DW_op_reg in DW_OP_bit_piece is refused:
DWARF-2 expression error: DW_OP_reg operations must be used either alone or in
conjuction with DW_OP_piece.
I believe it is wrong, since DW_OP_bit_piece has same restrictions as
DW_OP_piece. I would like to use DW_OP_bit_piece in GCC to output SRAed
structures, so it would be cool to fix this ;)
AFAICT DW_OP_bit_piece is not handled at all.
I checked in a fix.