pa.c

gcc库的原代码,对编程有很大帮助.

    }
  else if (FP_REG_P (operands[1]))
    {
      output_asm_insn ("fstds%F0 %1,%0", operands);
    }
  else if (operands[1] == CONST0_RTX (GET_MODE (operands[0])))
    {
      if (GET_CODE (operands[0]) == REG)
	{
	  rtx xoperands[2];
	  xoperands[1] = gen_rtx (REG, SImode, REGNO (operands[0]) + 1);
	  xoperands[0] = operands[0];
	  output_asm_insn ("copy %%r0,%0\n\tcopy %%r0,%1", xoperands);
	}
      /* This is a pain.  You have to be prepared to deal with an
	 arbitrary address here including pre/post increment/decrement.

	 so avoid this in the MD.  */
      else
	abort ();
    }
  else abort ();
  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 ();
}

/* Emit code to perform a block move.

   Restriction: If the length argument is non-constant, alignment
   must be 4.

   OPERANDS[0] is the destination pointer as a REG, clobbered.
   OPERANDS[1] is the source pointer as a REG, clobbered.
   if SIZE_IS_CONSTANT
     OPERANDS[2] is a register for temporary storage.
     OPERANDS[4] is the size as a CONST_INT
   else
     OPERANDS[2] is a REG which will contain the size, clobbered.
   OPERANDS[3] is a register for temporary storage.
   OPERANDS[5] is the alignment safe to use, as a CONST_INT.  */

char *
output_block_move (operands, size_is_constant)
     rtx *operands;
     int size_is_constant;
{
  int align = INTVAL (operands[5]);
  unsigned long n_bytes;

  /* We can't move more than four bytes at a time because the PA
     has no longer integer move insns.  (Could use fp mem ops?)  */
  if (align > 4)
    align = 4;

  if (size_is_constant)
    {
      unsigned long offset;
      rtx temp;

      n_bytes = INTVAL (operands[4]);
      if (n_bytes == 0)
	return "";

      if (align >= 4)
	{
	  /* Don't unroll too large blocks.  */
	  if (n_bytes > 32)
	    goto copy_with_loop;

	  /* Read and store using two registers, and hide latency
	     by deferring the stores until three instructions after
	     the corresponding load.  The last load insn will read
	     the entire word were the last bytes are, possibly past
	     the end of the source block, but since loads are aligned,
	     this is harmless.  */

	  output_asm_insn ("ldws,ma 4(0,%1),%2", operands);

	  for (offset = 4; offset < n_bytes; offset += 4)
	    {
	      output_asm_insn ("ldws,ma 4(0,%1),%3", operands);
	      output_asm_insn ("stws,ma %2,4(0,%0)", operands);

	      temp = operands[2];
	      operands[2] = operands[3];
	      operands[3] = temp;
	    }
	  if (n_bytes % 4 == 0)
	    /* Store the last word.  */
	    output_asm_insn ("stw %2,0(0,%0)", operands);
	  else
	    {
	      /* Store the last, partial word.  */
	      operands[4] = GEN_INT (n_bytes % 4);
	      output_asm_insn ("stbys,e %2,%4(0,%0)", operands);
	    }
	  return "";
	}

      if (align >= 2 && n_bytes >= 2)
	{
	  output_asm_insn ("ldhs,ma 2(0,%1),%2", operands);

	  for (offset = 2; offset + 2 <= n_bytes; offset += 2)
	    {
	      output_asm_insn ("ldhs,ma 2(0,%1),%3", operands);
	      output_asm_insn ("sths,ma %2,2(0,%0)", operands);

	      temp = operands[2];
	      operands[2] = operands[3];
	      operands[3] = temp;
	    }
	  if (n_bytes % 2 != 0)
	    output_asm_insn ("ldb 0(0,%1),%3", operands);

	  output_asm_insn ("sths,ma %2,2(0,%0)", operands);

	  if (n_bytes % 2 != 0)
	    output_asm_insn ("stb %3,0(0,%0)", operands);

	  return "";
	}

      output_asm_insn ("ldbs,ma 1(0,%1),%2", operands);

      for (offset = 1; offset + 1 <= n_bytes; offset += 1)
	{
	  output_asm_insn ("ldbs,ma 1(0,%1),%3", operands);
	  output_asm_insn ("stbs,ma %2,1(0,%0)", operands);

	  temp = operands[2];
	  operands[2] = operands[3];
	  operands[3] = temp;
	}
      output_asm_insn ("stb %2,0(0,%0)", operands);

      return "";
    }

  if (align != 4)
    abort();

 copy_with_loop:

  if (size_is_constant)
    {
      /* Size is compile-time determined, and also not
	 very small (such small cases are handled above).  */
      operands[4] = GEN_INT (n_bytes - 4);
      output_asm_insn ("ldo %4(0),%2", operands);
    }
  else
    {
      /* Decrement counter by 4, and if it becomes negative, jump past the
	 word copying loop.  */
      output_asm_insn ("addib,<,n -4,%2,.+16", operands);
    }

  /* Copying loop.  Note that the first load is in the annulled delay slot
     of addib.  Is it OK on PA to have a load in a delay slot, i.e. is a
     possible page fault stopped in time?  */
  output_asm_insn ("ldws,ma 4(0,%1),%3", operands);
  output_asm_insn ("addib,>= -4,%2,.-4", operands);
  output_asm_insn ("stws,ma %3,4(0,%0)", operands);

  /* The counter is negative, >= -4.  The remaining number of bytes are
     determined by the two least significant bits.  */

  if (size_is_constant)
    {
      if (n_bytes % 4 != 0)
	{
	  /* Read the entire word of the source block tail.  */
	  output_asm_insn ("ldw 0(0,%1),%3", operands);
	  operands[4] = GEN_INT (n_bytes % 4);
	  output_asm_insn ("stbys,e %3,%4(0,%0)", operands);
	}
    }
  else
    {
      /* Add 4 to counter.  If it becomes zero, we're done.  */
      output_asm_insn ("addib,=,n 4,%2,.+16", operands);

      /* Read the entire word of the source block tail.  (Also this
	 load is in an annulled delay slot.)  */
      output_asm_insn ("ldw 0(0,%1),%3", operands);

      /* Make %0 point at the first byte after the destination block.  */
      output_asm_insn ("addl %2,%0,%0", operands);
      /* Store the leftmost bytes, up to, but not including, the address
	 in %0.  */
      output_asm_insn ("stbys,e %3,0(0,%0)", operands);
    }
  return "";
}

/* Count the number of insns necessary to handle this block move.

   Basic structure is the same as emit_block_move, except that we
   count insns rather than emit them.  */

int
compute_movstrsi_length (insn)
     rtx insn;
{
  rtx pat = PATTERN (insn);
  int size_is_constant;
  int align = INTVAL (XEXP (XVECEXP (pat, 0, 6), 0));
  unsigned long n_bytes;
  int insn_count = 0;

  if (GET_CODE (XEXP (XVECEXP (pat, 0, 5), 0)) == CONST_INT)
    {
      size_is_constant = 1;
      n_bytes = INTVAL (XEXP (XVECEXP (pat, 0, 5), 0));
    }
  else
    {
      size_is_constant = 0;
      n_bytes = 0;
    }

  /* We can't move more than four bytes at a time because the PA
     has no longer integer move insns.  (Could use fp mem ops?)  */
  if (align > 4)
    align = 4;

  if (size_is_constant)
    {
      unsigned long offset;

      if (n_bytes == 0)
	return 0;

      if (align >= 4)
	{
	  /* Don't unroll too large blocks.  */
	  if (n_bytes > 32)
	    goto copy_with_loop;

	  /* first load */
	  insn_count = 1;

	  /* Count the unrolled insns.  */
	  for (offset = 4; offset < n_bytes; offset += 4)
	    insn_count += 2;

	  /* Count last store or partial store.  */
	  insn_count += 1;
	  return insn_count * 4;
	}

      if (align >= 2 && n_bytes >= 2)
	{
	  /* initial load.  */
	  insn_count = 1;

	  /* Unrolled loop.  */
	  for (offset = 2; offset + 2 <= n_bytes; offset += 2)
	    insn_count += 2;

	  /* ??? odd load/store */
	  if (n_bytes % 2 != 0)
	    insn_count += 2;

	  /* ??? final store from loop.  */
	  insn_count += 1;

	  return insn_count * 4;
	}

      /* First load.  */
      insn_count = 1;

      /* The unrolled loop.  */
      for (offset = 1; offset + 1 <= n_bytes; offset += 1)
	insn_count += 2;

      /* Final store.  */
      insn_count += 1;

      return insn_count * 4;
    }

  if (align != 4)
    abort();

 copy_with_loop:

  /* setup for constant and non-constant case.  */
  insn_count = 1;

  /* The copying loop.  */
  insn_count += 3;

  /* The counter is negative, >= -4.  The remaining number of bytes are
     determined by the two least significant bits.  */

  if (size_is_constant)
    {
      if (n_bytes % 4 != 0)
	insn_count += 2;
    }
  else
    insn_count += 4;
  return insn_count * 4;
}


char *
output_and (operands)
     rtx *operands;
{
  if (GET_CODE (operands[2]) == CONST_INT && INTVAL (operands[2]) != 0)
    {
      unsigned HOST_WIDE_INT mask = INTVAL (operands[2]);
      int ls0, ls1, ms0, p, len;

      for (ls0 = 0; ls0 < 32; ls0++)
	if ((mask & (1 << ls0)) == 0)
	  break;

      for (ls1 = ls0; ls1 < 32; ls1++)
	if ((mask & (1 << ls1)) != 0)
	  break;

      for (ms0 = ls1; ms0 < 32; ms0++)
	if ((mask & (1 << ms0)) == 0)
	  break;

      if (ms0 != 32)
	abort();

      if (ls1 == 32)
	{
	  len = ls0;

	  if (len == 0)
	    abort ();

	  operands[2] = GEN_INT (len);
	  return "extru %1,31,%2,%0";
	}
      else
	{
	  /* We could use this `depi' for the case above as well, but `depi'
	     requires one more register file access than an `extru'.  */

	  p = 31 - ls0;
	  len = ls1 - ls0;

	  operands[2] = GEN_INT (p);
	  operands[3] = GEN_INT (len);
	  return "depi 0,%2,%3,%0";
	}
    }
  else
    return "and %1,%2,%0";
}

char *
output_ior (operands)
     rtx *operands;
{
  unsigned HOST_WIDE_INT mask = INTVAL (operands[2]);
  int bs0, bs1, p, len;

  if (INTVAL (operands[2]) == 0)
    return "copy %1,%0";

  for (bs0 = 0; bs0 < 32; bs0++)
    if ((mask & (1 << bs0)) != 0)
      break;

  for (bs1 = bs0; bs1 < 32; bs1++)
    if ((mask & (1 << bs1)) == 0)
      break;

  if (bs1 != 32 && ((unsigned HOST_WIDE_INT) 1 << bs1) <= mask)
    abort();

  p = 31 - bs0;
  len = bs1 - bs0;

  operands[2] = GEN_INT (p);
  operands[3] = GEN_INT (len);
  return "depi -1,%2,%3,%0";
}

/* Output an ascii string.  */
void
output_ascii (file, p, size)
     FILE *file;
     unsigned char *p;
     int size;
{
  int i;
  int chars_output;
  unsigned char partial_output[16];	/* Max space 4 chars can occupy.   */

  /* The HP assembler can only take strings of 256 characters at one
     time.  This is a limitation on input line length, *not* the
     length of the string.  Sigh.  Even worse, it seems that the
     restriction is in number of input characters (see \xnn &
     \whatever).  So we have to do this very carefully.  */

  fprintf (file, "\t.STRING \"");

  chars_output = 0;
  for (i = 0; i < size; i += 4)
    {
      int co = 0;
      int io = 0;
      for (io = 0, co = 0; io < MIN (4, size - i); io++)
	{
	  register unsigned int c = p[i + io];

	  if (c == '\"' || c == '\\')
	    partial_output[co++] = '\\';
	  if (c >= ' ' && c < 0177)
	    partial_output[co++] = c;
	  else
	    {
	      unsigned int hexd;
	      partial_output[co++] = '\\';
	      partial_output[co++] = 'x';
	      hexd =  c  / 16 - 0 + '0';
	      if (hexd > '9')
		hexd -= '9' - 'a' + 1;
	      partial_output[co++] = hexd;
	      hexd =  c % 16 - 0 + '0';
	      if (hexd > '9')
		hexd -= '9' - 'a' + 1;
	      partial_output[co++] = hexd;
	    }
	}
      if (chars_output + co > 243)
	{
	  fprintf (file, "\"\n\t.STRING \"");
	  chars_output = 0;
	}
      fwrite (partial_output, 1, co, file);
      chars_output += co;
      co = 0;
    }