A method for processing data in a graphics processing unit (GPU) including receiving an instance identifier for an instance and a shader program comprising a preamble code block and a main shader code block, assigning, the instance identifier to a general purpose register at wave creation, allocating address space within the constant memory for instance uniforms, and determining the preamble code block has not been executed and the wave is a first wave of the instance to be executed, based on determining the preamble code block has not been executed and the wave is the first wave to be executed, executing the preamble code block to store the plurality of instance uniforms in the constant memory and based, at least in part, on executing the preamble code block, executing the wave of the plurality of waves using at least one of the plurality of instance constants stored inconstant memory.