Essentially this. There was a talk by Sony at the 2013 LLVM Developers' Meeting: http://llvm.org/devmtg/2013-11/#talk8 http://llvm.org/devmtg/2013-11/#talk8 Fr

Essentially this. There was a talk by Sony at the 2013 LLVM Developers' Meeting: http://llvm.org/devmtg/2013-11/#talk8 http://llvm.org/devmtg/2013-11/#talk8 From the slides: Initial development hampered by secrecy - Blanket secrecy policy included compiler project - No advice/feedback from the group consciousness - Sitting on features and bugs and fixes applicable upstream Clear value to working openly with upstream - File a bug; somebody else might fix it - Send a patch; people will review/advise - Bigger features can get better design review - Putting private changes upstream reduces merge pain And: Merging once per upstream release was a nightmare - We stuck our fingers in everywhere - The 3.0 merge work took three months