 * Significant changes to the preheader insertion pass:    - Now we perform loop exit-block splitting to ensure exit blocks are      always dominated by the loop header.    - We now preserve dominance frontier information    - This fixes bug: LICM/2003-02-26-LoopExitNotDominated.ll
 * Significant changes to the preheader insertion pass:
   - Now we perform loop exit-block splitting to ensure exit blocks are
     always dominated by the loop header.
   - We now preserve dominance frontier information
   - This fixes bug: LICM/2003-02-26-LoopExitNotDominated.ll


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@5652 91177308-0d34-0410-b5e6-96231b3b80d8

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