* Compute the attrib values on the upper-left corner of each quad.
*/
- a = LLVMBuildFAdd(builder, a, dadq2, "");
+ if (interp != LP_INTERP_CONSTANT &&
+ interp != LP_INTERP_FACING) {
+ a = LLVMBuildFAdd(builder, a, dadq2, "");
+ }
#if PERSPECTIVE_DIVIDE_PER_QUAD
/*