This is the largest remaining direct user of CallSite in the IR
I pushed this change down through most of the statepoint infrastructure,
completely removing the use of CallSite where I could reasonably do so.
I ended up making a couple of cut-points: generic call handling
(instcombine, TLI, SDAG). As soon as it hit truly generic handling with
users outside the immediate code, I simply transitioned into or out of
a CallSite to make this a reasonable sized chunk.
The next big chunk will be cleaning out the Analysis APIs, however it
may be unreasonable to make easy cut points there and so I may jointly
migrate all of Analysis and Transforms due to their tightly coupled
The last big chunk will be migrating codegen and SDAG.
Amidst these, of course, will be migrating implementation-only code in
various libraries when convenient. However, that is likely to be less