Re: Segment register support for the i386

[Denis Chertykov <denisc at overta dot ru>]

Sergey Larin <larin@overta.ru> writes:


[...]

> Porting would be much more easier if all that we need is *.h file and
> instructions description file (*.id) that contains
> all kinds of machine instructions description of particular target
> look like RTL expressions.

Really I think only about something like this:

(define-address "VOID" ; for any mode
  (match_operand:HI 0 "immediate_operand" "")
  "/* remain C condition */"
  "%0"
  [(set_attr "cost" "4")])


(define-address "QI,HI,SI,SF"
  (match_operand:HI 0 "register_operand" "e")
  ""
  "*{
  switch (REGNO (operands[0]))
    {
    case REG_X: return \"X\";
    case REG_Y: return \"Y\";
    case REG_Z: return \"Z\";
    default:
      fatal (\"Incorrect register as address\");
    }
  }"
  [(set_attr "cost" "2")])

(define-address "QI,HI,SI,SF"
  (post_inc:HI (match_operand:HI 0 "register_operand" "e"))
  ""
  "*{
  switch (REGNO (operands[0]))
    {
    case REG_X: return \"X+\";
    case REG_Y: return \"Y+\";
    case REG_Z: return \"Z+\";
    default:
      fatal ("Incorrect register as address");
    }
  }"
  [(set_attr "cost" "2")
   (set_attr "mode_dependent" "1")])

(define-address "QI,HI,SI,SF"
  (plus:HI (match_operand:HI 0 "register_operand" "b")
	   (match_operand:HI 1 "const_int_operand" "I"))
  "INTVAL (operands[1]) >= 0 && INTVAL (operands[1]) <= 63"
  "*{
  if (REGNO (operands[0]) == REG_Y)
    return \"Y+%1\";
  else if (REGNO (operands[0] == REG_Z))
    return \"Z+%1\";
  else
    fatal (\"Incorrect register as address\");
  }"
  [(set_attr "cost" "2")])

This is a full (except pre_dec) description of the AVR addressing modes.

Where: `b' - base pointer regs;
       `e' - any reg which can be a pointer.
       `I' - numbers lower than 64 and more or equal than 0.

From this descriptions I can generate:
 - GO_IF_LEGITIMATE_ADDRESS;
 - LEGITIMIZE_RELOAD_ADDRESS;
 - ADDRESS_COST;
 - HAVE_POST_INCREMENT, HAVE_POST_DECREMENT,
   HAVE_PRE_INCREMENT, HAVE_PRE_DECREMENT;
 - BASE_REG_CLASS;
 - INDEX_REG_CLASS;
 - REGNO_MODE_OK_FOR_BASE_P;
 - REGNO_OK_FOR_INDEX_P;
 - REG_OK_FOR_BASE_P;
 - REG_OK_FOR_INDEX_P;

Any suggestions ?

Denis.