[ArgPromote] Re-arrange the code in a more typical, logical way.
[ArgPromote] Re-arrange the code in a more typical, logical way.

This arranges the static helpers in an order where they are defined
prior to their use to avoid the need of forward declarations, and
collect the core pass components at the bottom below their helpers.

This also folds one trivial function into the pass itself. Factoring
this 'runImpl' was an attempt to help porting to the new pass manager,
however in my attempt to begin this port in earnest it turned out to not
be a substantial help. I think it will be easier to factor things
without it.

This is an NFC change and does a minimal amount of edits over all.
Subsequent NFC cleanups will normalize the formatting with clang-format
and improve the basic doxygen commenting.

Differential Revision: https://reviews.llvm.org/D29247

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@293424 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm