is 24 bits not 20 and the decoding needed to correctly handle converting the
J1 and J2 bits to their I1 and I2 values to reconstruct the displacement.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166982 91177308-0d34-0410-b5e6-96231b3b80d8