m68k.c

gcc库的原代码,对编程有很大帮助.

  /* Make any unoffsettable addresses point at high-numbered word.  */
  if (addreg0)
    output_asm_insn ("addq%.l %#4,%0", &addreg0);
  if (addreg1)
    output_asm_insn ("addq%.l %#4,%0", &addreg1);

  /* Do that word.  */
  output_asm_insn (singlemove_string (latehalf), latehalf);

  /* Undo the adds we just did.  */
  if (addreg0)
    {
      if (size == 12)
        output_asm_insn ("subq%.l %#8,%0", &addreg0);
      else
        output_asm_insn ("subq%.l %#4,%0", &addreg0);
    }
  if (addreg1)
    {
      if (size == 12)
        output_asm_insn ("subq%.l %#8,%0", &addreg1);
      else
        output_asm_insn ("subq%.l %#4,%0", &addreg1);
    }

  return "";
}

/* Return a REG that occurs in ADDR with coefficient 1.
   ADDR can be effectively incremented by incrementing REG.  */

static rtx
find_addr_reg (addr)
     rtx addr;
{
  while (GET_CODE (addr) == PLUS)
    {
      if (GET_CODE (XEXP (addr, 0)) == REG)
	addr = XEXP (addr, 0);
      else if (GET_CODE (XEXP (addr, 1)) == REG)
	addr = XEXP (addr, 1);
      else if (CONSTANT_P (XEXP (addr, 0)))
	addr = XEXP (addr, 1);
      else if (CONSTANT_P (XEXP (addr, 1)))
	addr = XEXP (addr, 0);
      else
	abort ();
    }
  if (GET_CODE (addr) == REG)
    return addr;
  abort ();
}

/* Store in cc_status the expressions that the condition codes will
   describe after execution of an instruction whose pattern is EXP.
   Do not alter them if the instruction would not alter the cc's.  */

/* On the 68000, all the insns to store in an address register fail to
   set the cc's.  However, in some cases these instructions can make it
   possibly invalid to use the saved cc's.  In those cases we clear out
   some or all of the saved cc's so they won't be used.  */

notice_update_cc (exp, insn)
     rtx exp;
     rtx insn;
{
  /* If the cc is being set from the fpa and the expression is not an
     explicit floating point test instruction (which has code to deal with
     this), reinit the CC.  */
  if (((cc_status.value1 && FPA_REG_P (cc_status.value1))
       || (cc_status.value2 && FPA_REG_P (cc_status.value2)))
      && !(GET_CODE (exp) == PARALLEL
	   && GET_CODE (XVECEXP (exp, 0, 0)) == SET
	   && XEXP (XVECEXP (exp, 0, 0), 0) == cc0_rtx))
    {
      CC_STATUS_INIT; 
    }
  else if (GET_CODE (exp) == SET)
    {
      if (GET_CODE (SET_SRC (exp)) == CALL)
	{
	  CC_STATUS_INIT; 
	}
      else if (ADDRESS_REG_P (SET_DEST (exp)))
	{
	  if (cc_status.value1
	      && reg_overlap_mentioned_p (SET_DEST (exp), cc_status.value1))
	    cc_status.value1 = 0;
	  if (cc_status.value2
	      && reg_overlap_mentioned_p (SET_DEST (exp), cc_status.value2))
	    cc_status.value2 = 0; 
	}
      else if (!FP_REG_P (SET_DEST (exp))
	       && SET_DEST (exp) != cc0_rtx
	       && (FP_REG_P (SET_SRC (exp))
		   || GET_CODE (SET_SRC (exp)) == FIX
		   || GET_CODE (SET_SRC (exp)) == FLOAT_TRUNCATE
		   || GET_CODE (SET_SRC (exp)) == FLOAT_EXTEND))
	{
	  CC_STATUS_INIT; 
	}
      /* A pair of move insns doesn't produce a useful overall cc.  */
      else if (!FP_REG_P (SET_DEST (exp))
	       && !FP_REG_P (SET_SRC (exp))
	       && GET_MODE_SIZE (GET_MODE (SET_SRC (exp))) > 4
	       && (GET_CODE (SET_SRC (exp)) == REG
		   || GET_CODE (SET_SRC (exp)) == MEM
		   || GET_CODE (SET_SRC (exp)) == CONST_DOUBLE))
	{
	  CC_STATUS_INIT; 
	}
      else if (GET_CODE (SET_SRC (exp)) == CALL)
	{
	  CC_STATUS_INIT; 
	}
      else if (XEXP (exp, 0) != pc_rtx)
	{
	  cc_status.flags = 0;
	  cc_status.value1 = XEXP (exp, 0);
	  cc_status.value2 = XEXP (exp, 1);
	}
    }
  else if (GET_CODE (exp) == PARALLEL
	   && GET_CODE (XVECEXP (exp, 0, 0)) == SET)
    {
      if (ADDRESS_REG_P (XEXP (XVECEXP (exp, 0, 0), 0)))
	CC_STATUS_INIT;
      else if (XEXP (XVECEXP (exp, 0, 0), 0) != pc_rtx)
	{
	  cc_status.flags = 0;
	  cc_status.value1 = XEXP (XVECEXP (exp, 0, 0), 0);
	  cc_status.value2 = XEXP (XVECEXP (exp, 0, 0), 1);
	}
    }
  else
    CC_STATUS_INIT;
  if (cc_status.value2 != 0
      && ADDRESS_REG_P (cc_status.value2)
      && GET_MODE (cc_status.value2) == QImode)
    CC_STATUS_INIT;
  if (cc_status.value2 != 0
      && !(cc_status.value1 && FPA_REG_P (cc_status.value1)))
    switch (GET_CODE (cc_status.value2))
      {
      case PLUS: case MINUS: case MULT:
      case DIV: case UDIV: case MOD: case UMOD: case NEG:
      case ASHIFT: case ASHIFTRT: case LSHIFTRT:
      case ROTATE: case ROTATERT:
	if (GET_MODE (cc_status.value2) != VOIDmode)
	  cc_status.flags |= CC_NO_OVERFLOW;
	break;
      case ZERO_EXTEND:
	/* (SET r1 (ZERO_EXTEND r2)) on this machine
	   ends with a move insn moving r2 in r2's mode.
	   Thus, the cc's are set for r2.
	   This can set N bit spuriously. */
	cc_status.flags |= CC_NOT_NEGATIVE; 
      }
  if (cc_status.value1 && GET_CODE (cc_status.value1) == REG
      && cc_status.value2
      && reg_overlap_mentioned_p (cc_status.value1, cc_status.value2))
    cc_status.value2 = 0;
  if (((cc_status.value1 && FP_REG_P (cc_status.value1))
       || (cc_status.value2 && FP_REG_P (cc_status.value2)))
      && !((cc_status.value1 && FPA_REG_P (cc_status.value1))
	   || (cc_status.value2 && FPA_REG_P (cc_status.value2))))
    cc_status.flags = CC_IN_68881;
}

char *
output_move_const_double (operands)
     rtx *operands;
{
#ifdef SUPPORT_SUN_FPA
  if (TARGET_FPA && FPA_REG_P (operands[0]))
    {
      int code = standard_sun_fpa_constant_p (operands[1]);

      if (code != 0)
	{
	  static char buf[40];

	  sprintf (buf, "fpmove%%.d %%%%%d,%%0", code & 0x1ff);
	  return buf;
	}
      return "fpmove%.d %1,%0";
    }
  else
#endif
    {
      int code = standard_68881_constant_p (operands[1]);

      if (code != 0)
	{
	  static char buf[40];

	  sprintf (buf, "fmovecr %%#0x%x,%%0", code & 0xff);
	  return buf;
	}
      return "fmove%.d %1,%0";
    }
}

char *
output_move_const_single (operands)
     rtx *operands;
{
#ifdef SUPPORT_SUN_FPA
  if (TARGET_FPA)
    {
      int code = standard_sun_fpa_constant_p (operands[1]);

      if (code != 0)
	{
	  static char buf[40];

	  sprintf (buf, "fpmove%%.s %%%%%d,%%0", code & 0x1ff);
	  return buf;
	}
      return "fpmove%.s %1,%0";
    }
  else
#endif /* defined SUPPORT_SUN_FPA */
    {
      int code = standard_68881_constant_p (operands[1]);

      if (code != 0)
	{
	  static char buf[40];

	  sprintf (buf, "fmovecr %%#0x%x,%%0", code & 0xff);
	  return buf;
	}
      return "fmove%.s %f1,%0";
    }
}

/* Return nonzero if X, a CONST_DOUBLE, has a value that we can get
   from the "fmovecr" instruction.
   The value, anded with 0xff, gives the code to use in fmovecr
   to get the desired constant.  */

/* This code has been fixed for cross-compilation. */
  
static int inited_68881_table = 0;

char *strings_68881[7] = {
  "0.0",
  "1.0",
  "10.0",
  "100.0",
  "10000.0",
  "1e8",
  "1e16"
  };

int codes_68881[7] = {
  0x0f,
  0x32,
  0x33,
  0x34,
  0x35,
  0x36,
  0x37
  };

REAL_VALUE_TYPE values_68881[7];

/* Set up values_68881 array by converting the decimal values
   strings_68881 to binary.   */

void
init_68881_table ()
{
  int i;
  REAL_VALUE_TYPE r;
  enum machine_mode mode;

  mode = DFmode;
  for (i = 0; i < 7; i++)
    {
      if (i == 6)
        mode = SFmode;
      r = REAL_VALUE_ATOF (strings_68881[i], mode);
      values_68881[i] = r;
    }
  inited_68881_table = 1;
}

int
standard_68881_constant_p (x)
     rtx x;
{
  REAL_VALUE_TYPE r;
  int i;
  enum machine_mode mode;

#ifdef NO_ASM_FMOVECR
  return 0;
#endif

  /* fmovecr must be emulated on the 68040, so it shouldn't be used at all. */
  if (TARGET_68040)
    return 0;

#ifndef REAL_ARITHMETIC
#if HOST_FLOAT_FORMAT != TARGET_FLOAT_FORMAT
  if (! flag_pretend_float)
    return 0;
#endif
#endif

  if (! inited_68881_table)
    init_68881_table ();

  REAL_VALUE_FROM_CONST_DOUBLE (r, x);

  for (i = 0; i < 6; i++)
    {
      if (REAL_VALUES_EQUAL (r, values_68881[i]))
        return (codes_68881[i]);
    }
  
  if (GET_MODE (x) == SFmode)
    return 0;

  if (REAL_VALUES_EQUAL (r, values_68881[6]))
    return (codes_68881[6]);

  /* larger powers of ten in the constants ram are not used
     because they are not equal to a `double' C constant.  */
  return 0;
}

/* If X is a floating-point constant, return the logarithm of X base 2,
   or 0 if X is not a power of 2.  */

int
floating_exact_log2 (x)
     rtx x;
{
  REAL_VALUE_TYPE r, r1;
  int i;

#ifndef REAL_ARITHMETIC
#if HOST_FLOAT_FORMAT != TARGET_FLOAT_FORMAT
  if (! flag_pretend_float)
    return 0;
#endif
#endif

  REAL_VALUE_FROM_CONST_DOUBLE (r, x);

  if (REAL_VALUES_LESS (r, dconst0))
    return 0;

  r1 = dconst1;
  i = 0;
  while (REAL_VALUES_LESS (r1, r))
    {
      r1 = REAL_VALUE_LDEXP (dconst1, i);
      if (REAL_VALUES_EQUAL (r1, r))
        return i;
      i = i + 1;
    }
  return 0;
}

#ifdef SUPPORT_SUN_FPA
/* Return nonzero if X, a CONST_DOUBLE, has a value that we can get
   from the Sun FPA's constant RAM.
   The value returned, anded with 0x1ff, gives the code to use in fpmove
   to get the desired constant. */

static int inited_FPA_table = 0;

char *strings_FPA[38] = {
/* small rationals */
  "0.0",
  "1.0",
  "0.5",
  "-1.0",
  "2.0",
  "3.0",
  "4.0",
  "8.0",
  "0.25",
  "0.125",
  "10.0",
  "-0.5",
/* Decimal equivalents of double precision values */
  "2.718281828459045091", /* D_E */
  "6.283185307179586477", /* 2 pi */
  "3.141592653589793116", /* D_PI */
  "1.570796326794896619", /* pi/2 */
  "1.414213562373095145", /* D_SQRT2 */
  "0.7071067811865475244", /* 1/sqrt(2) */
  "-1.570796326794896619", /* -pi/2 */
  "1.442695040888963387", /* D_LOG2ofE */
  "3.321928024887362182", /* D_LOG2of10 */
  "0.6931471805599452862", /* D_LOGEof2 */
  "2.302585092994045901", /* D_LOGEof10 */
  "0.3010299956639811980", /* D_LOG10of2 */
  "0.4342944819032518167", /* D_LOG10ofE */
/* Decimal equivalents of single precision values */
  "2.718281745910644531", /* S_E */
  "6.283185307179586477", /* 2 pi */
  "3.141592741012573242", /* S_PI */
  "1.570796326794896619", /* pi/2 */
  "1.414213538169860840", /* S_SQRT2 */
  "0.7071067811865475244", /* 1/sqrt(2) */
  "-1.570796326794896619", /* -pi/2 */
  "1.442695021629333496", /* S_LOG2ofE */
  "3.321928024291992188", /* S_LOG2of10 */
  "0.6931471824645996094", /* S_LOGEof2 */
  "2.302585124969482442", /* S_LOGEof10 */
  "0.3010300099849700928", /* S_LOG10of2 */
  "0.4342944920063018799", /* S_LOG10ofE */
};


int codes_FPA[38] = {
/* small rationals */
  0x200,
  0xe,
  0xf,
  0x10,
  0x11,
  0xb1,
  0x12,
  0x13,
  0x15,
  0x16,
  0x17,
  0x2e,
/* double precision */
  0x8,
  0x9,
  0xa,
  0xb,
  0xc,
  0xd,
  0x27,
  0x28,
  0x29,
  0x2a,
  0x2b,
  0x2c,
  0x2d,
/* single precision */
  0x8,
  0x9,
  0xa,
  0xb,
  0xc,
  0xd,
  0x27,
  0x28,
  0x29,
  0x2a,
  0x2b,
  0x2c,
  0x2d
  };

REAL_VALUE_TYPE values_FPA[38];

/* This code has been fixed for cross-compilation. */

void
init_FPA_table ()
{
  enum machine_mode mode;
  int i;
  REAL_VALUE_TYPE r;

  mode = DFmode;
  for (i = 0; i < 38; i++)
    {
      if (i == 25)
        mode = SFmode;
      r = REAL_VALUE_ATOF (strings_FPA[i], mode);
      values_FPA[i] = r;
    }
  inited_FPA_table = 1;
}


int
standard_sun_fpa_constant_p (x)
     rtx x;
{
  REAL_VALUE_TYPE r;
  int i;

#ifndef REAL_ARITHMETIC
#if HOST_FLOAT_FORMAT != TARGET_FLOAT_FORMAT
  if (! flag_pretend_float)
    return 0;
#endif