1. A method for optimizing graphics program execution, comprising: accessing a graphics program using a programmable shader pipeline of a GPU (graphics processor unit); if a texture projective instruction is included in the graphics program, determining whether a texture projective parameter indicates a non-projective texture; replacing the texture projective instruction with a demoted texture projective instruction when the parameter indicates a non-projective texture; and executing the demoted texture instruction using a plurality of interpolators of the shader pipeline.