1. A graphics processing unit, comprising: at least one execution unit, the execution unit configured to execute a shader, the shader comprising instructions that are to cause the execution unit to: process a plurality of pixels in parallel until each of the plurality of pixels is discarded and execution of a last write instruction; and execute a conditional end of thread instruction after each of the plurality of pixels is discarded and after execution of the last write instruction, wherein execution of the conditional end of thread instruction is to terminate the thread.