Decompose GVN::processNonLocalLoad() (about 400 LOC) into smaller helper functions. No function change. 
Decompose GVN::processNonLocalLoad() (about 400 LOC) into smaller helper functions. No function change. 

This function consists of following steps:
   1. Collect dependent memory accesses.
   2. Analyze availability.
   3. Perform fully redundancy elimination, or 
   4. Perform PRE, depending on the availability

 Step 2, 3 and 4 are now moved to three helper routines.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@181047 91177308-0d34-0410-b5e6-96231b3b80d8

dslab-epfl/asap,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,dslab-epfl/asap,apple/swift-llvm,dslab-epfl/asap,apple/swift-llvm,chubbymaggie/asap,chubbymaggie/asap,llvm-mirror/llvm,dslab-epfl/asap,llvm-mirror/llvm,chubbymaggie/asap,dslab-epfl/asap,chubbymaggie/asap,chubbymaggie/asap,GPUOpen-Drivers/llvm,apple/swift-llvm,chubbymaggie/asap,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,dslab-epfl/asap,llvm-mirror/llvm,dslab-epfl/asap,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm