The LIRAssembler::leal member function on SPARC complains about loading the effecting addresses where the address has an index operand, with the following assert stating it is not yet supported:

assert(addr->index()->is_illegal() && addr->scale() == LIR_Address::times_1, "can't handle complex addresses yet");

Support for index operands in the address is required for subsequent changes, therefore it needs to be supported.