Updated the llvm.mem.parallel_loop_access semantics to include the possibility to have only some of the loop's memory instructions be annotated and still _help_ the loop carried dependence analysis. 
Updated the llvm.mem.parallel_loop_access semantics to include the possibility
to have only some of the loop's memory instructions be annotated and still _help_
the loop carried dependence analysis. 

This was discussed in the llvmdev ML (topic: "parallel loop metadata question").


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@209507 91177308-0d34-0410-b5e6-96231b3b80d8

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