[PATCH] Rewrite calculateDbgValueHistory to make it (hopefully) more transparent.

[David Blaikie]

Given that this is a substantial rewrite/change to the algorithm, would it be worthwhile to make it even more readable to begin with. What I have in mind (but perhaps it doesn't make sense - this is just an off-the-cuff idea) is trying to break down the new algorithm into some smaller functions with meaningful names that would make it easier to read through the code.

(since I'm going to have to read through the new code and understand it from scratch, since it doesn't map simply to the old algorithm, even if they produce the same result)

http://reviews.llvm.org/D3597