rs6000.c

gcc库的原代码,对编程有很大帮助.

  low = operand_subword (op, 1, 0, mode);

  if (high == 0 || ! input_operand (high, word_mode))
    return 0;

  return (mode == SFmode
	  || (low != 0 && input_operand (low, word_mode)));
}

/* Return 1 if the operand is an offsettable memory address.  */

int
offsettable_addr_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return offsettable_address_p (reload_completed | reload_in_progress,
				mode, op);
}

/* Return 1 if the operand is either a floating-point register, a pseudo
   register, or memory.  */

int
fp_reg_or_mem_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (memory_operand (op, mode)
	  || (register_operand (op, mode)
	      && (GET_CODE (op) != REG
		  || REGNO (op) >= FIRST_PSEUDO_REGISTER
		  || FP_REGNO_P (REGNO (op)))));
}

/* Return 1 if the operand is either an easy FP constant (see above) or
   memory.  */

int
mem_or_easy_const_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return memory_operand (op, mode) || easy_fp_constant (op, mode);
}

/* Return 1 if the operand is either a non-special register or an item
   that can be used as the operand of an SI add insn.  */

int
add_operand (op, mode)
    register rtx op;
    enum machine_mode mode;
{
  return (reg_or_short_operand (op, mode)
	  || (GET_CODE (op) == CONST_INT && (INTVAL (op) & 0xffff) == 0));
}

/* Return 1 if OP is a constant but not a valid add_operand.  */

int
non_add_cint_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (GET_CODE (op) == CONST_INT
	  && (unsigned) (INTVAL (op) + 0x8000) >= 0x10000
	  && (INTVAL (op) & 0xffff) != 0);
}

/* Return 1 if the operand is a non-special register or a constant that
   can be used as the operand of an OR or XOR insn on the RS/6000.  */

int
logical_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (gpc_reg_operand (op, mode)
	  || (GET_CODE (op) == CONST_INT
	      && ((INTVAL (op) & 0xffff0000) == 0
		  || (INTVAL (op) & 0xffff) == 0)));
}

/* Return 1 if C is a constant that is not a logical operand (as
   above).  */

int
non_logical_cint_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (GET_CODE (op) == CONST_INT
	  && (INTVAL (op) & 0xffff0000) != 0
	  && (INTVAL (op) & 0xffff) != 0);
}

/* Return 1 if C is a constant that can be encoded in a mask on the
   RS/6000.  It is if there are no more than two 1->0 or 0->1 transitions.
   Reject all ones and all zeros, since these should have been optimized
   away and confuse the making of MB and ME.  */

int
mask_constant (c)
     register int c;
{
  int i;
  int last_bit_value;
  int transitions = 0;

  if (c == 0 || c == ~0)
    return 0;

  last_bit_value = c & 1;

  for (i = 1; i < 32; i++)
    if (((c >>= 1) & 1) != last_bit_value)
      last_bit_value ^= 1, transitions++;

  return transitions <= 2;
}

/* Return 1 if the operand is a constant that is a mask on the RS/6000. */

int
mask_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return GET_CODE (op) == CONST_INT && mask_constant (INTVAL (op));
}

/* Return 1 if the operand is either a non-special register or a
   constant that can be used as the operand of an RS/6000 logical AND insn.  */

int
and_operand (op, mode)
    register rtx op;
    enum machine_mode mode;
{
  return (reg_or_short_operand (op, mode)
	  || logical_operand (op, mode)
	  || mask_operand (op, mode));
}

/* Return 1 if the operand is a constant but not a valid operand for an AND
   insn.  */

int
non_and_cint_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return GET_CODE (op) == CONST_INT && ! and_operand (op, mode);
}

/* Return 1 if the operand is a general register or memory operand.  */

int
reg_or_mem_operand (op, mode)
     register rtx op;
     register enum machine_mode mode;
{
  return gpc_reg_operand (op, mode) || memory_operand (op, mode);
}

/* Return 1 if the operand is a general register or memory operand without
   pre-inc or pre_dec which produces invalid form of PowerPC lwa
   instruction.  */

int
lwa_operand (op, mode)
     register rtx op;
     register enum machine_mode mode;
{
  rtx inner = op;

  if (reload_completed && GET_CODE (inner) == SUBREG)
    inner = SUBREG_REG (inner);
    
  return gpc_reg_operand (inner, mode)
    || (memory_operand (inner, mode)
	&& GET_CODE (XEXP (inner, 0)) != PRE_INC
	&& GET_CODE (XEXP (inner, 0)) != PRE_DEC);
}

/* Return 1 if the operand, used inside a MEM, is a valid first argument
   to CALL.  This is a SYMBOL_REF or a pseudo-register, which will be
   forced to lr.  */

int
call_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  if (mode != VOIDmode && GET_MODE (op) != mode)
    return 0;

  return (GET_CODE (op) == SYMBOL_REF
	  || (GET_CODE (op) == REG && REGNO (op) >= FIRST_PSEUDO_REGISTER));
}


/* Return 1 if the operand is a SYMBOL_REF for a function known to be in
   this file.  */

int
current_file_function_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (GET_CODE (op) == SYMBOL_REF
	  && (SYMBOL_REF_FLAG (op)
	      || op == XEXP (DECL_RTL (current_function_decl), 0)));
}


/* Return 1 if this operand is a valid input for a move insn.  */

int
input_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  /* Memory is always valid.  */
  if (memory_operand (op, mode))
    return 1;

  /* For floating-point, easy constants are valid.  */
  if (GET_MODE_CLASS (mode) == MODE_FLOAT
      && CONSTANT_P (op)
      && easy_fp_constant (op, mode))
    return 1;

  /* For floating-point or multi-word mode, the only remaining valid type
     is a register.  */
  if (GET_MODE_CLASS (mode) == MODE_FLOAT
      || GET_MODE_SIZE (mode) > UNITS_PER_WORD)
    return register_operand (op, mode);

  /* The only cases left are integral modes one word or smaller (we
     do not get called for MODE_CC values).  These can be in any
     register.  */
  if (register_operand (op, mode))
    return 1;

  /* For HImode and QImode, any constant is valid. */
  if ((mode == HImode || mode == QImode)
      && GET_CODE (op) == CONST_INT)
    return 1;

  /* A SYMBOL_REF referring to the TOC is valid.  */
  if (LEGITIMATE_CONSTANT_POOL_ADDRESS_P (op))
    return 1;

  /* Otherwise, we will be doing this SET with an add, so anything valid
     for an add will be valid.  */
  return add_operand (op, mode);
}

/* 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.

   For incoming args we set the number of arguments in the prototype large
   so we never return an EXPR_LIST.  */

void
init_cumulative_args (cum, fntype, libname, incoming)
     CUMULATIVE_ARGS *cum;
     tree fntype;
     rtx libname;
     int incoming;
{
  static CUMULATIVE_ARGS zero_cumulative;

  *cum = zero_cumulative;
  cum->words = 0;
  cum->fregno = FP_ARG_MIN_REG;
  cum->prototype = (fntype && TYPE_ARG_TYPES (fntype));

  if (incoming)
    {
      cum->nargs_prototype = 1000;		/* don't return an EXPR_LIST */
#ifdef TARGET_V4_CALLS
      if (TARGET_V4_CALLS)
	cum->varargs_offset = RS6000_VARARGS_OFFSET;
#endif
    }

  else if (cum->prototype)
    cum->nargs_prototype = (list_length (TYPE_ARG_TYPES (fntype)) - 1
			    + (TYPE_MODE (TREE_TYPE (fntype)) == BLKmode
			       || RETURN_IN_MEMORY (TREE_TYPE (fntype))));

  else
    cum->nargs_prototype = 0;

  cum->orig_nargs = cum->nargs_prototype;
  if (TARGET_DEBUG_ARG)
    {
      fprintf (stderr, "\ninit_cumulative_args:");
      if (fntype)
	{
	  tree ret_type = TREE_TYPE (fntype);
	  fprintf (stderr, " ret code = %s,",
		   tree_code_name[ (int)TREE_CODE (ret_type) ]);
	}

#ifdef TARGET_V4_CALLS
      if (TARGET_V4_CALLS && incoming)
	fprintf (stderr, " varargs = %d, ", cum->varargs_offset);
#endif

      fprintf (stderr, " proto = %d, nargs = %d\n",
	       cum->prototype, cum->nargs_prototype);
    }
}

/* 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
function_arg_advance (cum, mode, type, named)
     CUMULATIVE_ARGS *cum;
     enum machine_mode mode;
     tree type;
     int named;
{
  cum->nargs_prototype--;

#ifdef TARGET_V4_CALLS
  if (TARGET_V4_CALLS)
    {
      /* Long longs must not be split between registers and stack */
      if ((GET_MODE_CLASS (mode) != MODE_FLOAT || TARGET_SOFT_FLOAT)
	  && type && !AGGREGATE_TYPE_P (type)
	  && cum->words < GP_ARG_NUM_REG
	  && cum->words + RS6000_ARG_SIZE (mode, type, named) > GP_ARG_NUM_REG)
	{
	  cum->words = GP_ARG_NUM_REG;
	}

      /* Aggregates get passed as pointers */
      if (type && AGGREGATE_TYPE_P (type))
	cum->words++;

      /* Floats go in registers, & don't occupy space in the GP registers
	 like they do for AIX unless software floating point.  */
      else if (GET_MODE_CLASS (mode) == MODE_FLOAT
	       && TARGET_HARD_FLOAT
	       && cum->fregno <= FP_ARG_V4_MAX_REG)
	cum->fregno++;

      else
	cum->words += RS6000_ARG_SIZE (mode, type, 1);
    }
  else
#endif
    if (named)
      {
	cum->words += RS6000_ARG_SIZE (mode, type, named);
	if (GET_MODE_CLASS (mode) == MODE_FLOAT && TARGET_HARD_FLOAT)
	  cum->fregno++;
      }

  if (TARGET_DEBUG_ARG)
    fprintf (stderr,
	     "function_adv: words = %2d, fregno = %2d, nargs = %4d, proto = %d, mode = %4s, named = %d\n",
	     cum->words, cum->fregno, cum->nargs_prototype, cum->prototype, GET_MODE_NAME (mode), named);
}

/* Determine where to put an argument to a function.
   Value is zero to push the argument on the stack,
   or a hard register in which to store the argument.

   MODE is the argument's machine mode.
   TYPE is the data type of the argument (as a tree).
    This is null for libcalls where that information may
    not be available.
   CUM is a variable of type CUMULATIVE_ARGS which gives info about
    the preceding args and about the function being called.
   NAMED is nonzero if this argument is a named parameter
    (otherwise it is an extra parameter matching an ellipsis).

   On RS/6000 the first eight words of non-FP are normally in registers
   and the rest are pushed.  Under AIX, the first 13 FP args are in registers.
   Under V.4, the first 8 FP args are in registers.

   If this is floating-point and no prototype is specified, we use
   both an FP and integer register (or possibly FP reg and stack).  Library
   functions (when TYPE is zero) always have the proper types for args,
   so we can pass the FP value just in one register.  emit_library_function
   doesn't support EXPR_LIST anyway.  */

struct rtx_def *
function_arg (cum, mode, type, named)
     CUMULATIVE_ARGS *cum;
     enum machine_mode mode;
     tree type;
     int named;
{
  if (TARGET_DEBUG_ARG)
    fprintf (stderr,
	     "function_arg: words = %2d, fregno = %2d, nargs = %4d, proto = %d, mode = %4s, named = %d\n",
	     cum->words, cum->fregno, cum->nargs_prototype, cum->prototype, GET_MODE_NAME (mode), named);

  /* Return a marker to indicate whether CR1 needs to set or clear the bit that V.4
     uses to say fp args were passed in registers.  Assume that we don't need the
     marker for software floating point, or compiler generated library calls.  */
  if (mode == VOIDmode)
    {
#ifdef TARGET_V4_CALLS
      if (TARGET_V4_CALLS && TARGET_HARD_FLOAT && cum->nargs_prototype < 0
	  && type && (cum->prototype || TARGET_NO_PROTOTYPE))
	return GEN_INT ((cum->fregno == FP_ARG_MIN_REG) ? -1 : 1);
#endif

      return GEN_INT (0);
    }

  if (!named)
    {
#ifdef TARGET_V4_CALLS
      if (!TARGET_V4_CALLS)
#endif
	return NULL_RTX;
    }

  if (type && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
    return NULL_RTX;

  if (USE_FP_FOR_ARG_P (*cum, mode, type))
    {
      if ((cum->nargs_prototype > 0)
#ifdef TARGET_V4_CALLS
	  || TARGET_V4_CALLS	/* V.4 never passes FP values in GP registers */
#endif
	  || !type)
	return gen_rtx (REG, mode, cum->fregno);

      return gen_rtx (EXPR_LIST, VOIDmode,
		      ((cum->words < GP_ARG_NUM_REG)
		       ? gen_rtx (REG, mode, GP_ARG_MIN_REG + cum->words)
		       : NULL_RTX),
		      gen_rtx (REG, mode, cum->fregno));
    }

#ifdef TARGET_V4_CALLS
  /* Long longs won't be split between register and stack */
  else if (TARGET_V4_CALLS &&
	   cum->words + RS6000_ARG_SIZE (mode, type, named) > GP_ARG_NUM_REG)
    {
      return NULL_RTX;
    }
#endif

  else if (cum->words < GP_ARG_NUM_REG)
    return gen_rtx (REG, mode, GP_ARG_MIN_REG + cum->words);

  return NULL_RTX;
}

/* For an arg passed partly in registers and partly in memory,
   this is the number of registers used.
   For args passed entirely in registers or entirely in memory, zero.  */

int
function_arg_partial_nregs (cum, mode, type, named)
     CUMULATIVE_ARGS *cum;
     enum machine_mode mode;
     tree type;
     int named;
{
  if (! named)
    return 0;

#ifdef TARGET_V4_CALLS