Preshaders: optimization of GPU programs

摘要

A shader program capable of execution on a GPU is analyzed for constant expressions. These constant expressions are replaced with references to registers or memory addresses on the GPU. A preshader is created that comprises two executable files. The first executable file contains the shader program with the each constant expression removed and replaced with a unique reference accessible by the GPU. The first file is executable at the GPU. A second file contains the removed constant expressions along with instructions to place the values generated at the associated reference. The second executable file is executable at a CPU. When the preshader is executed, an instance of the first file is executed at the GPU for each vertex or pixel that is displayed. One instance of the second file is executed at the CPU. As the preshader is executed, the constant expressions in the second file are evaluated and the resulting intermediate values are passed to each instance of the first file on the GPU.