are provided for processing a received workload in order to generate result data. A thread group generator generates from the received workload a plurality of thread groups to be executed to process the received workload. Each thread group consists of a plurality of threads, and at least one thread group has an inter-thread dependency existing between the plurality of threads. Each thread may be either an active thread whose output is required to form the result data, or a dummy thread required to resolve the inter-thread dependency for one of the active threads but whose output is not required to form the result data. The thread group generator identifies for each thread group any dummy thread within that thread group. A thread execution unit then executes each thread within a thread group received from the thread group generator by executing a predetermined program comprising a plurality of program instructions. Execution flow modification circuitry is responsive to the received thread group having at least one dummy thread, to cause the thread execution unit to selectively omit at least part of the execution of at least one of the plurality of instructions when executing each dummy thread, in dependence on control information associated with the predetermined program. In one particular embodiment the received workload is a graphics rendering workload and the thread execution unit performs graphics rendering operations in order to generate as the result data pixel values and associated control values. Such an approach can yield significant improvements in performance, as well as reducing power consumption.