m68hc11.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

stack_register_operand (operand, mode)
     rtx operand;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return SP_REG_P (operand);
}

int
d_register_operand (operand, mode)
     rtx operand;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  if (GET_MODE (operand) != mode && mode != VOIDmode)
    return 0;

  if (GET_CODE (operand) == SUBREG)
    operand = XEXP (operand, 0);

  return GET_CODE (operand) == REG
    && (REGNO (operand) >= FIRST_PSEUDO_REGISTER
	|| REGNO (operand) == HARD_D_REGNUM
        || (mode == QImode && REGNO (operand) == HARD_B_REGNUM));
}

int
hard_addr_reg_operand (operand, mode)
     rtx operand;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  if (GET_MODE (operand) != mode && mode != VOIDmode)
    return 0;

  if (GET_CODE (operand) == SUBREG)
    operand = XEXP (operand, 0);

  return GET_CODE (operand) == REG
    && (REGNO (operand) == HARD_X_REGNUM
	|| REGNO (operand) == HARD_Y_REGNUM
	|| REGNO (operand) == HARD_Z_REGNUM);
}

int
hard_reg_operand (operand, mode)
     rtx operand;
     enum machine_mode mode;
{
  if (GET_MODE (operand) != mode && mode != VOIDmode)
    return 0;

  if (GET_CODE (operand) == SUBREG)
    operand = XEXP (operand, 0);

  return GET_CODE (operand) == REG
    && (REGNO (operand) >= FIRST_PSEUDO_REGISTER
	|| H_REGNO_P (REGNO (operand)));
}

int
memory_indexed_operand (operand, mode)
     rtx operand;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  if (GET_CODE (operand) != MEM)
    return 0;

  operand = XEXP (operand, 0);
  if (GET_CODE (operand) == PLUS)
    {
      if (GET_CODE (XEXP (operand, 0)) == REG)
	operand = XEXP (operand, 0);
      else if (GET_CODE (XEXP (operand, 1)) == REG)
	operand = XEXP (operand, 1);
    }
  return GET_CODE (operand) == REG
    && (REGNO (operand) >= FIRST_PSEUDO_REGISTER
	|| A_REGNO_P (REGNO (operand)));
}

int
push_pop_operand_p (operand)
     rtx operand;
{
  if (GET_CODE (operand) != MEM)
    {
      return 0;
    }
  operand = XEXP (operand, 0);
  return PUSH_POP_ADDRESS_P (operand);
}

/* Returns 1 if OP is either a symbol reference or a sum of a symbol
   reference and a constant.  */

int
symbolic_memory_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  switch (GET_CODE (op))
    {
    case SYMBOL_REF:
    case LABEL_REF:
      return 1;

    case CONST:
      op = XEXP (op, 0);
      return ((GET_CODE (XEXP (op, 0)) == SYMBOL_REF
	       || GET_CODE (XEXP (op, 0)) == LABEL_REF)
	      && GET_CODE (XEXP (op, 1)) == CONST_INT);

      /* ??? This clause seems to be irrelevant.  */
    case CONST_DOUBLE:
      return GET_MODE (op) == mode;

    case PLUS:
      return symbolic_memory_operand (XEXP (op, 0), mode)
	&& symbolic_memory_operand (XEXP (op, 1), mode);

    default:
      return 0;
    }
}

int
m68hc11_eq_compare_operator (op, mode)
     register rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return GET_CODE (op) == EQ || GET_CODE (op) == NE;
}

int
m68hc11_logical_operator (op, mode)
     register rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return GET_CODE (op) == AND || GET_CODE (op) == IOR || GET_CODE (op) == XOR;
}

int
m68hc11_arith_operator (op, mode)
     register rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return GET_CODE (op) == AND || GET_CODE (op) == IOR || GET_CODE (op) == XOR
    || GET_CODE (op) == PLUS || GET_CODE (op) == MINUS
    || GET_CODE (op) == ASHIFT || GET_CODE (op) == ASHIFTRT
    || GET_CODE (op) == LSHIFTRT || GET_CODE (op) == ROTATE
    || GET_CODE (op) == ROTATERT;
}

int
m68hc11_non_shift_operator (op, mode)
     register rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return GET_CODE (op) == AND || GET_CODE (op) == IOR || GET_CODE (op) == XOR
    || GET_CODE (op) == PLUS || GET_CODE (op) == MINUS;
}

/* Return true if op is a shift operator.  */
int
m68hc11_shift_operator (op, mode)
     register rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return GET_CODE (op) == ROTATE || GET_CODE (op) == ROTATERT
    || GET_CODE (op) == LSHIFTRT || GET_CODE (op) == ASHIFT
    || GET_CODE (op) == ASHIFTRT;
}

int
m68hc11_unary_operator (op, mode)
     register rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return GET_CODE (op) == NEG || GET_CODE (op) == NOT
    || GET_CODE (op) == SIGN_EXTEND || GET_CODE (op) == ZERO_EXTEND;
}

/* Emit the code to build the trampoline used to call a nested function.
   
   68HC11               68HC12

   ldy #&CXT            movw #&CXT,*_.d1
   sty *_.d1            jmp FNADDR
   jmp FNADDR

*/
void
m68hc11_initialize_trampoline (tramp, fnaddr, cxt)
     rtx tramp;
     rtx fnaddr;
     rtx cxt;
{
  const char *static_chain_reg = reg_names[STATIC_CHAIN_REGNUM];

  /* Skip the '*'.  */
  if (*static_chain_reg == '*')
    static_chain_reg++;
  if (TARGET_M6811)
    {
      emit_move_insn (gen_rtx_MEM (HImode, tramp), GEN_INT (0x18ce));
      emit_move_insn (gen_rtx_MEM (HImode, plus_constant (tramp, 2)), cxt);
      emit_move_insn (gen_rtx_MEM (HImode, plus_constant (tramp, 4)),
                      GEN_INT (0x18df));
      emit_move_insn (gen_rtx_MEM (QImode, plus_constant (tramp, 6)),
                      gen_rtx_CONST (QImode,
                                     gen_rtx_SYMBOL_REF (Pmode,
                                                         static_chain_reg)));
      emit_move_insn (gen_rtx_MEM (QImode, plus_constant (tramp, 7)),
                      GEN_INT (0x7e));
      emit_move_insn (gen_rtx_MEM (HImode, plus_constant (tramp, 8)), fnaddr);
    }
  else
    {
      emit_move_insn (gen_rtx_MEM (HImode, tramp), GEN_INT (0x1803));
      emit_move_insn (gen_rtx_MEM (HImode, plus_constant (tramp, 2)), cxt);
      emit_move_insn (gen_rtx_MEM (HImode, plus_constant (tramp, 4)),
                      gen_rtx_CONST (HImode,
                                     gen_rtx_SYMBOL_REF (Pmode,
                                                         static_chain_reg)));
      emit_move_insn (gen_rtx_MEM (QImode, plus_constant (tramp, 6)),
                      GEN_INT (0x06));
      emit_move_insn (gen_rtx_MEM (HImode, plus_constant (tramp, 7)), fnaddr);
    }
}

/* Declaration of types.  */

const struct attribute_spec m68hc11_attribute_table[] =
{
  /* { name, min_len, max_len, decl_req, type_req, fn_type_req, handler } */
  { "interrupt", 0, 0, false, true,  true,  m68hc11_handle_fntype_attribute },
  { "trap",      0, 0, false, true,  true,  m68hc11_handle_fntype_attribute },
  { "far",       0, 0, false, true,  true,  m68hc11_handle_fntype_attribute },
  { "near",      0, 0, false, true,  true,  m68hc11_handle_fntype_attribute },
  { NULL,        0, 0, false, false, false, NULL }
};

/* Keep track of the symbol which has a `trap' attribute and which uses
   the `swi' calling convention.  Since there is only one trap, we only
   record one such symbol.  If there are several, a warning is reported.  */
static rtx trap_handler_symbol = 0;

/* Handle an attribute requiring a FUNCTION_TYPE, FIELD_DECL or TYPE_DECL;
   arguments as in struct attribute_spec.handler.  */
static tree
m68hc11_handle_fntype_attribute (node, name, args, flags, no_add_attrs)
     tree *node;
     tree name;
     tree args ATTRIBUTE_UNUSED;
     int flags ATTRIBUTE_UNUSED;
     bool *no_add_attrs;
{
  if (TREE_CODE (*node) != FUNCTION_TYPE
      && TREE_CODE (*node) != METHOD_TYPE
      && TREE_CODE (*node) != FIELD_DECL
      && TREE_CODE (*node) != TYPE_DECL)
    {
      warning ("`%s' attribute only applies to functions",
	       IDENTIFIER_POINTER (name));
      *no_add_attrs = true;
    }

  return NULL_TREE;
}

/* We want to recognize trap handlers so that we handle calls to traps
   in a special manner (by issuing the trap).  This information is stored
   in SYMBOL_REF_FLAG.  */

static void
m68hc11_encode_section_info (decl, first)
     tree decl;
     int first ATTRIBUTE_UNUSED;
{
  tree func_attr;
  int trap_handler;
  int is_far = 0;
  rtx rtl;
  
  if (TREE_CODE (decl) != FUNCTION_DECL)
    return;

  rtl = DECL_RTL (decl);

  func_attr = TYPE_ATTRIBUTES (TREE_TYPE (decl));


  if (lookup_attribute ("far", func_attr) != NULL_TREE)
    is_far = 1;
  else if (lookup_attribute ("near", func_attr) == NULL_TREE)
    is_far = TARGET_LONG_CALLS != 0;

  trap_handler = lookup_attribute ("trap", func_attr) != NULL_TREE;
  if (trap_handler && is_far)
    {
      warning ("`trap' and `far' attributes are not compatible, ignoring `far'");
      trap_handler = 0;
    }
  if (trap_handler)
    {
      if (trap_handler_symbol != 0)
        warning ("`trap' attribute is already used");
      else
        trap_handler_symbol = XEXP (rtl, 0);
    }
  SYMBOL_REF_FLAG (XEXP (rtl, 0)) = is_far;
}

int
m68hc11_is_far_symbol (sym)
     rtx sym;
{
  if (GET_CODE (sym) == MEM)
    sym = XEXP (sym, 0);

  return SYMBOL_REF_FLAG (sym);
}

int
m68hc11_is_trap_symbol (sym)
     rtx sym;
{
  if (GET_CODE (sym) == MEM)
    sym = XEXP (sym, 0);

  return trap_handler_symbol != 0 && rtx_equal_p (trap_handler_symbol, sym);
}


/* Argument support functions.  */

/* Handle the FUNCTION_ARG_PASS_BY_REFERENCE macro.
   Arrays are passed by references and other types by value.

   SCz: I tried to pass DImode by reference but it seems that this
   does not work very well.  */
int
m68hc11_function_arg_pass_by_reference (cum, mode, type, named)
     const CUMULATIVE_ARGS *cum ATTRIBUTE_UNUSED;
     enum machine_mode mode ATTRIBUTE_UNUSED;
     tree type;
     int named ATTRIBUTE_UNUSED;
{
  return ((type && TREE_CODE (type) == ARRAY_TYPE)
	  /* Consider complex values as aggregates, so care for TCmode.  */
	  /*|| GET_MODE_SIZE (mode) > 4 SCz, temporary */
	  /*|| (type && AGGREGATE_TYPE_P (type))) */ );
}


/* Define the offset between two registers, one to be eliminated, and the
   other its replacement, at the start of a routine.  */
int
m68hc11_initial_elimination_offset (from, to)
     int from;
     int to;
{
  int trap_handler;
  tree func_attr;
  int size;
  int regno;

  /* For a trap handler, we must take into account the registers which
     are pushed on the stack during the trap (except the PC).  */
  func_attr = TYPE_ATTRIBUTES (TREE_TYPE (current_function_decl));

  if (lookup_attribute ("far", func_attr) != 0)
    current_function_far = 1;
  else if (lookup_attribute ("near", func_attr) != 0)
    current_function_far = 0;
  else
    current_function_far = TARGET_LONG_CALLS != 0;

  trap_handler = lookup_attribute ("trap", func_attr) != NULL_TREE;
  if (trap_handler && from == ARG_POINTER_REGNUM)
    size = 7;

  /* For a function using 'call/rtc' we must take into account the
     page register which is pushed in the call.  */
  else if (current_function_far && from == ARG_POINTER_REGNUM)
    size = 1;
  else
    size = 0;

  if (from == ARG_POINTER_REGNUM && to == HARD_FRAME_POINTER_REGNUM)
    {
      /* 2 is for the saved frame.
         1 is for the 'sts' correction when creating the frame.  */
      return get_frame_size () + 2 + m68hc11_sp_correction + size;
    }

  if (from == FRAME_POINTER_REGNUM && to == HARD_FRAME_POINTER_REGNUM)
    {
      return m68hc11_sp_correction;
    }

  /* Push any 2 byte pseudo hard registers that we need to save.  */
  for (regno = SOFT_REG_FIRST; regno < SOFT_REG_LAST; regno++)
    {
      if (regs_ever_live[regno] && !call_used_regs[regno])
	{
	  size += 2;
	}
    }

  if (from == ARG_POINTER_REGNUM && to == HARD_SP_REGNUM)
    {
      return get_frame_size () + size;
    }

  if (from == FRAME_POINTER_REGNUM && to == HARD_SP_REGNUM)
    {
      return size;
    }
  return 0;
}

/* Initialize a variable CUM of type CUMULATIVE_ARGS
   for a call to a function whose data type is FNTYPE.
   For a library call, FNTYPE is 0.  */

void
m68hc11_init_cumulative_args (cum, fntype, libname)
     CUMULATIVE_ARGS *cum;
     tree fntype;
     rtx libname;
{
  tree ret_type;

  z_replacement_completed = 0;
  cum->words = 0;
  cum->nregs = 0;

  /* For a library call, we must find out the type of the return value.
     When the return value is bigger than 4 bytes, it is returned in
     memory.  In that case, the first argument of the library call is a
     pointer to the memory location.  Because the first argument is passed in
     register D, we have to identify this, so that the first function
     parameter is not passed in D either.  */
  if (fntype == 0)
    {
      const char *name;
      size_t len;

      if (libname == 0 || GET_CODE (libname) != SYMBOL_REF)
	return;

      /* If the library ends in 'di' or in 'df', we assume it's
         returning some DImode or some DFmode which are 64-bit wide.  */
      name = XSTR (libname, 0);
      len = strlen (name);
      if (len > 3
	  && ((name[len - 2] == 'd'
	       && (name[len - 1] == 'f' || name[len - 1] == 'i'))
	      || (name[len - 3] == 'd'
		  && (name[len - 2] == 'i' || name[len - 2] == 'f'))))
	{
	  /* We are in.  Mark the first parameter register as already used.  */
	  cum->words = 1;
	  cum->nregs = 1;
	}
      return;
    }

  ret_type = TREE_TYPE (fntype);

  if (ret_type && aggregate_value_p (ret_type))
    {
      cum->words = 1;
      cum->nregs = 1;
    }
}

/* Update the data in CUM to advance over an argument
   of mode MODE and data type TYPE.
   (TYPE is null for libcalls where that information may not be available.)  */

void
m68hc11_function_arg_advance (cum, mode, type, named)
     CUMULATIVE_ARGS *cum;
     enum machine_mode mode;
     tree type;
     int named ATTRIBUTE_UNUSED;
{
  if (mode != BLKmode)
    {
      if (cum->words == 0 && GET_MODE_SIZE (mode) == 4)
	{
	  cum->nregs = 2;
	  cum->words = GET_MODE_SIZE (mode);
	}
      else
	{
	  cum->words += GET_MODE_SIZE (mode);
	  if (cum->words <= HARD_REG_SIZE)
	    cum->nregs = 1;
	}
    }
  else
    {