imageworks/OpenShadingLanguage — pull request #111 by lgritz (2012-02-15 19:38:24+00:00)
Title: Review: More aggressive elision of ops that only write to symbols that won't be subsequently read

Slight improvement on the last set of optimizations -- instead of only culling assignments to output params that aren't subsequently used (or connected downstream), cull *any* op that only writes to output params that won't be used.

Alas, it doesn't make a dramatic difference in performance. I can see from the debugging logs that it does find some additional ops to remove, but apparently most of the cullable ops were 'assign' after all. But let's do it anyway.