The dwarf FPR numbers are supposed to have the order F0, F2, F4, F6,
F1, F3, F5, F7, F8, etc., which matches the pairing of registers for
long doubles. E.g. a long double stored in F0 is paired with F2.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212701 91177308-0d34-0410-b5e6-96231b3b80d8