[pf3gnuchains/gcc-fork.git] / gcc / tree.c

/* Language-independent node constructors for parse phase of GNU compiler.
   Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */

/* This file contains the low level primitives for operating on tree nodes,
   including allocation, list operations, interning of identifiers,
   construction of data type nodes and statement nodes,
   and construction of type conversion nodes.  It also contains
   tables index by tree code that describe how to take apart
   nodes of that code.

   It is intended to be language-independent, but occasionally
   calls language-dependent routines defined (for C) in typecheck.c.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "flags.h"
#include "tree.h"
#include "real.h"
#include "tm_p.h"
#include "function.h"
#include "obstack.h"
#include "toplev.h"
#include "ggc.h"
#include "hashtab.h"
#include "output.h"
#include "target.h"
#include "langhooks.h"
#include "tree-iterator.h"
#include "basic-block.h"
#include "tree-flow.h"
#include "params.h"
#include "pointer-set.h"

/* Each tree code class has an associated string representation.
   These must correspond to the tree_code_class entries.  */

const char *const tree_code_class_strings[] =
{
  "exceptional",
  "constant",
  "type",
  "declaration",
  "reference",
  "comparison",
  "unary",
  "binary",
  "statement",
  "expression",
};

/* obstack.[ch] explicitly declined to prototype this.  */
extern int _obstack_allocated_p (struct obstack *h, void *obj);

#ifdef GATHER_STATISTICS
/* Statistics-gathering stuff.  */

int tree_node_counts[(int) all_kinds];
int tree_node_sizes[(int) all_kinds];

/* Keep in sync with tree.h:enum tree_node_kind.  */
static const char * const tree_node_kind_names[] = {
  "decls",
  "types",
  "blocks",
  "stmts",
  "refs",
  "exprs",
  "constants",
  "identifiers",
  "perm_tree_lists",
  "temp_tree_lists",
  "vecs",
  "binfos",
  "phi_nodes",
  "ssa names",
  "constructors",
  "random kinds",
  "lang_decl kinds",
  "lang_type kinds"
};
#endif /* GATHER_STATISTICS */

/* Unique id for next decl created.  */
static GTY(()) int next_decl_uid;
/* Unique id for next type created.  */
static GTY(()) int next_type_uid = 1;

/* Since we cannot rehash a type after it is in the table, we have to
   keep the hash code.  */

struct type_hash GTY(())
{
  unsigned long hash;
  tree type;
};

/* Initial size of the hash table (rounded to next prime).  */
#define TYPE_HASH_INITIAL_SIZE 1000

/* Now here is the hash table.  When recording a type, it is added to
   the slot whose index is the hash code.  Note that the hash table is
   used for several kinds of types (function types, array types and
   array index range types, for now).  While all these live in the
   same table, they are completely independent, and the hash code is
   computed differently for each of these.  */

static GTY ((if_marked ("type_hash_marked_p"), param_is (struct type_hash)))
     htab_t type_hash_table;

/* Hash table and temporary node for larger integer const values.  */
static GTY (()) tree int_cst_node;
static GTY ((if_marked ("ggc_marked_p"), param_is (union tree_node)))
     htab_t int_cst_hash_table;

/* General tree->tree mapping  structure for use in hash tables.  */


static GTY ((if_marked ("tree_map_marked_p"), param_is (struct tree_map))) 
     htab_t debug_expr_for_decl;

static GTY ((if_marked ("tree_map_marked_p"), param_is (struct tree_map))) 
     htab_t value_expr_for_decl;

static GTY ((if_marked ("tree_int_map_marked_p"), param_is (struct tree_int_map)))
  htab_t init_priority_for_decl;

static GTY ((if_marked ("tree_map_marked_p"), param_is (struct tree_map)))
  htab_t restrict_base_for_decl;

struct tree_int_map GTY(())
{
  tree from;
  unsigned short to;
};
static unsigned int tree_int_map_hash (const void *);
static int tree_int_map_eq (const void *, const void *);
static int tree_int_map_marked_p (const void *);
static void set_type_quals (tree, int);
static int type_hash_eq (const void *, const void *);
static hashval_t type_hash_hash (const void *);
static hashval_t int_cst_hash_hash (const void *);
static int int_cst_hash_eq (const void *, const void *);
static void print_type_hash_statistics (void);
static void print_debug_expr_statistics (void);
static void print_value_expr_statistics (void);
static tree make_vector_type (tree, int, enum machine_mode);
static int type_hash_marked_p (const void *);
static unsigned int type_hash_list (tree, hashval_t);
static unsigned int attribute_hash_list (tree, hashval_t);

tree global_trees[TI_MAX];
tree integer_types[itk_none];

unsigned char tree_contains_struct[256][64];
\f
/* Init tree.c.  */

void
init_ttree (void)
{

  /* Initialize the hash table of types.  */
  type_hash_table = htab_create_ggc (TYPE_HASH_INITIAL_SIZE, type_hash_hash,
                                     type_hash_eq, 0);

  debug_expr_for_decl = htab_create_ggc (512, tree_map_hash,
                                         tree_map_eq, 0);

  value_expr_for_decl = htab_create_ggc (512, tree_map_hash,
                                         tree_map_eq, 0);
  init_priority_for_decl = htab_create_ggc (512, tree_int_map_hash,
                                            tree_int_map_eq, 0);
  restrict_base_for_decl = htab_create_ggc (256, tree_map_hash,
                                            tree_map_eq, 0);

  int_cst_hash_table = htab_create_ggc (1024, int_cst_hash_hash,
                                        int_cst_hash_eq, NULL);
  
  int_cst_node = make_node (INTEGER_CST);

  tree_contains_struct[FUNCTION_DECL][TS_DECL_NON_COMMON] = 1;
  tree_contains_struct[TRANSLATION_UNIT_DECL][TS_DECL_NON_COMMON] = 1;
  tree_contains_struct[TYPE_DECL][TS_DECL_NON_COMMON] = 1;
  

  tree_contains_struct[CONST_DECL][TS_DECL_COMMON] = 1;
  tree_contains_struct[VAR_DECL][TS_DECL_COMMON] = 1;
  tree_contains_struct[PARM_DECL][TS_DECL_COMMON] = 1;
  tree_contains_struct[RESULT_DECL][TS_DECL_COMMON] = 1;
  tree_contains_struct[FUNCTION_DECL][TS_DECL_COMMON] = 1;
  tree_contains_struct[TYPE_DECL][TS_DECL_COMMON] = 1;
  tree_contains_struct[TRANSLATION_UNIT_DECL][TS_DECL_COMMON] = 1;
  tree_contains_struct[LABEL_DECL][TS_DECL_COMMON] = 1;
  tree_contains_struct[FIELD_DECL][TS_DECL_COMMON] = 1;


  tree_contains_struct[CONST_DECL][TS_DECL_WRTL] = 1;
  tree_contains_struct[VAR_DECL][TS_DECL_WRTL] = 1;
  tree_contains_struct[PARM_DECL][TS_DECL_WRTL] = 1;
  tree_contains_struct[RESULT_DECL][TS_DECL_WRTL] = 1;
  tree_contains_struct[FUNCTION_DECL][TS_DECL_WRTL] = 1;
  tree_contains_struct[LABEL_DECL][TS_DECL_WRTL] = 1; 

  tree_contains_struct[CONST_DECL][TS_DECL_MINIMAL] = 1;
  tree_contains_struct[VAR_DECL][TS_DECL_MINIMAL] = 1;
  tree_contains_struct[PARM_DECL][TS_DECL_MINIMAL] = 1;
  tree_contains_struct[RESULT_DECL][TS_DECL_MINIMAL] = 1;
  tree_contains_struct[FUNCTION_DECL][TS_DECL_MINIMAL] = 1;
  tree_contains_struct[TYPE_DECL][TS_DECL_MINIMAL] = 1;
  tree_contains_struct[TRANSLATION_UNIT_DECL][TS_DECL_MINIMAL] = 1;
  tree_contains_struct[LABEL_DECL][TS_DECL_MINIMAL] = 1;
  tree_contains_struct[FIELD_DECL][TS_DECL_MINIMAL] = 1;

  tree_contains_struct[VAR_DECL][TS_DECL_WITH_VIS] = 1;
  tree_contains_struct[FUNCTION_DECL][TS_DECL_WITH_VIS] = 1;
  tree_contains_struct[TYPE_DECL][TS_DECL_WITH_VIS] = 1;
  tree_contains_struct[TRANSLATION_UNIT_DECL][TS_DECL_WITH_VIS] = 1;
  
  tree_contains_struct[VAR_DECL][TS_VAR_DECL] = 1;
  tree_contains_struct[FIELD_DECL][TS_FIELD_DECL] = 1;
  tree_contains_struct[PARM_DECL][TS_PARM_DECL] = 1;
  tree_contains_struct[LABEL_DECL][TS_LABEL_DECL] = 1;
  tree_contains_struct[RESULT_DECL][TS_RESULT_DECL] = 1;
  tree_contains_struct[CONST_DECL][TS_CONST_DECL] = 1;
  tree_contains_struct[TYPE_DECL][TS_TYPE_DECL] = 1;
  tree_contains_struct[FUNCTION_DECL][TS_FUNCTION_DECL] = 1;

  lang_hooks.init_ts ();
}

\f
/* The name of the object as the assembler will see it (but before any
   translations made by ASM_OUTPUT_LABELREF).  Often this is the same
   as DECL_NAME.  It is an IDENTIFIER_NODE.  */
tree
decl_assembler_name (tree decl)
{
  if (!DECL_ASSEMBLER_NAME_SET_P (decl))
    lang_hooks.set_decl_assembler_name (decl);
  return DECL_WITH_VIS_CHECK (decl)->decl_with_vis.assembler_name;
}

/* Compute the number of bytes occupied by a tree with code CODE.
   This function cannot be used for TREE_VEC, PHI_NODE, or STRING_CST
   codes, which are of variable length.  */
size_t
tree_code_size (enum tree_code code)
{
  switch (TREE_CODE_CLASS (code))
    {
    case tcc_declaration:  /* A decl node */
      {
        switch (code)
          {
          case FIELD_DECL:
            return sizeof (struct tree_field_decl);
          case PARM_DECL:
            return sizeof (struct tree_parm_decl);
          case VAR_DECL:
            return sizeof (struct tree_var_decl);
          case LABEL_DECL:
            return sizeof (struct tree_label_decl);
          case RESULT_DECL:
            return sizeof (struct tree_result_decl);
          case CONST_DECL:
            return sizeof (struct tree_const_decl);
          case TYPE_DECL:
            return sizeof (struct tree_type_decl);
          case FUNCTION_DECL:
            return sizeof (struct tree_function_decl);
          default:
            return sizeof (struct tree_decl_non_common);
          }
      }

    case tcc_type:  /* a type node */
      return sizeof (struct tree_type);

    case tcc_reference:   /* a reference */
    case tcc_expression:  /* an expression */
    case tcc_statement:   /* an expression with side effects */
    case tcc_comparison:  /* a comparison expression */
    case tcc_unary:       /* a unary arithmetic expression */
    case tcc_binary:      /* a binary arithmetic expression */
      return (sizeof (struct tree_exp)
              + (TREE_CODE_LENGTH (code) - 1) * sizeof (char *));

    case tcc_constant:  /* a constant */
      switch (code)
        {
        case INTEGER_CST:       return sizeof (struct tree_int_cst);
        case REAL_CST:          return sizeof (struct tree_real_cst);
        case COMPLEX_CST:       return sizeof (struct tree_complex);
        case VECTOR_CST:        return sizeof (struct tree_vector);
        case STRING_CST:        gcc_unreachable ();
        default:
          return lang_hooks.tree_size (code);
        }

    case tcc_exceptional:  /* something random, like an identifier.  */
      switch (code)
        {
        case IDENTIFIER_NODE:   return lang_hooks.identifier_size;
        case TREE_LIST:         return sizeof (struct tree_list);

        case ERROR_MARK:
        case PLACEHOLDER_EXPR:  return sizeof (struct tree_common);

        case TREE_VEC:
        case PHI_NODE:          gcc_unreachable ();

        case SSA_NAME:          return sizeof (struct tree_ssa_name);

        case STATEMENT_LIST:    return sizeof (struct tree_statement_list);
        case BLOCK:             return sizeof (struct tree_block);
        case VALUE_HANDLE:      return sizeof (struct tree_value_handle);
        case CONSTRUCTOR:       return sizeof (struct tree_constructor);

        default:
          return lang_hooks.tree_size (code);
        }

    default:
      gcc_unreachable ();
    }
}

/* Compute the number of bytes occupied by NODE.  This routine only
   looks at TREE_CODE, except for PHI_NODE and TREE_VEC nodes.  */
size_t
tree_size (tree node)
{
  enum tree_code code = TREE_CODE (node);
  switch (code)
    {
    case PHI_NODE:
      return (sizeof (struct tree_phi_node)
              + (PHI_ARG_CAPACITY (node) - 1) * sizeof (struct phi_arg_d));

    case TREE_BINFO:
      return (offsetof (struct tree_binfo, base_binfos)
              + VEC_embedded_size (tree, BINFO_N_BASE_BINFOS (node)));

    case TREE_VEC:
      return (sizeof (struct tree_vec)
              + (TREE_VEC_LENGTH (node) - 1) * sizeof(char *));

    case STRING_CST:
      return sizeof (struct tree_string) + TREE_STRING_LENGTH (node) - 1;

    default:
      return tree_code_size (code);
    }
}

/* Return a newly allocated node of code CODE.  For decl and type
   nodes, some other fields are initialized.  The rest of the node is
   initialized to zero.  This function cannot be used for PHI_NODE or
   TREE_VEC nodes, which is enforced by asserts in tree_code_size.

   Achoo!  I got a code in the node.  */

tree
make_node_stat (enum tree_code code MEM_STAT_DECL)
{
  tree t;
  enum tree_code_class type = TREE_CODE_CLASS (code);
  size_t length = tree_code_size (code);
#ifdef GATHER_STATISTICS
  tree_node_kind kind;

  switch (type)
    {
    case tcc_declaration:  /* A decl node */
      kind = d_kind;
      break;

    case tcc_type:  /* a type node */
      kind = t_kind;
      break;

    case tcc_statement:  /* an expression with side effects */
      kind = s_kind;
      break;

    case tcc_reference:  /* a reference */
      kind = r_kind;
      break;

    case tcc_expression:  /* an expression */
    case tcc_comparison:  /* a comparison expression */
    case tcc_unary:  /* a unary arithmetic expression */
    case tcc_binary:  /* a binary arithmetic expression */
      kind = e_kind;
      break;

    case tcc_constant:  /* a constant */
      kind = c_kind;
      break;

    case tcc_exceptional:  /* something random, like an identifier.  */
      switch (code)
        {
        case IDENTIFIER_NODE:
          kind = id_kind;
          break;

        case TREE_VEC:
          kind = vec_kind;
          break;

        case TREE_BINFO:
          kind = binfo_kind;
          break;

        case PHI_NODE:
          kind = phi_kind;
          break;

        case SSA_NAME:
          kind = ssa_name_kind;
          break;

        case BLOCK:
          kind = b_kind;
          break;

        case CONSTRUCTOR:
          kind = constr_kind;
          break;

        default:
          kind = x_kind;
          break;
        }
      break;
      
    default:
      gcc_unreachable ();
    }

  tree_node_counts[(int) kind]++;
  tree_node_sizes[(int) kind] += length;
#endif

  if (code == IDENTIFIER_NODE)
    t = ggc_alloc_zone_pass_stat (length, &tree_id_zone);
  else
    t = ggc_alloc_zone_pass_stat (length, &tree_zone);

  memset (t, 0, length);

  TREE_SET_CODE (t, code);

  switch (type)
    {
    case tcc_statement:
      TREE_SIDE_EFFECTS (t) = 1;
      break;

    case tcc_declaration:
      if (code != FUNCTION_DECL)
        DECL_ALIGN (t) = 1;
      DECL_USER_ALIGN (t) = 0;
      if (CODE_CONTAINS_STRUCT (code, TS_DECL_WITH_VIS))
        DECL_IN_SYSTEM_HEADER (t) = in_system_header;
      /* We have not yet computed the alias set for this declaration.  */
      DECL_POINTER_ALIAS_SET (t) = -1;
      DECL_SOURCE_LOCATION (t) = input_location;
      DECL_UID (t) = next_decl_uid++;

      break;

    case tcc_type:
      TYPE_UID (t) = next_type_uid++;
      TYPE_ALIGN (t) = BITS_PER_UNIT;
      TYPE_USER_ALIGN (t) = 0;
      TYPE_MAIN_VARIANT (t) = t;

      /* Default to no attributes for type, but let target change that.  */
      TYPE_ATTRIBUTES (t) = NULL_TREE;
      targetm.set_default_type_attributes (t);

      /* We have not yet computed the alias set for this type.  */
      TYPE_ALIAS_SET (t) = -1;
      break;

    case tcc_constant:
      TREE_CONSTANT (t) = 1;
      TREE_INVARIANT (t) = 1;
      break;

    case tcc_expression:
      switch (code)
        {
        case INIT_EXPR:
        case MODIFY_EXPR:
        case VA_ARG_EXPR:
        case PREDECREMENT_EXPR:
        case PREINCREMENT_EXPR:
        case POSTDECREMENT_EXPR:
        case POSTINCREMENT_EXPR:
          /* All of these have side-effects, no matter what their
             operands are.  */
          TREE_SIDE_EFFECTS (t) = 1;
          break;

        default:
          break;
        }
      break;

    default:
      /* Other classes need no special treatment.  */
      break;
    }

  return t;
}
\f
/* Return a new node with the same contents as NODE except that its
   TREE_CHAIN is zero and it has a fresh uid.  */

tree
copy_node_stat (tree node MEM_STAT_DECL)
{
  tree t;
  enum tree_code code = TREE_CODE (node);
  size_t length;

  gcc_assert (code != STATEMENT_LIST);

  length = tree_size (node);
  t = ggc_alloc_zone_pass_stat (length, &tree_zone);
  memcpy (t, node, length);

  TREE_CHAIN (t) = 0;
  TREE_ASM_WRITTEN (t) = 0;
  TREE_VISITED (t) = 0;
  t->common.ann = 0;

  if (TREE_CODE_CLASS (code) == tcc_declaration)
    {
      DECL_UID (t) = next_decl_uid++;
      if ((TREE_CODE (node) == PARM_DECL || TREE_CODE (node) == VAR_DECL)
          && DECL_HAS_VALUE_EXPR_P (node))
        {
          SET_DECL_VALUE_EXPR (t, DECL_VALUE_EXPR (node));
          DECL_HAS_VALUE_EXPR_P (t) = 1;
        }
      if (TREE_CODE (node) == VAR_DECL && DECL_HAS_INIT_PRIORITY_P (node))
        {
          SET_DECL_INIT_PRIORITY (t, DECL_INIT_PRIORITY (node));
          DECL_HAS_INIT_PRIORITY_P (t) = 1;
        }
      if (TREE_CODE (node) == VAR_DECL && DECL_BASED_ON_RESTRICT_P (node))
        {
          SET_DECL_RESTRICT_BASE (t, DECL_GET_RESTRICT_BASE (node));
          DECL_BASED_ON_RESTRICT_P (t) = 1;
        }
    }
  else if (TREE_CODE_CLASS (code) == tcc_type)
    {
      TYPE_UID (t) = next_type_uid++;
      /* The following is so that the debug code for
         the copy is different from the original type.
         The two statements usually duplicate each other
         (because they clear fields of the same union),
         but the optimizer should catch that.  */
      TYPE_SYMTAB_POINTER (t) = 0;
      TYPE_SYMTAB_ADDRESS (t) = 0;
      
      /* Do not copy the values cache.  */
      if (TYPE_CACHED_VALUES_P(t))
        {
          TYPE_CACHED_VALUES_P (t) = 0;
          TYPE_CACHED_VALUES (t) = NULL_TREE;
        }
    }

  return t;
}

/* Return a copy of a chain of nodes, chained through the TREE_CHAIN field.
   For example, this can copy a list made of TREE_LIST nodes.  */

tree
copy_list (tree list)
{
  tree head;
  tree prev, next;

  if (list == 0)
    return 0;

  head = prev = copy_node (list);
  next = TREE_CHAIN (list);
  while (next)
    {
      TREE_CHAIN (prev) = copy_node (next);
      prev = TREE_CHAIN (prev);
      next = TREE_CHAIN (next);
    }
  return head;
}

\f
/* Create an INT_CST node with a LOW value sign extended.  */

tree
build_int_cst (tree type, HOST_WIDE_INT low)
{
  return build_int_cst_wide (type, low, low < 0 ? -1 : 0);
}

/* Create an INT_CST node with a LOW value zero extended.  */

tree
build_int_cstu (tree type, unsigned HOST_WIDE_INT low)
{
  return build_int_cst_wide (type, low, 0);
}

/* Create an INT_CST node with a LOW value in TYPE.  The value is sign extended
   if it is negative.  This function is similar to build_int_cst, but
   the extra bits outside of the type precision are cleared.  Constants
   with these extra bits may confuse the fold so that it detects overflows
   even in cases when they do not occur, and in general should be avoided.
   We cannot however make this a default behavior of build_int_cst without
   more intrusive changes, since there are parts of gcc that rely on the extra
   precision of the integer constants.  */

tree
build_int_cst_type (tree type, HOST_WIDE_INT low)
{
  unsigned HOST_WIDE_INT val = (unsigned HOST_WIDE_INT) low;
  unsigned HOST_WIDE_INT hi, mask;
  unsigned bits;
  bool signed_p;
  bool negative;

  if (!type)
    type = integer_type_node;

  bits = TYPE_PRECISION (type);
  signed_p = !TYPE_UNSIGNED (type);

  if (bits >= HOST_BITS_PER_WIDE_INT)
    negative = (low < 0);
  else
    {
      /* If the sign bit is inside precision of LOW, use it to determine
         the sign of the constant.  */
      negative = ((val >> (bits - 1)) & 1) != 0;

      /* Mask out the bits outside of the precision of the constant.  */
      mask = (((unsigned HOST_WIDE_INT) 2) << (bits - 1)) - 1;

      if (signed_p && negative)
        val |= ~mask;
      else
        val &= mask;
    }

  /* Determine the high bits.  */
  hi = (negative ? ~(unsigned HOST_WIDE_INT) 0 : 0);

  /* For unsigned type we need to mask out the bits outside of the type
     precision.  */
  if (!signed_p)
    {
      if (bits <= HOST_BITS_PER_WIDE_INT)
        hi = 0;
      else
        {
          bits -= HOST_BITS_PER_WIDE_INT;
          mask = (((unsigned HOST_WIDE_INT) 2) << (bits - 1)) - 1;
          hi &= mask;
        }
    }

  return build_int_cst_wide (type, val, hi);
}

/* These are the hash table functions for the hash table of INTEGER_CST
   nodes of a sizetype.  */

/* Return the hash code code X, an INTEGER_CST.  */

static hashval_t
int_cst_hash_hash (const void *x)
{
  tree t = (tree) x;

  return (TREE_INT_CST_HIGH (t) ^ TREE_INT_CST_LOW (t)
          ^ htab_hash_pointer (TREE_TYPE (t)));
}

/* Return nonzero if the value represented by *X (an INTEGER_CST tree node)
   is the same as that given by *Y, which is the same.  */

static int
int_cst_hash_eq (const void *x, const void *y)
{
  tree xt = (tree) x;
  tree yt = (tree) y;

  return (TREE_TYPE (xt) == TREE_TYPE (yt)
          && TREE_INT_CST_HIGH (xt) == TREE_INT_CST_HIGH (yt)
          && TREE_INT_CST_LOW (xt) == TREE_INT_CST_LOW (yt));
}

/* Create an INT_CST node of TYPE and value HI:LOW.  If TYPE is NULL,
   integer_type_node is used.  The returned node is always shared.
   For small integers we use a per-type vector cache, for larger ones
   we use a single hash table.  */

tree
build_int_cst_wide (tree type, unsigned HOST_WIDE_INT low, HOST_WIDE_INT hi)
{
  tree t;
  int ix = -1;
  int limit = 0;

  if (!type)
    type = integer_type_node;

  switch (TREE_CODE (type))
    {
    case POINTER_TYPE:
    case REFERENCE_TYPE:
      /* Cache NULL pointer.  */
      if (!hi && !low)
        {
          limit = 1;
          ix = 0;
        }
      break;

    case BOOLEAN_TYPE:
      /* Cache false or true.  */
      limit = 2;
      if (!hi && low < 2)
        ix = low;
      break;

    case INTEGER_TYPE:
    case CHAR_TYPE:
    case OFFSET_TYPE:
      if (TYPE_UNSIGNED (type))
        {
          /* Cache 0..N */
          limit = INTEGER_SHARE_LIMIT;
          if (!hi && low < (unsigned HOST_WIDE_INT)INTEGER_SHARE_LIMIT)
            ix = low;
        }
      else
        {
          /* Cache -1..N */
          limit = INTEGER_SHARE_LIMIT + 1;
          if (!hi && low < (unsigned HOST_WIDE_INT)INTEGER_SHARE_LIMIT)
            ix = low + 1;
          else if (hi == -1 && low == -(unsigned HOST_WIDE_INT)1)
            ix = 0;
        }
      break;
    default:
      break;
    }

  if (ix >= 0)
    {
      /* Look for it in the type's vector of small shared ints.  */
      if (!TYPE_CACHED_VALUES_P (type))
        {
          TYPE_CACHED_VALUES_P (type) = 1;
          TYPE_CACHED_VALUES (type) = make_tree_vec (limit);
        }

      t = TREE_VEC_ELT (TYPE_CACHED_VALUES (type), ix);
      if (t)
        {
          /* Make sure no one is clobbering the shared constant.  */
          gcc_assert (TREE_TYPE (t) == type);
          gcc_assert (TREE_INT_CST_LOW (t) == low);
          gcc_assert (TREE_INT_CST_HIGH (t) == hi);
        }
      else
        {
          /* Create a new shared int.  */
          t = make_node (INTEGER_CST);

          TREE_INT_CST_LOW (t) = low;
          TREE_INT_CST_HIGH (t) = hi;
          TREE_TYPE (t) = type;
          
          TREE_VEC_ELT (TYPE_CACHED_VALUES (type), ix) = t;
        }
    }
  else
    {
      /* Use the cache of larger shared ints.  */
      void **slot;

      TREE_INT_CST_LOW (int_cst_node) = low;
      TREE_INT_CST_HIGH (int_cst_node) = hi;
      TREE_TYPE (int_cst_node) = type;

      slot = htab_find_slot (int_cst_hash_table, int_cst_node, INSERT);
      t = *slot;
      if (!t)
        {
          /* Insert this one into the hash table.  */
          t = int_cst_node;
          *slot = t;
          /* Make a new node for next time round.  */
          int_cst_node = make_node (INTEGER_CST);
        }
    }

  return t;
}

/* Builds an integer constant in TYPE such that lowest BITS bits are ones
   and the rest are zeros.  */

tree
build_low_bits_mask (tree type, unsigned bits)
{
  unsigned HOST_WIDE_INT low;
  HOST_WIDE_INT high;
  unsigned HOST_WIDE_INT all_ones = ~(unsigned HOST_WIDE_INT) 0;

  gcc_assert (bits <= TYPE_PRECISION (type));

  if (bits == TYPE_PRECISION (type)
      && !TYPE_UNSIGNED (type))
    {
      /* Sign extended all-ones mask.  */
      low = all_ones;
      high = -1;
    }
  else if (bits <= HOST_BITS_PER_WIDE_INT)
    {
      low = all_ones >> (HOST_BITS_PER_WIDE_INT - bits);
      high = 0;
    }
  else
    {
      bits -= HOST_BITS_PER_WIDE_INT;
      low = all_ones;
      high = all_ones >> (HOST_BITS_PER_WIDE_INT - bits);
    }

  return build_int_cst_wide (type, low, high);
}

/* Checks that X is integer constant that can be expressed in (unsigned)
   HOST_WIDE_INT without loss of precision.  */

bool
cst_and_fits_in_hwi (tree x)
{
  if (TREE_CODE (x) != INTEGER_CST)
    return false;

  if (TYPE_PRECISION (TREE_TYPE (x)) > HOST_BITS_PER_WIDE_INT)
    return false;

  return (TREE_INT_CST_HIGH (x) == 0
          || TREE_INT_CST_HIGH (x) == -1);
}

/* Return a new VECTOR_CST node whose type is TYPE and whose values
   are in a list pointed to by VALS.  */

tree
build_vector (tree type, tree vals)
{
  tree v = make_node (VECTOR_CST);
  int over1 = 0, over2 = 0;
  tree link;

  TREE_VECTOR_CST_ELTS (v) = vals;
  TREE_TYPE (v) = type;

  /* Iterate through elements and check for overflow.  */
  for (link = vals; link; link = TREE_CHAIN (link))
    {
      tree value = TREE_VALUE (link);

      over1 |= TREE_OVERFLOW (value);
      over2 |= TREE_CONSTANT_OVERFLOW (value);
    }

  TREE_OVERFLOW (v) = over1;
  TREE_CONSTANT_OVERFLOW (v) = over2;

  return v;
}

/* Return a new VECTOR_CST node whose type is TYPE and whose values
   are extracted from V, a vector of CONSTRUCTOR_ELT.  */

tree
build_vector_from_ctor (tree type, VEC(constructor_elt,gc) *v)
{
  tree list = NULL_TREE;
  unsigned HOST_WIDE_INT idx;
  tree value;

  FOR_EACH_CONSTRUCTOR_VALUE (v, idx, value)
    list = tree_cons (NULL_TREE, value, list);
  return build_vector (type, nreverse (list));
}

/* Return a new CONSTRUCTOR node whose type is TYPE and whose values
   are in the VEC pointed to by VALS.  */
tree
build_constructor (tree type, VEC(constructor_elt,gc) *vals)
{
  tree c = make_node (CONSTRUCTOR);
  TREE_TYPE (c) = type;
  CONSTRUCTOR_ELTS (c) = vals;
  return c;
}

/* Build a CONSTRUCTOR node made of a single initializer, with the specified
   INDEX and VALUE.  */
tree
build_constructor_single (tree type, tree index, tree value)
{
  VEC(constructor_elt,gc) *v;
  constructor_elt *elt;

  v = VEC_alloc (constructor_elt, gc, 1);
  elt = VEC_quick_push (constructor_elt, v, NULL);
  elt->index = index;
  elt->value = value;

  return build_constructor (type, v);
}


/* Return a new CONSTRUCTOR node whose type is TYPE and whose values
   are in a list pointed to by VALS.  */
tree
build_constructor_from_list (tree type, tree vals)
{
  tree t;
  VEC(constructor_elt,gc) *v = NULL;

  if (vals)
    {
      v = VEC_alloc (constructor_elt, gc, list_length (vals));
      for (t = vals; t; t = TREE_CHAIN (t))
        {
          constructor_elt *elt = VEC_quick_push (constructor_elt, v, NULL);
          elt->index = TREE_PURPOSE (t);
          elt->value = TREE_VALUE (t);
        }
    }

  return build_constructor (type, v);
}


/* Return a new REAL_CST node whose type is TYPE and value is D.  */

tree
build_real (tree type, REAL_VALUE_TYPE d)
{
  tree v;
  REAL_VALUE_TYPE *dp;
  int overflow = 0;

  /* ??? Used to check for overflow here via CHECK_FLOAT_TYPE.
     Consider doing it via real_convert now.  */

  v = make_node (REAL_CST);
  dp = ggc_alloc (sizeof (REAL_VALUE_TYPE));
  memcpy (dp, &d, sizeof (REAL_VALUE_TYPE));

  TREE_TYPE (v) = type;
  TREE_REAL_CST_PTR (v) = dp;
  TREE_OVERFLOW (v) = TREE_CONSTANT_OVERFLOW (v) = overflow;
  return v;
}

/* Return a new REAL_CST node whose type is TYPE
   and whose value is the integer value of the INTEGER_CST node I.  */

REAL_VALUE_TYPE
real_value_from_int_cst (tree type, tree i)
{
  REAL_VALUE_TYPE d;

  /* Clear all bits of the real value type so that we can later do
     bitwise comparisons to see if two values are the same.  */
  memset (&d, 0, sizeof d);

  real_from_integer (&d, type ? TYPE_MODE (type) : VOIDmode,
                     TREE_INT_CST_LOW (i), TREE_INT_CST_HIGH (i),
                     TYPE_UNSIGNED (TREE_TYPE (i)));
  return d;
}

/* Given a tree representing an integer constant I, return a tree
   representing the same value as a floating-point constant of type TYPE.  */

tree
build_real_from_int_cst (tree type, tree i)
{
  tree v;
  int overflow = TREE_OVERFLOW (i);

  v = build_real (type, real_value_from_int_cst (type, i));

  TREE_OVERFLOW (v) |= overflow;
  TREE_CONSTANT_OVERFLOW (v) |= overflow;
  return v;
}

/* Return a newly constructed STRING_CST node whose value is
   the LEN characters at STR.
   The TREE_TYPE is not initialized.  */

tree
build_string (int len, const char *str)
{
  tree s;
  size_t length;
  
  length = len + sizeof (struct tree_string);

#ifdef GATHER_STATISTICS
  tree_node_counts[(int) c_kind]++;
  tree_node_sizes[(int) c_kind] += length;
#endif  

  s = ggc_alloc_tree (length);

  memset (s, 0, sizeof (struct tree_common));
  TREE_SET_CODE (s, STRING_CST);
  TREE_CONSTANT (s) = 1;
  TREE_INVARIANT (s) = 1;
  TREE_STRING_LENGTH (s) = len;
  memcpy ((char *) TREE_STRING_POINTER (s), str, len);
  ((char *) TREE_STRING_POINTER (s))[len] = '\0';

  return s;
}

/* Return a newly constructed COMPLEX_CST node whose value is
   specified by the real and imaginary parts REAL and IMAG.
   Both REAL and IMAG should be constant nodes.  TYPE, if specified,
   will be the type of the COMPLEX_CST; otherwise a new type will be made.  */

tree
build_complex (tree type, tree real, tree imag)
{
  tree t = make_node (COMPLEX_CST);

  TREE_REALPART (t) = real;
  TREE_IMAGPART (t) = imag;
  TREE_TYPE (t) = type ? type : build_complex_type (TREE_TYPE (real));
  TREE_OVERFLOW (t) = TREE_OVERFLOW (real) | TREE_OVERFLOW (imag);
  TREE_CONSTANT_OVERFLOW (t)
    = TREE_CONSTANT_OVERFLOW (real) | TREE_CONSTANT_OVERFLOW (imag);
  return t;
}

/* Build a BINFO with LEN language slots.  */

tree
make_tree_binfo_stat (unsigned base_binfos MEM_STAT_DECL)
{
  tree t;
  size_t length = (offsetof (struct tree_binfo, base_binfos)
                   + VEC_embedded_size (tree, base_binfos));

#ifdef GATHER_STATISTICS
  tree_node_counts[(int) binfo_kind]++;
  tree_node_sizes[(int) binfo_kind] += length;
#endif

  t = ggc_alloc_zone_pass_stat (length, &tree_zone);

  memset (t, 0, offsetof (struct tree_binfo, base_binfos));

  TREE_SET_CODE (t, TREE_BINFO);

  VEC_embedded_init (tree, BINFO_BASE_BINFOS (t), base_binfos);

  return t;
}


/* Build a newly constructed TREE_VEC node of length LEN.  */

tree
make_tree_vec_stat (int len MEM_STAT_DECL)
{
  tree t;
  int length = (len - 1) * sizeof (tree) + sizeof (struct tree_vec);

#ifdef GATHER_STATISTICS
  tree_node_counts[(int) vec_kind]++;
  tree_node_sizes[(int) vec_kind] += length;
#endif

  t = ggc_alloc_zone_pass_stat (length, &tree_zone);

  memset (t, 0, length);

  TREE_SET_CODE (t, TREE_VEC);
  TREE_VEC_LENGTH (t) = len;

  return t;
}
\f
/* Return 1 if EXPR is the integer constant zero or a complex constant
   of zero.  */

int
integer_zerop (tree expr)
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == INTEGER_CST
           && ! TREE_CONSTANT_OVERFLOW (expr)
           && TREE_INT_CST_LOW (expr) == 0
           && TREE_INT_CST_HIGH (expr) == 0)
          || (TREE_CODE (expr) == COMPLEX_CST
              && integer_zerop (TREE_REALPART (expr))
              && integer_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is the integer constant one or the corresponding
   complex constant.  */

int
integer_onep (tree expr)
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == INTEGER_CST
           && ! TREE_CONSTANT_OVERFLOW (expr)
           && TREE_INT_CST_LOW (expr) == 1
           && TREE_INT_CST_HIGH (expr) == 0)
          || (TREE_CODE (expr) == COMPLEX_CST
              && integer_onep (TREE_REALPART (expr))
              && integer_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is an integer containing all 1's in as much precision as
   it contains.  Likewise for the corresponding complex constant.  */

int
integer_all_onesp (tree expr)
{
  int prec;
  int uns;

  STRIP_NOPS (expr);

  if (TREE_CODE (expr) == COMPLEX_CST
      && integer_all_onesp (TREE_REALPART (expr))
      && integer_zerop (TREE_IMAGPART (expr)))
    return 1;

  else if (TREE_CODE (expr) != INTEGER_CST
           || TREE_CONSTANT_OVERFLOW (expr))
    return 0;

  uns = TYPE_UNSIGNED (TREE_TYPE (expr));
  if (!uns)
    return (TREE_INT_CST_LOW (expr) == ~(unsigned HOST_WIDE_INT) 0
            && TREE_INT_CST_HIGH (expr) == -1);

  /* Note that using TYPE_PRECISION here is wrong.  We care about the
     actual bits, not the (arbitrary) range of the type.  */
  prec = GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)));
  if (prec >= HOST_BITS_PER_WIDE_INT)
    {
      HOST_WIDE_INT high_value;
      int shift_amount;

      shift_amount = prec - HOST_BITS_PER_WIDE_INT;

      /* Can not handle precisions greater than twice the host int size.  */
      gcc_assert (shift_amount <= HOST_BITS_PER_WIDE_INT);
      if (shift_amount == HOST_BITS_PER_WIDE_INT)
        /* Shifting by the host word size is undefined according to the ANSI
           standard, so we must handle this as a special case.  */
        high_value = -1;
      else
        high_value = ((HOST_WIDE_INT) 1 << shift_amount) - 1;

      return (TREE_INT_CST_LOW (expr) == ~(unsigned HOST_WIDE_INT) 0
              && TREE_INT_CST_HIGH (expr) == high_value);
    }
  else
    return TREE_INT_CST_LOW (expr) == ((unsigned HOST_WIDE_INT) 1 << prec) - 1;
}

/* Return 1 if EXPR is an integer constant that is a power of 2 (i.e., has only
   one bit on).  */

int
integer_pow2p (tree expr)
{
  int prec;
  HOST_WIDE_INT high, low;

  STRIP_NOPS (expr);

  if (TREE_CODE (expr) == COMPLEX_CST
      && integer_pow2p (TREE_REALPART (expr))
      && integer_zerop (TREE_IMAGPART (expr)))
    return 1;

  if (TREE_CODE (expr) != INTEGER_CST || TREE_CONSTANT_OVERFLOW (expr))
    return 0;

  prec = (POINTER_TYPE_P (TREE_TYPE (expr))
          ? POINTER_SIZE : TYPE_PRECISION (TREE_TYPE (expr)));
  high = TREE_INT_CST_HIGH (expr);
  low = TREE_INT_CST_LOW (expr);

  /* First clear all bits that are beyond the type's precision in case
     we've been sign extended.  */

  if (prec == 2 * HOST_BITS_PER_WIDE_INT)
    ;
  else if (prec > HOST_BITS_PER_WIDE_INT)
    high &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
  else
    {
      high = 0;
      if (prec < HOST_BITS_PER_WIDE_INT)
        low &= ~((HOST_WIDE_INT) (-1) << prec);
    }

  if (high == 0 && low == 0)
    return 0;

  return ((high == 0 && (low & (low - 1)) == 0)
          || (low == 0 && (high & (high - 1)) == 0));
}

/* Return 1 if EXPR is an integer constant other than zero or a
   complex constant other than zero.  */

int
integer_nonzerop (tree expr)
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == INTEGER_CST
           && ! TREE_CONSTANT_OVERFLOW (expr)
           && (TREE_INT_CST_LOW (expr) != 0
               || TREE_INT_CST_HIGH (expr) != 0))
          || (TREE_CODE (expr) == COMPLEX_CST
              && (integer_nonzerop (TREE_REALPART (expr))
                  || integer_nonzerop (TREE_IMAGPART (expr)))));
}

/* Return the power of two represented by a tree node known to be a
   power of two.  */

int
tree_log2 (tree expr)
{
  int prec;
  HOST_WIDE_INT high, low;

  STRIP_NOPS (expr);

  if (TREE_CODE (expr) == COMPLEX_CST)
    return tree_log2 (TREE_REALPART (expr));

  prec = (POINTER_TYPE_P (TREE_TYPE (expr))
          ? POINTER_SIZE : TYPE_PRECISION (TREE_TYPE (expr)));

  high = TREE_INT_CST_HIGH (expr);
  low = TREE_INT_CST_LOW (expr);

  /* First clear all bits that are beyond the type's precision in case
     we've been sign extended.  */

  if (prec == 2 * HOST_BITS_PER_WIDE_INT)
    ;
  else if (prec > HOST_BITS_PER_WIDE_INT)
    high &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
  else
    {
      high = 0;
      if (prec < HOST_BITS_PER_WIDE_INT)
        low &= ~((HOST_WIDE_INT) (-1) << prec);
    }

  return (high != 0 ? HOST_BITS_PER_WIDE_INT + exact_log2 (high)
          : exact_log2 (low));
}

/* Similar, but return the largest integer Y such that 2 ** Y is less
   than or equal to EXPR.  */

int
tree_floor_log2 (tree expr)
{
  int prec;
  HOST_WIDE_INT high, low;

  STRIP_NOPS (expr);

  if (TREE_CODE (expr) == COMPLEX_CST)
    return tree_log2 (TREE_REALPART (expr));

  prec = (POINTER_TYPE_P (TREE_TYPE (expr))
          ? POINTER_SIZE : TYPE_PRECISION (TREE_TYPE (expr)));

  high = TREE_INT_CST_HIGH (expr);
  low = TREE_INT_CST_LOW (expr);

  /* First clear all bits that are beyond the type's precision in case
     we've been sign extended.  Ignore if type's precision hasn't been set
     since what we are doing is setting it.  */

  if (prec == 2 * HOST_BITS_PER_WIDE_INT || prec == 0)
    ;
  else if (prec > HOST_BITS_PER_WIDE_INT)
    high &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
  else
    {
      high = 0;
      if (prec < HOST_BITS_PER_WIDE_INT)
        low &= ~((HOST_WIDE_INT) (-1) << prec);
    }

  return (high != 0 ? HOST_BITS_PER_WIDE_INT + floor_log2 (high)
          : floor_log2 (low));
}

/* Return 1 if EXPR is the real constant zero.  */

int
real_zerop (tree expr)
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == REAL_CST
           && ! TREE_CONSTANT_OVERFLOW (expr)
           && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst0))
          || (TREE_CODE (expr) == COMPLEX_CST
              && real_zerop (TREE_REALPART (expr))
              && real_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is the real constant one in real or complex form.  */

int
real_onep (tree expr)
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == REAL_CST
           && ! TREE_CONSTANT_OVERFLOW (expr)
           && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst1))
          || (TREE_CODE (expr) == COMPLEX_CST
              && real_onep (TREE_REALPART (expr))
              && real_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is the real constant two.  */

int
real_twop (tree expr)
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == REAL_CST
           && ! TREE_CONSTANT_OVERFLOW (expr)
           && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst2))
          || (TREE_CODE (expr) == COMPLEX_CST
              && real_twop (TREE_REALPART (expr))
              && real_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is the real constant minus one.  */

int
real_minus_onep (tree expr)
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == REAL_CST
           && ! TREE_CONSTANT_OVERFLOW (expr)
           && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconstm1))
          || (TREE_CODE (expr) == COMPLEX_CST
              && real_minus_onep (TREE_REALPART (expr))
              && real_zerop (TREE_IMAGPART (expr))));
}

/* Nonzero if EXP is a constant or a cast of a constant.  */

int
really_constant_p (tree exp)
{
  /* This is not quite the same as STRIP_NOPS.  It does more.  */
  while (TREE_CODE (exp) == NOP_EXPR
         || TREE_CODE (exp) == CONVERT_EXPR
         || TREE_CODE (exp) == NON_LVALUE_EXPR)
    exp = TREE_OPERAND (exp, 0);
  return TREE_CONSTANT (exp);
}
\f
/* Return first list element whose TREE_VALUE is ELEM.
   Return 0 if ELEM is not in LIST.  */

tree
value_member (tree elem, tree list)
{
  while (list)
    {
      if (elem == TREE_VALUE (list))
        return list;
      list = TREE_CHAIN (list);
    }
  return NULL_TREE;
}

/* Return first list element whose TREE_PURPOSE is ELEM.
   Return 0 if ELEM is not in LIST.  */

tree
purpose_member (tree elem, tree list)
{
  while (list)
    {
      if (elem == TREE_PURPOSE (list))
        return list;
      list = TREE_CHAIN (list);
    }
  return NULL_TREE;
}

/* Return nonzero if ELEM is part of the chain CHAIN.  */

int
chain_member (tree elem, tree chain)
{
  while (chain)
    {
      if (elem == chain)
        return 1;
      chain = TREE_CHAIN (chain);
    }

  return 0;
}

/* Return the length of a chain of nodes chained through TREE_CHAIN.
   We expect a null pointer to mark the end of the chain.
   This is the Lisp primitive `length'.  */

int
list_length (tree t)
{
  tree p = t;
#ifdef ENABLE_TREE_CHECKING
  tree q = t;
#endif
  int len = 0;

  while (p)
    {
      p = TREE_CHAIN (p);
#ifdef ENABLE_TREE_CHECKING
      if (len % 2)
        q = TREE_CHAIN (q);
      gcc_assert (p != q);
#endif
      len++;
    }

  return len;
}

/* Returns the number of FIELD_DECLs in TYPE.  */

int
fields_length (tree type)
{
  tree t = TYPE_FIELDS (type);
  int count = 0;

  for (; t; t = TREE_CHAIN (t))
    if (TREE_CODE (t) == FIELD_DECL)
      ++count;

  return count;
}

/* Concatenate two chains of nodes (chained through TREE_CHAIN)
   by modifying the last node in chain 1 to point to chain 2.
   This is the Lisp primitive `nconc'.  */

tree
chainon (tree op1, tree op2)
{
  tree t1;

  if (!op1)
    return op2;
  if (!op2)
    return op1;

  for (t1 = op1; TREE_CHAIN (t1); t1 = TREE_CHAIN (t1))
    continue;
  TREE_CHAIN (t1) = op2;

#ifdef ENABLE_TREE_CHECKING
  {
    tree t2;
    for (t2 = op2; t2; t2 = TREE_CHAIN (t2))
      gcc_assert (t2 != t1);
  }
#endif

  return op1;
}

/* Return the last node in a chain of nodes (chained through TREE_CHAIN).  */

tree
tree_last (tree chain)
{
  tree next;
  if (chain)
    while ((next = TREE_CHAIN (chain)))
      chain = next;
  return chain;
}

/* Reverse the order of elements in the chain T,
   and return the new head of the chain (old last element).  */

tree
nreverse (tree t)
{
  tree prev = 0, decl, next;
  for (decl = t; decl; decl = next)
    {
      next = TREE_CHAIN (decl);
      TREE_CHAIN (decl) = prev;
      prev = decl;
    }
  return prev;
}
\f
/* Return a newly created TREE_LIST node whose
   purpose and value fields are PARM and VALUE.  */

tree
build_tree_list_stat (tree parm, tree value MEM_STAT_DECL)
{
  tree t = make_node_stat (TREE_LIST PASS_MEM_STAT);
  TREE_PURPOSE (t) = parm;
  TREE_VALUE (t) = value;
  return t;
}

/* Return a newly created TREE_LIST node whose
   purpose and value fields are PURPOSE and VALUE
   and whose TREE_CHAIN is CHAIN.  */

tree
tree_cons_stat (tree purpose, tree value, tree chain MEM_STAT_DECL)
{
  tree node;

  node = ggc_alloc_zone_pass_stat (sizeof (struct tree_list), &tree_zone);

  memset (node, 0, sizeof (struct tree_common));

#ifdef GATHER_STATISTICS
  tree_node_counts[(int) x_kind]++;
  tree_node_sizes[(int) x_kind] += sizeof (struct tree_list);
#endif

  TREE_SET_CODE (node, TREE_LIST);
  TREE_CHAIN (node) = chain;
  TREE_PURPOSE (node) = purpose;
  TREE_VALUE (node) = value;
  return node;
}

\f
/* Return the size nominally occupied by an object of type TYPE
   when it resides in memory.  The value is measured in units of bytes,
   and its data type is that normally used for type sizes
   (which is the first type created by make_signed_type or
   make_unsigned_type).  */

tree
size_in_bytes (tree type)
{
  tree t;

  if (type == error_mark_node)
    return integer_zero_node;

  type = TYPE_MAIN_VARIANT (type);
  t = TYPE_SIZE_UNIT (type);

  if (t == 0)
    {
      lang_hooks.types.incomplete_type_error (NULL_TREE, type);
      return size_zero_node;
    }

  if (TREE_CODE (t) == INTEGER_CST)
    t = force_fit_type (t, 0, false, false);

  return t;
}

/* Return the size of TYPE (in bytes) as a wide integer
   or return -1 if the size can vary or is larger than an integer.  */

HOST_WIDE_INT
int_size_in_bytes (tree type)
{
  tree t;

  if (type == error_mark_node)
    return 0;

  type = TYPE_MAIN_VARIANT (type);
  t = TYPE_SIZE_UNIT (type);
  if (t == 0
      || TREE_CODE (t) != INTEGER_CST
      || TREE_OVERFLOW (t)
      || TREE_INT_CST_HIGH (t) != 0
      /* If the result would appear negative, it's too big to represent.  */
      || (HOST_WIDE_INT) TREE_INT_CST_LOW (t) < 0)
    return -1;

  return TREE_INT_CST_LOW (t);
}
\f
/* Return the bit position of FIELD, in bits from the start of the record.
   This is a tree of type bitsizetype.  */

tree
bit_position (tree field)
{
  return bit_from_pos (DECL_FIELD_OFFSET (field),
                       DECL_FIELD_BIT_OFFSET (field));
}

/* Likewise, but return as an integer.  It must be representable in
   that way (since it could be a signed value, we don't have the
   option of returning -1 like int_size_in_byte can.  */

HOST_WIDE_INT
int_bit_position (tree field)
{
  return tree_low_cst (bit_position (field), 0);
}
\f
/* Return the byte position of FIELD, in bytes from the start of the record.
   This is a tree of type sizetype.  */

tree
byte_position (tree field)
{
  return byte_from_pos (DECL_FIELD_OFFSET (field),
                        DECL_FIELD_BIT_OFFSET (field));
}

/* Likewise, but return as an integer.  It must be representable in
   that way (since it could be a signed value, we don't have the
   option of returning -1 like int_size_in_byte can.  */

HOST_WIDE_INT
int_byte_position (tree field)
{
  return tree_low_cst (byte_position (field), 0);
}
\f
/* Return the strictest alignment, in bits, that T is known to have.  */

unsigned int
expr_align (tree t)
{
  unsigned int align0, align1;

  switch (TREE_CODE (t))
    {
    case NOP_EXPR:  case CONVERT_EXPR:  case NON_LVALUE_EXPR:
      /* If we have conversions, we know that the alignment of the
         object must meet each of the alignments of the types.  */
      align0 = expr_align (TREE_OPERAND (t, 0));
      align1 = TYPE_ALIGN (TREE_TYPE (t));
      return MAX (align0, align1);

    case SAVE_EXPR:         case COMPOUND_EXPR:       case MODIFY_EXPR:
    case INIT_EXPR:         case TARGET_EXPR:         case WITH_CLEANUP_EXPR:
    case CLEANUP_POINT_EXPR:
      /* These don't change the alignment of an object.  */
      return expr_align (TREE_OPERAND (t, 0));

    case COND_EXPR:
      /* The best we can do is say that the alignment is the least aligned
         of the two arms.  */
      align0 = expr_align (TREE_OPERAND (t, 1));
      align1 = expr_align (TREE_OPERAND (t, 2));
      return MIN (align0, align1);

    case LABEL_DECL:     case CONST_DECL:
    case VAR_DECL:       case PARM_DECL:   case RESULT_DECL:
      if (DECL_ALIGN (t) != 0)
        return DECL_ALIGN (t);
      break;

    case FUNCTION_DECL:
      return FUNCTION_BOUNDARY;

    default:
      break;
    }

  /* Otherwise take the alignment from that of the type.  */
  return TYPE_ALIGN (TREE_TYPE (t));
}
\f
/* Return, as a tree node, the number of elements for TYPE (which is an
   ARRAY_TYPE) minus one. This counts only elements of the top array.  */

tree
array_type_nelts (tree type)
{
  tree index_type, min, max;

  /* If they did it with unspecified bounds, then we should have already
     given an error about it before we got here.  */
  if (! TYPE_DOMAIN (type))
    return error_mark_node;

  index_type = TYPE_DOMAIN (type);
  min = TYPE_MIN_VALUE (index_type);
  max = TYPE_MAX_VALUE (index_type);

  return (integer_zerop (min)
          ? max
          : fold_build2 (MINUS_EXPR, TREE_TYPE (max), max, min));
}
\f
/* If arg is static -- a reference to an object in static storage -- then
   return the object.  This is not the same as the C meaning of `static'.
   If arg isn't static, return NULL.  */

tree
staticp (tree arg)
{
  switch (TREE_CODE (arg))
    {
    case FUNCTION_DECL:
      /* Nested functions are static, even though taking their address will
         involve a trampoline as we unnest the nested function and create
         the trampoline on the tree level.  */
      return arg;

    case VAR_DECL:
      return ((TREE_STATIC (arg) || DECL_EXTERNAL (arg))
              && ! DECL_THREAD_LOCAL_P (arg)
              && ! DECL_DLLIMPORT_P (arg)
              ? arg : NULL);

    case CONST_DECL:
      return ((TREE_STATIC (arg) || DECL_EXTERNAL (arg))
              ? arg : NULL);

    case CONSTRUCTOR:
      return TREE_STATIC (arg) ? arg : NULL;

    case LABEL_DECL:
    case STRING_CST:
      return arg;

    case COMPONENT_REF:
      /* If the thing being referenced is not a field, then it is
         something language specific.  */
      if (TREE_CODE (TREE_OPERAND (arg, 1)) != FIELD_DECL)
        return (*lang_hooks.staticp) (arg);

      /* If we are referencing a bitfield, we can't evaluate an
         ADDR_EXPR at compile time and so it isn't a constant.  */
      if (DECL_BIT_FIELD (TREE_OPERAND (arg, 1)))
        return NULL;

      return staticp (TREE_OPERAND (arg, 0));

    case BIT_FIELD_REF:
      return NULL;

    case MISALIGNED_INDIRECT_REF:
    case ALIGN_INDIRECT_REF:
    case INDIRECT_REF:
      return TREE_CONSTANT (TREE_OPERAND (arg, 0)) ? arg : NULL;

    case ARRAY_REF:
    case ARRAY_RANGE_REF:
      if (TREE_CODE (TYPE_SIZE (TREE_TYPE (arg))) == INTEGER_CST
          && TREE_CODE (TREE_OPERAND (arg, 1)) == INTEGER_CST)
        return staticp (TREE_OPERAND (arg, 0));
      else
        return false;

    default:
      if ((unsigned int) TREE_CODE (arg)
          >= (unsigned int) LAST_AND_UNUSED_TREE_CODE)
        return lang_hooks.staticp (arg);
      else
        return NULL;
    }
}
\f
/* Wrap a SAVE_EXPR around EXPR, if appropriate.
   Do this to any expression which may be used in more than one place,
   but must be evaluated only once.

   Normally, expand_expr would reevaluate the expression each time.
   Calling save_expr produces something that is evaluated and recorded
   the first time expand_expr is called on it.  Subsequent calls to
   expand_expr just reuse the recorded value.

   The call to expand_expr that generates code that actually computes
   the value is the first call *at compile time*.  Subsequent calls
   *at compile time* generate code to use the saved value.
   This produces correct result provided that *at run time* control
   always flows through the insns made by the first expand_expr
   before reaching the other places where the save_expr was evaluated.
   You, the caller of save_expr, must make sure this is so.

   Constants, and certain read-only nodes, are returned with no
   SAVE_EXPR because that is safe.  Expressions containing placeholders
   are not touched; see tree.def for an explanation of what these
   are used for.  */

tree
save_expr (tree expr)
{
  tree t = fold (expr);
  tree inner;

  /* If the tree evaluates to a constant, then we don't want to hide that
     fact (i.e. this allows further folding, and direct checks for constants).
     However, a read-only object that has side effects cannot be bypassed.
     Since it is no problem to reevaluate literals, we just return the
     literal node.  */
  inner = skip_simple_arithmetic (t);

  if (TREE_INVARIANT (inner)
      || (TREE_READONLY (inner) && ! TREE_SIDE_EFFECTS (inner))
      || TREE_CODE (inner) == SAVE_EXPR
      || TREE_CODE (inner) == ERROR_MARK)
    return t;

  /* If INNER contains a PLACEHOLDER_EXPR, we must evaluate it each time, since
     it means that the size or offset of some field of an object depends on
     the value within another field.

     Note that it must not be the case that T contains both a PLACEHOLDER_EXPR
     and some variable since it would then need to be both evaluated once and
     evaluated more than once.  Front-ends must assure this case cannot
     happen by surrounding any such subexpressions in their own SAVE_EXPR
     and forcing evaluation at the proper time.  */
  if (contains_placeholder_p (inner))
    return t;

  t = build1 (SAVE_EXPR, TREE_TYPE (expr), t);

  /* This expression might be placed ahead of a jump to ensure that the
     value was computed on both sides of the jump.  So make sure it isn't
     eliminated as dead.  */
  TREE_SIDE_EFFECTS (t) = 1;
  TREE_INVARIANT (t) = 1;
  return t;
}

/* Look inside EXPR and into any simple arithmetic operations.  Return
   the innermost non-arithmetic node.  */

tree
skip_simple_arithmetic (tree expr)
{
  tree inner;

  /* We don't care about whether this can be used as an lvalue in this
     context.  */
  while (TREE_CODE (expr) == NON_LVALUE_EXPR)
    expr = TREE_OPERAND (expr, 0);

  /* If we have simple operations applied to a SAVE_EXPR or to a SAVE_EXPR and
     a constant, it will be more efficient to not make another SAVE_EXPR since
     it will allow better simplification and GCSE will be able to merge the
     computations if they actually occur.  */
  inner = expr;
  while (1)
    {
      if (UNARY_CLASS_P (inner))
        inner = TREE_OPERAND (inner, 0);
      else if (BINARY_CLASS_P (inner))
        {
          if (TREE_INVARIANT (TREE_OPERAND (inner, 1)))
            inner = TREE_OPERAND (inner, 0);
          else if (TREE_INVARIANT (TREE_OPERAND (inner, 0)))
            inner = TREE_OPERAND (inner, 1);
          else
            break;
        }
      else
        break;
    }

  return inner;
}

/* Return which tree structure is used by T.  */

enum tree_node_structure_enum
tree_node_structure (tree t)
{
  enum tree_code code = TREE_CODE (t);

  switch (TREE_CODE_CLASS (code))
    {      
    case tcc_declaration:
      {
        switch (code)
          {
          case FIELD_DECL:
            return TS_FIELD_DECL;
          case PARM_DECL:
            return TS_PARM_DECL;
          case VAR_DECL:
            return TS_VAR_DECL;
          case LABEL_DECL:
            return TS_LABEL_DECL;
          case RESULT_DECL:
            return TS_RESULT_DECL;
          case CONST_DECL:
            return TS_CONST_DECL;
          case TYPE_DECL:
            return TS_TYPE_DECL;
          case FUNCTION_DECL:
            return TS_FUNCTION_DECL;
          default:
            return TS_DECL_NON_COMMON;
          }
      }
    case tcc_type:
      return TS_TYPE;
    case tcc_reference:
    case tcc_comparison:
    case tcc_unary:
    case tcc_binary:
    case tcc_expression:
    case tcc_statement:
      return TS_EXP;
    default:  /* tcc_constant and tcc_exceptional */
      break;
    }
  switch (code)
    {
      /* tcc_constant cases.  */
    case INTEGER_CST:           return TS_INT_CST;
    case REAL_CST:              return TS_REAL_CST;
    case COMPLEX_CST:           return TS_COMPLEX;
    case VECTOR_CST:            return TS_VECTOR;
    case STRING_CST:            return TS_STRING;
      /* tcc_exceptional cases.  */
    case ERROR_MARK:            return TS_COMMON;
    case IDENTIFIER_NODE:       return TS_IDENTIFIER;
    case TREE_LIST:             return TS_LIST;
    case TREE_VEC:              return TS_VEC;
    case PHI_NODE:              return TS_PHI_NODE;
    case SSA_NAME:              return TS_SSA_NAME;
    case PLACEHOLDER_EXPR:      return TS_COMMON;
    case STATEMENT_LIST:        return TS_STATEMENT_LIST;
    case BLOCK:                 return TS_BLOCK;
    case CONSTRUCTOR:           return TS_CONSTRUCTOR;
    case TREE_BINFO:            return TS_BINFO;
    case VALUE_HANDLE:          return TS_VALUE_HANDLE;

    default:
      gcc_unreachable ();
    }
}
\f
/* Return 1 if EXP contains a PLACEHOLDER_EXPR; i.e., if it represents a size
   or offset that depends on a field within a record.  */

bool
contains_placeholder_p (tree exp)
{
  enum tree_code code;

  if (!exp)
    return 0;

  code = TREE_CODE (exp);
  if (code == PLACEHOLDER_EXPR)
    return 1;

  switch (TREE_CODE_CLASS (code))
    {
    case tcc_reference:
      /* Don't look at any PLACEHOLDER_EXPRs that might be in index or bit
         position computations since they will be converted into a
         WITH_RECORD_EXPR involving the reference, which will assume
         here will be valid.  */
      return CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 0));

    case tcc_exceptional:
      if (code == TREE_LIST)
        return (CONTAINS_PLACEHOLDER_P (TREE_VALUE (exp))
                || CONTAINS_PLACEHOLDER_P (TREE_CHAIN (exp)));
      break;

    case tcc_unary:
    case tcc_binary:
    case tcc_comparison:
    case tcc_expression:
      switch (code)
        {
        case COMPOUND_EXPR:
          /* Ignoring the first operand isn't quite right, but works best.  */
          return CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 1));

        case COND_EXPR:
          return (CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 0))
                  || CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 1))
                  || CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 2)));

        case CALL_EXPR:
          return CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 1));

        default:
          break;
        }

      switch (TREE_CODE_LENGTH (code))
        {
        case 1:
          return CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 0));
        case 2:
          return (CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 0))
                  || CONTAINS_PLACEHOLDER_P (TREE_OPERAND (exp, 1)));
        default:
          return 0;
        }

    default:
      return 0;
    }
  return 0;
}

/* Return true if any part of the computation of TYPE involves a
   PLACEHOLDER_EXPR.  This includes size, bounds, qualifiers
   (for QUAL_UNION_TYPE) and field positions.  */

static bool
type_contains_placeholder_1 (tree type)
{
  /* If the size contains a placeholder or the parent type (component type in
     the case of arrays) type involves a placeholder, this type does.  */
  if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE (type))
      || CONTAINS_PLACEHOLDER_P (TYPE_SIZE_UNIT (type))
      || (TREE_TYPE (type) != 0
          && type_contains_placeholder_p (TREE_TYPE (type))))
    return true;

  /* Now do type-specific checks.  Note that the last part of the check above
     greatly limits what we have to do below.  */
  switch (TREE_CODE (type))
    {
    case VOID_TYPE:
    case COMPLEX_TYPE:
    case ENUMERAL_TYPE:
    case BOOLEAN_TYPE:
    case CHAR_TYPE:
    case POINTER_TYPE:
    case OFFSET_TYPE:
    case REFERENCE_TYPE:
    case METHOD_TYPE:
    case FUNCTION_TYPE:
    case VECTOR_TYPE:
      return false;

    case INTEGER_TYPE:
    case REAL_TYPE:
      /* Here we just check the bounds.  */
      return (CONTAINS_PLACEHOLDER_P (TYPE_MIN_VALUE (type))
              || CONTAINS_PLACEHOLDER_P (TYPE_MAX_VALUE (type)));

    case ARRAY_TYPE:
      /* We're already checked the component type (TREE_TYPE), so just check
         the index type.  */
      return type_contains_placeholder_p (TYPE_DOMAIN (type));

    case RECORD_TYPE:
    case UNION_TYPE:
    case QUAL_UNION_TYPE:
      {
        tree field;

        for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
          if (TREE_CODE (field) == FIELD_DECL
              && (CONTAINS_PLACEHOLDER_P (DECL_FIELD_OFFSET (field))
                  || (TREE_CODE (type) == QUAL_UNION_TYPE
                      && CONTAINS_PLACEHOLDER_P (DECL_QUALIFIER (field)))
                  || type_contains_placeholder_p (TREE_TYPE (field))))
            return true;

        return false;
      }

    default:
      gcc_unreachable ();
    }
}

bool
type_contains_placeholder_p (tree type)
{
  bool result;

  /* If the contains_placeholder_bits field has been initialized,
     then we know the answer.  */
  if (TYPE_CONTAINS_PLACEHOLDER_INTERNAL (type) > 0)
    return TYPE_CONTAINS_PLACEHOLDER_INTERNAL (type) - 1;

  /* Indicate that we've seen this type node, and the answer is false.
     This is what we want to return if we run into recursion via fields.  */
  TYPE_CONTAINS_PLACEHOLDER_INTERNAL (type) = 1;

  /* Compute the real value.  */
  result = type_contains_placeholder_1 (type);

  /* Store the real value.  */
  TYPE_CONTAINS_PLACEHOLDER_INTERNAL (type) = result + 1;

  return result;
}
\f
/* Given a tree EXP, a FIELD_DECL F, and a replacement value R,
   return a tree with all occurrences of references to F in a
   PLACEHOLDER_EXPR replaced by R.   Note that we assume here that EXP
   contains only arithmetic expressions or a CALL_EXPR with a
   PLACEHOLDER_EXPR occurring only in its arglist.  */

tree
substitute_in_expr (tree exp, tree f, tree r)
{
  enum tree_code code = TREE_CODE (exp);
  tree op0, op1, op2, op3;
  tree new;
  tree inner;

  /* We handle TREE_LIST and COMPONENT_REF separately.  */
  if (code == TREE_LIST)
    {
      op0 = SUBSTITUTE_IN_EXPR (TREE_CHAIN (exp), f, r);
      op1 = SUBSTITUTE_IN_EXPR (TREE_VALUE (exp), f, r);
      if (op0 == TREE_CHAIN (exp) && op1 == TREE_VALUE (exp))
        return exp;

      return tree_cons (TREE_PURPOSE (exp), op1, op0);
    }
  else if (code == COMPONENT_REF)
   {
     /* If this expression is getting a value from a PLACEHOLDER_EXPR
        and it is the right field, replace it with R.  */
     for (inner = TREE_OPERAND (exp, 0);
          REFERENCE_CLASS_P (inner);
          inner = TREE_OPERAND (inner, 0))
       ;
     if (TREE_CODE (inner) == PLACEHOLDER_EXPR
         && TREE_OPERAND (exp, 1) == f)
       return r;

     /* If this expression hasn't been completed let, leave it alone.  */
     if (TREE_CODE (inner) == PLACEHOLDER_EXPR && TREE_TYPE (inner) == 0)
       return exp;

     op0 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 0), f, r);
     if (op0 == TREE_OPERAND (exp, 0))
       return exp;

     new = fold_build3 (COMPONENT_REF, TREE_TYPE (exp),
                        op0, TREE_OPERAND (exp, 1), NULL_TREE);
   }
  else
    switch (TREE_CODE_CLASS (code))
      {
      case tcc_constant:
      case tcc_declaration:
        return exp;

      case tcc_exceptional:
      case tcc_unary:
      case tcc_binary:
      case tcc_comparison:
      case tcc_expression:
      case tcc_reference:
        switch (TREE_CODE_LENGTH (code))
          {
          case 0:
            return exp;

          case 1:
            op0 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 0), f, r);
            if (op0 == TREE_OPERAND (exp, 0))
              return exp;

            new = fold_build1 (code, TREE_TYPE (exp), op0);
            break;

          case 2:
            op0 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 0), f, r);
            op1 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 1), f, r);

            if (op0 == TREE_OPERAND (exp, 0) && op1 == TREE_OPERAND (exp, 1))
              return exp;

            new = fold_build2 (code, TREE_TYPE (exp), op0, op1);
            break;

          case 3:
            op0 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 0), f, r);
            op1 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 1), f, r);
            op2 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 2), f, r);

            if (op0 == TREE_OPERAND (exp, 0) && op1 == TREE_OPERAND (exp, 1)
                && op2 == TREE_OPERAND (exp, 2))
              return exp;

            new = fold_build3 (code, TREE_TYPE (exp), op0, op1, op2);
            break;

          case 4:
            op0 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 0), f, r);
            op1 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 1), f, r);
            op2 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 2), f, r);
            op3 = SUBSTITUTE_IN_EXPR (TREE_OPERAND (exp, 3), f, r);

            if (op0 == TREE_OPERAND (exp, 0) && op1 == TREE_OPERAND (exp, 1)
                && op2 == TREE_OPERAND (exp, 2)
                && op3 == TREE_OPERAND (exp, 3))
              return exp;

            new = fold (build4 (code, TREE_TYPE (exp), op0, op1, op2, op3));
            break;

          default:
            gcc_unreachable ();
          }
        break;

      default:
        gcc_unreachable ();
      }

  TREE_READONLY (new) = TREE_READONLY (exp);
  return new;
}

/* Similar, but look for a PLACEHOLDER_EXPR in EXP and find a replacement
   for it within OBJ, a tree that is an object or a chain of references.  */

tree
substitute_placeholder_in_expr (tree exp, tree obj)
{
  enum tree_code code = TREE_CODE (exp);
  tree op0, op1, op2, op3;

  /* If this is a PLACEHOLDER_EXPR, see if we find a corresponding type
     in the chain of OBJ.  */
  if (code == PLACEHOLDER_EXPR)
    {
      tree need_type = TYPE_MAIN_VARIANT (TREE_TYPE (exp));
      tree elt;

      for (elt = obj; elt != 0;
           elt = ((TREE_CODE (elt) == COMPOUND_EXPR
                   || TREE_CODE (elt) == COND_EXPR)
                  ? TREE_OPERAND (elt, 1)
                  : (REFERENCE_CLASS_P (elt)
                     || UNARY_CLASS_P (elt)
                     || BINARY_CLASS_P (elt)
                     || EXPRESSION_CLASS_P (elt))
                  ? TREE_OPERAND (elt, 0) : 0))
        if (TYPE_MAIN_VARIANT (TREE_TYPE (elt)) == need_type)
          return elt;

      for (elt = obj; elt != 0;
           elt = ((TREE_CODE (elt) == COMPOUND_EXPR
                   || TREE_CODE (elt) == COND_EXPR)
                  ? TREE_OPERAND (elt, 1)
                  : (REFERENCE_CLASS_P (elt)
                     || UNARY_CLASS_P (elt)
                     || BINARY_CLASS_P (elt)
                     || EXPRESSION_CLASS_P (elt))
                  ? TREE_OPERAND (elt, 0) : 0))
        if (POINTER_TYPE_P (TREE_TYPE (elt))
            && (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (elt)))
                == need_type))
          return fold_build1 (INDIRECT_REF, need_type, elt);

      /* If we didn't find it, return the original PLACEHOLDER_EXPR.  If it
         survives until RTL generation, there will be an error.  */
      return exp;
    }

  /* TREE_LIST is special because we need to look at TREE_VALUE
     and TREE_CHAIN, not TREE_OPERANDS.  */
  else if (code == TREE_LIST)
    {
      op0 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_CHAIN (exp), obj);
      op1 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_VALUE (exp), obj);
      if (op0 == TREE_CHAIN (exp) && op1 == TREE_VALUE (exp))
        return exp;

      return tree_cons (TREE_PURPOSE (exp), op1, op0);
    }
  else
    switch (TREE_CODE_CLASS (code))
      {
      case tcc_constant:
      case tcc_declaration:
        return exp;

      case tcc_exceptional:
      case tcc_unary:
      case tcc_binary:
      case tcc_comparison:
      case tcc_expression:
      case tcc_reference:
      case tcc_statement:
        switch (TREE_CODE_LENGTH (code))
          {
          case 0:
            return exp;

          case 1:
            op0 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 0), obj);
            if (op0 == TREE_OPERAND (exp, 0))
              return exp;
            else
              return fold_build1 (code, TREE_TYPE (exp), op0);

          case 2:
            op0 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 0), obj);
            op1 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 1), obj);

            if (op0 == TREE_OPERAND (exp, 0) && op1 == TREE_OPERAND (exp, 1))
              return exp;
            else
              return fold_build2 (code, TREE_TYPE (exp), op0, op1);

          case 3:
            op0 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 0), obj);
            op1 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 1), obj);
            op2 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 2), obj);

            if (op0 == TREE_OPERAND (exp, 0) && op1 == TREE_OPERAND (exp, 1)
                && op2 == TREE_OPERAND (exp, 2))
              return exp;
            else
              return fold_build3 (code, TREE_TYPE (exp), op0, op1, op2);

          case 4:
            op0 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 0), obj);
            op1 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 1), obj);
            op2 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 2), obj);
            op3 = SUBSTITUTE_PLACEHOLDER_IN_EXPR (TREE_OPERAND (exp, 3), obj);

            if (op0 == TREE_OPERAND (exp, 0) && op1 == TREE_OPERAND (exp, 1)
                && op2 == TREE_OPERAND (exp, 2)
                && op3 == TREE_OPERAND (exp, 3))
              return exp;
            else
              return fold (build4 (code, TREE_TYPE (exp), op0, op1, op2, op3));

          default:
            gcc_unreachable ();
          }
        break;

      default:
        gcc_unreachable ();
      }
}
\f
/* Stabilize a reference so that we can use it any number of times
   without causing its operands to be evaluated more than once.
   Returns the stabilized reference.  This works by means of save_expr,
   so see the caveats in the comments about save_expr.

   Also allows conversion expressions whose operands are references.
   Any other kind of expression is returned unchanged.  */

tree
stabilize_reference (tree ref)
{
  tree result;
  enum tree_code code = TREE_CODE (ref);

  switch (code)
    {
    case VAR_DECL:
    case PARM_DECL:
    case RESULT_DECL:
      /* No action is needed in this case.  */
      return ref;

    case NOP_EXPR:
    case CONVERT_EXPR:
    case FLOAT_EXPR:
    case FIX_TRUNC_EXPR:
    case FIX_FLOOR_EXPR:
    case FIX_ROUND_EXPR:
    case FIX_CEIL_EXPR:
      result = build_nt (code, stabilize_reference (TREE_OPERAND (ref, 0)));
      break;

    case INDIRECT_REF:
      result = build_nt (INDIRECT_REF,
                         stabilize_reference_1 (TREE_OPERAND (ref, 0)));
      break;

    case COMPONENT_REF:
      result = build_nt (COMPONENT_REF,
                         stabilize_reference (TREE_OPERAND (ref, 0)),
                         TREE_OPERAND (ref, 1), NULL_TREE);
      break;

    case BIT_FIELD_REF:
      result = build_nt (BIT_FIELD_REF,
                         stabilize_reference (TREE_OPERAND (ref, 0)),
                         stabilize_reference_1 (TREE_OPERAND (ref, 1)),
                         stabilize_reference_1 (TREE_OPERAND (ref, 2)));
      break;

    case ARRAY_REF:
      result = build_nt (ARRAY_REF,
                         stabilize_reference (TREE_OPERAND (ref, 0)),
                         stabilize_reference_1 (TREE_OPERAND (ref, 1)),
                         TREE_OPERAND (ref, 2), TREE_OPERAND (ref, 3));
      break;

    case ARRAY_RANGE_REF:
      result = build_nt (ARRAY_RANGE_REF,
                         stabilize_reference (TREE_OPERAND (ref, 0)),
                         stabilize_reference_1 (TREE_OPERAND (ref, 1)),
                         TREE_OPERAND (ref, 2), TREE_OPERAND (ref, 3));
      break;

    case COMPOUND_EXPR:
      /* We cannot wrap the first expression in a SAVE_EXPR, as then
         it wouldn't be ignored.  This matters when dealing with
         volatiles.  */
      return stabilize_reference_1 (ref);

      /* If arg isn't a kind of lvalue we recognize, make no change.
         Caller should recognize the error for an invalid lvalue.  */
    default:
      return ref;

    case ERROR_MARK:
      return error_mark_node;
    }

  TREE_TYPE (result) = TREE_TYPE (ref);
  TREE_READONLY (result) = TREE_READONLY (ref);
  TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (ref);
  TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (ref);

  return result;
}

/* Subroutine of stabilize_reference; this is called for subtrees of
   references.  Any expression with side-effects must be put in a SAVE_EXPR
   to ensure that it is only evaluated once.

   We don't put SAVE_EXPR nodes around everything, because assigning very
   simple expressions to temporaries causes us to miss good opportunities
   for optimizations.  Among other things, the opportunity to fold in the
   addition of a constant into an addressing mode often gets lost, e.g.
   "y[i+1] += x;".  In general, we take the approach that we should not make
   an assignment unless we are forced into it - i.e., that any non-side effect
   operator should be allowed, and that cse should take care of coalescing
   multiple utterances of the same expression should that prove fruitful.  */

tree
stabilize_reference_1 (tree e)
{
  tree result;
  enum tree_code code = TREE_CODE (e);

  /* We cannot ignore const expressions because it might be a reference
     to a const array but whose index contains side-effects.  But we can
     ignore things that are actual constant or that already have been
     handled by this function.  */

  if (TREE_INVARIANT (e))
    return e;

  switch (TREE_CODE_CLASS (code))
    {
    case tcc_exceptional:
    case tcc_type:
    case tcc_declaration:
    case tcc_comparison:
    case tcc_statement:
    case tcc_expression:
    case tcc_reference:
      /* If the expression has side-effects, then encase it in a SAVE_EXPR
         so that it will only be evaluated once.  */
      /* The reference (r) and comparison (<) classes could be handled as
         below, but it is generally faster to only evaluate them once.  */
      if (TREE_SIDE_EFFECTS (e))
        return save_expr (e);
      return e;

    case tcc_constant:
      /* Constants need no processing.  In fact, we should never reach
         here.  */
      return e;

    case tcc_binary:
      /* Division is slow and tends to be compiled with jumps,
         especially the division by powers of 2 that is often
         found inside of an array reference.  So do it just once.  */
      if (code == TRUNC_DIV_EXPR || code == TRUNC_MOD_EXPR
          || code == FLOOR_DIV_EXPR || code == FLOOR_MOD_EXPR
          || code == CEIL_DIV_EXPR || code == CEIL_MOD_EXPR
          || code == ROUND_DIV_EXPR || code == ROUND_MOD_EXPR)
        return save_expr (e);
      /* Recursively stabilize each operand.  */
      result = build_nt (code, stabilize_reference_1 (TREE_OPERAND (e, 0)),
                         stabilize_reference_1 (TREE_OPERAND (e, 1)));
      break;

    case tcc_unary:
      /* Recursively stabilize each operand.  */
      result = build_nt (code, stabilize_reference_1 (TREE_OPERAND (e, 0)));
      break;

    default:
      gcc_unreachable ();
    }

  TREE_TYPE (result) = TREE_TYPE (e);
  TREE_READONLY (result) = TREE_READONLY (e);
  TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e);
  TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e);
  TREE_INVARIANT (result) = 1;

  return result;
}
\f
/* Low-level constructors for expressions.  */

/* A helper function for build1 and constant folders.  Set TREE_CONSTANT,
   TREE_INVARIANT, and TREE_SIDE_EFFECTS for an ADDR_EXPR.  */

void
recompute_tree_invarant_for_addr_expr (tree t)
{
  tree node;
  bool tc = true, ti = true, se = false;

  /* We started out assuming this address is both invariant and constant, but
     does not have side effects.  Now go down any handled components and see if
     any of them involve offsets that are either non-constant or non-invariant.
     Also check for side-effects.

     ??? Note that this code makes no attempt to deal with the case where
     taking the address of something causes a copy due to misalignment.  */

#define UPDATE_TITCSE(NODE)  \
do { tree _node = (NODE); \
     if (_node && !TREE_INVARIANT (_node)) ti = false; \
     if (_node && !TREE_CONSTANT (_node)) tc = false; \
     if (_node && TREE_SIDE_EFFECTS (_node)) se = true; } while (0)

  for (node = TREE_OPERAND (t, 0); handled_component_p (node);
       node = TREE_OPERAND (node, 0))
    {
      /* If the first operand doesn't have an ARRAY_TYPE, this is a bogus
         array reference (probably made temporarily by the G++ front end),
         so ignore all the operands.  */
      if ((TREE_CODE (node) == ARRAY_REF
           || TREE_CODE (node) == ARRAY_RANGE_REF)
          && TREE_CODE (TREE_TYPE (TREE_OPERAND (node, 0))) == ARRAY_TYPE)
        {
          UPDATE_TITCSE (TREE_OPERAND (node, 1));
          if (TREE_OPERAND (node, 2))
            UPDATE_TITCSE (TREE_OPERAND (node, 2));
          if (TREE_OPERAND (node, 3))
            UPDATE_TITCSE (TREE_OPERAND (node, 3));
        }
      /* Likewise, just because this is a COMPONENT_REF doesn't mean we have a
         FIELD_DECL, apparently.  The G++ front end can put something else
         there, at least temporarily.  */
      else if (TREE_CODE (node) == COMPONENT_REF
               && TREE_CODE (TREE_OPERAND (node, 1)) == FIELD_DECL)
        {
          if (TREE_OPERAND (node, 2))
            UPDATE_TITCSE (TREE_OPERAND (node, 2));
        }
      else if (TREE_CODE (node) == BIT_FIELD_REF)
        UPDATE_TITCSE (TREE_OPERAND (node, 2));
    }

  node = lang_hooks.expr_to_decl (node, &tc, &ti, &se);

  /* Now see what's inside.  If it's an INDIRECT_REF, copy our properties from
     the address, since &(*a)->b is a form of addition.  If it's a decl, it's
     invariant and constant if the decl is static.  It's also invariant if it's
     a decl in the current function.  Taking the address of a volatile variable
     is not volatile.  If it's a constant, the address is both invariant and
     constant.  Otherwise it's neither.  */
  if (TREE_CODE (node) == INDIRECT_REF)
    UPDATE_TITCSE (TREE_OPERAND (node, 0));
  else if (DECL_P (node))
    {
      if (staticp (node))
        ;
      else if (decl_function_context (node) == current_function_decl
               /* Addresses of thread-local variables are invariant.  */
               || (TREE_CODE (node) == VAR_DECL
                   && DECL_THREAD_LOCAL_P (node)))
        tc = false;
      else
        ti = tc = false;
    }
  else if (CONSTANT_CLASS_P (node))
    ;
  else
    {
      ti = tc = false;
      se |= TREE_SIDE_EFFECTS (node);
    }

  TREE_CONSTANT (t) = tc;
  TREE_INVARIANT (t) = ti;
  TREE_SIDE_EFFECTS (t) = se;
#undef UPDATE_TITCSE
}

/* Build an expression of code CODE, data type TYPE, and operands as
   specified.  Expressions and reference nodes can be created this way.
   Constants, decls, types and misc nodes cannot be.

   We define 5 non-variadic functions, from 0 to 4 arguments.  This is
   enough for all extant tree codes.  These functions can be called
   directly (preferably!), but can also be obtained via GCC preprocessor
   magic within the build macro.  */

tree
build0_stat (enum tree_code code, tree tt MEM_STAT_DECL)
{
  tree t;

  gcc_assert (TREE_CODE_LENGTH (code) == 0);

  t = make_node_stat (code PASS_MEM_STAT);
  TREE_TYPE (t) = tt;

  return t;
}

tree
build1_stat (enum tree_code code, tree type, tree node MEM_STAT_DECL)
{
  int length = sizeof (struct tree_exp);
#ifdef GATHER_STATISTICS
  tree_node_kind kind;
#endif
  tree t;

#ifdef GATHER_STATISTICS
  switch (TREE_CODE_CLASS (code))
    {
    case tcc_statement:  /* an expression with side effects */
      kind = s_kind;
      break;
    case tcc_reference:  /* a reference */
      kind = r_kind;
      break;
    default:
      kind = e_kind;
      break;
    }

  tree_node_counts[(int) kind]++;
  tree_node_sizes[(int) kind] += length;
#endif

  gcc_assert (TREE_CODE_LENGTH (code) == 1);

  t = ggc_alloc_zone_pass_stat (length, &tree_zone);

  memset (t, 0, sizeof (struct tree_common));

  TREE_SET_CODE (t, code);

  TREE_TYPE (t) = type;
#ifdef USE_MAPPED_LOCATION
  SET_EXPR_LOCATION (t, UNKNOWN_LOCATION);
#else
  SET_EXPR_LOCUS (t, NULL);
#endif
  TREE_COMPLEXITY (t) = 0;
  TREE_OPERAND (t, 0) = node;
  TREE_BLOCK (t) = NULL_TREE;
  if (node && !TYPE_P (node))
    {
      TREE_SIDE_EFFECTS (t) = TREE_SIDE_EFFECTS (node);
      TREE_READONLY (t) = TREE_READONLY (node);
    }

  if (TREE_CODE_CLASS (code) == tcc_statement)
    TREE_SIDE_EFFECTS (t) = 1;
  else switch (code)
    {
    case VA_ARG_EXPR:
      /* All of these have side-effects, no matter what their
         operands are.  */
      TREE_SIDE_EFFECTS (t) = 1;
      TREE_READONLY (t) = 0;
      break;

    case MISALIGNED_INDIRECT_REF:
    case ALIGN_INDIRECT_REF:
    case INDIRECT_REF:
      /* Whether a dereference is readonly has nothing to do with whether
         its operand is readonly.  */
      TREE_READONLY (t) = 0;
      break;

    case ADDR_EXPR:
      if (node)
        recompute_tree_invarant_for_addr_expr (t);
      break;

    default:
      if (TREE_CODE_CLASS (code) == tcc_unary
          && node && !TYPE_P (node)
          && TREE_CONSTANT (node))
        TREE_CONSTANT (t) = 1;
      if (TREE_CODE_CLASS (code) == tcc_unary
          && node && TREE_INVARIANT (node))
        TREE_INVARIANT (t) = 1;
      if (TREE_CODE_CLASS (code) == tcc_reference
          && node && TREE_THIS_VOLATILE (node))
        TREE_THIS_VOLATILE (t) = 1;
      break;
    }

  return t;
}

#define PROCESS_ARG(N)                  \
  do {                                  \
    TREE_OPERAND (t, N) = arg##N;       \
    if (arg##N &&!TYPE_P (arg##N))      \
      {                                 \
        if (TREE_SIDE_EFFECTS (arg##N)) \
          side_effects = 1;             \
        if (!TREE_READONLY (arg##N))    \
          read_only = 0;                \
        if (!TREE_CONSTANT (arg##N))    \
          constant = 0;                 \
        if (!TREE_INVARIANT (arg##N))   \
          invariant = 0;                \
      }                                 \
  } while (0)

tree
build2_stat (enum tree_code code, tree tt, tree arg0, tree arg1 MEM_STAT_DECL)
{
  bool constant, read_only, side_effects, invariant;
  tree t;

  gcc_assert (TREE_CODE_LENGTH (code) == 2);

  t = make_node_stat (code PASS_MEM_STAT);
  TREE_TYPE (t) = tt;

  /* Below, we automatically set TREE_SIDE_EFFECTS and TREE_READONLY for the
     result based on those same flags for the arguments.  But if the
     arguments aren't really even `tree' expressions, we shouldn't be trying
     to do this.  */

  /* Expressions without side effects may be constant if their
     arguments are as well.  */
  constant = (TREE_CODE_CLASS (code) == tcc_comparison
              || TREE_CODE_CLASS (code) == tcc_binary);
  read_only = 1;
  side_effects = TREE_SIDE_EFFECTS (t);
  invariant = constant;

  PROCESS_ARG(0);
  PROCESS_ARG(1);

  TREE_READONLY (t) = read_only;
  TREE_CONSTANT (t) = constant;
  TREE_INVARIANT (t) = invariant;
  TREE_SIDE_EFFECTS (t) = side_effects;
  TREE_THIS_VOLATILE (t)
    = (TREE_CODE_CLASS (code) == tcc_reference
       && arg0 && TREE_THIS_VOLATILE (arg0));

  return t;
}

tree
build3_stat (enum tree_code code, tree tt, tree arg0, tree arg1,
             tree arg2 MEM_STAT_DECL)
{
  bool constant, read_only, side_effects, invariant;
  tree t;

  gcc_assert (TREE_CODE_LENGTH (code) == 3);

  t = make_node_stat (code PASS_MEM_STAT);
  TREE_TYPE (t) = tt;

  side_effects = TREE_SIDE_EFFECTS (t);

  PROCESS_ARG(0);
  PROCESS_ARG(1);
  PROCESS_ARG(2);

  if (code == CALL_EXPR && !side_effects)
    {
      tree node;
      int i;

      /* Calls have side-effects, except those to const or
         pure functions.  */
      i = call_expr_flags (t);
      if (!(i & (ECF_CONST | ECF_PURE)))
        side_effects = 1;

      /* And even those have side-effects if their arguments do.  */
      else for (node = arg1; node; node = TREE_CHAIN (node))
        if (TREE_SIDE_EFFECTS (TREE_VALUE (node)))
          {
            side_effects = 1;
            break;
          }
    }

  TREE_SIDE_EFFECTS (t) = side_effects;
  TREE_THIS_VOLATILE (t)
    = (TREE_CODE_CLASS (code) == tcc_reference
       && arg0 && TREE_THIS_VOLATILE (arg0));

  return t;
}

tree
build4_stat (enum tree_code code, tree tt, tree arg0, tree arg1,
             tree arg2, tree arg3 MEM_STAT_DECL)
{
  bool constant, read_only, side_effects, invariant;
  tree t;

  gcc_assert (TREE_CODE_LENGTH (code) == 4);

  t = make_node_stat (code PASS_MEM_STAT);
  TREE_TYPE (t) = tt;

  side_effects = TREE_SIDE_EFFECTS (t);

  PROCESS_ARG(0);
  PROCESS_ARG(1);
  PROCESS_ARG(2);
  PROCESS_ARG(3);

  TREE_SIDE_EFFECTS (t) = side_effects;
  TREE_THIS_VOLATILE (t)
    = (TREE_CODE_CLASS (code) == tcc_reference
       && arg0 && TREE_THIS_VOLATILE (arg0));

  return t;
}

tree
build7_stat (enum tree_code code, tree tt, tree arg0, tree arg1,
             tree arg2, tree arg3, tree arg4, tree arg5,
             tree arg6 MEM_STAT_DECL)
{
  bool constant, read_only, side_effects, invariant;
  tree t;

  gcc_assert (code == TARGET_MEM_REF);

  t = make_node_stat (code PASS_MEM_STAT);
  TREE_TYPE (t) = tt;

  side_effects = TREE_SIDE_EFFECTS (t);

  PROCESS_ARG(0);
  PROCESS_ARG(1);
  PROCESS_ARG(2);
  PROCESS_ARG(3);
  PROCESS_ARG(4);
  PROCESS_ARG(5);
  PROCESS_ARG(6);

  TREE_SIDE_EFFECTS (t) = side_effects;
  TREE_THIS_VOLATILE (t) = 0;

  return t;
}

/* Backup definition for non-gcc build compilers.  */

tree
(build) (enum tree_code code, tree tt, ...)
{
  tree t, arg0, arg1, arg2, arg3, arg4, arg5, arg6;
  int length = TREE_CODE_LENGTH (code);
  va_list p;

  va_start (p, tt);
  switch (length)
    {
    case 0:
      t = build0 (code, tt);
      break;
    case 1:
      arg0 = va_arg (p, tree);
      t = build1 (code, tt, arg0);
      break;
    case 2:
      arg0 = va_arg (p, tree);
      arg1 = va_arg (p, tree);
      t = build2 (code, tt, arg0, arg1);
      break;
    case 3:
      arg0 = va_arg (p, tree);
      arg1 = va_arg (p, tree);
      arg2 = va_arg (p, tree);
      t = build3 (code, tt, arg0, arg1, arg2);
      break;
    case 4:
      arg0 = va_arg (p, tree);
      arg1 = va_arg (p, tree);
      arg2 = va_arg (p, tree);
      arg3 = va_arg (p, tree);
      t = build4 (code, tt, arg0, arg1, arg2, arg3);
      break;
    case 7:
      arg0 = va_arg (p, tree);
      arg1 = va_arg (p, tree);
      arg2 = va_arg (p, tree);
      arg3 = va_arg (p, tree);
      arg4 = va_arg (p, tree);
      arg5 = va_arg (p, tree);
      arg6 = va_arg (p, tree);
      t = build7 (code, tt, arg0, arg1, arg2, arg3, arg4, arg5, arg6);
      break;
    default:
      gcc_unreachable ();
    }
  va_end (p);

  return t;
}

/* Similar except don't specify the TREE_TYPE
   and leave the TREE_SIDE_EFFECTS as 0.
   It is permissible for arguments to be null,
   or even garbage if their values do not matter.  */

tree
build_nt (enum tree_code code, ...)
{
  tree t;
  int length;
  int i;
  va_list p;

  va_start (p, code);

  t = make_node (code);
  length = TREE_CODE_LENGTH (code);

  for (i = 0; i < length; i++)
    TREE_OPERAND (t, i) = va_arg (p, tree);

  va_end (p);
  return t;
}
\f
/* Create a DECL_... node of code CODE, name NAME and data type TYPE.
   We do NOT enter this node in any sort of symbol table.

   layout_decl is used to set up the decl's storage layout.
   Other slots are initialized to 0 or null pointers.  */

tree
build_decl_stat (enum tree_code code, tree name, tree type MEM_STAT_DECL)
{
  tree t;

  t = make_node_stat (code PASS_MEM_STAT);

/*  if (type == error_mark_node)
    type = integer_type_node; */
/* That is not done, deliberately, so that having error_mark_node
   as the type can suppress useless errors in the use of this variable.  */

  DECL_NAME (t) = name;
  TREE_TYPE (t) = type;

  if (code == VAR_DECL || code == PARM_DECL || code == RESULT_DECL)
    layout_decl (t, 0);
  else if (code == FUNCTION_DECL)
    DECL_MODE (t) = FUNCTION_MODE;

  if (CODE_CONTAINS_STRUCT (code, TS_DECL_WITH_VIS))
    {
      /* Set default visibility to whatever the user supplied with
         visibility_specified depending on #pragma GCC visibility.  */
      DECL_VISIBILITY (t) = default_visibility;
      DECL_VISIBILITY_SPECIFIED (t) = visibility_options.inpragma;
    }

  return t;
}

/* Builds and returns function declaration with NAME and TYPE.  */

tree
build_fn_decl (const char *name, tree type)
{
  tree id = get_identifier (name);
  tree decl = build_decl (FUNCTION_DECL, id, type);

  DECL_EXTERNAL (decl) = 1;
  TREE_PUBLIC (decl) = 1;
  DECL_ARTIFICIAL (decl) = 1;
  TREE_NOTHROW (decl) = 1;

  return decl;
}

\f
/* BLOCK nodes are used to represent the structure of binding contours
   and declarations, once those contours have been exited and their contents
   compiled.  This information is used for outputting debugging info.  */

tree
build_block (tree vars, tree subblocks, tree supercontext, tree chain)
{
  tree block = make_node (BLOCK);

  BLOCK_VARS (block) = vars;
  BLOCK_SUBBLOCKS (block) = subblocks;
  BLOCK_SUPERCONTEXT (block) = supercontext;
  BLOCK_CHAIN (block) = chain;
  return block;
}

#if 1 /* ! defined(USE_MAPPED_LOCATION) */
/* ??? gengtype doesn't handle conditionals */
static GTY(()) location_t *last_annotated_node;
#endif

#ifdef USE_MAPPED_LOCATION

expanded_location
expand_location (source_location loc)
{
  expanded_location xloc;
  if (loc == 0) { xloc.file = NULL; xloc.line = 0;  xloc.column = 0; }
  else
    {
      const struct line_map *map = linemap_lookup (&line_table, loc);
      xloc.file = map->to_file;
      xloc.line = SOURCE_LINE (map, loc);
      xloc.column = SOURCE_COLUMN (map, loc);
    };
  return xloc;
}

#else

/* Record the exact location where an expression or an identifier were
   encountered.  */

void
annotate_with_file_line (tree node, const char *file, int line)
{
  /* Roughly one percent of the calls to this function are to annotate
     a node with the same information already attached to that node!
     Just return instead of wasting memory.  */
  if (EXPR_LOCUS (node)
      && EXPR_LINENO (node) == line
      && (EXPR_FILENAME (node) == file
          || !strcmp (EXPR_FILENAME (node), file)))
    {
      last_annotated_node = EXPR_LOCUS (node);
      return;
    }

  /* In heavily macroized code (such as GCC itself) this single
     entry cache can reduce the number of allocations by more
     than half.  */
  if (last_annotated_node
      && last_annotated_node->line == line
      && (last_annotated_node->file == file
          || !strcmp (last_annotated_node->file, file)))
    {
      SET_EXPR_LOCUS (node, last_annotated_node);
      return;
    }

  SET_EXPR_LOCUS (node, ggc_alloc (sizeof (location_t)));
  EXPR_LINENO (node) = line;
  EXPR_FILENAME (node) = file;
  last_annotated_node = EXPR_LOCUS (node);
}

void
annotate_with_locus (tree node, location_t locus)
{
  annotate_with_file_line (node, locus.file, locus.line);
}
#endif
\f
/* Return a declaration like DDECL except that its DECL_ATTRIBUTES
   is ATTRIBUTE.  */

tree
build_decl_attribute_variant (tree ddecl, tree attribute)
{
  DECL_ATTRIBUTES (ddecl) = attribute;
  return ddecl;
}

/* Borrowed from hashtab.c iterative_hash implementation.  */
#define mix(a,b,c) \
{ \
  a -= b; a -= c; a ^= (c>>13); \
  b -= c; b -= a; b ^= (a<< 8); \
  c -= a; c -= b; c ^= ((b&0xffffffff)>>13); \
  a -= b; a -= c; a ^= ((c&0xffffffff)>>12); \
  b -= c; b -= a; b = (b ^ (a<<16)) & 0xffffffff; \
  c -= a; c -= b; c = (c ^ (b>> 5)) & 0xffffffff; \
  a -= b; a -= c; a = (a ^ (c>> 3)) & 0xffffffff; \
  b -= c; b -= a; b = (b ^ (a<<10)) & 0xffffffff; \
  c -= a; c -= b; c = (c ^ (b>>15)) & 0xffffffff; \
}


/* Produce good hash value combining VAL and VAL2.  */
static inline hashval_t
iterative_hash_hashval_t (hashval_t val, hashval_t val2)
{
  /* the golden ratio; an arbitrary value.  */
  hashval_t a = 0x9e3779b9;

  mix (a, val, val2);
  return val2;
}

/* Produce good hash value combining PTR and VAL2.  */
static inline hashval_t
iterative_hash_pointer (void *ptr, hashval_t val2)
{
  if (sizeof (ptr) == sizeof (hashval_t))
    return iterative_hash_hashval_t ((size_t) ptr, val2);
  else
    {
      hashval_t a = (hashval_t) (size_t) ptr;
      /* Avoid warnings about shifting of more than the width of the type on
         hosts that won't execute this path.  */
      int zero = 0;
      hashval_t b = (hashval_t) ((size_t) ptr >> (sizeof (hashval_t) * 8 + zero));
      mix (a, b, val2);
      return val2;
    }
}

/* Produce good hash value combining VAL and VAL2.  */
static inline hashval_t
iterative_hash_host_wide_int (HOST_WIDE_INT val, hashval_t val2)
{
  if (sizeof (HOST_WIDE_INT) == sizeof (hashval_t))
    return iterative_hash_hashval_t (val, val2);
  else
    {
      hashval_t a = (hashval_t) val;
      /* Avoid warnings about shifting of more than the width of the type on
         hosts that won't execute this path.  */
      int zero = 0;
      hashval_t b = (hashval_t) (val >> (sizeof (hashval_t) * 8 + zero));
      mix (a, b, val2);
      if (sizeof (HOST_WIDE_INT) > 2 * sizeof (hashval_t))
        {
          hashval_t a = (hashval_t) (val >> (sizeof (hashval_t) * 16 + zero));
          hashval_t b = (hashval_t) (val >> (sizeof (hashval_t) * 24 + zero));
          mix (a, b, val2);
        }
      return val2;
    }
}

/* Return a type like TTYPE except that its TYPE_ATTRIBUTE
   is ATTRIBUTE.

   Record such modified types already made so we don't make duplicates.  */

tree
build_type_attribute_variant (tree ttype, tree attribute)
{
  if (! attribute_list_equal (TYPE_ATTRIBUTES (ttype), attribute))
    {
      hashval_t hashcode = 0;
      tree ntype;
      enum tree_code code = TREE_CODE (ttype);

      ntype = copy_node (ttype);

      TYPE_POINTER_TO (ntype) = 0;
      TYPE_REFERENCE_TO (ntype) = 0;
      TYPE_ATTRIBUTES (ntype) = attribute;

      /* Create a new main variant of TYPE.  */
      TYPE_MAIN_VARIANT (ntype) = ntype;
      TYPE_NEXT_VARIANT (ntype) = 0;
      set_type_quals (ntype, TYPE_UNQUALIFIED);

      hashcode = iterative_hash_object (code, hashcode);
      if (TREE_TYPE (ntype))
        hashcode = iterative_hash_object (TYPE_HASH (TREE_TYPE (ntype)),
                                          hashcode);
      hashcode = attribute_hash_list (attribute, hashcode);

      switch (TREE_CODE (ntype))
        {
        case FUNCTION_TYPE:
          hashcode = type_hash_list (TYPE_ARG_TYPES (ntype), hashcode);
          break;
        case ARRAY_TYPE:
          hashcode = iterative_hash_object (TYPE_HASH (TYPE_DOMAIN (ntype)),
                                            hashcode);
          break;
        case INTEGER_TYPE:
          hashcode = iterative_hash_object
            (TREE_INT_CST_LOW (TYPE_MAX_VALUE (ntype)), hashcode);
          hashcode = iterative_hash_object
            (TREE_INT_CST_HIGH (TYPE_MAX_VALUE (ntype)), hashcode);
          break;
        case REAL_TYPE:
          {
            unsigned int precision = TYPE_PRECISION (ntype);
            hashcode = iterative_hash_object (precision, hashcode);
          }
          break;
        default:
          break;
        }

      ntype = type_hash_canon (hashcode, ntype);
      ttype = build_qualified_type (ntype, TYPE_QUALS (ttype));
    }

  return ttype;
}


/* Return nonzero if IDENT is a valid name for attribute ATTR,
   or zero if not.

   We try both `text' and `__text__', ATTR may be either one.  */
/* ??? It might be a reasonable simplification to require ATTR to be only
   `text'.  One might then also require attribute lists to be stored in
   their canonicalized form.  */

static int
is_attribute_with_length_p (const char *attr, int attr_len, tree ident)
{
  int ident_len;
  const char *p;

  if (TREE_CODE (ident) != IDENTIFIER_NODE)
    return 0;
  
  p = IDENTIFIER_POINTER (ident);
  ident_len = IDENTIFIER_LENGTH (ident);
  
  if (ident_len == attr_len
      && strcmp (attr, p) == 0)
    return 1;

  /* If ATTR is `__text__', IDENT must be `text'; and vice versa.  */
  if (attr[0] == '_')
    {
      gcc_assert (attr[1] == '_');
      gcc_assert (attr[attr_len - 2] == '_');
      gcc_assert (attr[attr_len - 1] == '_');
      gcc_assert (attr[1] == '_');
      if (ident_len == attr_len - 4
          && strncmp (attr + 2, p, attr_len - 4) == 0)
        return 1;
    }
  else
    {
      if (ident_len == attr_len + 4
          && p[0] == '_' && p[1] == '_'
          && p[ident_len - 2] == '_' && p[ident_len - 1] == '_'
          && strncmp (attr, p + 2, attr_len) == 0)
        return 1;
    }

  return 0;
}

/* Return nonzero if IDENT is a valid name for attribute ATTR,
   or zero if not.

   We try both `text' and `__text__', ATTR may be either one.  */

int
is_attribute_p (const char *attr, tree ident)
{
  return is_attribute_with_length_p (attr, strlen (attr), ident);
}

/* Given an attribute name and a list of attributes, return a pointer to the
   attribute's list element if the attribute is part of the list, or NULL_TREE
   if not found.  If the attribute appears more than once, this only
   returns the first occurrence; the TREE_CHAIN of the return value should
   be passed back in if further occurrences are wanted.  */

tree
lookup_attribute (const char *attr_name, tree list)
{
  tree l;
  size_t attr_len = strlen (attr_name);

  for (l = list; l; l = TREE_CHAIN (l))
    {
      gcc_assert (TREE_CODE (TREE_PURPOSE (l)) == IDENTIFIER_NODE);
      if (is_attribute_with_length_p (attr_name, attr_len, TREE_PURPOSE (l)))
        return l;
    }

  return NULL_TREE;
}

/* Return an attribute list that is the union of a1 and a2.  */

tree
merge_attributes (tree a1, tree a2)
{
  tree attributes;

  /* Either one unset?  Take the set one.  */

  if ((attributes = a1) == 0)
    attributes = a2;

  /* One that completely contains the other?  Take it.  */

  else if (a2 != 0 && ! attribute_list_contained (a1, a2))
    {
      if (attribute_list_contained (a2, a1))
        attributes = a2;
      else
        {
          /* Pick the longest list, and hang on the other list.  */

          if (list_length (a1) < list_length (a2))
            attributes = a2, a2 = a1;

          for (; a2 != 0; a2 = TREE_CHAIN (a2))
            {
              tree a;
              for (a = lookup_attribute (IDENTIFIER_POINTER (TREE_PURPOSE (a2)),
                                         attributes);
                   a != NULL_TREE;
                   a = lookup_attribute (IDENTIFIER_POINTER (TREE_PURPOSE (a2)),
                                         TREE_CHAIN (a)))
                {
                  if (simple_cst_equal (TREE_VALUE (a), TREE_VALUE (a2)) == 1)
                    break;
                }
              if (a == NULL_TREE)
                {
                  a1 = copy_node (a2);
                  TREE_CHAIN (a1) = attributes;
                  attributes = a1;
                }
            }
        }
    }
  return attributes;
}

/* Given types T1 and T2, merge their attributes and return
  the result.  */

tree
merge_type_attributes (tree t1, tree t2)
{
  return merge_attributes (TYPE_ATTRIBUTES (t1),
                           TYPE_ATTRIBUTES (t2));
}

/* Given decls OLDDECL and NEWDECL, merge their attributes and return
   the result.  */

tree
merge_decl_attributes (tree olddecl, tree newdecl)
{
  return merge_attributes (DECL_ATTRIBUTES (olddecl),
                           DECL_ATTRIBUTES (newdecl));
}

#if TARGET_DLLIMPORT_DECL_ATTRIBUTES

/* Specialization of merge_decl_attributes for various Windows targets.

   This handles the following situation:

     __declspec (dllimport) int foo;
     int foo;

   The second instance of `foo' nullifies the dllimport.  */

tree
merge_dllimport_decl_attributes (tree old, tree new)
{
  tree a;
  int delete_dllimport_p = 1;

  /* What we need to do here is remove from `old' dllimport if it doesn't
     appear in `new'.  dllimport behaves like extern: if a declaration is
     marked dllimport and a definition appears later, then the object
     is not dllimport'd.  We also remove a `new' dllimport if the old list
     contains dllexport:  dllexport always overrides dllimport, regardless
     of the order of declaration.  */     
  if (!VAR_OR_FUNCTION_DECL_P (new))
    delete_dllimport_p = 0;
  else if (DECL_DLLIMPORT_P (new)
           && lookup_attribute ("dllexport", DECL_ATTRIBUTES (old)))
    { 
      DECL_DLLIMPORT_P (new) = 0;
      warning (OPT_Wattributes, "%q+D already declared with dllexport attribute: "
              "dllimport ignored", new);
    }
  else if (DECL_DLLIMPORT_P (old) && !DECL_DLLIMPORT_P (new))
    {
      /* Warn about overriding a symbol that has already been used. eg:
           extern int __attribute__ ((dllimport)) foo;
           int* bar () {return &foo;}
           int foo;
      */
      if (TREE_USED (old))
        {
          warning (0, "%q+D redeclared without dllimport attribute "
                   "after being referenced with dll linkage", new);
          /* If we have used a variable's address with dllimport linkage,
              keep the old DECL_DLLIMPORT_P flag: the ADDR_EXPR using the
              decl may already have had TREE_INVARIANT and TREE_CONSTANT
              computed.
              We still remove the attribute so that assembler code refers
              to '&foo rather than '_imp__foo'.  */
          if (TREE_CODE (old) == VAR_DECL && TREE_ADDRESSABLE (old))
            DECL_DLLIMPORT_P (new) = 1;
        }

      /* Let an inline definition silently override the external reference,
         but otherwise warn about attribute inconsistency.  */ 
      else if (TREE_CODE (new) == VAR_DECL
               || !DECL_DECLARED_INLINE_P (new))
        warning (OPT_Wattributes, "%q+D redeclared without dllimport attribute: "
                  "previous dllimport ignored", new);
    }
  else
    delete_dllimport_p = 0;

  a = merge_attributes (DECL_ATTRIBUTES (old), DECL_ATTRIBUTES (new));

  if (delete_dllimport_p) 
    {
      tree prev, t;
      const size_t attr_len = strlen ("dllimport"); 
     
      /* Scan the list for dllimport and delete it.  */
      for (prev = NULL_TREE, t = a; t; prev = t, t = TREE_CHAIN (t))
        {
          if (is_attribute_with_length_p ("dllimport", attr_len,
                                          TREE_PURPOSE (t)))
            {
              if (prev == NULL_TREE)
                a = TREE_CHAIN (a);
              else
                TREE_CHAIN (prev) = TREE_CHAIN (t);
              break;
            }
        }
    }

  return a;
}

/* Handle a "dllimport" or "dllexport" attribute; arguments as in
   struct attribute_spec.handler.  */

tree
handle_dll_attribute (tree * pnode, tree name, tree args, int flags,
                      bool *no_add_attrs)
{
  tree node = *pnode;

  /* These attributes may apply to structure and union types being created,
     but otherwise should pass to the declaration involved.  */
  if (!DECL_P (node))
    {
      if (flags & ((int) ATTR_FLAG_DECL_NEXT | (int) ATTR_FLAG_FUNCTION_NEXT
                   | (int) ATTR_FLAG_ARRAY_NEXT))
        {
          *no_add_attrs = true;
          return tree_cons (name, args, NULL_TREE);
        }
      if (TREE_CODE (node) != RECORD_TYPE && TREE_CODE (node) != UNION_TYPE)
        {
          warning (OPT_Wattributes, "%qs attribute ignored",
                   IDENTIFIER_POINTER (name));
          *no_add_attrs = true;
        }

      return NULL_TREE;
    }

  /* Report error on dllimport ambiguities seen now before they cause
     any damage.  */
  if (is_attribute_p ("dllimport", name))
    {
      /* Honor any target-specific overrides. */ 
      if (!targetm.valid_dllimport_attribute_p (node))
        *no_add_attrs = true;

     else if (TREE_CODE (node) == FUNCTION_DECL
                && DECL_DECLARED_INLINE_P (node))
        {
          warning (OPT_Wattributes, "inline function %q+D declared as "
                  " dllimport: attribute ignored", node); 
          *no_add_attrs = true;
        }
      /* Like MS, treat definition of dllimported variables and
         non-inlined functions on declaration as syntax errors. */
     else if (TREE_CODE (node) == FUNCTION_DECL && DECL_INITIAL (node))
        {
          error ("function %q+D definition is marked dllimport", node);
          *no_add_attrs = true;
        }

     else if (TREE_CODE (node) == VAR_DECL)
        {
          if (DECL_INITIAL (node))
            {
              error ("variable %q+D definition is marked dllimport",
                     node);
              *no_add_attrs = true;
            }

          /* `extern' needn't be specified with dllimport.
             Specify `extern' now and hope for the best.  Sigh.  */
          DECL_EXTERNAL (node) = 1;
          /* Also, implicitly give dllimport'd variables declared within
             a function global scope, unless declared static.  */
          if (current_function_decl != NULL_TREE && !TREE_STATIC (node))
            TREE_PUBLIC (node) = 1;
        }

      if (*no_add_attrs == false)
        DECL_DLLIMPORT_P (node) = 1;
    }

  /*  Report error if symbol is not accessible at global scope.  */
  if (!TREE_PUBLIC (node)
      && (TREE_CODE (node) == VAR_DECL
          || TREE_CODE (node) == FUNCTION_DECL))
    {
      error ("external linkage required for symbol %q+D because of "
             "%qs attribute", node, IDENTIFIER_POINTER (name));
      *no_add_attrs = true;
    }

  return NULL_TREE;
}

#endif /* TARGET_DLLIMPORT_DECL_ATTRIBUTES  */
\f
/* Set the type qualifiers for TYPE to TYPE_QUALS, which is a bitmask
   of the various TYPE_QUAL values.  */

static void
set_type_quals (tree type, int type_quals)
{
  TYPE_READONLY (type) = (type_quals & TYPE_QUAL_CONST) != 0;
  TYPE_VOLATILE (type) = (type_quals & TYPE_QUAL_VOLATILE) != 0;
  TYPE_RESTRICT (type) = (type_quals & TYPE_QUAL_RESTRICT) != 0;
}

/* Returns true iff cand is equivalent to base with type_quals.  */

bool
check_qualified_type (tree cand, tree base, int type_quals)
{
  return (TYPE_QUALS (cand) == type_quals
          && TYPE_NAME (cand) == TYPE_NAME (base)
          /* Apparently this is needed for Objective-C.  */
          && TYPE_CONTEXT (cand) == TYPE_CONTEXT (base)
          && attribute_list_equal (TYPE_ATTRIBUTES (cand),
                                   TYPE_ATTRIBUTES (base)));
}

/* Return a version of the TYPE, qualified as indicated by the
   TYPE_QUALS, if one exists.  If no qualified version exists yet,
   return NULL_TREE.  */

tree
get_qualified_type (tree type, int type_quals)
{
  tree t;

  if (TYPE_QUALS (type) == type_quals)
    return type;

  /* Search the chain of variants to see if there is already one there just
     like the one we need to have.  If so, use that existing one.  We must
     preserve the TYPE_NAME, since there is code that depends on this.  */
  for (t = TYPE_MAIN_VARIANT (type); t; t = TYPE_NEXT_VARIANT (t))
    if (check_qualified_type (t, type, type_quals))
      return t;

  return NULL_TREE;
}

/* Like get_qualified_type, but creates the type if it does not
   exist.  This function never returns NULL_TREE.  */

tree
build_qualified_type (tree type, int type_quals)
{
  tree t;

  /* See if we already have the appropriate qualified variant.  */
  t = get_qualified_type (type, type_quals);

  /* If not, build it.  */
  if (!t)
    {
      t = build_variant_type_copy (type);
      set_type_quals (t, type_quals);

      /* If it's a pointer type, the new variant points to the same type.  */
      if (TREE_CODE (type) == POINTER_TYPE)
        {
          TYPE_NEXT_PTR_TO (t) = TYPE_NEXT_PTR_TO (type);
          TYPE_NEXT_PTR_TO (type) = t;
        }

      /* Same for a reference type.  */
      else if (TREE_CODE (type) == REFERENCE_TYPE)
        {
          TYPE_NEXT_REF_TO (t) = TYPE_NEXT_REF_TO (type);
          TYPE_NEXT_REF_TO (type) = t;
        }
    }

  return t;
}

/* Create a new distinct copy of TYPE.  The new type is made its own
   MAIN_VARIANT.  */

tree
build_distinct_type_copy (tree type)
{
  tree t = copy_node (type);
  
  TYPE_POINTER_TO (t) = 0;
  TYPE_REFERENCE_TO (t) = 0;

  /* Make it its own variant.  */
  TYPE_MAIN_VARIANT (t) = t;
  TYPE_NEXT_VARIANT (t) = 0;
  
  return t;
}

/* Create a new variant of TYPE, equivalent but distinct.
   This is so the caller can modify it.  */

tree
build_variant_type_copy (tree type)
{
  tree t, m = TYPE_MAIN_VARIANT (type);

  t = build_distinct_type_copy (type);
  
  /* Add the new type to the chain of variants of TYPE.  */
  TYPE_NEXT_VARIANT (t) = TYPE_NEXT_VARIANT (m);
  TYPE_NEXT_VARIANT (m) = t;
  TYPE_MAIN_VARIANT (t) = m;

  return t;
}
\f
/* Return true if the from tree in both tree maps are equal.  */

int
tree_map_eq (const void *va, const void *vb)
{
  const struct tree_map  *a = va, *b = vb;
  return (a->from == b->from);
}

/* Hash a from tree in a tree_map.  */

unsigned int
tree_map_hash (const void *item)
{
  return (((const struct tree_map *) item)->hash);
}

/* Return true if this tree map structure is marked for garbage collection
   purposes.  We simply return true if the from tree is marked, so that this
   structure goes away when the from tree goes away.  */

int
tree_map_marked_p (const void *p)
{
  tree from = ((struct tree_map *) p)->from;

  return ggc_marked_p (from);
}

/* Return true if the trees in the tree_int_map *'s VA and VB are equal.  */

static int
tree_int_map_eq (const void *va, const void *vb)
{
  const struct tree_int_map  *a = va, *b = vb;
  return (a->from == b->from);
}

/* Hash a from tree in the tree_int_map * ITEM.  */

static unsigned int
tree_int_map_hash (const void *item)
{
  return htab_hash_pointer (((const struct tree_int_map *)item)->from);
}

/* Return true if this tree int map structure is marked for garbage collection
   purposes.  We simply return true if the from tree_int_map *P's from tree is marked, so that this
   structure goes away when the from tree goes away.  */

static int
tree_int_map_marked_p (const void *p)
{
  tree from = ((struct tree_int_map *) p)->from;

  return ggc_marked_p (from);
}
/* Lookup an init priority for FROM, and return it if we find one.  */

unsigned short
decl_init_priority_lookup (tree from)
{
  struct tree_int_map *h, in;
  in.from = from;

  h = htab_find_with_hash (init_priority_for_decl, 
                           &in, htab_hash_pointer (from));
  if (h)
    return h->to;
  return 0;
}

/* Insert a mapping FROM->TO in the init priority hashtable.  */

void
decl_init_priority_insert (tree from, unsigned short to)
{
  struct tree_int_map *h;
  void **loc;

  h = ggc_alloc (sizeof (struct tree_int_map));
  h->from = from;
  h->to = to;
  loc = htab_find_slot_with_hash (init_priority_for_decl, h, 
                                  htab_hash_pointer (from), INSERT);
  *(struct tree_int_map **) loc = h;
}  

/* Look up a restrict qualified base decl for FROM.  */

tree
decl_restrict_base_lookup (tree from)
{
  struct tree_map *h;
  struct tree_map in;

  in.from = from;
  h = htab_find_with_hash (restrict_base_for_decl, &in,
                           htab_hash_pointer (from));
  return h ? h->to : NULL_TREE;
}

/* Record the restrict qualified base TO for FROM.  */

void
decl_restrict_base_insert (tree from, tree to)
{
  struct tree_map *h;
  void **loc;

  h = ggc_alloc (sizeof (struct tree_map));
  h->hash = htab_hash_pointer (from);
  h->from = from;
  h->to = to;
  loc = htab_find_slot_with_hash (restrict_base_for_decl, h, h->hash, INSERT);
  *(struct tree_map **) loc = h;
}

/* Print out the statistics for the DECL_DEBUG_EXPR hash table.  */

static void
print_debug_expr_statistics (void)
{
  fprintf (stderr, "DECL_DEBUG_EXPR  hash: size %ld, %ld elements, %f collisions\n",
           (long) htab_size (debug_expr_for_decl),
           (long) htab_elements (debug_expr_for_decl),
           htab_collisions (debug_expr_for_decl));
}

/* Print out the statistics for the DECL_VALUE_EXPR hash table.  */

static void
print_value_expr_statistics (void)
{
  fprintf (stderr, "DECL_VALUE_EXPR  hash: size %ld, %ld elements, %f collisions\n",
           (long) htab_size (value_expr_for_decl),
           (long) htab_elements (value_expr_for_decl),
           htab_collisions (value_expr_for_decl));
}

/* Print out statistics for the RESTRICT_BASE_FOR_DECL hash table, but
   don't print anything if the table is empty.  */

static void
print_restrict_base_statistics (void)
{
  if (htab_elements (restrict_base_for_decl) != 0)
    fprintf (stderr,
             "RESTRICT_BASE    hash: size %ld, %ld elements, %f collisions\n",
             (long) htab_size (restrict_base_for_decl),
             (long) htab_elements (restrict_base_for_decl),
             htab_collisions (restrict_base_for_decl));
}

/* Lookup a debug expression for FROM, and return it if we find one.  */

tree 
decl_debug_expr_lookup (tree from)
{
  struct tree_map *h, in;
  in.from = from;

  h = htab_find_with_hash (debug_expr_for_decl, &in, htab_hash_pointer (from));
  if (h)
    return h->to;
  return NULL_TREE;
}

/* Insert a mapping FROM->TO in the debug expression hashtable.  */

void
decl_debug_expr_insert (tree from, tree to)
{
  struct tree_map *h;
  void **loc;

  h = ggc_alloc (sizeof (struct tree_map));
  h->hash = htab_hash_pointer (from);
  h->from = from;
  h->to = to;
  loc = htab_find_slot_with_hash (debug_expr_for_decl, h, h->hash, INSERT);
  *(struct tree_map **) loc = h;
}  

/* Lookup a value expression for FROM, and return it if we find one.  */

tree 
decl_value_expr_lookup (tree from)
{
  struct tree_map *h, in;
  in.from = from;

  h = htab_find_with_hash (value_expr_for_decl, &in, htab_hash_pointer (from));
  if (h)
    return h->to;
  return NULL_TREE;
}

/* Insert a mapping FROM->TO in the value expression hashtable.  */

void
decl_value_expr_insert (tree from, tree to)
{
  struct tree_map *h;
  void **loc;

  h = ggc_alloc (sizeof (struct tree_map));
  h->hash = htab_hash_pointer (from);
  h->from = from;
  h->to = to;
  loc = htab_find_slot_with_hash (value_expr_for_decl, h, h->hash, INSERT);
  *(struct tree_map **) loc = h;
}

/* Hashing of types so that we don't make duplicates.
   The entry point is `type_hash_canon'.  */

/* Compute a hash code for a list of types (chain of TREE_LIST nodes
   with types in the TREE_VALUE slots), by adding the hash codes
   of the individual types.  */

unsigned int
type_hash_list (tree list, hashval_t hashcode)
{
  tree tail;

  for (tail = list; tail; tail = TREE_CHAIN (tail))
    if (TREE_VALUE (tail) != error_mark_node)
      hashcode = iterative_hash_object (TYPE_HASH (TREE_VALUE (tail)),
                                        hashcode);

  return hashcode;
}

/* These are the Hashtable callback functions.  */

/* Returns true iff the types are equivalent.  */

static int
type_hash_eq (const void *va, const void *vb)
{
  const struct type_hash *a = va, *b = vb;

  /* First test the things that are the same for all types.  */
  if (a->hash != b->hash
      || TREE_CODE (a->type) != TREE_CODE (b->type)
      || TREE_TYPE (a->type) != TREE_TYPE (b->type)
      || !attribute_list_equal (TYPE_ATTRIBUTES (a->type),
                                 TYPE_ATTRIBUTES (b->type))
      || TYPE_ALIGN (a->type) != TYPE_ALIGN (b->type)
      || TYPE_MODE (a->type) != TYPE_MODE (b->type))
    return 0;

  switch (TREE_CODE (a->type))
    {
    case VOID_TYPE:
    case COMPLEX_TYPE:
    case POINTER_TYPE:
    case REFERENCE_TYPE:
      return 1;

    case VECTOR_TYPE:
      return TYPE_VECTOR_SUBPARTS (a->type) == TYPE_VECTOR_SUBPARTS (b->type);

    case ENUMERAL_TYPE:
      if (TYPE_VALUES (a->type) != TYPE_VALUES (b->type)
          && !(TYPE_VALUES (a->type)
               && TREE_CODE (TYPE_VALUES (a->type)) == TREE_LIST
               && TYPE_VALUES (b->type)
               && TREE_CODE (TYPE_VALUES (b->type)) == TREE_LIST
               && type_list_equal (TYPE_VALUES (a->type),
                                   TYPE_VALUES (b->type))))
        return 0;

      /* ... fall through ... */

    case INTEGER_TYPE:
    case REAL_TYPE:
    case BOOLEAN_TYPE:
    case CHAR_TYPE:
      return ((TYPE_MAX_VALUE (a->type) == TYPE_MAX_VALUE (b->type)
               || tree_int_cst_equal (TYPE_MAX_VALUE (a->type),
                                      TYPE_MAX_VALUE (b->type)))
              && (TYPE_MIN_VALUE (a->type) == TYPE_MIN_VALUE (b->type)
                  || tree_int_cst_equal (TYPE_MIN_VALUE (a->type),
                                         TYPE_MIN_VALUE (b->type))));

    case OFFSET_TYPE:
      return TYPE_OFFSET_BASETYPE (a->type) == TYPE_OFFSET_BASETYPE (b->type);

    case METHOD_TYPE:
      return (TYPE_METHOD_BASETYPE (a->type) == TYPE_METHOD_BASETYPE (b->type)
              && (TYPE_ARG_TYPES (a->type) == TYPE_ARG_TYPES (b->type)
                  || (TYPE_ARG_TYPES (a->type)
                      && TREE_CODE (TYPE_ARG_TYPES (a->type)) == TREE_LIST
                      && TYPE_ARG_TYPES (b->type)
                      && TREE_CODE (TYPE_ARG_TYPES (b->type)) == TREE_LIST
                      && type_list_equal (TYPE_ARG_TYPES (a->type),
                                          TYPE_ARG_TYPES (b->type)))));

    case ARRAY_TYPE:
      return TYPE_DOMAIN (a->type) == TYPE_DOMAIN (b->type);

    case RECORD_TYPE:
    case UNION_TYPE:
    case QUAL_UNION_TYPE:
      return (TYPE_FIELDS (a->type) == TYPE_FIELDS (b->type)
              || (TYPE_FIELDS (a->type)
                  && TREE_CODE (TYPE_FIELDS (a->type)) == TREE_LIST
                  && TYPE_FIELDS (b->type)
                  && TREE_CODE (TYPE_FIELDS (b->type)) == TREE_LIST
                  && type_list_equal (TYPE_FIELDS (a->type),
                                      TYPE_FIELDS (b->type))));

    case FUNCTION_TYPE:
      return (TYPE_ARG_TYPES (a->type) == TYPE_ARG_TYPES (b->type)
              || (TYPE_ARG_TYPES (a->type)
                  && TREE_CODE (TYPE_ARG_TYPES (a->type)) == TREE_LIST
                  && TYPE_ARG_TYPES (b->type)
                  && TREE_CODE (TYPE_ARG_TYPES (b->type)) == TREE_LIST
                  && type_list_equal (TYPE_ARG_TYPES (a->type),
                                      TYPE_ARG_TYPES (b->type))));

    default:
      return 0;
    }
}

/* Return the cached hash value.  */

static hashval_t
type_hash_hash (const void *item)
{
  return ((const struct type_hash *) item)->hash;
}

/* Look in the type hash table for a type isomorphic to TYPE.
   If one is found, return it.  Otherwise return 0.  */

tree
type_hash_lookup (hashval_t hashcode, tree type)
{
  struct type_hash *h, in;

  /* The TYPE_ALIGN field of a type is set by layout_type(), so we
     must call that routine before comparing TYPE_ALIGNs.  */
  layout_type (type);

  in.hash = hashcode;
  in.type = type;

  h = htab_find_with_hash (type_hash_table, &in, hashcode);
  if (h)
    return h->type;
  return NULL_TREE;
}

/* Add an entry to the type-hash-table
   for a type TYPE whose hash code is HASHCODE.  */

void
type_hash_add (hashval_t hashcode, tree type)
{
  struct type_hash *h;
  void **loc;

  h = ggc_alloc (sizeof (struct type_hash));
  h->hash = hashcode;
  h->type = type;
  loc = htab_find_slot_with_hash (type_hash_table, h, hashcode, INSERT);
  *(struct type_hash **) loc = h;
}

/* Given TYPE, and HASHCODE its hash code, return the canonical
   object for an identical type if one already exists.
   Otherwise, return TYPE, and record it as the canonical object.

   To use this function, first create a type of the sort you want.
   Then compute its hash code from the fields of the type that
   make it different from other similar types.
   Then call this function and use the value.  */

tree
type_hash_canon (unsigned int hashcode, tree type)
{
  tree t1;

  /* The hash table only contains main variants, so ensure that's what we're
     being passed.  */
  gcc_assert (TYPE_MAIN_VARIANT (type) == type);

  if (!lang_hooks.types.hash_types)
    return type;

  /* See if the type is in the hash table already.  If so, return it.
     Otherwise, add the type.  */
  t1 = type_hash_lookup (hashcode, type);
  if (t1 != 0)
    {
#ifdef GATHER_STATISTICS
      tree_node_counts[(int) t_kind]--;
      tree_node_sizes[(int) t_kind] -= sizeof (struct tree_type);
#endif
      return t1;
    }
  else
    {
      type_hash_add (hashcode, type);
      return type;
    }
}

/* See if the data pointed to by the type hash table is marked.  We consider
   it marked if the type is marked or if a debug type number or symbol
   table entry has been made for the type.  This reduces the amount of
   debugging output and eliminates that dependency of the debug output on
   the number of garbage collections.  */

static int
type_hash_marked_p (const void *p)
{
  tree type = ((struct type_hash *) p)->type;

  return ggc_marked_p (type) || TYPE_SYMTAB_POINTER (type);
}

static void
print_type_hash_statistics (void)
{
  fprintf (stderr, "Type hash: size %ld, %ld elements, %f collisions\n",
           (long) htab_size (type_hash_table),
           (long) htab_elements (type_hash_table),
           htab_collisions (type_hash_table));
}

/* Compute a hash code for a list of attributes (chain of TREE_LIST nodes
   with names in the TREE_PURPOSE slots and args in the TREE_VALUE slots),
   by adding the hash codes of the individual attributes.  */

unsigned int
attribute_hash_list (tree list, hashval_t hashcode)
{
  tree tail;

  for (tail = list; tail; tail = TREE_CHAIN (tail))
    /* ??? Do we want to add in TREE_VALUE too? */
    hashcode = iterative_hash_object
      (IDENTIFIER_HASH_VALUE (TREE_PURPOSE (tail)), hashcode);
  return hashcode;
}

/* Given two lists of attributes, return true if list l2 is
   equivalent to l1.  */

int
attribute_list_equal (tree l1, tree l2)
{
  return attribute_list_contained (l1, l2)
         && attribute_list_contained (l2, l1);
}

/* Given two lists of attributes, return true if list L2 is
   completely contained within L1.  */
/* ??? This would be faster if attribute names were stored in a canonicalized
   form.  Otherwise, if L1 uses `foo' and L2 uses `__foo__', the long method
   must be used to show these elements are equivalent (which they are).  */
/* ??? It's not clear that attributes with arguments will always be handled
   correctly.  */

int
attribute_list_contained (tree l1, tree l2)
{
  tree t1, t2;

  /* First check the obvious, maybe the lists are identical.  */
  if (l1 == l2)
    return 1;

  /* Maybe the lists are similar.  */
  for (t1 = l1, t2 = l2;
       t1 != 0 && t2 != 0
        && TREE_PURPOSE (t1) == TREE_PURPOSE (t2)
        && TREE_VALUE (t1) == TREE_VALUE (t2);
       t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2));

  /* Maybe the lists are equal.  */
  if (t1 == 0 && t2 == 0)
    return 1;

  for (; t2 != 0; t2 = TREE_CHAIN (t2))
    {
      tree attr;
      for (attr = lookup_attribute (IDENTIFIER_POINTER (TREE_PURPOSE (t2)), l1);
           attr != NULL_TREE;
           attr = lookup_attribute (IDENTIFIER_POINTER (TREE_PURPOSE (t2)),
                                    TREE_CHAIN (attr)))
        {
          if (simple_cst_equal (TREE_VALUE (t2), TREE_VALUE (attr)) == 1)
            break;
        }

      if (attr == 0)
        return 0;

      if (simple_cst_equal (TREE_VALUE (t2), TREE_VALUE (attr)) != 1)
        return 0;
    }

  return 1;
}

/* Given two lists of types
   (chains of TREE_LIST nodes with types in the TREE_VALUE slots)
   return 1 if the lists contain the same types in the same order.
   Also, the TREE_PURPOSEs must match.  */

int
type_list_equal (tree l1, tree l2)
{
  tree t1, t2;

  for (t1 = l1, t2 = l2; t1 && t2; t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
    if (TREE_VALUE (t1) != TREE_VALUE (t2)
        || (TREE_PURPOSE (t1) != TREE_PURPOSE (t2)
            && ! (1 == simple_cst_equal (TREE_PURPOSE (t1), TREE_PURPOSE (t2))
                  && (TREE_TYPE (TREE_PURPOSE (t1))
                      == TREE_TYPE (TREE_PURPOSE (t2))))))
      return 0;

  return t1 == t2;
}

/* Returns the number of arguments to the FUNCTION_TYPE or METHOD_TYPE
   given by TYPE.  If the argument list accepts variable arguments,
   then this function counts only the ordinary arguments.  */

int
type_num_arguments (tree type)
{
  int i = 0;
  tree t;

  for (t = TYPE_ARG_TYPES (type); t; t = TREE_CHAIN (t))
    /* If the function does not take a variable number of arguments,
       the last element in the list will have type `void'.  */
    if (VOID_TYPE_P (TREE_VALUE (t)))
      break;
    else
      ++i;

  return i;
}

/* Nonzero if integer constants T1 and T2
   represent the same constant value.  */

int
tree_int_cst_equal (tree t1, tree t2)
{
  if (t1 == t2)
    return 1;

  if (t1 == 0 || t2 == 0)
    return 0;

  if (TREE_CODE (t1) == INTEGER_CST
      && TREE_CODE (t2) == INTEGER_CST
      && TREE_INT_CST_LOW (t1) == TREE_INT_CST_LOW (t2)
      && TREE_INT_CST_HIGH (t1) == TREE_INT_CST_HIGH (t2))
    return 1;

  return 0;
}

/* Nonzero if integer constants T1 and T2 represent values that satisfy <.
   The precise way of comparison depends on their data type.  */

int
tree_int_cst_lt (tree t1, tree t2)
{
  if (t1 == t2)
    return 0;

  if (TYPE_UNSIGNED (TREE_TYPE (t1)) != TYPE_UNSIGNED (TREE_TYPE (t2)))
    {
      int t1_sgn = tree_int_cst_sgn (t1);
      int t2_sgn = tree_int_cst_sgn (t2);

      if (t1_sgn < t2_sgn)
        return 1;
      else if (t1_sgn > t2_sgn)
        return 0;
      /* Otherwise, both are non-negative, so we compare them as
         unsigned just in case one of them would overflow a signed
         type.  */
    }
  else if (!TYPE_UNSIGNED (TREE_TYPE (t1)))
    return INT_CST_LT (t1, t2);

  return INT_CST_LT_UNSIGNED (t1, t2);
}

/* Returns -1 if T1 < T2, 0 if T1 == T2, and 1 if T1 > T2.  */

int
tree_int_cst_compare (tree t1, tree t2)
{
  if (tree_int_cst_lt (t1, t2))
    return -1;
  else if (tree_int_cst_lt (t2, t1))
    return 1;
  else
    return 0;
}

/* Return 1 if T is an INTEGER_CST that can be manipulated efficiently on
   the host.  If POS is zero, the value can be represented in a single
   HOST_WIDE_INT.  If POS is nonzero, the value must be non-negative and can
   be represented in a single unsigned HOST_WIDE_INT.  */

int
host_integerp (tree t, int pos)
{
  return (TREE_CODE (t) == INTEGER_CST
          && ! TREE_OVERFLOW (t)
          && ((TREE_INT_CST_HIGH (t) == 0
               && (HOST_WIDE_INT) TREE_INT_CST_LOW (t) >= 0)
              || (! pos && TREE_INT_CST_HIGH (t) == -1
                  && (HOST_WIDE_INT) TREE_INT_CST_LOW (t) < 0
                  && !TYPE_UNSIGNED (TREE_TYPE (t)))
              || (pos && TREE_INT_CST_HIGH (t) == 0)));
}

/* Return the HOST_WIDE_INT least significant bits of T if it is an
   INTEGER_CST and there is no overflow.  POS is nonzero if the result must
   be non-negative.  We must be able to satisfy the above conditions.  */

HOST_WIDE_INT
tree_low_cst (tree t, int pos)
{
  gcc_assert (host_integerp (t, pos));
  return TREE_INT_CST_LOW (t);
}

/* Return the most significant bit of the integer constant T.  */

int
tree_int_cst_msb (tree t)
{
  int prec;
  HOST_WIDE_INT h;
  unsigned HOST_WIDE_INT l;

  /* Note that using TYPE_PRECISION here is wrong.  We care about the
     actual bits, not the (arbitrary) range of the type.  */
  prec = GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (t))) - 1;
  rshift_double (TREE_INT_CST_LOW (t), TREE_INT_CST_HIGH (t), prec,
                 2 * HOST_BITS_PER_WIDE_INT, &l, &h, 0);
  return (l & 1) == 1;
}

/* Return an indication of the sign of the integer constant T.
   The return value is -1 if T < 0, 0 if T == 0, and 1 if T > 0.
   Note that -1 will never be returned if T's type is unsigned.  */

int
tree_int_cst_sgn (tree t)
{
  if (TREE_INT_CST_LOW (t) == 0 && TREE_INT_CST_HIGH (t) == 0)
    return 0;
  else if (TYPE_UNSIGNED (TREE_TYPE (t)))
    return 1;
  else if (TREE_INT_CST_HIGH (t) < 0)
    return -1;
  else
    return 1;
}

/* Compare two constructor-element-type constants.  Return 1 if the lists
   are known to be equal; otherwise return 0.  */

int
simple_cst_list_equal (tree l1, tree l2)
{
  while (l1 != NULL_TREE && l2 != NULL_TREE)
    {
      if (simple_cst_equal (TREE_VALUE (l1), TREE_VALUE (l2)) != 1)
        return 0;

      l1 = TREE_CHAIN (l1);
      l2 = TREE_CHAIN (l2);
    }

  return l1 == l2;
}

/* Return truthvalue of whether T1 is the same tree structure as T2.
   Return 1 if they are the same.
   Return 0 if they are understandably different.
   Return -1 if either contains tree structure not understood by
   this function.  */

int
simple_cst_equal (tree t1, tree t2)
{
  enum tree_code code1, code2;