alpha.c

Mac OS X 10.4.9 for x86 Source Code gcc 实现源代码

  }

  /* Default the definition of "small data" to 8 bytes.  */
  if (!g_switch_set)
    g_switch_value = 8;

  /* Infer TARGET_SMALL_DATA from -fpic/-fPIC.  */
  if (flag_pic == 1)
    target_flags |= MASK_SMALL_DATA;
  else if (flag_pic == 2)
    target_flags &= ~MASK_SMALL_DATA;

  /* Align labels and loops for optimal branching.  */
  /* ??? Kludge these by not doing anything if we don't optimize and also if
     we are writing ECOFF symbols to work around a bug in DEC's assembler.  */
  if (optimize > 0 && write_symbols != SDB_DEBUG)
    {
      if (align_loops <= 0)
	align_loops = 16;
      if (align_jumps <= 0)
	align_jumps = 16;
    }
  if (align_functions <= 0)
    align_functions = 16;

  /* Acquire a unique set number for our register saves and restores.  */
  alpha_sr_alias_set = new_alias_set ();

  /* Register variables and functions with the garbage collector.  */

  /* Set up function hooks.  */
  init_machine_status = alpha_init_machine_status;

  /* Tell the compiler when we're using VAX floating point.  */
  if (TARGET_FLOAT_VAX)
    {
      REAL_MODE_FORMAT (SFmode) = &vax_f_format;
      REAL_MODE_FORMAT (DFmode) = &vax_g_format;
      REAL_MODE_FORMAT (TFmode) = NULL;
    }
}

/* Returns 1 if VALUE is a mask that contains full bytes of zero or ones.  */

int
zap_mask (HOST_WIDE_INT value)
{
  int i;

  for (i = 0; i < HOST_BITS_PER_WIDE_INT / HOST_BITS_PER_CHAR;
       i++, value >>= 8)
    if ((value & 0xff) != 0 && (value & 0xff) != 0xff)
      return 0;

  return 1;
}

/* Return true if OP is valid for a particular TLS relocation.
   We are already guaranteed that OP is a CONST.  */

int
tls_symbolic_operand_1 (rtx op, int size, int unspec)
{
  op = XEXP (op, 0);

  if (GET_CODE (op) != UNSPEC || XINT (op, 1) != unspec)
    return 0;
  op = XVECEXP (op, 0, 0);

  if (GET_CODE (op) != SYMBOL_REF)
    return 0;

  if (SYMBOL_REF_LOCAL_P (op))
    {
      if (alpha_tls_size > size)
	return 0;
    }
  else
    {
      if (size != 64)
	return 0;
    }

  switch (SYMBOL_REF_TLS_MODEL (op))
    {
    case TLS_MODEL_LOCAL_DYNAMIC:
      return unspec == UNSPEC_DTPREL;
    case TLS_MODEL_INITIAL_EXEC:
      return unspec == UNSPEC_TPREL && size == 64;
    case TLS_MODEL_LOCAL_EXEC:
      return unspec == UNSPEC_TPREL;
    default:
      abort ();
    }
}

/* Used by aligned_memory_operand and unaligned_memory_operand to
   resolve what reload is going to do with OP if it's a register.  */

rtx
resolve_reload_operand (rtx op)
{
  if (reload_in_progress)
    {
      rtx tmp = op;
      if (GET_CODE (tmp) == SUBREG)
	tmp = SUBREG_REG (tmp);
      if (GET_CODE (tmp) == REG
	  && REGNO (tmp) >= FIRST_PSEUDO_REGISTER)
	{
	  op = reg_equiv_memory_loc[REGNO (tmp)];
	  if (op == 0)
	    return 0;
	}
    }
  return op;
}

/* Implements CONST_OK_FOR_LETTER_P.  Return true if the value matches
   the range defined for C in [I-P].  */

bool
alpha_const_ok_for_letter_p (HOST_WIDE_INT value, int c)
{
  switch (c)
    {
    case 'I':
      /* An unsigned 8 bit constant.  */
      return (unsigned HOST_WIDE_INT) value < 0x100;
    case 'J':
      /* The constant zero.  */
      return value == 0;
    case 'K':
      /* A signed 16 bit constant.  */
      return (unsigned HOST_WIDE_INT) (value + 0x8000) < 0x10000;
    case 'L':
      /* A shifted signed 16 bit constant appropriate for LDAH.  */
      return ((value & 0xffff) == 0
              && ((value) >> 31 == -1 || value >> 31 == 0));
    case 'M':
      /* A constant that can be AND'ed with using a ZAP insn.  */
      return zap_mask (value);
    case 'N':
      /* A complemented unsigned 8 bit constant.  */
      return (unsigned HOST_WIDE_INT) (~ value) < 0x100;
    case 'O':
      /* A negated unsigned 8 bit constant.  */
      return (unsigned HOST_WIDE_INT) (- value) < 0x100;
    case 'P':
      /* The constant 1, 2 or 3.  */
      return value == 1 || value == 2 || value == 3;

    default:
      return false;
    }
}

/* Implements CONST_DOUBLE_OK_FOR_LETTER_P.  Return true if VALUE
   matches for C in [GH].  */

bool
alpha_const_double_ok_for_letter_p (rtx value, int c)
{
  switch (c)
    {
    case 'G':
      /* The floating point zero constant.  */
      return (GET_MODE_CLASS (GET_MODE (value)) == MODE_FLOAT
	      && value == CONST0_RTX (GET_MODE (value)));

    case 'H':
      /* A valid operand of a ZAP insn.  */
      return (GET_MODE (value) == VOIDmode
	      && zap_mask (CONST_DOUBLE_LOW (value))
	      && zap_mask (CONST_DOUBLE_HIGH (value)));

    default:
      return false;
    }
}

/* Implements CONST_DOUBLE_OK_FOR_LETTER_P.  Return true if VALUE
   matches for C.  */

bool
alpha_extra_constraint (rtx value, int c)
{
  switch (c)
    {
    case 'Q':
      return normal_memory_operand (value, VOIDmode);
    case 'R':
      return direct_call_operand (value, Pmode);
    case 'S':
      return (GET_CODE (value) == CONST_INT
	      && (unsigned HOST_WIDE_INT) INTVAL (value) < 64);
    case 'T':
      return GET_CODE (value) == HIGH;
    case 'U':
      return TARGET_ABI_UNICOSMK && symbolic_operand (value, VOIDmode);
    case 'W':
      return (GET_CODE (value) == CONST_VECTOR
	      && value == CONST0_RTX (GET_MODE (value)));
    default:
      return false;
    }
}

/* The scalar modes supported differs from the default check-what-c-supports
   version in that sometimes TFmode is available even when long double
   indicates only DFmode.  On unicosmk, we have the situation that HImode
   doesn't map to any C type, but of course we still support that.  */

static bool
alpha_scalar_mode_supported_p (enum machine_mode mode)
{
  switch (mode)
    {
    case QImode:
    case HImode:
    case SImode:
    case DImode:
    case TImode: /* via optabs.c */
      return true;

    case SFmode:
    case DFmode:
      return true;

    case TFmode:
      return TARGET_HAS_XFLOATING_LIBS;

    default:
      return false;
    }
}

/* Alpha implements a couple of integer vector mode operations when
   TARGET_MAX is enabled.  We do not check TARGET_MAX here, however,
   which allows the vectorizer to operate on e.g. move instructions,
   or when expand_vector_operations can do something useful.  */

static bool
alpha_vector_mode_supported_p (enum machine_mode mode)
{
  return mode == V8QImode || mode == V4HImode || mode == V2SImode;
}

/* Return 1 if this function can directly return via $26.  */

int
direct_return (void)
{
  return (! TARGET_ABI_OPEN_VMS && ! TARGET_ABI_UNICOSMK
	  && reload_completed
	  && alpha_sa_size () == 0
	  && get_frame_size () == 0
	  && current_function_outgoing_args_size == 0
	  && current_function_pretend_args_size == 0);
}

/* Return the ADDR_VEC associated with a tablejump insn.  */

rtx
alpha_tablejump_addr_vec (rtx insn)
{
  rtx tmp;

  tmp = JUMP_LABEL (insn);
  if (!tmp)
    return NULL_RTX;
  tmp = NEXT_INSN (tmp);
  if (!tmp)
    return NULL_RTX;
  if (GET_CODE (tmp) == JUMP_INSN
      && GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC)
    return PATTERN (tmp);
  return NULL_RTX;
}

/* Return the label of the predicted edge, or CONST0_RTX if we don't know.  */

rtx
alpha_tablejump_best_label (rtx insn)
{
  rtx jump_table = alpha_tablejump_addr_vec (insn);
  rtx best_label = NULL_RTX;

  /* ??? Once the CFG doesn't keep getting completely rebuilt, look
     there for edge frequency counts from profile data.  */

  if (jump_table)
    {
      int n_labels = XVECLEN (jump_table, 1);
      int best_count = -1;
      int i, j;

      for (i = 0; i < n_labels; i++)
	{
	  int count = 1;

	  for (j = i + 1; j < n_labels; j++)
	    if (XEXP (XVECEXP (jump_table, 1, i), 0)
		== XEXP (XVECEXP (jump_table, 1, j), 0))
	      count++;

	  if (count > best_count)
	    best_count = count, best_label = XVECEXP (jump_table, 1, i);
	}
    }

  return best_label ? best_label : const0_rtx;
}

/* Return the TLS model to use for SYMBOL.  */

static enum tls_model
tls_symbolic_operand_type (rtx symbol)
{
  enum tls_model model;

  if (GET_CODE (symbol) != SYMBOL_REF)
    return 0;
  model = SYMBOL_REF_TLS_MODEL (symbol);

  /* Local-exec with a 64-bit size is the same code as initial-exec.  */
  if (model == TLS_MODEL_LOCAL_EXEC && alpha_tls_size == 64)
    model = TLS_MODEL_INITIAL_EXEC;

  return model;
}

/* Return true if the function DECL will share the same GP as any
   function in the current unit of translation.  */

static bool
decl_has_samegp (tree decl)
{
  /* Functions that are not local can be overridden, and thus may
     not share the same gp.  */
  if (!(*targetm.binds_local_p) (decl))
    return false;

  /* If -msmall-data is in effect, assume that there is only one GP
     for the module, and so any local symbol has this property.  We
     need explicit relocations to be able to enforce this for symbols
     not defined in this unit of translation, however.  */
  if (TARGET_EXPLICIT_RELOCS && TARGET_SMALL_DATA)
    return true;

  /* Functions that are not external are defined in this UoT.  */
  /* ??? Irritatingly, static functions not yet emitted are still
     marked "external".  Apply this to non-static functions only.  */
  return !TREE_PUBLIC (decl) || !DECL_EXTERNAL (decl);
}

/* Return true if EXP should be placed in the small data section.  */

static bool
alpha_in_small_data_p (tree exp)
{
  /* We want to merge strings, so we never consider them small data.  */
  if (TREE_CODE (exp) == STRING_CST)
    return false;

  /* Functions are never in the small data area.  Duh.  */
  if (TREE_CODE (exp) == FUNCTION_DECL)
    return false;

  if (TREE_CODE (exp) == VAR_DECL && DECL_SECTION_NAME (exp))
    {
      const char *section = TREE_STRING_POINTER (DECL_SECTION_NAME (exp));
      if (strcmp (section, ".sdata") == 0
	  || strcmp (section, ".sbss") == 0)
	return true;
    }
  else
    {
      HOST_WIDE_INT size = int_size_in_bytes (TREE_TYPE (exp));

      /* If this is an incomplete type with size 0, then we can't put it
	 in sdata because it might be too big when completed.  */
      if (size > 0 && (unsigned HOST_WIDE_INT) size <= g_switch_value)
	return true;
    }

  return false;
}

#if TARGET_ABI_OPEN_VMS
static bool
alpha_linkage_symbol_p (const char *symname)
{
  int symlen = strlen (symname);

  if (symlen > 4)
    return strcmp (&symname [symlen - 4], "..lk") == 0;

  return false;
}

#define LINKAGE_SYMBOL_REF_P(X) \
  ((GET_CODE (X) == SYMBOL_REF   \
    && alpha_linkage_symbol_p (XSTR (X, 0))) \
   || (GET_CODE (X) == CONST                 \
       && GET_CODE (XEXP (X, 0)) == PLUS     \
       && GET_CODE (XEXP (XEXP (X, 0), 0)) == SYMBOL_REF \
       && alpha_linkage_symbol_p (XSTR (XEXP (XEXP (X, 0), 0), 0))))
#endif

/* legitimate_address_p recognizes an RTL expression that is a valid
   memory address for an instruction.  The MODE argument is the
   machine mode for the MEM expression that wants to use this address.

   For Alpha, we have either a constant address or the sum of a
   register and a constant address, or just a register.  For DImode,
   any of those forms can be surrounded with an AND that clear the
   low-order three bits; this is an "unaligned" access.  */

bool
alpha_legitimate_address_p (enum machine_mode mode, rtx x, int strict)
{
  /* If this is an ldq_u type address, discard the outer AND.  */
  if (mode == DImode
      && GET_CODE (x) == AND
      && GET_CODE (XEXP (x, 1)) == CONST_INT
      && INTVAL (XEXP (x, 1)) == -8)
    x = XEXP (x, 0);

  /* Discard non-paradoxical subregs.  */
  if (GET_CODE (x) == SUBREG
      && (GET_MODE_SIZE (GET_MODE (x))
	  < GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
    x = SUBREG_REG (x);

  /* Unadorned general registers are valid.  */
  if (REG_P (x)
      && (strict
	  ? STRICT_REG_OK_FOR_BASE_P (x)
	  : NONSTRICT_REG_OK_FOR_BASE_P (x)))
    return true;

  /* Constant addresses (i.e. +/- 32k) are valid.  */
  if (CONSTANT_ADDRESS_P (x))
    return true;

#if TARGET_ABI_OPEN_VMS
  if (LINKAGE_SYMBOL_REF_P (x))
    return true;
#endif

  /* Register plus a small constant offset is valid.  */
  if (GET_CODE (x) == PLUS)
    {
      rtx ofs = XEXP (x, 1);
      x = XEXP (x, 0);

      /* Discard non-paradoxical subregs.  */
      if (GET_CODE (x) == SUBREG
          && (GET_MODE_SIZE (GET_MODE (x))
	      < GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
	x = SUBREG_REG (x);

      if (REG_P (x))