[LLVMdev] Removing AvailableExternal values in GlobalDCE (was Re: RFC: ThinLTO Impementation Plan)

[David Chisnall]

On 8 Jun 2015, at 21:26, Eric Christopher <echristo at gmail.com> wrote:
> 
> We already have the injection machinery anyhow and that's only used to for some very small things (printing)

For what it’s worth, the GNUstep Objective-C runtime ships with an LLVM library that injects some optimisations that are specific to this Objective-C implementation into the pass sequence.  It’s not very widely used though, mainly because the lack of stability in the APIs (not to mention ABIs) for things that passes need mean that it’s basically impossible to ship out-of-tree passes unless you sync your release schedule with LLVMs.  This is a shame, as there are a lot of other libraries that would benefit from having specific optimisations for some of their common patterns (Qt springs to mind), but that’s a different discussion.

David