alpha.c

linux下的gcc编译器

int
reg_or_unaligned_mem_operand (op, mode)
     rtx op;
     enum machine_mode mode;
{
  return register_operand (op, mode) || unaligned_memory_operand (op, mode);
}

/* Return 1 if OP is any memory location.  During reload a pseudo matches.  */

int
any_memory_operand (op, mode)
     register rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return (GET_CODE (op) == MEM
	  || (GET_CODE (op) == SUBREG && GET_CODE (SUBREG_REG (op)) == REG)
	  || (reload_in_progress && GET_CODE (op) == REG
	      && REGNO (op) >= FIRST_PSEUDO_REGISTER)
	  || (reload_in_progress && GET_CODE (op) == SUBREG
	      && GET_CODE (SUBREG_REG (op)) == REG
	      && REGNO (SUBREG_REG (op)) >= FIRST_PSEUDO_REGISTER));
}

/* Returns 1 if OP is not an eliminable register.

   This exists to cure a pathological abort in the s8addq (et al) patterns,

	long foo () { long t; bar(); return (long) &t * 26107; }

   which run afoul of a hack in reload to cure a (presumably) similar
   problem with lea-type instructions on other targets.  But there is
   one of us and many of them, so work around the problem by selectively
   preventing combine from making the optimization.  */

int
reg_not_elim_operand (op, mode)
      register rtx op;
      enum machine_mode mode;
{
  rtx inner = op;
  if (GET_CODE (op) == SUBREG)
    inner = SUBREG_REG (op);
  if (inner == frame_pointer_rtx || inner == arg_pointer_rtx)
    return 0;

  return register_operand (op, mode);
}

/* Return 1 is OP is a memory location that is not a reference (using
   an AND) to an unaligned location.  Take into account what reload
   will do.  */

int
normal_memory_operand (op, mode)
     register rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  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)];

	  /* This may not have been assigned an equivalent address if it will
	     be eliminated.  In that case, it doesn't matter what we do.  */
	  if (op == 0)
	    return 1;
	}
    }

  return GET_CODE (op) == MEM && GET_CODE (XEXP (op, 0)) != AND;
}

/* Accept a register, but not a subreg of any kind.  This allows us to
   avoid pathological cases in reload wrt data movement common in 
   int->fp conversion.  */

int
reg_no_subreg_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  if (GET_CODE (op) != REG)
    return 0;
  return register_operand (op, mode);
}

/* Recognize an addition operation that includes a constant.  Used to
   convince reload to canonize (plus (plus reg c1) c2) during register
   elimination.  */

int
addition_operation (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  if (GET_MODE (op) != mode && mode != VOIDmode)
    return 0;
  if (GET_CODE (op) == PLUS
      && register_operand (XEXP (op, 0), mode)
      && GET_CODE (XEXP (op, 1)) == CONST_INT
      && CONST_OK_FOR_LETTER_P (INTVAL (XEXP (op, 1)), 'K'))
    return 1;
  return 0;
}

/* 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 (value, c)
     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 (value, c)
     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 (value, c)
     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;
    }
}

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

int
direct_return ()
{
  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 (insn)
     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 (insn)
     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 (symbol)
     rtx symbol;
{
  const char *str;

  if (GET_CODE (symbol) != SYMBOL_REF)
    return 0;
  str = XSTR (symbol, 0);

  if (str[0] == '%')
    {
      /* ??? Be prepared for -ftls-model=local-dynamic.  Perhaps we shouldn't
	 have separately encoded local-ness.  On well, maybe the user will use
	 attribute visibility next time.  At least we don't crash...  */
      if (str[1] == 'G' || str[1] == 'D')
	return TLS_MODEL_GLOBAL_DYNAMIC;
      if (str[1] == 'I' || str[1] == 'T')
	return TLS_MODEL_INITIAL_EXEC;
    }
  else if (str[0] == '@')
    {
      if (str[1] == 'D')
	{
	  /* Local dynamic is a waste if we're not going to combine
	     the __tls_get_addr calls.  So avoid it if not optimizing.  */
	  if (optimize)
	    return TLS_MODEL_LOCAL_DYNAMIC;
	  else
	    return TLS_MODEL_GLOBAL_DYNAMIC;
	}
      if (str[1] == 'I')
	return TLS_MODEL_INITIAL_EXEC;
      if (str[1] == 'T')
	{
	  /* 64-bit local exec is the same as initial exec except without
	     the dynamic relocation.  In either case we use a got entry.  */
	  if (alpha_tls_size == 64)
	    return TLS_MODEL_INITIAL_EXEC;
	  else
	    return TLS_MODEL_LOCAL_EXEC;
	}
    }

  return 0;
}


/* Return true if the function DECL will be placed in the default text
   section.  */
/* ??? Ideally we'd be able to always move from a SYMBOL_REF back to the
   decl, as that would allow us to determine if two functions are in the
   same section, which is what we really want to know.  */

static bool
decl_in_text_section (decl)
     tree decl;
{
  return (DECL_SECTION_NAME (decl) == NULL_TREE
	  && ! (flag_function_sections
	        || (targetm.have_named_sections
		    && DECL_ONE_ONLY (decl))));
}

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

static bool
alpha_in_small_data_p (exp)
     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 && size <= g_switch_value)
	return true;
    }

  return false;
}

/* If we are referencing a function that is static, make the SYMBOL_REF
   special.  We use this to see indicate we can branch to this function
   without setting PV or restoring GP. 

   If this is a variable that is known to be defined locally, add "@v"
   to the name.  If in addition the variable is to go in .sdata/.sbss,
   then add "@s" instead.  */

static void
alpha_encode_section_info (decl, first)
     tree decl;
     int first ATTRIBUTE_UNUSED;
{
  const char *symbol_str;
  bool is_local;
  char encoding = 0;
  rtx rtl, symbol;

  rtl = DECL_P (decl) ? DECL_RTL (decl) : TREE_CST_RTL (decl);

  /* Careful not to prod global register variables.  */
  if (GET_CODE (rtl) != MEM)
    return;
  symbol = XEXP (rtl, 0);
  if (GET_CODE (symbol) != SYMBOL_REF)
    return;
    
  if (TREE_CODE (decl) == FUNCTION_DECL)
    {
      /* We mark public functions once they are emitted; otherwise we
	 don't know that they exist in this unit of translation.  */
      if (TREE_PUBLIC (decl))
	return;

      /* Do not mark functions that are not in .text; otherwise we
	 don't know that they are near enough for a direct branch.  */
      if (! decl_in_text_section (decl))
	return;

      SYMBOL_REF_FLAG (symbol) = 1;
      return;
    }

  /* Early out if we're not going to do anything with this data.  */
  if (! TARGET_EXPLICIT_RELOCS)
    return;

  symbol_str = XSTR (symbol, 0);

  /* A variable is considered "local" if it is defined in this module.  */
  is_local = (*targetm.binds_local_p) (decl);

  /* Care for TLS variables.  */
  if (TREE_CODE (decl) == VAR_DECL && DECL_THREAD_LOCAL (decl))
    {
      switch (decl_tls_model (decl))
	{
	case TLS_MODEL_GLOBAL_DYNAMIC:
	  encoding = 'G';
	  break;
	case TLS_MODEL_LOCAL_DYNAMIC:
	  encoding = 'D';
	  break;
	case TLS_MODEL_INITIAL_EXEC:
	  encoding = 'I';
	  break;
	case TLS_MODEL_LOCAL_EXEC:
	  encoding = 'T';
	  break;
	}
    }
  else if (is_local)
    {
      /* Determine if DECL will wind up in .sdata/.sbss.  */
      if (alpha_in_small_data_p (decl))
	encoding = 'S';
      else
	encoding = 'L';
    }

  /* Finally, encode this into the symbol string.  */
  if (encoding)
    {
      char *newstr;
      size_t len;
      char want_prefix = (is_local ? '@' : '%');
      char other_prefix = (is_local ? '%' : '@');

      if (symbol_str[0] == want_prefix)
	{
	  if (symbol_str[1] == encoding)
	    return;
	  symbol_str += 2;
	}
      else if (symbol_str[0] == other_prefix)
	symbol_str += 2;

      len = strlen (symbol_str) + 1;
      newstr = alloca (len + 2);

      newstr[0] = want_prefix;
      newstr[1] = encoding;
      memcpy (newstr + 2, symbol_str, len);
	  
      XSTR (symbol, 0) = ggc_alloc_string (newstr, len + 2 - 1);
    }
}

/* Undo the effects of the above.  */

static const char *
alpha_strip_name_encoding (str)
     const char *str;
{
  if (str[0] == '@' || str[0] == '%')
    str += 2;
  if (str[0] == '*')