Called value propagation pass

Hi,

I wanted to give everyone a heads up that I’m planning to add a new pass to the pipeline after IPSCCP. For indirect call sites having a small set of possible callees, the pass attaches metadata to the call sites indicating what those callees are. I plan to use the metadata to facilitate optimizations like intersecting the function attributes of the possible callees, refining the call graph, performing indirect call promotion, etc. The patch has been reviewed at https://reviews.llvm.org/D37355 if you’d like to take a look.

Thanks!

– Matt