Fix PR557 and basictest[34].ll.
Fix PR557 and basictest[34].ll.

This makes reassociate realize that loads should be treated as unmovable, and
gives distinct ranks to distinct values defined in the same basic block, allowing
reassociate to do its thing.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@21783 91177308-0d34-0410-b5e6-96231b3b80d8

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