For a RISC target that doesn't allow memory-indirect addressing, the
proper way to represent an access of a symbol found in the GOT is to
first load the symbol from the GOT into a register, and then use
that register for memory access or call as needed.

For proper scheduling and instruction selection, the symbol load
source should be represented as what it is, i.e. a MEM.
So we have a (MEM (unspec ... UNSPEC_GOT)) .
For the purposes of debug output, this should be translated back into
the symbol_ref it represents.

However, loc_descriptor looks only into the address inside a MEM,
it does not process the entire mem with targetm.delegitimize_address.
I.e. there is no way to get rid of the MEM if it is not nested in
another MEM.