imageworks/OpenShadingLanguage — pull request #277 by fpsunflower (2013-07-17 23:45:08+00:00)
Title: Make sure multiplying by a closure by 0 produces NULL

This small change gives a measurable speedup with small shaders in which the optimizer cannot prove that the closure weights are 0 (because they come from texture lookups or `lockgeom=0` parameters).