4.2.3. Information Functions for the OpenRISC 1000 Architecture

These struct gdbarch functions provide information about the architecture.

set_gdbarch_return_value          (gdbarch, or1k_return_value);
set_gdbarch_breakpoint_from_pc    (gdbarch, or1k_breakpoint_from_pc);
set_gdbarch_single_step_through_delay
                                  (gdbarch, or1k_single_step_through_delay);
set_gdbarch_have_nonsteppable_watchpoint
                                  (gdbarch, 1);
switch (gdbarch_byte_order (gdbarch))
  {
  case BFD_ENDIAN_BIG:
    set_gdbarch_print_insn        (gdbarch, print_insn_big_or32);
    break;

  case BFD_ENDIAN_LITTLE:
    set_gdbarch_print_insn        (gdbarch, print_insn_little_or32);
    break;

  case BFD_ENDIAN_UNKNOWN:
    error ("or1k_gdbarch_init: Unknown endianism");
    break;
    }

or1k_return_value. This function tells GDB how a value of a particular type would be returned by the ABI. Structures/unions and large scalars (> 4 bytes) are placed in memory and returned by reference (RETURN_VALUE_ABI_RETURNS_ADDRESS. Smaller scalars are returned in GPR 11 (RETURN_VALUE_REGISTER_CONVENTION).
or1k_breakpoint_from_pc returns the breakpoint function to be used at a given program counter address. Since all OpenRISC 1000 instructions are the same size, this function always returns the same value, the instruction sequence for a l.trap instruction.
or1k_single_step_through_delay. This function is used to determine if a single stepped instruction is actually executing a delay slot. This is the case if the previously executed instruction was a branch or jump.
print_insn_big_or32 and print_insn_little_or32. There are two variants of the disassembler, depending on the endianism. The disassembler is discussed in more detail in Section 4.4.