ShadowChicken should integrate with DFG's existing debug data about inlined tail calls

• Component: JavaScriptCore
• Status: NEW ---

[Filip Pizlo]

Currently ShadowChicken will give you confusing information when there was inlining.  That's easy to fix.  ShadowChicken doesn't need to log anything about tail calls.  We can just use the DFG's existing InlineCallFrame meta-data to fill in the missing frames.

To do this well, we need to refactor StackVisitor.  There shouldn't be a thing called StackVisitor.  There should be a functor on CallFrame, and a full-fledged object like AbstractFrame.  AbstractFrame contains all of the data about a logical stack frame, i.e. either an inline frame or machine frame.  Then, ShadowChicken::Frame can just be replaced with AbstractFrame, and the CallFrame iteration functor would use it, too.