Make the case I just checked in stronger.  Now we compile this:
Make the case I just checked in stronger.  Now we compile this:

short test2(short X, short x) {
  int Y = (short)(X+x);
  return Y >> 1;
}

to:

_test2:
        add r2, r3, r4
        extsh r2, r2
        srawi r3, r2, 1
        blr

instead of:

_test2:
        add r2, r3, r4
        extsh r2, r2
        srwi r2, r2, 1
        extsh r3, r2
        blr


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@28175 91177308-0d34-0410-b5e6-96231b3b80d8

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