A software-based instruction scoreboard indicates dependencies between closely-issued instructions issued to an arithmetic logic unit (ALU) pipeline. The software-based instruction scoreboard inserts one or more control words into the command stream between the dependent instructions, which is then executed by the ALU pipeline. The control words identify the instruction(s) upon which the dependent instructions depend (parent instructions) so that the GPU hardware can ensure that the ALU pipeline does not stall while the dependent instruction waits for results from the parent instruction.