trans.h (struct gfc_loopinfo): New field parent.

[thirdparty/gcc.git] / gcc / fortran / trans-array.c

/* Array translation routines
   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
   2011
   Free Software Foundation, Inc.
   Contributed by Paul Brook <paul@nowt.org>
   and Steven Bosscher <s.bosscher@student.tudelft.nl>

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 3, 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 COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

/* trans-array.c-- Various array related code, including scalarization,
                   allocation, initialization and other support routines.  */

/* How the scalarizer works.
   In gfortran, array expressions use the same core routines as scalar
   expressions.
   First, a Scalarization State (SS) chain is built.  This is done by walking
   the expression tree, and building a linear list of the terms in the
   expression.  As the tree is walked, scalar subexpressions are translated.

   The scalarization parameters are stored in a gfc_loopinfo structure.
   First the start and stride of each term is calculated by
   gfc_conv_ss_startstride.  During this process the expressions for the array
   descriptors and data pointers are also translated.

   If the expression is an assignment, we must then resolve any dependencies.
   In fortran all the rhs values of an assignment must be evaluated before
   any assignments take place.  This can require a temporary array to store the
   values.  We also require a temporary when we are passing array expressions
   or vector subscripts as procedure parameters.

   Array sections are passed without copying to a temporary.  These use the
   scalarizer to determine the shape of the section.  The flag
   loop->array_parameter tells the scalarizer that the actual values and loop
   variables will not be required.

   The function gfc_conv_loop_setup generates the scalarization setup code.
   It determines the range of the scalarizing loop variables.  If a temporary
   is required, this is created and initialized.  Code for scalar expressions
   taken outside the loop is also generated at this time.  Next the offset and
   scaling required to translate from loop variables to array indices for each
   term is calculated.

   A call to gfc_start_scalarized_body marks the start of the scalarized
   expression.  This creates a scope and declares the loop variables.  Before
   calling this gfc_make_ss_chain_used must be used to indicate which terms
   will be used inside this loop.

   The scalar gfc_conv_* functions are then used to build the main body of the
   scalarization loop.  Scalarization loop variables and precalculated scalar
   values are automatically substituted.  Note that gfc_advance_se_ss_chain
   must be used, rather than changing the se->ss directly.

   For assignment expressions requiring a temporary two sub loops are
   generated.  The first stores the result of the expression in the temporary,
   the second copies it to the result.  A call to
   gfc_trans_scalarized_loop_boundary marks the end of the main loop code and
   the start of the copying loop.  The temporary may be less than full rank.

   Finally gfc_trans_scalarizing_loops is called to generate the implicit do
   loops.  The loops are added to the pre chain of the loopinfo.  The post
   chain may still contain cleanup code.

   After the loop code has been added into its parent scope gfc_cleanup_loop
   is called to free all the SS allocated by the scalarizer.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tree.h"
#include "gimple.h"
#include "diagnostic-core.h"    /* For internal_error/fatal_error.  */
#include "flags.h"
#include "gfortran.h"
#include "constructor.h"
#include "trans.h"
#include "trans-stmt.h"
#include "trans-types.h"
#include "trans-array.h"
#include "trans-const.h"
#include "dependency.h"

static bool gfc_get_array_constructor_size (mpz_t *, gfc_constructor_base);

/* The contents of this structure aren't actually used, just the address.  */
static gfc_ss gfc_ss_terminator_var;
gfc_ss * const gfc_ss_terminator = &gfc_ss_terminator_var;


static tree
gfc_array_dataptr_type (tree desc)
{
  return (GFC_TYPE_ARRAY_DATAPTR_TYPE (TREE_TYPE (desc)));
}


/* Build expressions to access the members of an array descriptor.
   It's surprisingly easy to mess up here, so never access
   an array descriptor by "brute force", always use these
   functions.  This also avoids problems if we change the format
   of an array descriptor.

   To understand these magic numbers, look at the comments
   before gfc_build_array_type() in trans-types.c.

   The code within these defines should be the only code which knows the format
   of an array descriptor.

   Any code just needing to read obtain the bounds of an array should use
   gfc_conv_array_* rather than the following functions as these will return
   know constant values, and work with arrays which do not have descriptors.

   Don't forget to #undef these!  */

#define DATA_FIELD 0
#define OFFSET_FIELD 1
#define DTYPE_FIELD 2
#define DIMENSION_FIELD 3
#define CAF_TOKEN_FIELD 4

#define STRIDE_SUBFIELD 0
#define LBOUND_SUBFIELD 1
#define UBOUND_SUBFIELD 2

/* This provides READ-ONLY access to the data field.  The field itself
   doesn't have the proper type.  */

tree
gfc_conv_descriptor_data_get (tree desc)
{
  tree field, type, t;

  type = TREE_TYPE (desc);
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));

  field = TYPE_FIELDS (type);
  gcc_assert (DATA_FIELD == 0);

  t = fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field), desc,
                       field, NULL_TREE);
  t = fold_convert (GFC_TYPE_ARRAY_DATAPTR_TYPE (type), t);

  return t;
}

/* This provides WRITE access to the data field.

   TUPLES_P is true if we are generating tuples.
   
   This function gets called through the following macros:
     gfc_conv_descriptor_data_set
     gfc_conv_descriptor_data_set.  */

void
gfc_conv_descriptor_data_set (stmtblock_t *block, tree desc, tree value)
{
  tree field, type, t;

  type = TREE_TYPE (desc);
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));

  field = TYPE_FIELDS (type);
  gcc_assert (DATA_FIELD == 0);

  t = fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field), desc,
                       field, NULL_TREE);
  gfc_add_modify (block, t, fold_convert (TREE_TYPE (field), value));
}


/* This provides address access to the data field.  This should only be
   used by array allocation, passing this on to the runtime.  */

tree
gfc_conv_descriptor_data_addr (tree desc)
{
  tree field, type, t;

  type = TREE_TYPE (desc);
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));

  field = TYPE_FIELDS (type);
  gcc_assert (DATA_FIELD == 0);

  t = fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field), desc,
                       field, NULL_TREE);
  return gfc_build_addr_expr (NULL_TREE, t);
}

static tree
gfc_conv_descriptor_offset (tree desc)
{
  tree type;
  tree field;

  type = TREE_TYPE (desc);
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));

  field = gfc_advance_chain (TYPE_FIELDS (type), OFFSET_FIELD);
  gcc_assert (field != NULL_TREE && TREE_TYPE (field) == gfc_array_index_type);

  return fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field),
                          desc, field, NULL_TREE);
}

tree
gfc_conv_descriptor_offset_get (tree desc)
{
  return gfc_conv_descriptor_offset (desc);
}

void
gfc_conv_descriptor_offset_set (stmtblock_t *block, tree desc,
                                tree value)
{
  tree t = gfc_conv_descriptor_offset (desc);
  gfc_add_modify (block, t, fold_convert (TREE_TYPE (t), value));
}


tree
gfc_conv_descriptor_dtype (tree desc)
{
  tree field;
  tree type;

  type = TREE_TYPE (desc);
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));

  field = gfc_advance_chain (TYPE_FIELDS (type), DTYPE_FIELD);
  gcc_assert (field != NULL_TREE && TREE_TYPE (field) == gfc_array_index_type);

  return fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field),
                          desc, field, NULL_TREE);
}

static tree
gfc_conv_descriptor_dimension (tree desc, tree dim)
{
  tree field;
  tree type;
  tree tmp;

  type = TREE_TYPE (desc);
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));

  field = gfc_advance_chain (TYPE_FIELDS (type), DIMENSION_FIELD);
  gcc_assert (field != NULL_TREE
          && TREE_CODE (TREE_TYPE (field)) == ARRAY_TYPE
          && TREE_CODE (TREE_TYPE (TREE_TYPE (field))) == RECORD_TYPE);

  tmp = fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field),
                         desc, field, NULL_TREE);
  tmp = gfc_build_array_ref (tmp, dim, NULL);
  return tmp;
}


tree
gfc_conv_descriptor_token (tree desc)
{
  tree type;
  tree field;

  type = TREE_TYPE (desc);
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));
  gcc_assert (GFC_TYPE_ARRAY_AKIND (type) == GFC_ARRAY_ALLOCATABLE);
  gcc_assert (gfc_option.coarray == GFC_FCOARRAY_LIB);
  field = gfc_advance_chain (TYPE_FIELDS (type), CAF_TOKEN_FIELD);
  gcc_assert (field != NULL_TREE && TREE_TYPE (field) == prvoid_type_node);

  return fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field),
                          desc, field, NULL_TREE);
}


static tree
gfc_conv_descriptor_stride (tree desc, tree dim)
{
  tree tmp;
  tree field;

  tmp = gfc_conv_descriptor_dimension (desc, dim);
  field = TYPE_FIELDS (TREE_TYPE (tmp));
  field = gfc_advance_chain (field, STRIDE_SUBFIELD);
  gcc_assert (field != NULL_TREE && TREE_TYPE (field) == gfc_array_index_type);

  tmp = fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field),
                         tmp, field, NULL_TREE);
  return tmp;
}

tree
gfc_conv_descriptor_stride_get (tree desc, tree dim)
{
  tree type = TREE_TYPE (desc);
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));
  if (integer_zerop (dim)
      && (GFC_TYPE_ARRAY_AKIND (type) == GFC_ARRAY_ALLOCATABLE
          ||GFC_TYPE_ARRAY_AKIND (type) == GFC_ARRAY_ASSUMED_SHAPE_CONT
          ||GFC_TYPE_ARRAY_AKIND (type) == GFC_ARRAY_POINTER_CONT))
    return gfc_index_one_node;

  return gfc_conv_descriptor_stride (desc, dim);
}

void
gfc_conv_descriptor_stride_set (stmtblock_t *block, tree desc,
                                tree dim, tree value)
{
  tree t = gfc_conv_descriptor_stride (desc, dim);
  gfc_add_modify (block, t, fold_convert (TREE_TYPE (t), value));
}

static tree
gfc_conv_descriptor_lbound (tree desc, tree dim)
{
  tree tmp;
  tree field;

  tmp = gfc_conv_descriptor_dimension (desc, dim);
  field = TYPE_FIELDS (TREE_TYPE (tmp));
  field = gfc_advance_chain (field, LBOUND_SUBFIELD);
  gcc_assert (field != NULL_TREE && TREE_TYPE (field) == gfc_array_index_type);

  tmp = fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field),
                         tmp, field, NULL_TREE);
  return tmp;
}

tree
gfc_conv_descriptor_lbound_get (tree desc, tree dim)
{
  return gfc_conv_descriptor_lbound (desc, dim);
}

void
gfc_conv_descriptor_lbound_set (stmtblock_t *block, tree desc,
                                tree dim, tree value)
{
  tree t = gfc_conv_descriptor_lbound (desc, dim);
  gfc_add_modify (block, t, fold_convert (TREE_TYPE (t), value));
}

static tree
gfc_conv_descriptor_ubound (tree desc, tree dim)
{
  tree tmp;
  tree field;

  tmp = gfc_conv_descriptor_dimension (desc, dim);
  field = TYPE_FIELDS (TREE_TYPE (tmp));
  field = gfc_advance_chain (field, UBOUND_SUBFIELD);
  gcc_assert (field != NULL_TREE && TREE_TYPE (field) == gfc_array_index_type);

  tmp = fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (field),
                         tmp, field, NULL_TREE);
  return tmp;
}

tree
gfc_conv_descriptor_ubound_get (tree desc, tree dim)
{
  return gfc_conv_descriptor_ubound (desc, dim);
}

void
gfc_conv_descriptor_ubound_set (stmtblock_t *block, tree desc,
                                tree dim, tree value)
{
  tree t = gfc_conv_descriptor_ubound (desc, dim);
  gfc_add_modify (block, t, fold_convert (TREE_TYPE (t), value));
}

/* Build a null array descriptor constructor.  */

tree
gfc_build_null_descriptor (tree type)
{
  tree field;
  tree tmp;

  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));
  gcc_assert (DATA_FIELD == 0);
  field = TYPE_FIELDS (type);

  /* Set a NULL data pointer.  */
  tmp = build_constructor_single (type, field, null_pointer_node);
  TREE_CONSTANT (tmp) = 1;
  /* All other fields are ignored.  */

  return tmp;
}


/* Modify a descriptor such that the lbound of a given dimension is the value
   specified.  This also updates ubound and offset accordingly.  */

void
gfc_conv_shift_descriptor_lbound (stmtblock_t* block, tree desc,
                                  int dim, tree new_lbound)
{
  tree offs, ubound, lbound, stride;
  tree diff, offs_diff;

  new_lbound = fold_convert (gfc_array_index_type, new_lbound);

  offs = gfc_conv_descriptor_offset_get (desc);
  lbound = gfc_conv_descriptor_lbound_get (desc, gfc_rank_cst[dim]);
  ubound = gfc_conv_descriptor_ubound_get (desc, gfc_rank_cst[dim]);
  stride = gfc_conv_descriptor_stride_get (desc, gfc_rank_cst[dim]);

  /* Get difference (new - old) by which to shift stuff.  */
  diff = fold_build2_loc (input_location, MINUS_EXPR, gfc_array_index_type,
                          new_lbound, lbound);

  /* Shift ubound and offset accordingly.  This has to be done before
     updating the lbound, as they depend on the lbound expression!  */
  ubound = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                            ubound, diff);
  gfc_conv_descriptor_ubound_set (block, desc, gfc_rank_cst[dim], ubound);
  offs_diff = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                               diff, stride);
  offs = fold_build2_loc (input_location, MINUS_EXPR, gfc_array_index_type,
                          offs, offs_diff);
  gfc_conv_descriptor_offset_set (block, desc, offs);

  /* Finally set lbound to value we want.  */
  gfc_conv_descriptor_lbound_set (block, desc, gfc_rank_cst[dim], new_lbound);
}


/* Cleanup those #defines.  */

#undef DATA_FIELD
#undef OFFSET_FIELD
#undef DTYPE_FIELD
#undef DIMENSION_FIELD
#undef CAF_TOKEN_FIELD
#undef STRIDE_SUBFIELD
#undef LBOUND_SUBFIELD
#undef UBOUND_SUBFIELD


/* Mark a SS chain as used.  Flags specifies in which loops the SS is used.
   flags & 1 = Main loop body.
   flags & 2 = temp copy loop.  */

void
gfc_mark_ss_chain_used (gfc_ss * ss, unsigned flags)
{
  for (; ss != gfc_ss_terminator; ss = ss->next)
    ss->info->useflags = flags;
}

static void gfc_free_ss (gfc_ss *);


/* Free a gfc_ss chain.  */

void
gfc_free_ss_chain (gfc_ss * ss)
{
  gfc_ss *next;

  while (ss != gfc_ss_terminator)
    {
      gcc_assert (ss != NULL);
      next = ss->next;
      gfc_free_ss (ss);
      ss = next;
    }
}


static void
free_ss_info (gfc_ss_info *ss_info)
{
  ss_info->refcount--;
  if (ss_info->refcount > 0)
    return;

  gcc_assert (ss_info->refcount == 0);
  free (ss_info);
}


/* Free a SS.  */

static void
gfc_free_ss (gfc_ss * ss)
{
  gfc_ss_info *ss_info;
  int n;

  ss_info = ss->info;

  switch (ss_info->type)
    {
    case GFC_SS_SECTION:
      for (n = 0; n < ss->dimen; n++)
        {
          if (ss_info->data.array.subscript[ss->dim[n]])
            gfc_free_ss_chain (ss_info->data.array.subscript[ss->dim[n]]);
        }
      break;

    default:
      break;
    }

  free_ss_info (ss_info);
  free (ss);
}


/* Creates and initializes an array type gfc_ss struct.  */

gfc_ss *
gfc_get_array_ss (gfc_ss *next, gfc_expr *expr, int dimen, gfc_ss_type type)
{
  gfc_ss *ss;
  gfc_ss_info *ss_info;
  int i;

  ss_info = gfc_get_ss_info ();
  ss_info->refcount++;
  ss_info->type = type;
  ss_info->expr = expr;

  ss = gfc_get_ss ();
  ss->info = ss_info;
  ss->next = next;
  ss->dimen = dimen;
  for (i = 0; i < ss->dimen; i++)
    ss->dim[i] = i;

  return ss;
}


/* Creates and initializes a temporary type gfc_ss struct.  */

gfc_ss *
gfc_get_temp_ss (tree type, tree string_length, int dimen)
{
  gfc_ss *ss;
  gfc_ss_info *ss_info;
  int i;

  ss_info = gfc_get_ss_info ();
  ss_info->refcount++;
  ss_info->type = GFC_SS_TEMP;
  ss_info->string_length = string_length;
  ss_info->data.temp.type = type;

  ss = gfc_get_ss ();
  ss->info = ss_info;
  ss->next = gfc_ss_terminator;
  ss->dimen = dimen;
  for (i = 0; i < ss->dimen; i++)
    ss->dim[i] = i;

  return ss;
}
                

/* Creates and initializes a scalar type gfc_ss struct.  */

gfc_ss *
gfc_get_scalar_ss (gfc_ss *next, gfc_expr *expr)
{
  gfc_ss *ss;
  gfc_ss_info *ss_info;

  ss_info = gfc_get_ss_info ();
  ss_info->refcount++;
  ss_info->type = GFC_SS_SCALAR;
  ss_info->expr = expr;

  ss = gfc_get_ss ();
  ss->info = ss_info;
  ss->next = next;

  return ss;
}


/* Free all the SS associated with a loop.  */

void
gfc_cleanup_loop (gfc_loopinfo * loop)
{
  gfc_loopinfo *loop_next, **ploop;
  gfc_ss *ss;
  gfc_ss *next;

  ss = loop->ss;
  while (ss != gfc_ss_terminator)
    {
      gcc_assert (ss != NULL);
      next = ss->loop_chain;
      gfc_free_ss (ss);
      ss = next;
    }

  /* Remove reference to self in the parent loop.  */
  if (loop->parent)
    for (ploop = &loop->parent->nested; *ploop; ploop = &(*ploop)->next)
      if (*ploop == loop)
        {
          *ploop = loop->next;
          break;
        }

  /* Free non-freed nested loops.  */
  for (loop = loop->nested; loop; loop = loop_next)
    {
      loop_next = loop->next;
      gfc_cleanup_loop (loop);
      free (loop);
    }
}


static void
set_ss_loop (gfc_ss *ss, gfc_loopinfo *loop)
{
  int n;

  for (; ss != gfc_ss_terminator; ss = ss->next)
    {
      ss->loop = loop;

      if (ss->info->type == GFC_SS_SCALAR
          || ss->info->type == GFC_SS_REFERENCE
          || ss->info->type == GFC_SS_TEMP)
        continue;

      for (n = 0; n < GFC_MAX_DIMENSIONS; n++)
        if (ss->info->data.array.subscript[n] != NULL)
          set_ss_loop (ss->info->data.array.subscript[n], loop);
    }
}


/* Associate a SS chain with a loop.  */

void
gfc_add_ss_to_loop (gfc_loopinfo * loop, gfc_ss * head)
{
  gfc_ss *ss;
  gfc_loopinfo *nested_loop;

  if (head == gfc_ss_terminator)
    return;

  set_ss_loop (head, loop);

  ss = head;
  for (; ss && ss != gfc_ss_terminator; ss = ss->next)
    {
      if (ss->nested_ss)
        {
          nested_loop = ss->nested_ss->loop;

          /* More than one ss can belong to the same loop.  Hence, we add the
             loop to the chain only if it is different from the previously
             added one, to avoid duplicate nested loops.  */
          if (nested_loop != loop->nested)
            {
              gcc_assert (nested_loop->parent == NULL);
              nested_loop->parent = loop;

              gcc_assert (nested_loop->next == NULL);
              nested_loop->next = loop->nested;
              loop->nested = nested_loop;
            }
          else
            gcc_assert (nested_loop->parent == loop);
        }

      if (ss->next == gfc_ss_terminator)
        ss->loop_chain = loop->ss;
      else
        ss->loop_chain = ss->next;
    }
  gcc_assert (ss == gfc_ss_terminator);
  loop->ss = head;
}


/* Generate an initializer for a static pointer or allocatable array.  */

void
gfc_trans_static_array_pointer (gfc_symbol * sym)
{
  tree type;

  gcc_assert (TREE_STATIC (sym->backend_decl));
  /* Just zero the data member.  */
  type = TREE_TYPE (sym->backend_decl);
  DECL_INITIAL (sym->backend_decl) = gfc_build_null_descriptor (type);
}


/* If the bounds of SE's loop have not yet been set, see if they can be
   determined from array spec AS, which is the array spec of a called
   function.  MAPPING maps the callee's dummy arguments to the values
   that the caller is passing.  Add any initialization and finalization
   code to SE.  */

void
gfc_set_loop_bounds_from_array_spec (gfc_interface_mapping * mapping,
                                     gfc_se * se, gfc_array_spec * as)
{
  int n, dim, total_dim;
  gfc_se tmpse;
  gfc_ss *ss;
  tree lower;
  tree upper;
  tree tmp;

  total_dim = 0;

  if (!as || as->type != AS_EXPLICIT)
    return;

  for (ss = se->ss; ss; ss = ss->parent)
    {
      total_dim += ss->loop->dimen;
      for (n = 0; n < ss->loop->dimen; n++)
        {
          /* The bound is known, nothing to do.  */
          if (ss->loop->to[n] != NULL_TREE)
            continue;

          dim = ss->dim[n];
          gcc_assert (dim < as->rank);
          gcc_assert (ss->loop->dimen <= as->rank);

          /* Evaluate the lower bound.  */
          gfc_init_se (&tmpse, NULL);
          gfc_apply_interface_mapping (mapping, &tmpse, as->lower[dim]);
          gfc_add_block_to_block (&se->pre, &tmpse.pre);
          gfc_add_block_to_block (&se->post, &tmpse.post);
          lower = fold_convert (gfc_array_index_type, tmpse.expr);

          /* ...and the upper bound.  */
          gfc_init_se (&tmpse, NULL);
          gfc_apply_interface_mapping (mapping, &tmpse, as->upper[dim]);
          gfc_add_block_to_block (&se->pre, &tmpse.pre);
          gfc_add_block_to_block (&se->post, &tmpse.post);
          upper = fold_convert (gfc_array_index_type, tmpse.expr);

          /* Set the upper bound of the loop to UPPER - LOWER.  */
          tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                 gfc_array_index_type, upper, lower);
          tmp = gfc_evaluate_now (tmp, &se->pre);
          ss->loop->to[n] = tmp;
        }
    }

  gcc_assert (total_dim == as->rank);
}


/* Generate code to allocate an array temporary, or create a variable to
   hold the data.  If size is NULL, zero the descriptor so that the
   callee will allocate the array.  If DEALLOC is true, also generate code to
   free the array afterwards.

   If INITIAL is not NULL, it is packed using internal_pack and the result used
   as data instead of allocating a fresh, unitialized area of memory.

   Initialization code is added to PRE and finalization code to POST.
   DYNAMIC is true if the caller may want to extend the array later
   using realloc.  This prevents us from putting the array on the stack.  */

static void
gfc_trans_allocate_array_storage (stmtblock_t * pre, stmtblock_t * post,
                                  gfc_array_info * info, tree size, tree nelem,
                                  tree initial, bool dynamic, bool dealloc)
{
  tree tmp;
  tree desc;
  bool onstack;

  desc = info->descriptor;
  info->offset = gfc_index_zero_node;
  if (size == NULL_TREE || integer_zerop (size))
    {
      /* A callee allocated array.  */
      gfc_conv_descriptor_data_set (pre, desc, null_pointer_node);
      onstack = FALSE;
    }
  else
    {
      /* Allocate the temporary.  */
      onstack = !dynamic && initial == NULL_TREE
                         && (gfc_option.flag_stack_arrays
                             || gfc_can_put_var_on_stack (size));

      if (onstack)
        {
          /* Make a temporary variable to hold the data.  */
          tmp = fold_build2_loc (input_location, MINUS_EXPR, TREE_TYPE (nelem),
                                 nelem, gfc_index_one_node);
          tmp = gfc_evaluate_now (tmp, pre);
          tmp = build_range_type (gfc_array_index_type, gfc_index_zero_node,
                                  tmp);
          tmp = build_array_type (gfc_get_element_type (TREE_TYPE (desc)),
                                  tmp);
          tmp = gfc_create_var (tmp, "A");
          /* If we're here only because of -fstack-arrays we have to
             emit a DECL_EXPR to make the gimplifier emit alloca calls.  */
          if (!gfc_can_put_var_on_stack (size))
            gfc_add_expr_to_block (pre,
                                   fold_build1_loc (input_location,
                                                    DECL_EXPR, TREE_TYPE (tmp),
                                                    tmp));
          tmp = gfc_build_addr_expr (NULL_TREE, tmp);
          gfc_conv_descriptor_data_set (pre, desc, tmp);
        }
      else
        {
          /* Allocate memory to hold the data or call internal_pack.  */
          if (initial == NULL_TREE)
            {
              tmp = gfc_call_malloc (pre, NULL, size);
              tmp = gfc_evaluate_now (tmp, pre);
            }
          else
            {
              tree packed;
              tree source_data;
              tree was_packed;
              stmtblock_t do_copying;

              tmp = TREE_TYPE (initial); /* Pointer to descriptor.  */
              gcc_assert (TREE_CODE (tmp) == POINTER_TYPE);
              tmp = TREE_TYPE (tmp); /* The descriptor itself.  */
              tmp = gfc_get_element_type (tmp);
              gcc_assert (tmp == gfc_get_element_type (TREE_TYPE (desc)));
              packed = gfc_create_var (build_pointer_type (tmp), "data");

              tmp = build_call_expr_loc (input_location,
                                     gfor_fndecl_in_pack, 1, initial);
              tmp = fold_convert (TREE_TYPE (packed), tmp);
              gfc_add_modify (pre, packed, tmp);

              tmp = build_fold_indirect_ref_loc (input_location,
                                             initial);
              source_data = gfc_conv_descriptor_data_get (tmp);

              /* internal_pack may return source->data without any allocation
                 or copying if it is already packed.  If that's the case, we
                 need to allocate and copy manually.  */

              gfc_start_block (&do_copying);
              tmp = gfc_call_malloc (&do_copying, NULL, size);
              tmp = fold_convert (TREE_TYPE (packed), tmp);
              gfc_add_modify (&do_copying, packed, tmp);
              tmp = gfc_build_memcpy_call (packed, source_data, size);
              gfc_add_expr_to_block (&do_copying, tmp);

              was_packed = fold_build2_loc (input_location, EQ_EXPR,
                                            boolean_type_node, packed,
                                            source_data);
              tmp = gfc_finish_block (&do_copying);
              tmp = build3_v (COND_EXPR, was_packed, tmp,
                              build_empty_stmt (input_location));
              gfc_add_expr_to_block (pre, tmp);

              tmp = fold_convert (pvoid_type_node, packed);
            }

          gfc_conv_descriptor_data_set (pre, desc, tmp);
        }
    }
  info->data = gfc_conv_descriptor_data_get (desc);

  /* The offset is zero because we create temporaries with a zero
     lower bound.  */
  gfc_conv_descriptor_offset_set (pre, desc, gfc_index_zero_node);

  if (dealloc && !onstack)
    {
      /* Free the temporary.  */
      tmp = gfc_conv_descriptor_data_get (desc);
      tmp = gfc_call_free (fold_convert (pvoid_type_node, tmp));
      gfc_add_expr_to_block (post, tmp);
    }
}


/* Get the scalarizer array dimension corresponding to actual array dimension
   given by ARRAY_DIM.

   For example, if SS represents the array ref a(1,:,:,1), it is a
   bidimensional scalarizer array, and the result would be 0 for ARRAY_DIM=1,
   and 1 for ARRAY_DIM=2.
   If SS represents transpose(a(:,1,1,:)), it is again a bidimensional
   scalarizer array, and the result would be 1 for ARRAY_DIM=0 and 0 for
   ARRAY_DIM=3.
   If SS represents sum(a(:,:,:,1), dim=1), it is a 2+1-dimensional scalarizer
   array.  If called on the inner ss, the result would be respectively 0,1,2 for
   ARRAY_DIM=0,1,2.  If called on the outer ss, the result would be 0,1
   for ARRAY_DIM=1,2.  */

static int
get_scalarizer_dim_for_array_dim (gfc_ss *ss, int array_dim)
{
  int array_ref_dim;
  int n;

  array_ref_dim = 0;

  for (; ss; ss = ss->parent)
    for (n = 0; n < ss->dimen; n++)
      if (ss->dim[n] < array_dim)
        array_ref_dim++;

  return array_ref_dim;
}


static gfc_ss *
innermost_ss (gfc_ss *ss)
{
  while (ss->nested_ss != NULL)
    ss = ss->nested_ss;

  return ss;
}



/* Get the array reference dimension corresponding to the given loop dimension.
   It is different from the true array dimension given by the dim array in
   the case of a partial array reference (i.e. a(:,:,1,:) for example)
   It is different from the loop dimension in the case of a transposed array.
   */

static int
get_array_ref_dim_for_loop_dim (gfc_ss *ss, int loop_dim)
{
  return get_scalarizer_dim_for_array_dim (innermost_ss (ss),
                                           ss->dim[loop_dim]);
}


/* Generate code to create and initialize the descriptor for a temporary
   array.  This is used for both temporaries needed by the scalarizer, and
   functions returning arrays.  Adjusts the loop variables to be
   zero-based, and calculates the loop bounds for callee allocated arrays.
   Allocate the array unless it's callee allocated (we have a callee
   allocated array if 'callee_alloc' is true, or if loop->to[n] is
   NULL_TREE for any n).  Also fills in the descriptor, data and offset
   fields of info if known.  Returns the size of the array, or NULL for a
   callee allocated array.

   PRE, POST, INITIAL, DYNAMIC and DEALLOC are as for
   gfc_trans_allocate_array_storage.  */

tree
gfc_trans_create_temp_array (stmtblock_t * pre, stmtblock_t * post, gfc_ss * ss,
                             tree eltype, tree initial, bool dynamic,
                             bool dealloc, bool callee_alloc, locus * where)
{
  gfc_loopinfo *loop;
  gfc_ss *s;
  gfc_array_info *info;
  tree from[GFC_MAX_DIMENSIONS], to[GFC_MAX_DIMENSIONS];
  tree type;
  tree desc;
  tree tmp;
  tree size;
  tree nelem;
  tree cond;
  tree or_expr;
  int n, dim, tmp_dim;
  int total_dim = 0;

  memset (from, 0, sizeof (from));
  memset (to, 0, sizeof (to));

  info = &ss->info->data.array;

  gcc_assert (ss->dimen > 0);
  gcc_assert (ss->loop->dimen == ss->dimen);

  if (gfc_option.warn_array_temp && where)
    gfc_warning ("Creating array temporary at %L", where);

  /* Set the lower bound to zero.  */
  for (s = ss; s; s = s->parent)
    {
      loop = s->loop;

      total_dim += loop->dimen;
      for (n = 0; n < loop->dimen; n++)
        {
          dim = s->dim[n];

          /* Callee allocated arrays may not have a known bound yet.  */
          if (loop->to[n])
            loop->to[n] = gfc_evaluate_now (
                        fold_build2_loc (input_location, MINUS_EXPR,
                                         gfc_array_index_type,
                                         loop->to[n], loop->from[n]),
                        pre);
          loop->from[n] = gfc_index_zero_node;

          /* We have just changed the loop bounds, we must clear the
             corresponding specloop, so that delta calculation is not skipped
             later in set_delta.  */
          loop->specloop[n] = NULL;

          /* We are constructing the temporary's descriptor based on the loop
             dimensions.  As the dimensions may be accessed in arbitrary order
             (think of transpose) the size taken from the n'th loop may not map
             to the n'th dimension of the array.  We need to reconstruct loop
             infos in the right order before using it to set the descriptor
             bounds.  */
          tmp_dim = get_scalarizer_dim_for_array_dim (ss, dim);
          from[tmp_dim] = loop->from[n];
          to[tmp_dim] = loop->to[n];

          info->delta[dim] = gfc_index_zero_node;
          info->start[dim] = gfc_index_zero_node;
          info->end[dim] = gfc_index_zero_node;
          info->stride[dim] = gfc_index_one_node;
        }
    }

  /* Initialize the descriptor.  */
  type =
    gfc_get_array_type_bounds (eltype, total_dim, 0, from, to, 1,
                               GFC_ARRAY_UNKNOWN, true);
  desc = gfc_create_var (type, "atmp");
  GFC_DECL_PACKED_ARRAY (desc) = 1;

  info->descriptor = desc;
  size = gfc_index_one_node;

  /* Fill in the array dtype.  */
  tmp = gfc_conv_descriptor_dtype (desc);
  gfc_add_modify (pre, tmp, gfc_get_dtype (TREE_TYPE (desc)));

  /*
     Fill in the bounds and stride.  This is a packed array, so:

     size = 1;
     for (n = 0; n < rank; n++)
       {
         stride[n] = size
         delta = ubound[n] + 1 - lbound[n];
         size = size * delta;
       }
     size = size * sizeof(element);
  */

  or_expr = NULL_TREE;

  /* If there is at least one null loop->to[n], it is a callee allocated
     array.  */
  for (n = 0; n < total_dim; n++)
    if (to[n] == NULL_TREE)
      {
        size = NULL_TREE;
        break;
      }

  if (size == NULL_TREE)
    for (s = ss; s; s = s->parent)
      for (n = 0; n < s->loop->dimen; n++)
        {
          dim = get_scalarizer_dim_for_array_dim (ss, ss->dim[n]);

          /* For a callee allocated array express the loop bounds in terms
             of the descriptor fields.  */
          tmp = fold_build2_loc (input_location,
                MINUS_EXPR, gfc_array_index_type,
                gfc_conv_descriptor_ubound_get (desc, gfc_rank_cst[dim]),
                gfc_conv_descriptor_lbound_get (desc, gfc_rank_cst[dim]));
          s->loop->to[n] = tmp;
        }
  else
    {
      for (n = 0; n < total_dim; n++)
        {
          /* Store the stride and bound components in the descriptor.  */
          gfc_conv_descriptor_stride_set (pre, desc, gfc_rank_cst[n], size);

          gfc_conv_descriptor_lbound_set (pre, desc, gfc_rank_cst[n],
                                          gfc_index_zero_node);

          gfc_conv_descriptor_ubound_set (pre, desc, gfc_rank_cst[n], to[n]);

          tmp = fold_build2_loc (input_location, PLUS_EXPR,
                                 gfc_array_index_type,
                                 to[n], gfc_index_one_node);

          /* Check whether the size for this dimension is negative.  */
          cond = fold_build2_loc (input_location, LE_EXPR, boolean_type_node,
                                  tmp, gfc_index_zero_node);
          cond = gfc_evaluate_now (cond, pre);

          if (n == 0)
            or_expr = cond;
          else
            or_expr = fold_build2_loc (input_location, TRUTH_OR_EXPR,
                                       boolean_type_node, or_expr, cond);

          size = fold_build2_loc (input_location, MULT_EXPR,
                                  gfc_array_index_type, size, tmp);
          size = gfc_evaluate_now (size, pre);
        }
    }

  /* Get the size of the array.  */
  if (size && !callee_alloc)
    {
      /* If or_expr is true, then the extent in at least one
         dimension is zero and the size is set to zero.  */
      size = fold_build3_loc (input_location, COND_EXPR, gfc_array_index_type,
                              or_expr, gfc_index_zero_node, size);

      nelem = size;
      size = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                size,
                fold_convert (gfc_array_index_type,
                              TYPE_SIZE_UNIT (gfc_get_element_type (type))));
    }
  else
    {
      nelem = size;
      size = NULL_TREE;
    }

  gfc_trans_allocate_array_storage (pre, post, info, size, nelem, initial,
                                    dynamic, dealloc);

  while (ss->parent)
    ss = ss->parent;

  if (ss->dimen > ss->loop->temp_dim)
    ss->loop->temp_dim = ss->dimen;

  return size;
}


/* Return the number of iterations in a loop that starts at START,
   ends at END, and has step STEP.  */

static tree
gfc_get_iteration_count (tree start, tree end, tree step)
{
  tree tmp;
  tree type;

  type = TREE_TYPE (step);
  tmp = fold_build2_loc (input_location, MINUS_EXPR, type, end, start);
  tmp = fold_build2_loc (input_location, FLOOR_DIV_EXPR, type, tmp, step);
  tmp = fold_build2_loc (input_location, PLUS_EXPR, type, tmp,
                         build_int_cst (type, 1));
  tmp = fold_build2_loc (input_location, MAX_EXPR, type, tmp,
                         build_int_cst (type, 0));
  return fold_convert (gfc_array_index_type, tmp);
}


/* Extend the data in array DESC by EXTRA elements.  */

static void
gfc_grow_array (stmtblock_t * pblock, tree desc, tree extra)
{
  tree arg0, arg1;
  tree tmp;
  tree size;
  tree ubound;

  if (integer_zerop (extra))
    return;

  ubound = gfc_conv_descriptor_ubound_get (desc, gfc_rank_cst[0]);

  /* Add EXTRA to the upper bound.  */
  tmp = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                         ubound, extra);
  gfc_conv_descriptor_ubound_set (pblock, desc, gfc_rank_cst[0], tmp);

  /* Get the value of the current data pointer.  */
  arg0 = gfc_conv_descriptor_data_get (desc);

  /* Calculate the new array size.  */
  size = TYPE_SIZE_UNIT (gfc_get_element_type (TREE_TYPE (desc)));
  tmp = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                         ubound, gfc_index_one_node);
  arg1 = fold_build2_loc (input_location, MULT_EXPR, size_type_node,
                          fold_convert (size_type_node, tmp),
                          fold_convert (size_type_node, size));

  /* Call the realloc() function.  */
  tmp = gfc_call_realloc (pblock, arg0, arg1);
  gfc_conv_descriptor_data_set (pblock, desc, tmp);
}


/* Return true if the bounds of iterator I can only be determined
   at run time.  */

static inline bool
gfc_iterator_has_dynamic_bounds (gfc_iterator * i)
{
  return (i->start->expr_type != EXPR_CONSTANT
          || i->end->expr_type != EXPR_CONSTANT
          || i->step->expr_type != EXPR_CONSTANT);
}


/* Split the size of constructor element EXPR into the sum of two terms,
   one of which can be determined at compile time and one of which must
   be calculated at run time.  Set *SIZE to the former and return true
   if the latter might be nonzero.  */

static bool
gfc_get_array_constructor_element_size (mpz_t * size, gfc_expr * expr)
{
  if (expr->expr_type == EXPR_ARRAY)
    return gfc_get_array_constructor_size (size, expr->value.constructor);
  else if (expr->rank > 0)
    {
      /* Calculate everything at run time.  */
      mpz_set_ui (*size, 0);
      return true;
    }
  else
    {
      /* A single element.  */
      mpz_set_ui (*size, 1);
      return false;
    }
}


/* Like gfc_get_array_constructor_element_size, but applied to the whole
   of array constructor C.  */

static bool
gfc_get_array_constructor_size (mpz_t * size, gfc_constructor_base base)
{
  gfc_constructor *c;
  gfc_iterator *i;
  mpz_t val;
  mpz_t len;
  bool dynamic;

  mpz_set_ui (*size, 0);
  mpz_init (len);
  mpz_init (val);

  dynamic = false;
  for (c = gfc_constructor_first (base); c; c = gfc_constructor_next (c))
    {
      i = c->iterator;
      if (i && gfc_iterator_has_dynamic_bounds (i))
        dynamic = true;
      else
        {
          dynamic |= gfc_get_array_constructor_element_size (&len, c->expr);
          if (i)
            {
              /* Multiply the static part of the element size by the
                 number of iterations.  */
              mpz_sub (val, i->end->value.integer, i->start->value.integer);
              mpz_fdiv_q (val, val, i->step->value.integer);
              mpz_add_ui (val, val, 1);
              if (mpz_sgn (val) > 0)
                mpz_mul (len, len, val);
              else
                mpz_set_ui (len, 0);
            }
          mpz_add (*size, *size, len);
        }
    }
  mpz_clear (len);
  mpz_clear (val);
  return dynamic;
}


/* Make sure offset is a variable.  */

static void
gfc_put_offset_into_var (stmtblock_t * pblock, tree * poffset,
                         tree * offsetvar)
{
  /* We should have already created the offset variable.  We cannot
     create it here because we may be in an inner scope.  */
  gcc_assert (*offsetvar != NULL_TREE);
  gfc_add_modify (pblock, *offsetvar, *poffset);
  *poffset = *offsetvar;
  TREE_USED (*offsetvar) = 1;
}


/* Variables needed for bounds-checking.  */
static bool first_len;
static tree first_len_val; 
static bool typespec_chararray_ctor;

static void
gfc_trans_array_ctor_element (stmtblock_t * pblock, tree desc,
                              tree offset, gfc_se * se, gfc_expr * expr)
{
  tree tmp;

  gfc_conv_expr (se, expr);

  /* Store the value.  */
  tmp = build_fold_indirect_ref_loc (input_location,
                                 gfc_conv_descriptor_data_get (desc));
  tmp = gfc_build_array_ref (tmp, offset, NULL);

  if (expr->ts.type == BT_CHARACTER)
    {
      int i = gfc_validate_kind (BT_CHARACTER, expr->ts.kind, false);
      tree esize;

      esize = size_in_bytes (gfc_get_element_type (TREE_TYPE (desc)));
      esize = fold_convert (gfc_charlen_type_node, esize);
      esize = fold_build2_loc (input_location, TRUNC_DIV_EXPR,
                           gfc_charlen_type_node, esize,
                           build_int_cst (gfc_charlen_type_node,
                                          gfc_character_kinds[i].bit_size / 8));

      gfc_conv_string_parameter (se);
      if (POINTER_TYPE_P (TREE_TYPE (tmp)))
        {
          /* The temporary is an array of pointers.  */
          se->expr = fold_convert (TREE_TYPE (tmp), se->expr);
          gfc_add_modify (&se->pre, tmp, se->expr);
        }
      else
        {
          /* The temporary is an array of string values.  */
          tmp = gfc_build_addr_expr (gfc_get_pchar_type (expr->ts.kind), tmp);
          /* We know the temporary and the value will be the same length,
             so can use memcpy.  */
          gfc_trans_string_copy (&se->pre, esize, tmp, expr->ts.kind,
                                 se->string_length, se->expr, expr->ts.kind);
        }
      if ((gfc_option.rtcheck & GFC_RTCHECK_BOUNDS) && !typespec_chararray_ctor)
        {
          if (first_len)
            {
              gfc_add_modify (&se->pre, first_len_val,
                                   se->string_length);
              first_len = false;
            }
          else
            {
              /* Verify that all constructor elements are of the same
                 length.  */
              tree cond = fold_build2_loc (input_location, NE_EXPR,
                                           boolean_type_node, first_len_val,
                                           se->string_length);
              gfc_trans_runtime_check
                (true, false, cond, &se->pre, &expr->where,
                 "Different CHARACTER lengths (%ld/%ld) in array constructor",
                 fold_convert (long_integer_type_node, first_len_val),
                 fold_convert (long_integer_type_node, se->string_length));
            }
        }
    }
  else
    {
      /* TODO: Should the frontend already have done this conversion?  */
      se->expr = fold_convert (TREE_TYPE (tmp), se->expr);
      gfc_add_modify (&se->pre, tmp, se->expr);
    }

  gfc_add_block_to_block (pblock, &se->pre);
  gfc_add_block_to_block (pblock, &se->post);
}


/* Add the contents of an array to the constructor.  DYNAMIC is as for
   gfc_trans_array_constructor_value.  */

static void
gfc_trans_array_constructor_subarray (stmtblock_t * pblock,
                                      tree type ATTRIBUTE_UNUSED,
                                      tree desc, gfc_expr * expr,
                                      tree * poffset, tree * offsetvar,
                                      bool dynamic)
{
  gfc_se se;
  gfc_ss *ss;
  gfc_loopinfo loop;
  stmtblock_t body;
  tree tmp;
  tree size;
  int n;

  /* We need this to be a variable so we can increment it.  */
  gfc_put_offset_into_var (pblock, poffset, offsetvar);

  gfc_init_se (&se, NULL);

  /* Walk the array expression.  */
  ss = gfc_walk_expr (expr);
  gcc_assert (ss != gfc_ss_terminator);

  /* Initialize the scalarizer.  */
  gfc_init_loopinfo (&loop);
  gfc_add_ss_to_loop (&loop, ss);

  /* Initialize the loop.  */
  gfc_conv_ss_startstride (&loop);
  gfc_conv_loop_setup (&loop, &expr->where);

  /* Make sure the constructed array has room for the new data.  */
  if (dynamic)
    {
      /* Set SIZE to the total number of elements in the subarray.  */
      size = gfc_index_one_node;
      for (n = 0; n < loop.dimen; n++)
        {
          tmp = gfc_get_iteration_count (loop.from[n], loop.to[n],
                                         gfc_index_one_node);
          size = fold_build2_loc (input_location, MULT_EXPR,
                                  gfc_array_index_type, size, tmp);
        }

      /* Grow the constructed array by SIZE elements.  */
      gfc_grow_array (&loop.pre, desc, size);
    }

  /* Make the loop body.  */
  gfc_mark_ss_chain_used (ss, 1);
  gfc_start_scalarized_body (&loop, &body);
  gfc_copy_loopinfo_to_se (&se, &loop);
  se.ss = ss;

  gfc_trans_array_ctor_element (&body, desc, *poffset, &se, expr);
  gcc_assert (se.ss == gfc_ss_terminator);

  /* Increment the offset.  */
  tmp = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                         *poffset, gfc_index_one_node);
  gfc_add_modify (&body, *poffset, tmp);

  /* Finish the loop.  */
  gfc_trans_scalarizing_loops (&loop, &body);
  gfc_add_block_to_block (&loop.pre, &loop.post);
  tmp = gfc_finish_block (&loop.pre);
  gfc_add_expr_to_block (pblock, tmp);

  gfc_cleanup_loop (&loop);
}


/* Assign the values to the elements of an array constructor.  DYNAMIC
   is true if descriptor DESC only contains enough data for the static
   size calculated by gfc_get_array_constructor_size.  When true, memory
   for the dynamic parts must be allocated using realloc.  */

static void
gfc_trans_array_constructor_value (stmtblock_t * pblock, tree type,
                                   tree desc, gfc_constructor_base base,
                                   tree * poffset, tree * offsetvar,
                                   bool dynamic)
{
  tree tmp;
  stmtblock_t body;
  gfc_se se;
  mpz_t size;
  gfc_constructor *c;

  tree shadow_loopvar = NULL_TREE;
  gfc_saved_var saved_loopvar;

  mpz_init (size);
  for (c = gfc_constructor_first (base); c; c = gfc_constructor_next (c))
    {
      /* If this is an iterator or an array, the offset must be a variable.  */
      if ((c->iterator || c->expr->rank > 0) && INTEGER_CST_P (*poffset))
        gfc_put_offset_into_var (pblock, poffset, offsetvar);

      /* Shadowing the iterator avoids changing its value and saves us from
         keeping track of it. Further, it makes sure that there's always a
         backend-decl for the symbol, even if there wasn't one before,
         e.g. in the case of an iterator that appears in a specification
         expression in an interface mapping.  */
      if (c->iterator)
        {
          gfc_symbol *sym = c->iterator->var->symtree->n.sym;
          tree type = gfc_typenode_for_spec (&sym->ts);

          shadow_loopvar = gfc_create_var (type, "shadow_loopvar");
          gfc_shadow_sym (sym, shadow_loopvar, &saved_loopvar);
        }

      gfc_start_block (&body);

      if (c->expr->expr_type == EXPR_ARRAY)
        {
          /* Array constructors can be nested.  */
          gfc_trans_array_constructor_value (&body, type, desc,
                                             c->expr->value.constructor,
                                             poffset, offsetvar, dynamic);
        }
      else if (c->expr->rank > 0)
        {
          gfc_trans_array_constructor_subarray (&body, type, desc, c->expr,
                                                poffset, offsetvar, dynamic);
        }
      else
        {
          /* This code really upsets the gimplifier so don't bother for now.  */
          gfc_constructor *p;
          HOST_WIDE_INT n;
          HOST_WIDE_INT size;

          p = c;
          n = 0;
          while (p && !(p->iterator || p->expr->expr_type != EXPR_CONSTANT))
            {
              p = gfc_constructor_next (p);
              n++;
            }
          if (n < 4)
            {
              /* Scalar values.  */
              gfc_init_se (&se, NULL);
              gfc_trans_array_ctor_element (&body, desc, *poffset,
                                            &se, c->expr);

              *poffset = fold_build2_loc (input_location, PLUS_EXPR,
                                          gfc_array_index_type,
                                          *poffset, gfc_index_one_node);
            }
          else
            {
              /* Collect multiple scalar constants into a constructor.  */
              VEC(constructor_elt,gc) *v = NULL;
              tree init;
              tree bound;
              tree tmptype;
              HOST_WIDE_INT idx = 0;

              p = c;
              /* Count the number of consecutive scalar constants.  */
              while (p && !(p->iterator
                            || p->expr->expr_type != EXPR_CONSTANT))
                {
                  gfc_init_se (&se, NULL);
                  gfc_conv_constant (&se, p->expr);

                  if (c->expr->ts.type != BT_CHARACTER)
                    se.expr = fold_convert (type, se.expr);
                  /* For constant character array constructors we build
                     an array of pointers.  */
                  else if (POINTER_TYPE_P (type))
                    se.expr = gfc_build_addr_expr
                                (gfc_get_pchar_type (p->expr->ts.kind),
                                 se.expr);

                  CONSTRUCTOR_APPEND_ELT (v,
                                          build_int_cst (gfc_array_index_type,
                                                         idx++),
                                          se.expr);
                  c = p;
                  p = gfc_constructor_next (p);
                }

              bound = size_int (n - 1);
              /* Create an array type to hold them.  */
              tmptype = build_range_type (gfc_array_index_type,
                                          gfc_index_zero_node, bound);
              tmptype = build_array_type (type, tmptype);

              init = build_constructor (tmptype, v);
              TREE_CONSTANT (init) = 1;
              TREE_STATIC (init) = 1;
              /* Create a static variable to hold the data.  */
              tmp = gfc_create_var (tmptype, "data");
              TREE_STATIC (tmp) = 1;
              TREE_CONSTANT (tmp) = 1;
              TREE_READONLY (tmp) = 1;
              DECL_INITIAL (tmp) = init;
              init = tmp;

              /* Use BUILTIN_MEMCPY to assign the values.  */
              tmp = gfc_conv_descriptor_data_get (desc);
              tmp = build_fold_indirect_ref_loc (input_location,
                                             tmp);
              tmp = gfc_build_array_ref (tmp, *poffset, NULL);
              tmp = gfc_build_addr_expr (NULL_TREE, tmp);
              init = gfc_build_addr_expr (NULL_TREE, init);

              size = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (type));
              bound = build_int_cst (size_type_node, n * size);
              tmp = build_call_expr_loc (input_location,
                                         builtin_decl_explicit (BUILT_IN_MEMCPY),
                                         3, tmp, init, bound);
              gfc_add_expr_to_block (&body, tmp);

              *poffset = fold_build2_loc (input_location, PLUS_EXPR,
                                      gfc_array_index_type, *poffset,
                                      build_int_cst (gfc_array_index_type, n));
            }
          if (!INTEGER_CST_P (*poffset))
            {
              gfc_add_modify (&body, *offsetvar, *poffset);
              *poffset = *offsetvar;
            }
        }

      /* The frontend should already have done any expansions
         at compile-time.  */
      if (!c->iterator)
        {
          /* Pass the code as is.  */
          tmp = gfc_finish_block (&body);
          gfc_add_expr_to_block (pblock, tmp);
        }
      else
        {
          /* Build the implied do-loop.  */
          stmtblock_t implied_do_block;
          tree cond;
          tree end;
          tree step;
          tree exit_label;
          tree loopbody;
          tree tmp2;

          loopbody = gfc_finish_block (&body);

          /* Create a new block that holds the implied-do loop. A temporary
             loop-variable is used.  */
          gfc_start_block(&implied_do_block);

          /* Initialize the loop.  */
          gfc_init_se (&se, NULL);
          gfc_conv_expr_val (&se, c->iterator->start);
          gfc_add_block_to_block (&implied_do_block, &se.pre);
          gfc_add_modify (&implied_do_block, shadow_loopvar, se.expr);

          gfc_init_se (&se, NULL);
          gfc_conv_expr_val (&se, c->iterator->end);
          gfc_add_block_to_block (&implied_do_block, &se.pre);
          end = gfc_evaluate_now (se.expr, &implied_do_block);

          gfc_init_se (&se, NULL);
          gfc_conv_expr_val (&se, c->iterator->step);
          gfc_add_block_to_block (&implied_do_block, &se.pre);
          step = gfc_evaluate_now (se.expr, &implied_do_block);

          /* If this array expands dynamically, and the number of iterations
             is not constant, we won't have allocated space for the static
             part of C->EXPR's size.  Do that now.  */
          if (dynamic && gfc_iterator_has_dynamic_bounds (c->iterator))
            {
              /* Get the number of iterations.  */
              tmp = gfc_get_iteration_count (shadow_loopvar, end, step);

              /* Get the static part of C->EXPR's size.  */
              gfc_get_array_constructor_element_size (&size, c->expr);
              tmp2 = gfc_conv_mpz_to_tree (size, gfc_index_integer_kind);

              /* Grow the array by TMP * TMP2 elements.  */
              tmp = fold_build2_loc (input_location, MULT_EXPR,
                                     gfc_array_index_type, tmp, tmp2);
              gfc_grow_array (&implied_do_block, desc, tmp);
            }

          /* Generate the loop body.  */
          exit_label = gfc_build_label_decl (NULL_TREE);
          gfc_start_block (&body);

          /* Generate the exit condition.  Depending on the sign of
             the step variable we have to generate the correct
             comparison.  */
          tmp = fold_build2_loc (input_location, GT_EXPR, boolean_type_node,
                                 step, build_int_cst (TREE_TYPE (step), 0));
          cond = fold_build3_loc (input_location, COND_EXPR,
                      boolean_type_node, tmp,
                      fold_build2_loc (input_location, GT_EXPR,
                                       boolean_type_node, shadow_loopvar, end),
                      fold_build2_loc (input_location, LT_EXPR,
                                       boolean_type_node, shadow_loopvar, end));
          tmp = build1_v (GOTO_EXPR, exit_label);
          TREE_USED (exit_label) = 1;
          tmp = build3_v (COND_EXPR, cond, tmp,
                          build_empty_stmt (input_location));
          gfc_add_expr_to_block (&body, tmp);

          /* The main loop body.  */
          gfc_add_expr_to_block (&body, loopbody);

          /* Increase loop variable by step.  */
          tmp = fold_build2_loc (input_location, PLUS_EXPR,
                                 TREE_TYPE (shadow_loopvar), shadow_loopvar,
                                 step);
          gfc_add_modify (&body, shadow_loopvar, tmp);

          /* Finish the loop.  */
          tmp = gfc_finish_block (&body);
          tmp = build1_v (LOOP_EXPR, tmp);
          gfc_add_expr_to_block (&implied_do_block, tmp);

          /* Add the exit label.  */
          tmp = build1_v (LABEL_EXPR, exit_label);
          gfc_add_expr_to_block (&implied_do_block, tmp);

          /* Finishe the implied-do loop.  */
          tmp = gfc_finish_block(&implied_do_block);
          gfc_add_expr_to_block(pblock, tmp);

          gfc_restore_sym (c->iterator->var->symtree->n.sym, &saved_loopvar);
        }
    }
  mpz_clear (size);
}


/* A catch-all to obtain the string length for anything that is not a
   a substring of non-constant length, a constant, array or variable.  */

static void
get_array_ctor_all_strlen (stmtblock_t *block, gfc_expr *e, tree *len)
{
  gfc_se se;
  gfc_ss *ss;

  /* Don't bother if we already know the length is a constant.  */
  if (*len && INTEGER_CST_P (*len))
    return;

  if (!e->ref && e->ts.u.cl && e->ts.u.cl->length
        && e->ts.u.cl->length->expr_type == EXPR_CONSTANT)
    {
      /* This is easy.  */
      gfc_conv_const_charlen (e->ts.u.cl);
      *len = e->ts.u.cl->backend_decl;
    }
  else
    {
      /* Otherwise, be brutal even if inefficient.  */
      ss = gfc_walk_expr (e);
      gfc_init_se (&se, NULL);

      /* No function call, in case of side effects.  */
      se.no_function_call = 1;
      if (ss == gfc_ss_terminator)
        gfc_conv_expr (&se, e);
      else
        gfc_conv_expr_descriptor (&se, e, ss);

      /* Fix the value.  */
      *len = gfc_evaluate_now (se.string_length, &se.pre);

      gfc_add_block_to_block (block, &se.pre);
      gfc_add_block_to_block (block, &se.post);

      e->ts.u.cl->backend_decl = *len;
    }
}


/* Figure out the string length of a variable reference expression.
   Used by get_array_ctor_strlen.  */

static void
get_array_ctor_var_strlen (stmtblock_t *block, gfc_expr * expr, tree * len)
{
  gfc_ref *ref;
  gfc_typespec *ts;
  mpz_t char_len;

  /* Don't bother if we already know the length is a constant.  */
  if (*len && INTEGER_CST_P (*len))
    return;

  ts = &expr->symtree->n.sym->ts;
  for (ref = expr->ref; ref; ref = ref->next)
    {
      switch (ref->type)
        {
        case REF_ARRAY:
          /* Array references don't change the string length.  */
          break;

        case REF_COMPONENT:
          /* Use the length of the component.  */
          ts = &ref->u.c.component->ts;
          break;

        case REF_SUBSTRING:
          if (ref->u.ss.start->expr_type != EXPR_CONSTANT
              || ref->u.ss.end->expr_type != EXPR_CONSTANT)
            {
              /* Note that this might evaluate expr.  */
              get_array_ctor_all_strlen (block, expr, len);
              return;
            }
          mpz_init_set_ui (char_len, 1);
          mpz_add (char_len, char_len, ref->u.ss.end->value.integer);
          mpz_sub (char_len, char_len, ref->u.ss.start->value.integer);
          *len = gfc_conv_mpz_to_tree (char_len, gfc_default_integer_kind);
          *len = convert (gfc_charlen_type_node, *len);
          mpz_clear (char_len);
          return;

        default:
         gcc_unreachable ();
        }
    }

  *len = ts->u.cl->backend_decl;
}


/* Figure out the string length of a character array constructor.
   If len is NULL, don't calculate the length; this happens for recursive calls
   when a sub-array-constructor is an element but not at the first position,
   so when we're not interested in the length.
   Returns TRUE if all elements are character constants.  */

bool
get_array_ctor_strlen (stmtblock_t *block, gfc_constructor_base base, tree * len)
{
  gfc_constructor *c;
  bool is_const;

  is_const = TRUE;

  if (gfc_constructor_first (base) == NULL)
    {
      if (len)
        *len = build_int_cstu (gfc_charlen_type_node, 0);
      return is_const;
    }

  /* Loop over all constructor elements to find out is_const, but in len we
     want to store the length of the first, not the last, element.  We can
     of course exit the loop as soon as is_const is found to be false.  */
  for (c = gfc_constructor_first (base);
       c && is_const; c = gfc_constructor_next (c))
    {
      switch (c->expr->expr_type)
        {
        case EXPR_CONSTANT:
          if (len && !(*len && INTEGER_CST_P (*len)))
            *len = build_int_cstu (gfc_charlen_type_node,
                                   c->expr->value.character.length);
          break;

        case EXPR_ARRAY:
          if (!get_array_ctor_strlen (block, c->expr->value.constructor, len))
            is_const = false;
          break;

        case EXPR_VARIABLE:
          is_const = false;
          if (len)
            get_array_ctor_var_strlen (block, c->expr, len);
          break;

        default:
          is_const = false;
          if (len)
            get_array_ctor_all_strlen (block, c->expr, len);
          break;
        }

      /* After the first iteration, we don't want the length modified.  */
      len = NULL;
    }

  return is_const;
}

/* Check whether the array constructor C consists entirely of constant
   elements, and if so returns the number of those elements, otherwise
   return zero.  Note, an empty or NULL array constructor returns zero.  */

unsigned HOST_WIDE_INT
gfc_constant_array_constructor_p (gfc_constructor_base base)
{
  unsigned HOST_WIDE_INT nelem = 0;

  gfc_constructor *c = gfc_constructor_first (base);
  while (c)
    {
      if (c->iterator
          || c->expr->rank > 0
          || c->expr->expr_type != EXPR_CONSTANT)
        return 0;
      c = gfc_constructor_next (c);
      nelem++;
    }
  return nelem;
}


/* Given EXPR, the constant array constructor specified by an EXPR_ARRAY,
   and the tree type of it's elements, TYPE, return a static constant
   variable that is compile-time initialized.  */

tree
gfc_build_constant_array_constructor (gfc_expr * expr, tree type)
{
  tree tmptype, init, tmp;
  HOST_WIDE_INT nelem;
  gfc_constructor *c;
  gfc_array_spec as;
  gfc_se se;
  int i;
  VEC(constructor_elt,gc) *v = NULL;

  /* First traverse the constructor list, converting the constants
     to tree to build an initializer.  */
  nelem = 0;
  c = gfc_constructor_first (expr->value.constructor);
  while (c)
    {
      gfc_init_se (&se, NULL);
      gfc_conv_constant (&se, c->expr);
      if (c->expr->ts.type != BT_CHARACTER)
        se.expr = fold_convert (type, se.expr);
      else if (POINTER_TYPE_P (type))
        se.expr = gfc_build_addr_expr (gfc_get_pchar_type (c->expr->ts.kind),
                                       se.expr);
      CONSTRUCTOR_APPEND_ELT (v, build_int_cst (gfc_array_index_type, nelem),
                              se.expr);
      c = gfc_constructor_next (c);
      nelem++;
    }

  /* Next determine the tree type for the array.  We use the gfortran
     front-end's gfc_get_nodesc_array_type in order to create a suitable
     GFC_ARRAY_TYPE_P that may be used by the scalarizer.  */

  memset (&as, 0, sizeof (gfc_array_spec));

  as.rank = expr->rank;
  as.type = AS_EXPLICIT;
  if (!expr->shape)
    {
      as.lower[0] = gfc_get_int_expr (gfc_default_integer_kind, NULL, 0);
      as.upper[0] = gfc_get_int_expr (gfc_default_integer_kind,
                                      NULL, nelem - 1);
    }
  else
    for (i = 0; i < expr->rank; i++)
      {
        int tmp = (int) mpz_get_si (expr->shape[i]);
        as.lower[i] = gfc_get_int_expr (gfc_default_integer_kind, NULL, 0);
        as.upper[i] = gfc_get_int_expr (gfc_default_integer_kind,
                                        NULL, tmp - 1);
      }

  tmptype = gfc_get_nodesc_array_type (type, &as, PACKED_STATIC, true);

  /* as is not needed anymore.  */
  for (i = 0; i < as.rank + as.corank; i++)
    {
      gfc_free_expr (as.lower[i]);
      gfc_free_expr (as.upper[i]);
    }

  init = build_constructor (tmptype, v);

  TREE_CONSTANT (init) = 1;
  TREE_STATIC (init) = 1;

  tmp = gfc_create_var (tmptype, "A");
  TREE_STATIC (tmp) = 1;
  TREE_CONSTANT (tmp) = 1;
  TREE_READONLY (tmp) = 1;
  DECL_INITIAL (tmp) = init;

  return tmp;
}


/* Translate a constant EXPR_ARRAY array constructor for the scalarizer.
   This mostly initializes the scalarizer state info structure with the
   appropriate values to directly use the array created by the function
   gfc_build_constant_array_constructor.  */

static void
trans_constant_array_constructor (gfc_ss * ss, tree type)
{
  gfc_array_info *info;
  tree tmp;
  int i;

  tmp = gfc_build_constant_array_constructor (ss->info->expr, type);

  info = &ss->info->data.array;

  info->descriptor = tmp;
  info->data = gfc_build_addr_expr (NULL_TREE, tmp);
  info->offset = gfc_index_zero_node;

  for (i = 0; i < ss->dimen; i++)
    {
      info->delta[i] = gfc_index_zero_node;
      info->start[i] = gfc_index_zero_node;
      info->end[i] = gfc_index_zero_node;
      info->stride[i] = gfc_index_one_node;
    }
}


/* Helper routine of gfc_trans_array_constructor to determine if the
   bounds of the loop specified by LOOP are constant and simple enough
   to use with trans_constant_array_constructor.  Returns the
   iteration count of the loop if suitable, and NULL_TREE otherwise.  */

static tree
constant_array_constructor_loop_size (gfc_loopinfo * loop)
{
  tree size = gfc_index_one_node;
  tree tmp;
  int i;

  for (i = 0; i < loop->dimen; i++)
    {
      /* If the bounds aren't constant, return NULL_TREE.  */
      if (!INTEGER_CST_P (loop->from[i]) || !INTEGER_CST_P (loop->to[i]))
        return NULL_TREE;
      if (!integer_zerop (loop->from[i]))
        {
          /* Only allow nonzero "from" in one-dimensional arrays.  */
          if (loop->dimen != 1)
            return NULL_TREE;
          tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                 gfc_array_index_type,
                                 loop->to[i], loop->from[i]);
        }
      else
        tmp = loop->to[i];
      tmp = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                             tmp, gfc_index_one_node);
      size = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                              size, tmp);
    }

  return size;
}


/* Array constructors are handled by constructing a temporary, then using that
   within the scalarization loop.  This is not optimal, but seems by far the
   simplest method.  */

static void
trans_array_constructor (gfc_ss * ss, locus * where)
{
  gfc_constructor_base c;
  tree offset;
  tree offsetvar;
  tree desc;
  tree type;
  tree tmp;
  bool dynamic;
  bool old_first_len, old_typespec_chararray_ctor;
  tree old_first_len_val;
  gfc_loopinfo *loop;
  gfc_ss_info *ss_info;
  gfc_expr *expr;
  gfc_ss *s;

  /* Save the old values for nested checking.  */
  old_first_len = first_len;
  old_first_len_val = first_len_val;
  old_typespec_chararray_ctor = typespec_chararray_ctor;

  loop = ss->loop;
  ss_info = ss->info;
  expr = ss_info->expr;

  /* Do bounds-checking here and in gfc_trans_array_ctor_element only if no
     typespec was given for the array constructor.  */
  typespec_chararray_ctor = (expr->ts.u.cl
                             && expr->ts.u.cl->length_from_typespec);

  if ((gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)
      && expr->ts.type == BT_CHARACTER && !typespec_chararray_ctor)
    {  
      first_len_val = gfc_create_var (gfc_charlen_type_node, "len");
      first_len = true;
    }

  gcc_assert (ss->dimen == loop->dimen);

  c = expr->value.constructor;
  if (expr->ts.type == BT_CHARACTER)
    {
      bool const_string;
      
      /* get_array_ctor_strlen walks the elements of the constructor, if a
         typespec was given, we already know the string length and want the one
         specified there.  */
      if (typespec_chararray_ctor && expr->ts.u.cl->length
          && expr->ts.u.cl->length->expr_type != EXPR_CONSTANT)
        {
          gfc_se length_se;

          const_string = false;
          gfc_init_se (&length_se, NULL);
          gfc_conv_expr_type (&length_se, expr->ts.u.cl->length,
                              gfc_charlen_type_node);
          ss_info->string_length = length_se.expr;
          gfc_add_block_to_block (&loop->pre, &length_se.pre);
          gfc_add_block_to_block (&loop->post, &length_se.post);
        }
      else
        const_string = get_array_ctor_strlen (&loop->pre, c,
                                              &ss_info->string_length);

      /* Complex character array constructors should have been taken care of
         and not end up here.  */
      gcc_assert (ss_info->string_length);

      expr->ts.u.cl->backend_decl = ss_info->string_length;

      type = gfc_get_character_type_len (expr->ts.kind, ss_info->string_length);
      if (const_string)
        type = build_pointer_type (type);
    }
  else
    type = gfc_typenode_for_spec (&expr->ts);

  /* See if the constructor determines the loop bounds.  */
  dynamic = false;

  if (expr->shape && loop->dimen > 1 && loop->to[0] == NULL_TREE)
    {
      /* We have a multidimensional parameter.  */
      for (s = ss; s; s = s->parent)
        {
          int n;
          for (n = 0; n < s->loop->dimen; n++)
            {
              s->loop->from[n] = gfc_index_zero_node;
              s->loop->to[n] = gfc_conv_mpz_to_tree (expr->shape[s->dim[n]],
                                                     gfc_index_integer_kind);
              s->loop->to[n] = fold_build2_loc (input_location, MINUS_EXPR,
                                                gfc_array_index_type,
                                                s->loop->to[n],
                                                gfc_index_one_node);
            }
        }
    }

  if (loop->to[0] == NULL_TREE)
    {
      mpz_t size;

      /* We should have a 1-dimensional, zero-based loop.  */
      gcc_assert (loop->parent == NULL && loop->nested == NULL);
      gcc_assert (loop->dimen == 1);
      gcc_assert (integer_zerop (loop->from[0]));

      /* Split the constructor size into a static part and a dynamic part.
         Allocate the static size up-front and record whether the dynamic
         size might be nonzero.  */
      mpz_init (size);
      dynamic = gfc_get_array_constructor_size (&size, c);
      mpz_sub_ui (size, size, 1);
      loop->to[0] = gfc_conv_mpz_to_tree (size, gfc_index_integer_kind);
      mpz_clear (size);
    }

  /* Special case constant array constructors.  */
  if (!dynamic)
    {
      unsigned HOST_WIDE_INT nelem = gfc_constant_array_constructor_p (c);
      if (nelem > 0)
        {
          tree size = constant_array_constructor_loop_size (loop);
          if (size && compare_tree_int (size, nelem) == 0)
            {
              trans_constant_array_constructor (ss, type);
              goto finish;
            }
        }
    }

  if (TREE_CODE (loop->to[0]) == VAR_DECL)
    dynamic = true;

  gfc_trans_create_temp_array (&loop->pre, &loop->post, ss, type, NULL_TREE,
                               dynamic, true, false, where);

  desc = ss_info->data.array.descriptor;
  offset = gfc_index_zero_node;
  offsetvar = gfc_create_var_np (gfc_array_index_type, "offset");
  TREE_NO_WARNING (offsetvar) = 1;
  TREE_USED (offsetvar) = 0;
  gfc_trans_array_constructor_value (&loop->pre, type, desc, c,
                                     &offset, &offsetvar, dynamic);

  /* If the array grows dynamically, the upper bound of the loop variable
     is determined by the array's final upper bound.  */
  if (dynamic)
    {
      tmp = fold_build2_loc (input_location, MINUS_EXPR,
                             gfc_array_index_type,
                             offsetvar, gfc_index_one_node);
      tmp = gfc_evaluate_now (tmp, &loop->pre);
      gfc_conv_descriptor_ubound_set (&loop->pre, desc, gfc_rank_cst[0], tmp);
      if (loop->to[0] && TREE_CODE (loop->to[0]) == VAR_DECL)
        gfc_add_modify (&loop->pre, loop->to[0], tmp);
      else
        loop->to[0] = tmp;
    }

  if (TREE_USED (offsetvar))
    pushdecl (offsetvar);
  else
    gcc_assert (INTEGER_CST_P (offset));

#if 0
  /* Disable bound checking for now because it's probably broken.  */
  if (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)
    {
      gcc_unreachable ();
    }
#endif

finish:
  /* Restore old values of globals.  */
  first_len = old_first_len;
  first_len_val = old_first_len_val;
  typespec_chararray_ctor = old_typespec_chararray_ctor;
}


/* INFO describes a GFC_SS_SECTION in loop LOOP, and this function is
   called after evaluating all of INFO's vector dimensions.  Go through
   each such vector dimension and see if we can now fill in any missing
   loop bounds.  */

static void
set_vector_loop_bounds (gfc_ss * ss)
{
  gfc_loopinfo *loop;
  gfc_array_info *info;
  gfc_se se;
  tree tmp;
  tree desc;
  tree zero;
  int n;
  int dim;

  info = &ss->info->data.array;

  for (; ss; ss = ss->parent)
    {
      loop = ss->loop;

      for (n = 0; n < loop->dimen; n++)
        {
          dim = ss->dim[n];
          if (info->ref->u.ar.dimen_type[dim] != DIMEN_VECTOR
              || loop->to[n] != NULL)
            continue;

          /* Loop variable N indexes vector dimension DIM, and we don't
             yet know the upper bound of loop variable N.  Set it to the
             difference between the vector's upper and lower bounds.  */
          gcc_assert (loop->from[n] == gfc_index_zero_node);
          gcc_assert (info->subscript[dim]
                      && info->subscript[dim]->info->type == GFC_SS_VECTOR);

          gfc_init_se (&se, NULL);
          desc = info->subscript[dim]->info->data.array.descriptor;
          zero = gfc_rank_cst[0];
          tmp = fold_build2_loc (input_location, MINUS_EXPR,
                             gfc_array_index_type,
                             gfc_conv_descriptor_ubound_get (desc, zero),
                             gfc_conv_descriptor_lbound_get (desc, zero));
          tmp = gfc_evaluate_now (tmp, &loop->pre);
          loop->to[n] = tmp;
        }
    }
}


/* Add the pre and post chains for all the scalar expressions in a SS chain
   to loop.  This is called after the loop parameters have been calculated,
   but before the actual scalarizing loops.  */

static void
gfc_add_loop_ss_code (gfc_loopinfo * loop, gfc_ss * ss, bool subscript,
                      locus * where)
{
  gfc_loopinfo *nested_loop;
  gfc_se se;
  gfc_ss_info *ss_info;
  gfc_array_info *info;
  gfc_expr *expr;
  bool skip_nested = false;
  int n;

  /* TODO: This can generate bad code if there are ordering dependencies,
     e.g., a callee allocated function and an unknown size constructor.  */
  gcc_assert (ss != NULL);

  for (; ss != gfc_ss_terminator; ss = ss->loop_chain)
    {
      gcc_assert (ss);

      /* Cross loop arrays are handled from within the most nested loop.  */
      if (ss->nested_ss != NULL)
        continue;

      ss_info = ss->info;
      expr = ss_info->expr;
      info = &ss_info->data.array;

      switch (ss_info->type)
        {
        case GFC_SS_SCALAR:
          /* Scalar expression.  Evaluate this now.  This includes elemental
             dimension indices, but not array section bounds.  */
          gfc_init_se (&se, NULL);
          gfc_conv_expr (&se, expr);
          gfc_add_block_to_block (&loop->pre, &se.pre);

          if (expr->ts.type != BT_CHARACTER)
            {
              /* Move the evaluation of scalar expressions outside the
                 scalarization loop, except for WHERE assignments.  */
              if (subscript)
                se.expr = convert(gfc_array_index_type, se.expr);
              if (!ss_info->where)
                se.expr = gfc_evaluate_now (se.expr, &loop->pre);
              gfc_add_block_to_block (&loop->pre, &se.post);
            }
          else
            gfc_add_block_to_block (&loop->post, &se.post);

          ss_info->data.scalar.value = se.expr;
          ss_info->string_length = se.string_length;
          break;

        case GFC_SS_REFERENCE:
          /* Scalar argument to elemental procedure.  Evaluate this
             now.  */
          gfc_init_se (&se, NULL);
          gfc_conv_expr (&se, expr);
          gfc_add_block_to_block (&loop->pre, &se.pre);
          gfc_add_block_to_block (&loop->post, &se.post);

          ss_info->data.scalar.value = gfc_evaluate_now (se.expr, &loop->pre);
          ss_info->string_length = se.string_length;
          break;

        case GFC_SS_SECTION:
          /* Add the expressions for scalar and vector subscripts.  */
          for (n = 0; n < GFC_MAX_DIMENSIONS; n++)
            if (info->subscript[n])
              {
                gfc_add_loop_ss_code (loop, info->subscript[n], true, where);
                /* The recursive call will have taken care of the nested loops.
                   No need to do it twice.  */
                skip_nested = true;
              }

          set_vector_loop_bounds (ss);
          break;

        case GFC_SS_VECTOR:
          /* Get the vector's descriptor and store it in SS.  */
          gfc_init_se (&se, NULL);
          gfc_conv_expr_descriptor (&se, expr, gfc_walk_expr (expr));
          gfc_add_block_to_block (&loop->pre, &se.pre);
          gfc_add_block_to_block (&loop->post, &se.post);
          info->descriptor = se.expr;
          break;

        case GFC_SS_INTRINSIC:
          gfc_add_intrinsic_ss_code (loop, ss);
          break;

        case GFC_SS_FUNCTION:
          /* Array function return value.  We call the function and save its
             result in a temporary for use inside the loop.  */
          gfc_init_se (&se, NULL);
          se.loop = loop;
          se.ss = ss;
          gfc_conv_expr (&se, expr);
          gfc_add_block_to_block (&loop->pre, &se.pre);
          gfc_add_block_to_block (&loop->post, &se.post);
          ss_info->string_length = se.string_length;
          break;

        case GFC_SS_CONSTRUCTOR:
          if (expr->ts.type == BT_CHARACTER
              && ss_info->string_length == NULL
              && expr->ts.u.cl
              && expr->ts.u.cl->length)
            {
              gfc_init_se (&se, NULL);
              gfc_conv_expr_type (&se, expr->ts.u.cl->length,
                                  gfc_charlen_type_node);
              ss_info->string_length = se.expr;
              gfc_add_block_to_block (&loop->pre, &se.pre);
              gfc_add_block_to_block (&loop->post, &se.post);
            }
          trans_array_constructor (ss, where);
          break;

        case GFC_SS_TEMP:
        case GFC_SS_COMPONENT:
          /* Do nothing.  These are handled elsewhere.  */
          break;

        default:
          gcc_unreachable ();
        }
    }

  if (!skip_nested)
    for (nested_loop = loop->nested; nested_loop;
         nested_loop = nested_loop->next)
      gfc_add_loop_ss_code (nested_loop, nested_loop->ss, subscript, where);
}


/* Translate expressions for the descriptor and data pointer of a SS.  */
/*GCC ARRAYS*/

static void
gfc_conv_ss_descriptor (stmtblock_t * block, gfc_ss * ss, int base)
{
  gfc_se se;
  gfc_ss_info *ss_info;
  gfc_array_info *info;
  tree tmp;

  ss_info = ss->info;
  info = &ss_info->data.array;

  /* Get the descriptor for the array to be scalarized.  */
  gcc_assert (ss_info->expr->expr_type == EXPR_VARIABLE);
  gfc_init_se (&se, NULL);
  se.descriptor_only = 1;
  gfc_conv_expr_lhs (&se, ss_info->expr);
  gfc_add_block_to_block (block, &se.pre);
  info->descriptor = se.expr;
  ss_info->string_length = se.string_length;

  if (base)
    {
      /* Also the data pointer.  */
      tmp = gfc_conv_array_data (se.expr);
      /* If this is a variable or address of a variable we use it directly.
         Otherwise we must evaluate it now to avoid breaking dependency
         analysis by pulling the expressions for elemental array indices
         inside the loop.  */
      if (!(DECL_P (tmp)
            || (TREE_CODE (tmp) == ADDR_EXPR
                && DECL_P (TREE_OPERAND (tmp, 0)))))
        tmp = gfc_evaluate_now (tmp, block);
      info->data = tmp;

      tmp = gfc_conv_array_offset (se.expr);
      info->offset = gfc_evaluate_now (tmp, block);

      /* Make absolutely sure that the saved_offset is indeed saved
         so that the variable is still accessible after the loops
         are translated.  */
      info->saved_offset = info->offset;
    }
}


/* Initialize a gfc_loopinfo structure.  */

void
gfc_init_loopinfo (gfc_loopinfo * loop)
{
  int n;

  memset (loop, 0, sizeof (gfc_loopinfo));
  gfc_init_block (&loop->pre);
  gfc_init_block (&loop->post);

  /* Initially scalarize in order and default to no loop reversal.  */
  for (n = 0; n < GFC_MAX_DIMENSIONS; n++)
    {
      loop->order[n] = n;
      loop->reverse[n] = GFC_INHIBIT_REVERSE;
    }

  loop->ss = gfc_ss_terminator;
}


/* Copies the loop variable info to a gfc_se structure. Does not copy the SS
   chain.  */

void
gfc_copy_loopinfo_to_se (gfc_se * se, gfc_loopinfo * loop)
{
  se->loop = loop;
}


/* Return an expression for the data pointer of an array.  */

tree
gfc_conv_array_data (tree descriptor)
{
  tree type;

  type = TREE_TYPE (descriptor);
  if (GFC_ARRAY_TYPE_P (type))
    {
      if (TREE_CODE (type) == POINTER_TYPE)
        return descriptor;
      else
        {
          /* Descriptorless arrays.  */
          return gfc_build_addr_expr (NULL_TREE, descriptor);
        }
    }
  else
    return gfc_conv_descriptor_data_get (descriptor);
}


/* Return an expression for the base offset of an array.  */

tree
gfc_conv_array_offset (tree descriptor)
{
  tree type;

  type = TREE_TYPE (descriptor);
  if (GFC_ARRAY_TYPE_P (type))
    return GFC_TYPE_ARRAY_OFFSET (type);
  else
    return gfc_conv_descriptor_offset_get (descriptor);
}


/* Get an expression for the array stride.  */

tree
gfc_conv_array_stride (tree descriptor, int dim)
{
  tree tmp;
  tree type;

  type = TREE_TYPE (descriptor);

  /* For descriptorless arrays use the array size.  */
  tmp = GFC_TYPE_ARRAY_STRIDE (type, dim);
  if (tmp != NULL_TREE)
    return tmp;

  tmp = gfc_conv_descriptor_stride_get (descriptor, gfc_rank_cst[dim]);
  return tmp;
}


/* Like gfc_conv_array_stride, but for the lower bound.  */

tree
gfc_conv_array_lbound (tree descriptor, int dim)
{
  tree tmp;
  tree type;

  type = TREE_TYPE (descriptor);

  tmp = GFC_TYPE_ARRAY_LBOUND (type, dim);
  if (tmp != NULL_TREE)
    return tmp;

  tmp = gfc_conv_descriptor_lbound_get (descriptor, gfc_rank_cst[dim]);
  return tmp;
}


/* Like gfc_conv_array_stride, but for the upper bound.  */

tree
gfc_conv_array_ubound (tree descriptor, int dim)
{
  tree tmp;
  tree type;

  type = TREE_TYPE (descriptor);

  tmp = GFC_TYPE_ARRAY_UBOUND (type, dim);
  if (tmp != NULL_TREE)
    return tmp;

  /* This should only ever happen when passing an assumed shape array
     as an actual parameter.  The value will never be used.  */
  if (GFC_ARRAY_TYPE_P (TREE_TYPE (descriptor)))
    return gfc_index_zero_node;

  tmp = gfc_conv_descriptor_ubound_get (descriptor, gfc_rank_cst[dim]);
  return tmp;
}


/* Generate code to perform an array index bound check.  */

static tree
trans_array_bound_check (gfc_se * se, gfc_ss *ss, tree index, int n,
                         locus * where, bool check_upper)
{
  tree fault;
  tree tmp_lo, tmp_up;
  tree descriptor;
  char *msg;
  const char * name = NULL;

  if (!(gfc_option.rtcheck & GFC_RTCHECK_BOUNDS))
    return index;

  descriptor = ss->info->data.array.descriptor;

  index = gfc_evaluate_now (index, &se->pre);

  /* We find a name for the error message.  */
  name = ss->info->expr->symtree->n.sym->name;
  gcc_assert (name != NULL);

  if (TREE_CODE (descriptor) == VAR_DECL)
    name = IDENTIFIER_POINTER (DECL_NAME (descriptor));

  /* If upper bound is present, include both bounds in the error message.  */
  if (check_upper)
    {
      tmp_lo = gfc_conv_array_lbound (descriptor, n);
      tmp_up = gfc_conv_array_ubound (descriptor, n);

      if (name)
        asprintf (&msg, "Index '%%ld' of dimension %d of array '%s' "
                  "outside of expected range (%%ld:%%ld)", n+1, name);
      else
        asprintf (&msg, "Index '%%ld' of dimension %d "
                  "outside of expected range (%%ld:%%ld)", n+1);

      fault = fold_build2_loc (input_location, LT_EXPR, boolean_type_node,
                               index, tmp_lo);
      gfc_trans_runtime_check (true, false, fault, &se->pre, where, msg,
                               fold_convert (long_integer_type_node, index),
                               fold_convert (long_integer_type_node, tmp_lo),
                               fold_convert (long_integer_type_node, tmp_up));
      fault = fold_build2_loc (input_location, GT_EXPR, boolean_type_node,
                               index, tmp_up);
      gfc_trans_runtime_check (true, false, fault, &se->pre, where, msg,
                               fold_convert (long_integer_type_node, index),
                               fold_convert (long_integer_type_node, tmp_lo),
                               fold_convert (long_integer_type_node, tmp_up));
      free (msg);
    }
  else
    {
      tmp_lo = gfc_conv_array_lbound (descriptor, n);

      if (name)
        asprintf (&msg, "Index '%%ld' of dimension %d of array '%s' "
                  "below lower bound of %%ld", n+1, name);
      else
        asprintf (&msg, "Index '%%ld' of dimension %d "
                  "below lower bound of %%ld", n+1);

      fault = fold_build2_loc (input_location, LT_EXPR, boolean_type_node,
                               index, tmp_lo);
      gfc_trans_runtime_check (true, false, fault, &se->pre, where, msg,
                               fold_convert (long_integer_type_node, index),
                               fold_convert (long_integer_type_node, tmp_lo));
      free (msg);
    }

  return index;
}


/* Return the offset for an index.  Performs bound checking for elemental
   dimensions.  Single element references are processed separately.
   DIM is the array dimension, I is the loop dimension.  */

static tree
conv_array_index_offset (gfc_se * se, gfc_ss * ss, int dim, int i,
                         gfc_array_ref * ar, tree stride)
{
  gfc_array_info *info;
  tree index;
  tree desc;
  tree data;

  info = &ss->info->data.array;

  /* Get the index into the array for this dimension.  */
  if (ar)
    {
      gcc_assert (ar->type != AR_ELEMENT);
      switch (ar->dimen_type[dim])
        {
        case DIMEN_THIS_IMAGE:
          gcc_unreachable ();
          break;
        case DIMEN_ELEMENT:
          /* Elemental dimension.  */
          gcc_assert (info->subscript[dim]
                      && info->subscript[dim]->info->type == GFC_SS_SCALAR);
          /* We've already translated this value outside the loop.  */
          index = info->subscript[dim]->info->data.scalar.value;

          index = trans_array_bound_check (se, ss, index, dim, &ar->where,
                                           ar->as->type != AS_ASSUMED_SIZE
                                           || dim < ar->dimen - 1);
          break;

        case DIMEN_VECTOR:
          gcc_assert (info && se->loop);
          gcc_assert (info->subscript[dim]
                      && info->subscript[dim]->info->type == GFC_SS_VECTOR);
          desc = info->subscript[dim]->info->data.array.descriptor;

          /* Get a zero-based index into the vector.  */
          index = fold_build2_loc (input_location, MINUS_EXPR,
                                   gfc_array_index_type,
                                   se->loop->loopvar[i], se->loop->from[i]);

          /* Multiply the index by the stride.  */
          index = fold_build2_loc (input_location, MULT_EXPR,
                                   gfc_array_index_type,
                                   index, gfc_conv_array_stride (desc, 0));

          /* Read the vector to get an index into info->descriptor.  */
          data = build_fold_indirect_ref_loc (input_location,
                                          gfc_conv_array_data (desc));
          index = gfc_build_array_ref (data, index, NULL);
          index = gfc_evaluate_now (index, &se->pre);
          index = fold_convert (gfc_array_index_type, index);

          /* Do any bounds checking on the final info->descriptor index.  */
          index = trans_array_bound_check (se, ss, index, dim, &ar->where,
                                           ar->as->type != AS_ASSUMED_SIZE
                                           || dim < ar->dimen - 1);
          break;

        case DIMEN_RANGE:
          /* Scalarized dimension.  */
          gcc_assert (info && se->loop);

          /* Multiply the loop variable by the stride and delta.  */
          index = se->loop->loopvar[i];
          if (!integer_onep (info->stride[dim]))
            index = fold_build2_loc (input_location, MULT_EXPR,
                                     gfc_array_index_type, index,
                                     info->stride[dim]);
          if (!integer_zerop (info->delta[dim]))
            index = fold_build2_loc (input_location, PLUS_EXPR,
                                     gfc_array_index_type, index,
                                     info->delta[dim]);
          break;

        default:
          gcc_unreachable ();
        }
    }
  else
    {
      /* Temporary array or derived type component.  */
      gcc_assert (se->loop);
      index = se->loop->loopvar[se->loop->order[i]];

      /* Pointer functions can have stride[0] different from unity. 
         Use the stride returned by the function call and stored in
         the descriptor for the temporary.  */ 
      if (se->ss && se->ss->info->type == GFC_SS_FUNCTION
          && se->ss->info->expr
          && se->ss->info->expr->symtree
          && se->ss->info->expr->symtree->n.sym->result
          && se->ss->info->expr->symtree->n.sym->result->attr.pointer)
        stride = gfc_conv_descriptor_stride_get (info->descriptor,
                                                 gfc_rank_cst[dim]);

      if (!integer_zerop (info->delta[dim]))
        index = fold_build2_loc (input_location, PLUS_EXPR,
                                 gfc_array_index_type, index, info->delta[dim]);
    }

  /* Multiply by the stride.  */
  if (!integer_onep (stride))
    index = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                             index, stride);

  return index;
}


/* Build a scalarized reference to an array.  */

static void
gfc_conv_scalarized_array_ref (gfc_se * se, gfc_array_ref * ar)
{
  gfc_array_info *info;
  tree decl = NULL_TREE;
  tree index;
  tree tmp;
  gfc_ss *ss;
  gfc_expr *expr;
  int n;

  ss = se->ss;
  expr = ss->info->expr;
  info = &ss->info->data.array;
  if (ar)
    n = se->loop->order[0];
  else
    n = 0;

  index = conv_array_index_offset (se, ss, ss->dim[n], n, ar, info->stride0);
  /* Add the offset for this dimension to the stored offset for all other
     dimensions.  */
  if (!integer_zerop (info->offset))
    index = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                             index, info->offset);

  if (expr && is_subref_array (expr))
    decl = expr->symtree->n.sym->backend_decl;

  tmp = build_fold_indirect_ref_loc (input_location, info->data);
  se->expr = gfc_build_array_ref (tmp, index, decl);
}


/* Translate access of temporary array.  */

void
gfc_conv_tmp_array_ref (gfc_se * se)
{
  se->string_length = se->ss->info->string_length;
  gfc_conv_scalarized_array_ref (se, NULL);
  gfc_advance_se_ss_chain (se);
}

/* Add T to the offset pair *OFFSET, *CST_OFFSET.  */

static void
add_to_offset (tree *cst_offset, tree *offset, tree t)
{
  if (TREE_CODE (t) == INTEGER_CST)
    *cst_offset = int_const_binop (PLUS_EXPR, *cst_offset, t);
  else
    {
      if (!integer_zerop (*offset))
        *offset = fold_build2_loc (input_location, PLUS_EXPR,
                                   gfc_array_index_type, *offset, t);
      else
        *offset = t;
    }
}

/* Build an array reference.  se->expr already holds the array descriptor.
   This should be either a variable, indirect variable reference or component
   reference.  For arrays which do not have a descriptor, se->expr will be
   the data pointer.
   a(i, j, k) = base[offset + i * stride[0] + j * stride[1] + k * stride[2]]*/

void
gfc_conv_array_ref (gfc_se * se, gfc_array_ref * ar, gfc_symbol * sym,
                    locus * where)
{
  int n;
  tree offset, cst_offset;
  tree tmp;
  tree stride;
  gfc_se indexse;
  gfc_se tmpse;

  if (ar->dimen == 0)
    {
      gcc_assert (ar->codimen);

      if (GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (se->expr)))
        se->expr = build_fold_indirect_ref (gfc_conv_array_data (se->expr));
      else
        {
          if (GFC_ARRAY_TYPE_P (TREE_TYPE (se->expr))
              && TREE_CODE (TREE_TYPE (se->expr)) == POINTER_TYPE)
            se->expr = build_fold_indirect_ref_loc (input_location, se->expr);

          /* Use the actual tree type and not the wrapped coarray. */
          if (!se->want_pointer)
            se->expr = fold_convert (TYPE_MAIN_VARIANT (TREE_TYPE (se->expr)),
                                     se->expr);
        }

      return;
    }

  /* Handle scalarized references separately.  */
  if (ar->type != AR_ELEMENT)
    {
      gfc_conv_scalarized_array_ref (se, ar);
      gfc_advance_se_ss_chain (se);
      return;
    }

  cst_offset = offset = gfc_index_zero_node;
  add_to_offset (&cst_offset, &offset, gfc_conv_array_offset (se->expr));

  /* Calculate the offsets from all the dimensions.  Make sure to associate
     the final offset so that we form a chain of loop invariant summands.  */
  for (n = ar->dimen - 1; n >= 0; n--)
    {
      /* Calculate the index for this dimension.  */
      gfc_init_se (&indexse, se);
      gfc_conv_expr_type (&indexse, ar->start[n], gfc_array_index_type);
      gfc_add_block_to_block (&se->pre, &indexse.pre);

      if (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)
        {
          /* Check array bounds.  */
          tree cond;
          char *msg;

          /* Evaluate the indexse.expr only once.  */
          indexse.expr = save_expr (indexse.expr);

          /* Lower bound.  */
          tmp = gfc_conv_array_lbound (se->expr, n);
          if (sym->attr.temporary)
            {
              gfc_init_se (&tmpse, se);
              gfc_conv_expr_type (&tmpse, ar->as->lower[n],
                                  gfc_array_index_type);
              gfc_add_block_to_block (&se->pre, &tmpse.pre);
              tmp = tmpse.expr;
            }

          cond = fold_build2_loc (input_location, LT_EXPR, boolean_type_node, 
                                  indexse.expr, tmp);
          asprintf (&msg, "Index '%%ld' of dimension %d of array '%s' "
                    "below lower bound of %%ld", n+1, sym->name);
          gfc_trans_runtime_check (true, false, cond, &se->pre, where, msg,
                                   fold_convert (long_integer_type_node,
                                                 indexse.expr),
                                   fold_convert (long_integer_type_node, tmp));
          free (msg);

          /* Upper bound, but not for the last dimension of assumed-size
             arrays.  */
          if (n < ar->dimen - 1 || ar->as->type != AS_ASSUMED_SIZE)
            {
              tmp = gfc_conv_array_ubound (se->expr, n);
              if (sym->attr.temporary)
                {
                  gfc_init_se (&tmpse, se);
                  gfc_conv_expr_type (&tmpse, ar->as->upper[n],
                                      gfc_array_index_type);
                  gfc_add_block_to_block (&se->pre, &tmpse.pre);
                  tmp = tmpse.expr;
                }

              cond = fold_build2_loc (input_location, GT_EXPR,
                                      boolean_type_node, indexse.expr, tmp);
              asprintf (&msg, "Index '%%ld' of dimension %d of array '%s' "
                        "above upper bound of %%ld", n+1, sym->name);
              gfc_trans_runtime_check (true, false, cond, &se->pre, where, msg,
                                   fold_convert (long_integer_type_node,
                                                 indexse.expr),
                                   fold_convert (long_integer_type_node, tmp));
              free (msg);
            }
        }

      /* Multiply the index by the stride.  */
      stride = gfc_conv_array_stride (se->expr, n);
      tmp = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                             indexse.expr, stride);

      /* And add it to the total.  */
      add_to_offset (&cst_offset, &offset, tmp);
    }

  if (!integer_zerop (cst_offset))
    offset = fold_build2_loc (input_location, PLUS_EXPR,
                              gfc_array_index_type, offset, cst_offset);

  /* Access the calculated element.  */
  tmp = gfc_conv_array_data (se->expr);
  tmp = build_fold_indirect_ref (tmp);
  se->expr = gfc_build_array_ref (tmp, offset, sym->backend_decl);
}


/* Add the offset corresponding to array's ARRAY_DIM dimension and loop's
   LOOP_DIM dimension (if any) to array's offset.  */

static void
add_array_offset (stmtblock_t *pblock, gfc_loopinfo *loop, gfc_ss *ss,
                  gfc_array_ref *ar, int array_dim, int loop_dim)
{
  gfc_se se;
  gfc_array_info *info;
  tree stride, index;

  info = &ss->info->data.array;

  gfc_init_se (&se, NULL);
  se.loop = loop;
  se.expr = info->descriptor;
  stride = gfc_conv_array_stride (info->descriptor, array_dim);
  index = conv_array_index_offset (&se, ss, array_dim, loop_dim, ar, stride);
  gfc_add_block_to_block (pblock, &se.pre);

  info->offset = fold_build2_loc (input_location, PLUS_EXPR,
                                  gfc_array_index_type,
                                  info->offset, index);
  info->offset = gfc_evaluate_now (info->offset, pblock);
}


/* Generate the code to be executed immediately before entering a
   scalarization loop.  */

static void
gfc_trans_preloop_setup (gfc_loopinfo * loop, int dim, int flag,
                         stmtblock_t * pblock)
{
  tree stride;
  gfc_ss_info *ss_info;
  gfc_array_info *info;
  gfc_ss_type ss_type;
  gfc_ss *ss;
  gfc_array_ref *ar;
  int i;

  /* This code will be executed before entering the scalarization loop
     for this dimension.  */
  for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
    {
      ss_info = ss->info;

      if ((ss_info->useflags & flag) == 0)
        continue;

      ss_type = ss_info->type;
      if (ss_type != GFC_SS_SECTION
          && ss_type != GFC_SS_FUNCTION
          && ss_type != GFC_SS_CONSTRUCTOR
          && ss_type != GFC_SS_COMPONENT)
        continue;

      info = &ss_info->data.array;

      gcc_assert (dim < ss->dimen);
      gcc_assert (ss->dimen == loop->dimen);

      if (info->ref)
        ar = &info->ref->u.ar;
      else
        ar = NULL;

      if (dim == loop->dimen - 1)
        i = 0;
      else
        i = dim + 1;

      /* For the time being, there is no loop reordering.  */
      gcc_assert (i == loop->order[i]);
      i = loop->order[i];

      if (dim == loop->dimen - 1)
        {
          stride = gfc_conv_array_stride (info->descriptor, ss->dim[i]);

          /* Calculate the stride of the innermost loop.  Hopefully this will
             allow the backend optimizers to do their stuff more effectively.
           */
          info->stride0 = gfc_evaluate_now (stride, pblock);

          /* For the outermost loop calculate the offset due to any
             elemental dimensions.  It will have been initialized with the
             base offset of the array.  */
          if (info->ref)
            {
              for (i = 0; i < ar->dimen; i++)
                {
                  if (ar->dimen_type[i] != DIMEN_ELEMENT)
                    continue;

                  add_array_offset (pblock, loop, ss, ar, i, /* unused */ -1);
                }
            }
        }
      else
        /* Add the offset for the previous loop dimension.  */
        add_array_offset (pblock, loop, ss, ar, ss->dim[i], i);

      /* Remember this offset for the second loop.  */
      if (dim == loop->temp_dim - 1)
        info->saved_offset = info->offset;
    }
}


/* Start a scalarized expression.  Creates a scope and declares loop
   variables.  */

void
gfc_start_scalarized_body (gfc_loopinfo * loop, stmtblock_t * pbody)
{
  int dim;
  int n;
  int flags;

  gcc_assert (!loop->array_parameter);

  for (dim = loop->dimen - 1; dim >= 0; dim--)
    {
      n = loop->order[dim];

      gfc_start_block (&loop->code[n]);

      /* Create the loop variable.  */
      loop->loopvar[n] = gfc_create_var (gfc_array_index_type, "S");

      if (dim < loop->temp_dim)
        flags = 3;
      else
        flags = 1;
      /* Calculate values that will be constant within this loop.  */
      gfc_trans_preloop_setup (loop, dim, flags, &loop->code[n]);
    }
  gfc_start_block (pbody);
}


/* Generates the actual loop code for a scalarization loop.  */

void
gfc_trans_scalarized_loop_end (gfc_loopinfo * loop, int n,
                               stmtblock_t * pbody)
{
  stmtblock_t block;
  tree cond;
  tree tmp;
  tree loopbody;
  tree exit_label;
  tree stmt;
  tree init;
  tree incr;

  if ((ompws_flags & (OMPWS_WORKSHARE_FLAG | OMPWS_SCALARIZER_WS))
      == (OMPWS_WORKSHARE_FLAG | OMPWS_SCALARIZER_WS)
      && n == loop->dimen - 1)
    {
      /* We create an OMP_FOR construct for the outermost scalarized loop.  */
      init = make_tree_vec (1);
      cond = make_tree_vec (1);
      incr = make_tree_vec (1);

      /* Cycle statement is implemented with a goto.  Exit statement must not
         be present for this loop.  */
      exit_label = gfc_build_label_decl (NULL_TREE);
      TREE_USED (exit_label) = 1;

      /* Label for cycle statements (if needed).  */
      tmp = build1_v (LABEL_EXPR, exit_label);
      gfc_add_expr_to_block (pbody, tmp);

      stmt = make_node (OMP_FOR);

      TREE_TYPE (stmt) = void_type_node;
      OMP_FOR_BODY (stmt) = loopbody = gfc_finish_block (pbody);

      OMP_FOR_CLAUSES (stmt) = build_omp_clause (input_location,
                                                 OMP_CLAUSE_SCHEDULE);
      OMP_CLAUSE_SCHEDULE_KIND (OMP_FOR_CLAUSES (stmt))
        = OMP_CLAUSE_SCHEDULE_STATIC;
      if (ompws_flags & OMPWS_NOWAIT)
        OMP_CLAUSE_CHAIN (OMP_FOR_CLAUSES (stmt))
          = build_omp_clause (input_location, OMP_CLAUSE_NOWAIT);

      /* Initialize the loopvar.  */
      TREE_VEC_ELT (init, 0) = build2_v (MODIFY_EXPR, loop->loopvar[n],
                                         loop->from[n]);
      OMP_FOR_INIT (stmt) = init;
      /* The exit condition.  */
      TREE_VEC_ELT (cond, 0) = build2_loc (input_location, LE_EXPR,
                                           boolean_type_node,
                                           loop->loopvar[n], loop->to[n]);
      SET_EXPR_LOCATION (TREE_VEC_ELT (cond, 0), input_location);
      OMP_FOR_COND (stmt) = cond;
      /* Increment the loopvar.  */
      tmp = build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                        loop->loopvar[n], gfc_index_one_node);
      TREE_VEC_ELT (incr, 0) = fold_build2_loc (input_location, MODIFY_EXPR,
          void_type_node, loop->loopvar[n], tmp);
      OMP_FOR_INCR (stmt) = incr;

      ompws_flags &= ~OMPWS_CURR_SINGLEUNIT;
      gfc_add_expr_to_block (&loop->code[n], stmt);
    }
  else
    {
      bool reverse_loop = (loop->reverse[n] == GFC_REVERSE_SET)
                             && (loop->temp_ss == NULL);

      loopbody = gfc_finish_block (pbody);

      if (reverse_loop)
        {
          tmp = loop->from[n];
          loop->from[n] = loop->to[n];
          loop->to[n] = tmp;
        }

      /* Initialize the loopvar.  */
      if (loop->loopvar[n] != loop->from[n])
        gfc_add_modify (&loop->code[n], loop->loopvar[n], loop->from[n]);

      exit_label = gfc_build_label_decl (NULL_TREE);

      /* Generate the loop body.  */
      gfc_init_block (&block);

      /* The exit condition.  */
      cond = fold_build2_loc (input_location, reverse_loop ? LT_EXPR : GT_EXPR,
                          boolean_type_node, loop->loopvar[n], loop->to[n]);
      tmp = build1_v (GOTO_EXPR, exit_label);
      TREE_USED (exit_label) = 1;
      tmp = build3_v (COND_EXPR, cond, tmp, build_empty_stmt (input_location));
      gfc_add_expr_to_block (&block, tmp);

      /* The main body.  */
      gfc_add_expr_to_block (&block, loopbody);

      /* Increment the loopvar.  */
      tmp = fold_build2_loc (input_location,
                             reverse_loop ? MINUS_EXPR : PLUS_EXPR,
                             gfc_array_index_type, loop->loopvar[n],
                             gfc_index_one_node);

      gfc_add_modify (&block, loop->loopvar[n], tmp);

      /* Build the loop.  */
      tmp = gfc_finish_block (&block);
      tmp = build1_v (LOOP_EXPR, tmp);
      gfc_add_expr_to_block (&loop->code[n], tmp);

      /* Add the exit label.  */
      tmp = build1_v (LABEL_EXPR, exit_label);
      gfc_add_expr_to_block (&loop->code[n], tmp);
    }

}


/* Finishes and generates the loops for a scalarized expression.  */

void
gfc_trans_scalarizing_loops (gfc_loopinfo * loop, stmtblock_t * body)
{
  int dim;
  int n;
  gfc_ss *ss;
  stmtblock_t *pblock;
  tree tmp;

  pblock = body;
  /* Generate the loops.  */
  for (dim = 0; dim < loop->dimen; dim++)
    {
      n = loop->order[dim];
      gfc_trans_scalarized_loop_end (loop, n, pblock);
      loop->loopvar[n] = NULL_TREE;
      pblock = &loop->code[n];
    }

  tmp = gfc_finish_block (pblock);
  gfc_add_expr_to_block (&loop->pre, tmp);

  /* Clear all the used flags.  */
  for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
    if (ss->parent == NULL)
      ss->info->useflags = 0;
}


/* Finish the main body of a scalarized expression, and start the secondary
   copying body.  */

void
gfc_trans_scalarized_loop_boundary (gfc_loopinfo * loop, stmtblock_t * body)
{
  int dim;
  int n;
  stmtblock_t *pblock;
  gfc_ss *ss;

  pblock = body;
  /* We finish as many loops as are used by the temporary.  */
  for (dim = 0; dim < loop->temp_dim - 1; dim++)
    {
      n = loop->order[dim];
      gfc_trans_scalarized_loop_end (loop, n, pblock);
      loop->loopvar[n] = NULL_TREE;
      pblock = &loop->code[n];
    }

  /* We don't want to finish the outermost loop entirely.  */
  n = loop->order[loop->temp_dim - 1];
  gfc_trans_scalarized_loop_end (loop, n, pblock);

  /* Restore the initial offsets.  */
  for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
    {
      gfc_ss_type ss_type;
      gfc_ss_info *ss_info;

      ss_info = ss->info;

      if ((ss_info->useflags & 2) == 0)
        continue;

      ss_type = ss_info->type;
      if (ss_type != GFC_SS_SECTION
          && ss_type != GFC_SS_FUNCTION
          && ss_type != GFC_SS_CONSTRUCTOR
          && ss_type != GFC_SS_COMPONENT)
        continue;

      ss_info->data.array.offset = ss_info->data.array.saved_offset;
    }

  /* Restart all the inner loops we just finished.  */
  for (dim = loop->temp_dim - 2; dim >= 0; dim--)
    {
      n = loop->order[dim];

      gfc_start_block (&loop->code[n]);

      loop->loopvar[n] = gfc_create_var (gfc_array_index_type, "Q");

      gfc_trans_preloop_setup (loop, dim, 2, &loop->code[n]);
    }

  /* Start a block for the secondary copying code.  */
  gfc_start_block (body);
}


/* Precalculate (either lower or upper) bound of an array section.
     BLOCK: Block in which the (pre)calculation code will go.
     BOUNDS[DIM]: Where the bound value will be stored once evaluated.
     VALUES[DIM]: Specified bound (NULL <=> unspecified).
     DESC: Array descriptor from which the bound will be picked if unspecified
       (either lower or upper bound according to LBOUND).  */

static void
evaluate_bound (stmtblock_t *block, tree *bounds, gfc_expr ** values,
                tree desc, int dim, bool lbound)
{
  gfc_se se;
  gfc_expr * input_val = values[dim];
  tree *output = &bounds[dim];


  if (input_val)
    {
      /* Specified section bound.  */
      gfc_init_se (&se, NULL);
      gfc_conv_expr_type (&se, input_val, gfc_array_index_type);
      gfc_add_block_to_block (block, &se.pre);
      *output = se.expr;
    }
  else
    {
      /* No specific bound specified so use the bound of the array.  */
      *output = lbound ? gfc_conv_array_lbound (desc, dim) :
                         gfc_conv_array_ubound (desc, dim);
    }
  *output = gfc_evaluate_now (*output, block);
}


/* Calculate the lower bound of an array section.  */

static void
gfc_conv_section_startstride (gfc_loopinfo * loop, gfc_ss * ss, int dim)
{
  gfc_expr *stride = NULL;
  tree desc;
  gfc_se se;
  gfc_array_info *info;
  gfc_array_ref *ar;

  gcc_assert (ss->info->type == GFC_SS_SECTION);

  info = &ss->info->data.array;
  ar = &info->ref->u.ar;

  if (ar->dimen_type[dim] == DIMEN_VECTOR)
    {
      /* We use a zero-based index to access the vector.  */
      info->start[dim] = gfc_index_zero_node;
      info->end[dim] = NULL;
      info->stride[dim] = gfc_index_one_node;
      return;
    }

  gcc_assert (ar->dimen_type[dim] == DIMEN_RANGE
              || ar->dimen_type[dim] == DIMEN_THIS_IMAGE);
  desc = info->descriptor;
  stride = ar->stride[dim];

  /* Calculate the start of the range.  For vector subscripts this will
     be the range of the vector.  */
  evaluate_bound (&loop->pre, info->start, ar->start, desc, dim, true);

  /* Similarly calculate the end.  Although this is not used in the
     scalarizer, it is needed when checking bounds and where the end
     is an expression with side-effects.  */
  evaluate_bound (&loop->pre, info->end, ar->end, desc, dim, false);

  /* Calculate the stride.  */
  if (stride == NULL)
    info->stride[dim] = gfc_index_one_node;
  else
    {
      gfc_init_se (&se, NULL);
      gfc_conv_expr_type (&se, stride, gfc_array_index_type);
      gfc_add_block_to_block (&loop->pre, &se.pre);
      info->stride[dim] = gfc_evaluate_now (se.expr, &loop->pre);
    }
}


/* Calculates the range start and stride for a SS chain.  Also gets the
   descriptor and data pointer.  The range of vector subscripts is the size
   of the vector.  Array bounds are also checked.  */

void
gfc_conv_ss_startstride (gfc_loopinfo * loop)
{
  int n;
  tree tmp;
  gfc_ss *ss;
  tree desc;

  loop->dimen = 0;
  /* Determine the rank of the loop.  */
  for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
    {
      switch (ss->info->type)
        {
        case GFC_SS_SECTION:
        case GFC_SS_CONSTRUCTOR:
        case GFC_SS_FUNCTION:
        case GFC_SS_COMPONENT:
          loop->dimen = ss->dimen;
          goto done;

        /* As usual, lbound and ubound are exceptions!.  */
        case GFC_SS_INTRINSIC:
          switch (ss->info->expr->value.function.isym->id)
            {
            case GFC_ISYM_LBOUND:
            case GFC_ISYM_UBOUND:
            case GFC_ISYM_LCOBOUND:
            case GFC_ISYM_UCOBOUND:
            case GFC_ISYM_THIS_IMAGE:
              loop->dimen = ss->dimen;
              goto done;

            default:
              break;
            }

        default:
          break;
        }
    }

  /* We should have determined the rank of the expression by now.  If
     not, that's bad news.  */
  gcc_unreachable ();

done:
  /* Loop over all the SS in the chain.  */
  for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
    {
      gfc_ss_info *ss_info;
      gfc_array_info *info;
      gfc_expr *expr;

      ss_info = ss->info;
      expr = ss_info->expr;
      info = &ss_info->data.array;

      if (expr && expr->shape && !info->shape)
        info->shape = expr->shape;

      switch (ss_info->type)
        {
        case GFC_SS_SECTION:
          /* Get the descriptor for the array.  If it is a cross loops array,
             we got the descriptor already in the outermost loop.  */
          if (ss->parent == NULL)
            gfc_conv_ss_descriptor (&loop->pre, ss, !loop->array_parameter);

          for (n = 0; n < ss->dimen; n++)
            gfc_conv_section_startstride (loop, ss, ss->dim[n]);
          break;

        case GFC_SS_INTRINSIC:
          switch (expr->value.function.isym->id)
            {
            /* Fall through to supply start and stride.  */
            case GFC_ISYM_LBOUND:
            case GFC_ISYM_UBOUND:
            case GFC_ISYM_LCOBOUND:
            case GFC_ISYM_UCOBOUND:
            case GFC_ISYM_THIS_IMAGE:
              break;

            default:
              continue;
            }

        case GFC_SS_CONSTRUCTOR:
        case GFC_SS_FUNCTION:
          for (n = 0; n < ss->dimen; n++)
            {
              int dim = ss->dim[n];

              info->start[dim]  = gfc_index_zero_node;
              info->end[dim]    = gfc_index_zero_node;
              info->stride[dim] = gfc_index_one_node;
            }
          break;

        default:
          break;
        }
    }

  /* The rest is just runtime bound checking.  */
  if (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)
    {
      stmtblock_t block;
      tree lbound, ubound;
      tree end;
      tree size[GFC_MAX_DIMENSIONS];
      tree stride_pos, stride_neg, non_zerosized, tmp2, tmp3;
      gfc_array_info *info;
      char *msg;
      int dim;

      gfc_start_block (&block);

      for (n = 0; n < loop->dimen; n++)
        size[n] = NULL_TREE;

      for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
        {
          stmtblock_t inner;
          gfc_ss_info *ss_info;
          gfc_expr *expr;
          locus *expr_loc;
          const char *expr_name;

          ss_info = ss->info;
          if (ss_info->type != GFC_SS_SECTION)
            continue;

          /* Catch allocatable lhs in f2003.  */
          if (gfc_option.flag_realloc_lhs && ss->is_alloc_lhs)
            continue;

          expr = ss_info->expr;
          expr_loc = &expr->where;
          expr_name = expr->symtree->name;

          gfc_start_block (&inner);

          /* TODO: range checking for mapped dimensions.  */
          info = &ss_info->data.array;

          /* This code only checks ranges.  Elemental and vector
             dimensions are checked later.  */
          for (n = 0; n < loop->dimen; n++)
            {
              bool check_upper;

              dim = ss->dim[n];
              if (info->ref->u.ar.dimen_type[dim] != DIMEN_RANGE)
                continue;

              if (dim == info->ref->u.ar.dimen - 1
                  && info->ref->u.ar.as->type == AS_ASSUMED_SIZE)
                check_upper = false;
              else
                check_upper = true;

              /* Zero stride is not allowed.  */
              tmp = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node,
                                     info->stride[dim], gfc_index_zero_node);
              asprintf (&msg, "Zero stride is not allowed, for dimension %d "
                        "of array '%s'", dim + 1, expr_name);
              gfc_trans_runtime_check (true, false, tmp, &inner,
                                       expr_loc, msg);
              free (msg);

              desc = info->descriptor;

              /* This is the run-time equivalent of resolve.c's
                 check_dimension().  The logical is more readable there
                 than it is here, with all the trees.  */
              lbound = gfc_conv_array_lbound (desc, dim);
              end = info->end[dim];
              if (check_upper)
                ubound = gfc_conv_array_ubound (desc, dim);
              else
                ubound = NULL;

              /* non_zerosized is true when the selected range is not
                 empty.  */
              stride_pos = fold_build2_loc (input_location, GT_EXPR,
                                        boolean_type_node, info->stride[dim],
                                        gfc_index_zero_node);
              tmp = fold_build2_loc (input_location, LE_EXPR, boolean_type_node,
                                     info->start[dim], end);
              stride_pos = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                                            boolean_type_node, stride_pos, tmp);

              stride_neg = fold_build2_loc (input_location, LT_EXPR,
                                     boolean_type_node,
                                     info->stride[dim], gfc_index_zero_node);
              tmp = fold_build2_loc (input_location, GE_EXPR, boolean_type_node,
                                     info->start[dim], end);
              stride_neg = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                                            boolean_type_node,
                                            stride_neg, tmp);
              non_zerosized = fold_build2_loc (input_location, TRUTH_OR_EXPR,
                                               boolean_type_node,
                                               stride_pos, stride_neg);

              /* Check the start of the range against the lower and upper
                 bounds of the array, if the range is not empty. 
                 If upper bound is present, include both bounds in the 
                 error message.  */
              if (check_upper)
                {
                  tmp = fold_build2_loc (input_location, LT_EXPR,
                                         boolean_type_node,
                                         info->start[dim], lbound);
                  tmp = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                                         boolean_type_node,
                                         non_zerosized, tmp);
                  tmp2 = fold_build2_loc (input_location, GT_EXPR,
                                          boolean_type_node,
                                          info->start[dim], ubound);
                  tmp2 = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                                          boolean_type_node,
                                          non_zerosized, tmp2);
                  asprintf (&msg, "Index '%%ld' of dimension %d of array '%s' "
                            "outside of expected range (%%ld:%%ld)",
                            dim + 1, expr_name);
                  gfc_trans_runtime_check (true, false, tmp, &inner,
                                           expr_loc, msg,
                     fold_convert (long_integer_type_node, info->start[dim]),
                     fold_convert (long_integer_type_node, lbound),
                     fold_convert (long_integer_type_node, ubound));
                  gfc_trans_runtime_check (true, false, tmp2, &inner,
                                           expr_loc, msg,
                     fold_convert (long_integer_type_node, info->start[dim]),
                     fold_convert (long_integer_type_node, lbound),
                     fold_convert (long_integer_type_node, ubound));
                  free (msg);
                }
              else
                {
                  tmp = fold_build2_loc (input_location, LT_EXPR,
                                         boolean_type_node,
                                         info->start[dim], lbound);
                  tmp = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                                         boolean_type_node, non_zerosized, tmp);
                  asprintf (&msg, "Index '%%ld' of dimension %d of array '%s' "
                            "below lower bound of %%ld",
                            dim + 1, expr_name);
                  gfc_trans_runtime_check (true, false, tmp, &inner,
                                           expr_loc, msg,
                     fold_convert (long_integer_type_node, info->start[dim]),
                     fold_convert (long_integer_type_node, lbound));
                  free (msg);
                }
              
              /* Compute the last element of the range, which is not
                 necessarily "end" (think 0:5:3, which doesn't contain 5)
                 and check it against both lower and upper bounds.  */

              tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                     gfc_array_index_type, end,
                                     info->start[dim]);
              tmp = fold_build2_loc (input_location, TRUNC_MOD_EXPR,
                                     gfc_array_index_type, tmp,
                                     info->stride[dim]);
              tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                     gfc_array_index_type, end, tmp);
              tmp2 = fold_build2_loc (input_location, LT_EXPR,
                                      boolean_type_node, tmp, lbound);
              tmp2 = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                                      boolean_type_node, non_zerosized, tmp2);
              if (check_upper)
                {
                  tmp3 = fold_build2_loc (input_location, GT_EXPR,
                                          boolean_type_node, tmp, ubound);
                  tmp3 = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                                          boolean_type_node, non_zerosized, tmp3);
                  asprintf (&msg, "Index '%%ld' of dimension %d of array '%s' "
                            "outside of expected range (%%ld:%%ld)",
                            dim + 1, expr_name);
                  gfc_trans_runtime_check (true, false, tmp2, &inner,
                                           expr_loc, msg,
                     fold_convert (long_integer_type_node, tmp),
                     fold_convert (long_integer_type_node, ubound), 
                     fold_convert (long_integer_type_node, lbound));
                  gfc_trans_runtime_check (true, false, tmp3, &inner,
                                           expr_loc, msg,
                     fold_convert (long_integer_type_node, tmp),
                     fold_convert (long_integer_type_node, ubound), 
                     fold_convert (long_integer_type_node, lbound));
                  free (msg);
                }
              else
                {
                  asprintf (&msg, "Index '%%ld' of dimension %d of array '%s' "
                            "below lower bound of %%ld",
                            dim + 1, expr_name);
                  gfc_trans_runtime_check (true, false, tmp2, &inner,
                                           expr_loc, msg,
                     fold_convert (long_integer_type_node, tmp),
                     fold_convert (long_integer_type_node, lbound));
                  free (msg);
                }

              /* Check the section sizes match.  */
              tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                     gfc_array_index_type, end,
                                     info->start[dim]);
              tmp = fold_build2_loc (input_location, FLOOR_DIV_EXPR,
                                     gfc_array_index_type, tmp,
                                     info->stride[dim]);
              tmp = fold_build2_loc (input_location, PLUS_EXPR,
                                     gfc_array_index_type,
                                     gfc_index_one_node, tmp);
              tmp = fold_build2_loc (input_location, MAX_EXPR,
                                     gfc_array_index_type, tmp,
                                     build_int_cst (gfc_array_index_type, 0));
              /* We remember the size of the first section, and check all the
                 others against this.  */
              if (size[n])
                {
                  tmp3 = fold_build2_loc (input_location, NE_EXPR,
                                          boolean_type_node, tmp, size[n]);
                  asprintf (&msg, "Array bound mismatch for dimension %d "
                            "of array '%s' (%%ld/%%ld)",
                            dim + 1, expr_name);

                  gfc_trans_runtime_check (true, false, tmp3, &inner,
                                           expr_loc, msg,
                        fold_convert (long_integer_type_node, tmp),
                        fold_convert (long_integer_type_node, size[n]));

                  free (msg);
                }
              else
                size[n] = gfc_evaluate_now (tmp, &inner);
            }

          tmp = gfc_finish_block (&inner);

          /* For optional arguments, only check bounds if the argument is
             present.  */
          if (expr->symtree->n.sym->attr.optional
              || expr->symtree->n.sym->attr.not_always_present)
            tmp = build3_v (COND_EXPR,
                            gfc_conv_expr_present (expr->symtree->n.sym),
                            tmp, build_empty_stmt (input_location));

          gfc_add_expr_to_block (&block, tmp);

        }

      tmp = gfc_finish_block (&block);
      gfc_add_expr_to_block (&loop->pre, tmp);
    }

  for (loop = loop->nested; loop; loop = loop->next)
    gfc_conv_ss_startstride (loop);
}

/* Return true if both symbols could refer to the same data object.  Does
   not take account of aliasing due to equivalence statements.  */

static int
symbols_could_alias (gfc_symbol *lsym, gfc_symbol *rsym, bool lsym_pointer,
                     bool lsym_target, bool rsym_pointer, bool rsym_target)
{
  /* Aliasing isn't possible if the symbols have different base types.  */
  if (gfc_compare_types (&lsym->ts, &rsym->ts) == 0)
    return 0;

  /* Pointers can point to other pointers and target objects.  */

  if ((lsym_pointer && (rsym_pointer || rsym_target))
      || (rsym_pointer && (lsym_pointer || lsym_target)))
    return 1;

  /* Special case: Argument association, cf. F90 12.4.1.6, F2003 12.4.1.7
     and F2008 12.5.2.13 items 3b and 4b. The pointer case (a) is already
     checked above.  */
  if (lsym_target && rsym_target
      && ((lsym->attr.dummy && !lsym->attr.contiguous
           && (!lsym->attr.dimension || lsym->as->type == AS_ASSUMED_SHAPE))
          || (rsym->attr.dummy && !rsym->attr.contiguous
              && (!rsym->attr.dimension
                  || rsym->as->type == AS_ASSUMED_SHAPE))))
    return 1;

  return 0;
}


/* Return true if the two SS could be aliased, i.e. both point to the same data
   object.  */
/* TODO: resolve aliases based on frontend expressions.  */

static int
gfc_could_be_alias (gfc_ss * lss, gfc_ss * rss)
{
  gfc_ref *lref;
  gfc_ref *rref;
  gfc_expr *lexpr, *rexpr;
  gfc_symbol *lsym;
  gfc_symbol *rsym;
  bool lsym_pointer, lsym_target, rsym_pointer, rsym_target;

  lexpr = lss->info->expr;
  rexpr = rss->info->expr;

  lsym = lexpr->symtree->n.sym;
  rsym = rexpr->symtree->n.sym;

  lsym_pointer = lsym->attr.pointer;
  lsym_target = lsym->attr.target;
  rsym_pointer = rsym->attr.pointer;
  rsym_target = rsym->attr.target;

  if (symbols_could_alias (lsym, rsym, lsym_pointer, lsym_target,
                           rsym_pointer, rsym_target))
    return 1;

  if (rsym->ts.type != BT_DERIVED && rsym->ts.type != BT_CLASS
      && lsym->ts.type != BT_DERIVED && lsym->ts.type != BT_CLASS)
    return 0;

  /* For derived types we must check all the component types.  We can ignore
     array references as these will have the same base type as the previous
     component ref.  */
  for (lref = lexpr->ref; lref != lss->info->data.array.ref; lref = lref->next)
    {
      if (lref->type != REF_COMPONENT)
        continue;

      lsym_pointer = lsym_pointer || lref->u.c.sym->attr.pointer;
      lsym_target  = lsym_target  || lref->u.c.sym->attr.target;

      if (symbols_could_alias (lref->u.c.sym, rsym, lsym_pointer, lsym_target,
                               rsym_pointer, rsym_target))
        return 1;

      if ((lsym_pointer && (rsym_pointer || rsym_target))
          || (rsym_pointer && (lsym_pointer || lsym_target)))
        {
          if (gfc_compare_types (&lref->u.c.component->ts,
                                 &rsym->ts))
            return 1;
        }

      for (rref = rexpr->ref; rref != rss->info->data.array.ref;
           rref = rref->next)
        {
          if (rref->type != REF_COMPONENT)
            continue;

          rsym_pointer = rsym_pointer || rref->u.c.sym->attr.pointer;
          rsym_target  = lsym_target  || rref->u.c.sym->attr.target;

          if (symbols_could_alias (lref->u.c.sym, rref->u.c.sym,
                                   lsym_pointer, lsym_target,
                                   rsym_pointer, rsym_target))
            return 1;

          if ((lsym_pointer && (rsym_pointer || rsym_target))
              || (rsym_pointer && (lsym_pointer || lsym_target)))
            {
              if (gfc_compare_types (&lref->u.c.component->ts,
                                     &rref->u.c.sym->ts))
                return 1;
              if (gfc_compare_types (&lref->u.c.sym->ts,
                                     &rref->u.c.component->ts))
                return 1;
              if (gfc_compare_types (&lref->u.c.component->ts,
                                     &rref->u.c.component->ts))
                return 1;
            }
        }
    }

  lsym_pointer = lsym->attr.pointer;
  lsym_target = lsym->attr.target;
  lsym_pointer = lsym->attr.pointer;
  lsym_target = lsym->attr.target;

  for (rref = rexpr->ref; rref != rss->info->data.array.ref; rref = rref->next)
    {
      if (rref->type != REF_COMPONENT)
        break;

      rsym_pointer = rsym_pointer || rref->u.c.sym->attr.pointer;
      rsym_target  = lsym_target  || rref->u.c.sym->attr.target;

      if (symbols_could_alias (rref->u.c.sym, lsym,
                               lsym_pointer, lsym_target,
                               rsym_pointer, rsym_target))
        return 1;

      if ((lsym_pointer && (rsym_pointer || rsym_target))
          || (rsym_pointer && (lsym_pointer || lsym_target)))
        {
          if (gfc_compare_types (&lsym->ts, &rref->u.c.component->ts))
            return 1;
        }
    }

  return 0;
}


/* Resolve array data dependencies.  Creates a temporary if required.  */
/* TODO: Calc dependencies with gfc_expr rather than gfc_ss, and move to
   dependency.c.  */

void
gfc_conv_resolve_dependencies (gfc_loopinfo * loop, gfc_ss * dest,
                               gfc_ss * rss)
{
  gfc_ss *ss;
  gfc_ref *lref;
  gfc_ref *rref;
  gfc_expr *dest_expr;
  gfc_expr *ss_expr;
  int nDepend = 0;
  int i, j;

  loop->temp_ss = NULL;
  dest_expr = dest->info->expr;

  for (ss = rss; ss != gfc_ss_terminator; ss = ss->next)
    {
      if (ss->info->type != GFC_SS_SECTION)
        continue;

      ss_expr = ss->info->expr;

      if (dest_expr->symtree->n.sym != ss_expr->symtree->n.sym)
        {
          if (gfc_could_be_alias (dest, ss)
              || gfc_are_equivalenced_arrays (dest_expr, ss_expr))
            {
              nDepend = 1;
              break;
            }
        }
      else
        {
          lref = dest_expr->ref;
          rref = ss_expr->ref;

          nDepend = gfc_dep_resolver (lref, rref, &loop->reverse[0]);

          if (nDepend == 1)
            break;

          for (i = 0; i < dest->dimen; i++)
            for (j = 0; j < ss->dimen; j++)
              if (i != j
                  && dest->dim[i] == ss->dim[j])
                {
                  /* If we don't access array elements in the same order,
                     there is a dependency.  */
                  nDepend = 1;
                  goto temporary;
                }
#if 0
          /* TODO : loop shifting.  */
          if (nDepend == 1)
            {
              /* Mark the dimensions for LOOP SHIFTING */
              for (n = 0; n < loop->dimen; n++)
                {
                  int dim = dest->data.info.dim[n];

                  if (lref->u.ar.dimen_type[dim] == DIMEN_VECTOR)
                    depends[n] = 2;
                  else if (! gfc_is_same_range (&lref->u.ar,
                                                &rref->u.ar, dim, 0))
                    depends[n] = 1;
                 }

              /* Put all the dimensions with dependencies in the
                 innermost loops.  */
              dim = 0;
              for (n = 0; n < loop->dimen; n++)
                {
                  gcc_assert (loop->order[n] == n);
                  if (depends[n])
                  loop->order[dim++] = n;
                }
              for (n = 0; n < loop->dimen; n++)
                {
                  if (! depends[n])
                  loop->order[dim++] = n;
                }

              gcc_assert (dim == loop->dimen);
              break;
            }
#endif
        }
    }

temporary:

  if (nDepend == 1)
    {
      tree base_type = gfc_typenode_for_spec (&dest_expr->ts);
      if (GFC_ARRAY_TYPE_P (base_type)
          || GFC_DESCRIPTOR_TYPE_P (base_type))
        base_type = gfc_get_element_type (base_type);
      loop->temp_ss = gfc_get_temp_ss (base_type, dest->info->string_length,
                                       loop->dimen);
      gfc_add_ss_to_loop (loop, loop->temp_ss);
    }
  else
    loop->temp_ss = NULL;
}


/* Browse through each array's information from the scalarizer and set the loop
   bounds according to the "best" one (per dimension), i.e. the one which
   provides the most information (constant bounds, shape, etc).  */

static void
set_loop_bounds (gfc_loopinfo *loop)
{
  int n, dim, spec_dim;
  gfc_array_info *info;
  gfc_array_info *specinfo;
  gfc_ss *ss;
  tree tmp;
  gfc_ss **loopspec;
  bool dynamic[GFC_MAX_DIMENSIONS];
  mpz_t *cshape;
  mpz_t i;

  loopspec = loop->specloop;

  mpz_init (i);
  for (n = 0; n < loop->dimen; n++)
    {
      loopspec[n] = NULL;
      dynamic[n] = false;
      /* We use one SS term, and use that to determine the bounds of the
         loop for this dimension.  We try to pick the simplest term.  */
      for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
        {
          gfc_ss_type ss_type;

          ss_type = ss->info->type;
          if (ss_type == GFC_SS_SCALAR
              || ss_type == GFC_SS_TEMP
              || ss_type == GFC_SS_REFERENCE)
            continue;

          info = &ss->info->data.array;
          dim = ss->dim[n];

          if (loopspec[n] != NULL)
            {
              specinfo = &loopspec[n]->info->data.array;
              spec_dim = loopspec[n]->dim[n];
            }
          else
            {
              /* Silence unitialized warnings.  */
              specinfo = NULL;
              spec_dim = 0;
            }

          if (info->shape)
            {
              gcc_assert (info->shape[dim]);
              /* The frontend has worked out the size for us.  */
              if (!loopspec[n]
                  || !specinfo->shape
                  || !integer_zerop (specinfo->start[spec_dim]))
                /* Prefer zero-based descriptors if possible.  */
                loopspec[n] = ss;
              continue;
            }

          if (ss_type == GFC_SS_CONSTRUCTOR)
            {
              gfc_constructor_base base;
              /* An unknown size constructor will always be rank one.
                 Higher rank constructors will either have known shape,
                 or still be wrapped in a call to reshape.  */
              gcc_assert (loop->dimen == 1);

              /* Always prefer to use the constructor bounds if the size
                 can be determined at compile time.  Prefer not to otherwise,
                 since the general case involves realloc, and it's better to
                 avoid that overhead if possible.  */
              base = ss->info->expr->value.constructor;
              dynamic[n] = gfc_get_array_constructor_size (&i, base);
              if (!dynamic[n] || !loopspec[n])
                loopspec[n] = ss;
              continue;
            }

          /* TODO: Pick the best bound if we have a choice between a
             function and something else.  */
          if (ss_type == GFC_SS_FUNCTION)
            {
              loopspec[n] = ss;
              continue;
            }

          /* Avoid using an allocatable lhs in an assignment, since
             there might be a reallocation coming.  */
          if (loopspec[n] && ss->is_alloc_lhs)
            continue;

          if (ss_type != GFC_SS_SECTION)
            continue;

          if (!loopspec[n])
            loopspec[n] = ss;
          /* Criteria for choosing a loop specifier (most important first):
             doesn't need realloc
             stride of one
             known stride
             known lower bound
             known upper bound
           */
          else if ((loopspec[n]->info->type == GFC_SS_CONSTRUCTOR && dynamic[n])
                   || n >= loop->dimen)
            loopspec[n] = ss;
          else if (integer_onep (info->stride[dim])
                   && !integer_onep (specinfo->stride[spec_dim]))
            loopspec[n] = ss;
          else if (INTEGER_CST_P (info->stride[dim])
                   && !INTEGER_CST_P (specinfo->stride[spec_dim]))
            loopspec[n] = ss;
          else if (INTEGER_CST_P (info->start[dim])
                   && !INTEGER_CST_P (specinfo->start[spec_dim]))
            loopspec[n] = ss;
          /* We don't work out the upper bound.
             else if (INTEGER_CST_P (info->finish[n])
             && ! INTEGER_CST_P (specinfo->finish[n]))
             loopspec[n] = ss; */
        }

      /* We should have found the scalarization loop specifier.  If not,
         that's bad news.  */
      gcc_assert (loopspec[n]);

      info = &loopspec[n]->info->data.array;
      dim = loopspec[n]->dim[n];

      /* Set the extents of this range.  */
      cshape = info->shape;
      if (cshape && INTEGER_CST_P (info->start[dim])
          && INTEGER_CST_P (info->stride[dim]))
        {
          loop->from[n] = info->start[dim];
          mpz_set (i, cshape[get_array_ref_dim_for_loop_dim (loopspec[n], n)]);
          mpz_sub_ui (i, i, 1);
          /* To = from + (size - 1) * stride.  */
          tmp = gfc_conv_mpz_to_tree (i, gfc_index_integer_kind);
          if (!integer_onep (info->stride[dim]))
            tmp = fold_build2_loc (input_location, MULT_EXPR,
                                   gfc_array_index_type, tmp,
                                   info->stride[dim]);
          loop->to[n] = fold_build2_loc (input_location, PLUS_EXPR,
                                         gfc_array_index_type,
                                         loop->from[n], tmp);
        }
      else
        {
          loop->from[n] = info->start[dim];
          switch (loopspec[n]->info->type)
            {
            case GFC_SS_CONSTRUCTOR:
              /* The upper bound is calculated when we expand the
                 constructor.  */
              gcc_assert (loop->to[n] == NULL_TREE);
              break;

            case GFC_SS_SECTION:
              /* Use the end expression if it exists and is not constant,
                 so that it is only evaluated once.  */
              loop->to[n] = info->end[dim];
              break;

            case GFC_SS_FUNCTION:
              /* The loop bound will be set when we generate the call.  */
              gcc_assert (loop->to[n] == NULL_TREE);
              break;

            default:
              gcc_unreachable ();
            }
        }

      /* Transform everything so we have a simple incrementing variable.  */
      if (n < loop->dimen && integer_onep (info->stride[dim]))
        info->delta[dim] = gfc_index_zero_node;
      else if (n < loop->dimen)
        {
          /* Set the delta for this section.  */
          info->delta[dim] = gfc_evaluate_now (loop->from[n], &loop->pre);
          /* Number of iterations is (end - start + step) / step.
             with start = 0, this simplifies to
             last = end / step;
             for (i = 0; i<=last; i++){...};  */
          tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                 gfc_array_index_type, loop->to[n],
                                 loop->from[n]);
          tmp = fold_build2_loc (input_location, FLOOR_DIV_EXPR,
                                 gfc_array_index_type, tmp, info->stride[dim]);
          tmp = fold_build2_loc (input_location, MAX_EXPR, gfc_array_index_type,
                                 tmp, build_int_cst (gfc_array_index_type, -1));
          loop->to[n] = gfc_evaluate_now (tmp, &loop->pre);
          /* Make the loop variable start at 0.  */
          loop->from[n] = gfc_index_zero_node;
        }
    }
  mpz_clear (i);

  for (loop = loop->nested; loop; loop = loop->next)
    set_loop_bounds (loop);
}


static void set_delta (gfc_loopinfo *loop);


/* Initialize the scalarization loop.  Creates the loop variables.  Determines
   the range of the loop variables.  Creates a temporary if required.
   Also generates code for scalar expressions which have been
   moved outside the loop.  */

void
gfc_conv_loop_setup (gfc_loopinfo * loop, locus * where)
{
  gfc_ss *tmp_ss;
  tree tmp;

  set_loop_bounds (loop);

  /* Add all the scalar code that can be taken out of the loops.
     This may include calculating the loop bounds, so do it before
     allocating the temporary.  */
  gfc_add_loop_ss_code (loop, loop->ss, false, where);

  tmp_ss = loop->temp_ss;
  /* If we want a temporary then create it.  */
  if (tmp_ss != NULL)
    {
      gfc_ss_info *tmp_ss_info;

      tmp_ss_info = tmp_ss->info;
      gcc_assert (tmp_ss_info->type == GFC_SS_TEMP);
      gcc_assert (loop->parent == NULL);

      /* Make absolutely sure that this is a complete type.  */
      if (tmp_ss_info->string_length)
        tmp_ss_info->data.temp.type
                = gfc_get_character_type_len_for_eltype
                        (TREE_TYPE (tmp_ss_info->data.temp.type),
                         tmp_ss_info->string_length);

      tmp = tmp_ss_info->data.temp.type;
      memset (&tmp_ss_info->data.array, 0, sizeof (gfc_array_info));
      tmp_ss_info->type = GFC_SS_SECTION;

      gcc_assert (tmp_ss->dimen != 0);

      gfc_trans_create_temp_array (&loop->pre, &loop->post, tmp_ss, tmp,
                                   NULL_TREE, false, true, false, where);
    }

  /* For array parameters we don't have loop variables, so don't calculate the
     translations.  */
  if (loop->array_parameter)
    return;

  set_delta (loop);
}


/* Calculates how to transform from loop variables to array indices for each
   array: once loop bounds are chosen, sets the difference (DELTA field) between
   loop bounds and array reference bounds, for each array info.  */

static void
set_delta (gfc_loopinfo *loop)
{
  gfc_ss *ss, **loopspec;
  gfc_array_info *info;
  tree tmp;
  int n, dim;

  loopspec = loop->specloop;

  /* Calculate the translation from loop variables to array indices.  */
  for (ss = loop->ss; ss != gfc_ss_terminator; ss = ss->loop_chain)
    {
      gfc_ss_type ss_type;

      ss_type = ss->info->type;
      if (ss_type != GFC_SS_SECTION
          && ss_type != GFC_SS_COMPONENT
          && ss_type != GFC_SS_CONSTRUCTOR)
        continue;

      info = &ss->info->data.array;

      for (n = 0; n < ss->dimen; n++)
        {
          /* If we are specifying the range the delta is already set.  */
          if (loopspec[n] != ss)
            {
              dim = ss->dim[n];

              /* Calculate the offset relative to the loop variable.
                 First multiply by the stride.  */
              tmp = loop->from[n];
              if (!integer_onep (info->stride[dim]))
                tmp = fold_build2_loc (input_location, MULT_EXPR,
                                       gfc_array_index_type,
                                       tmp, info->stride[dim]);

              /* Then subtract this from our starting value.  */
              tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                     gfc_array_index_type,
                                     info->start[dim], tmp);

              info->delta[dim] = gfc_evaluate_now (tmp, &loop->pre);
            }
        }
    }

  for (loop = loop->nested; loop; loop = loop->next)
    set_delta (loop);
}


/* Calculate the size of a given array dimension from the bounds.  This
   is simply (ubound - lbound + 1) if this expression is positive
   or 0 if it is negative (pick either one if it is zero).  Optionally
   (if or_expr is present) OR the (expression != 0) condition to it.  */

tree
gfc_conv_array_extent_dim (tree lbound, tree ubound, tree* or_expr)
{
  tree res;
  tree cond;

  /* Calculate (ubound - lbound + 1).  */
  res = fold_build2_loc (input_location, MINUS_EXPR, gfc_array_index_type,
                         ubound, lbound);
  res = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type, res,
                         gfc_index_one_node);

  /* Check whether the size for this dimension is negative.  */
  cond = fold_build2_loc (input_location, LE_EXPR, boolean_type_node, res,
                          gfc_index_zero_node);
  res = fold_build3_loc (input_location, COND_EXPR, gfc_array_index_type, cond,
                         gfc_index_zero_node, res);

  /* Build OR expression.  */
  if (or_expr)
    *or_expr = fold_build2_loc (input_location, TRUTH_OR_EXPR,
                                boolean_type_node, *or_expr, cond);

  return res;
}


/* For an array descriptor, get the total number of elements.  This is just
   the product of the extents along from_dim to to_dim.  */

static tree
gfc_conv_descriptor_size_1 (tree desc, int from_dim, int to_dim)
{
  tree res;
  int dim;

  res = gfc_index_one_node;

  for (dim = from_dim; dim < to_dim; ++dim)
    {
      tree lbound;
      tree ubound;
      tree extent;

      lbound = gfc_conv_descriptor_lbound_get (desc, gfc_rank_cst[dim]);
      ubound = gfc_conv_descriptor_ubound_get (desc, gfc_rank_cst[dim]);

      extent = gfc_conv_array_extent_dim (lbound, ubound, NULL);
      res = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                             res, extent);
    }

  return res;
}


/* Full size of an array.  */

tree
gfc_conv_descriptor_size (tree desc, int rank)
{
  return gfc_conv_descriptor_size_1 (desc, 0, rank);
}


/* Size of a coarray for all dimensions but the last.  */

tree
gfc_conv_descriptor_cosize (tree desc, int rank, int corank)
{
  return gfc_conv_descriptor_size_1 (desc, rank, rank + corank - 1);
}


/* Fills in an array descriptor, and returns the size of the array.
   The size will be a simple_val, ie a variable or a constant.  Also
   calculates the offset of the base.  The pointer argument overflow,
   which should be of integer type, will increase in value if overflow
   occurs during the size calculation.  Returns the size of the array.
   {
    stride = 1;
    offset = 0;
    for (n = 0; n < rank; n++)
      {
        a.lbound[n] = specified_lower_bound;
        offset = offset + a.lbond[n] * stride;
        size = 1 - lbound;
        a.ubound[n] = specified_upper_bound;
        a.stride[n] = stride;
        size = size >= 0 ? ubound + size : 0; //size = ubound + 1 - lbound
        overflow += size == 0 ? 0: (MAX/size < stride ? 1: 0);
        stride = stride * size;
      }
    for (n = rank; n < rank+corank; n++)
      (Set lcobound/ucobound as above.)
    element_size = sizeof (array element);
    if (!rank)
      return element_size
    stride = (size_t) stride;
    overflow += element_size == 0 ? 0: (MAX/element_size < stride ? 1: 0);
    stride = stride * element_size;
    return (stride);
   }  */
/*GCC ARRAYS*/

static tree
gfc_array_init_size (tree descriptor, int rank, int corank, tree * poffset,
                     gfc_expr ** lower, gfc_expr ** upper, stmtblock_t * pblock,
                     stmtblock_t * descriptor_block, tree * overflow)
{
  tree type;
  tree tmp;
  tree size;
  tree offset;
  tree stride;
  tree element_size;
  tree or_expr;
  tree thencase;
  tree elsecase;
  tree cond;
  tree var;
  stmtblock_t thenblock;
  stmtblock_t elseblock;
  gfc_expr *ubound;
  gfc_se se;
  int n;

  type = TREE_TYPE (descriptor);

  stride = gfc_index_one_node;
  offset = gfc_index_zero_node;

  /* Set the dtype.  */
  tmp = gfc_conv_descriptor_dtype (descriptor);
  gfc_add_modify (descriptor_block, tmp, gfc_get_dtype (TREE_TYPE (descriptor)));

  or_expr = boolean_false_node;

  for (n = 0; n < rank; n++)
    {
      tree conv_lbound;
      tree conv_ubound;

      /* We have 3 possibilities for determining the size of the array:
         lower == NULL    => lbound = 1, ubound = upper[n]
         upper[n] = NULL  => lbound = 1, ubound = lower[n]
         upper[n] != NULL => lbound = lower[n], ubound = upper[n]  */
      ubound = upper[n];

      /* Set lower bound.  */
      gfc_init_se (&se, NULL);
      if (lower == NULL)
        se.expr = gfc_index_one_node;
      else
        {
          gcc_assert (lower[n]);
          if (ubound)
            {
              gfc_conv_expr_type (&se, lower[n], gfc_array_index_type);
              gfc_add_block_to_block (pblock, &se.pre);
            }
          else
            {
              se.expr = gfc_index_one_node;
              ubound = lower[n];
            }
        }
      gfc_conv_descriptor_lbound_set (descriptor_block, descriptor, 
                                      gfc_rank_cst[n], se.expr);
      conv_lbound = se.expr;

      /* Work out the offset for this component.  */
      tmp = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                             se.expr, stride);
      offset = fold_build2_loc (input_location, MINUS_EXPR,
                                gfc_array_index_type, offset, tmp);

      /* Set upper bound.  */
      gfc_init_se (&se, NULL);
      gcc_assert (ubound);
      gfc_conv_expr_type (&se, ubound, gfc_array_index_type);
      gfc_add_block_to_block (pblock, &se.pre);

      gfc_conv_descriptor_ubound_set (descriptor_block, descriptor,
                                      gfc_rank_cst[n], se.expr);
      conv_ubound = se.expr;

      /* Store the stride.  */
      gfc_conv_descriptor_stride_set (descriptor_block, descriptor,
                                      gfc_rank_cst[n], stride);

      /* Calculate size and check whether extent is negative.  */
      size = gfc_conv_array_extent_dim (conv_lbound, conv_ubound, &or_expr);
      size = gfc_evaluate_now (size, pblock);

      /* Check whether multiplying the stride by the number of
         elements in this dimension would overflow. We must also check
         whether the current dimension has zero size in order to avoid
         division by zero. 
      */
      tmp = fold_build2_loc (input_location, TRUNC_DIV_EXPR, 
                             gfc_array_index_type, 
                             fold_convert (gfc_array_index_type, 
                                           TYPE_MAX_VALUE (gfc_array_index_type)),
                                           size);
      cond = gfc_unlikely (fold_build2_loc (input_location, LT_EXPR,
                                            boolean_type_node, tmp, stride));
      tmp = fold_build3_loc (input_location, COND_EXPR, integer_type_node, cond,
                             integer_one_node, integer_zero_node);
      cond = gfc_unlikely (fold_build2_loc (input_location, EQ_EXPR,
                                            boolean_type_node, size,
                                            gfc_index_zero_node));
      tmp = fold_build3_loc (input_location, COND_EXPR, integer_type_node, cond,
                             integer_zero_node, tmp);
      tmp = fold_build2_loc (input_location, PLUS_EXPR, integer_type_node,
                             *overflow, tmp);
      *overflow = gfc_evaluate_now (tmp, pblock);
      
      /* Multiply the stride by the number of elements in this dimension.  */
      stride = fold_build2_loc (input_location, MULT_EXPR,
                                gfc_array_index_type, stride, size);
      stride = gfc_evaluate_now (stride, pblock);
    }

  for (n = rank; n < rank + corank; n++)
    {
      ubound = upper[n];

      /* Set lower bound.  */
      gfc_init_se (&se, NULL);
      if (lower == NULL || lower[n] == NULL)
        {
          gcc_assert (n == rank + corank - 1);
          se.expr = gfc_index_one_node;
        }
      else
        {
          if (ubound || n == rank + corank - 1)
            {
              gfc_conv_expr_type (&se, lower[n], gfc_array_index_type);
              gfc_add_block_to_block (pblock, &se.pre);
            }
          else
            {
              se.expr = gfc_index_one_node;
              ubound = lower[n];
            }
        }
      gfc_conv_descriptor_lbound_set (descriptor_block, descriptor, 
                                      gfc_rank_cst[n], se.expr);

      if (n < rank + corank - 1)
        {
          gfc_init_se (&se, NULL);
          gcc_assert (ubound);
          gfc_conv_expr_type (&se, ubound, gfc_array_index_type);
          gfc_add_block_to_block (pblock, &se.pre);
          gfc_conv_descriptor_ubound_set (descriptor_block, descriptor,
                                          gfc_rank_cst[n], se.expr);
        }
    }

  /* The stride is the number of elements in the array, so multiply by the
     size of an element to get the total size.  */
  tmp = TYPE_SIZE_UNIT (gfc_get_element_type (type));
  /* Convert to size_t.  */
  element_size = fold_convert (size_type_node, tmp);

  if (rank == 0)
    return element_size;

  stride = fold_convert (size_type_node, stride);

  /* First check for overflow. Since an array of type character can
     have zero element_size, we must check for that before
     dividing.  */
  tmp = fold_build2_loc (input_location, TRUNC_DIV_EXPR, 
                         size_type_node,
                         TYPE_MAX_VALUE (size_type_node), element_size);
  cond = gfc_unlikely (fold_build2_loc (input_location, LT_EXPR,
                                        boolean_type_node, tmp, stride));
  tmp = fold_build3_loc (input_location, COND_EXPR, integer_type_node, cond,
                         integer_one_node, integer_zero_node);
  cond = gfc_unlikely (fold_build2_loc (input_location, EQ_EXPR,
                                        boolean_type_node, element_size,
                                        build_int_cst (size_type_node, 0)));
  tmp = fold_build3_loc (input_location, COND_EXPR, integer_type_node, cond,
                         integer_zero_node, tmp);
  tmp = fold_build2_loc (input_location, PLUS_EXPR, integer_type_node,
                         *overflow, tmp);
  *overflow = gfc_evaluate_now (tmp, pblock);

  size = fold_build2_loc (input_location, MULT_EXPR, size_type_node,
                          stride, element_size);

  if (poffset != NULL)
    {
      offset = gfc_evaluate_now (offset, pblock);
      *poffset = offset;
    }

  if (integer_zerop (or_expr))
    return size;
  if (integer_onep (or_expr))
    return build_int_cst (size_type_node, 0);

  var = gfc_create_var (TREE_TYPE (size), "size");
  gfc_start_block (&thenblock);
  gfc_add_modify (&thenblock, var, build_int_cst (size_type_node, 0));
  thencase = gfc_finish_block (&thenblock);

  gfc_start_block (&elseblock);
  gfc_add_modify (&elseblock, var, size);
  elsecase = gfc_finish_block (&elseblock);

  tmp = gfc_evaluate_now (or_expr, pblock);
  tmp = build3_v (COND_EXPR, tmp, thencase, elsecase);
  gfc_add_expr_to_block (pblock, tmp);

  return var;
}


/* Initializes the descriptor and generates a call to _gfor_allocate.  Does
   the work for an ALLOCATE statement.  */
/*GCC ARRAYS*/

bool
gfc_array_allocate (gfc_se * se, gfc_expr * expr, tree status, tree errmsg,
                    tree errlen)
{
  tree tmp;
  tree pointer;
  tree offset = NULL_TREE;
  tree token = NULL_TREE;
  tree size;
  tree msg;
  tree error = NULL_TREE;
  tree overflow; /* Boolean storing whether size calculation overflows.  */
  tree var_overflow = NULL_TREE;
  tree cond;
  tree set_descriptor;
  stmtblock_t set_descriptor_block;
  stmtblock_t elseblock;
  gfc_expr **lower;
  gfc_expr **upper;
  gfc_ref *ref, *prev_ref = NULL;
  bool allocatable, coarray, dimension;

  ref = expr->ref;

  /* Find the last reference in the chain.  */
  while (ref && ref->next != NULL)
    {
      gcc_assert (ref->type != REF_ARRAY || ref->u.ar.type == AR_ELEMENT
                  || (ref->u.ar.dimen == 0 && ref->u.ar.codimen > 0));
      prev_ref = ref;
      ref = ref->next;
    }

  if (ref == NULL || ref->type != REF_ARRAY)
    return false;

  if (!prev_ref)
    {
      allocatable = expr->symtree->n.sym->attr.allocatable;
      coarray = expr->symtree->n.sym->attr.codimension;
      dimension = expr->symtree->n.sym->attr.dimension;
    }
  else
    {
      allocatable = prev_ref->u.c.component->attr.allocatable;
      coarray = prev_ref->u.c.component->attr.codimension;
      dimension = prev_ref->u.c.component->attr.dimension;
    }

  if (!dimension)
    gcc_assert (coarray);

  /* Figure out the size of the array.  */
  switch (ref->u.ar.type)
    {
    case AR_ELEMENT:
      if (!coarray)
        {
          lower = NULL;
          upper = ref->u.ar.start;
          break;
        }
      /* Fall through.  */

    case AR_SECTION:
      lower = ref->u.ar.start;
      upper = ref->u.ar.end;
      break;

    case AR_FULL:
      gcc_assert (ref->u.ar.as->type == AS_EXPLICIT);

      lower = ref->u.ar.as->lower;
      upper = ref->u.ar.as->upper;
      break;

    default:
      gcc_unreachable ();
      break;
    }

  overflow = integer_zero_node;

  gfc_init_block (&set_descriptor_block);
  size = gfc_array_init_size (se->expr, ref->u.ar.as->rank,
                              ref->u.ar.as->corank, &offset, lower, upper,
                              &se->pre, &set_descriptor_block, &overflow);

  if (dimension)
    {

      var_overflow = gfc_create_var (integer_type_node, "overflow");
      gfc_add_modify (&se->pre, var_overflow, overflow);

      /* Generate the block of code handling overflow.  */
      msg = gfc_build_addr_expr (pchar_type_node,
                gfc_build_localized_cstring_const
                        ("Integer overflow when calculating the amount of "
                         "memory to allocate"));
      error = build_call_expr_loc (input_location, gfor_fndecl_runtime_error,
                                   1, msg);
    }

  if (status != NULL_TREE)
    {
      tree status_type = TREE_TYPE (status);
      stmtblock_t set_status_block;

      gfc_start_block (&set_status_block);
      gfc_add_modify (&set_status_block, status,
                      build_int_cst (status_type, LIBERROR_ALLOCATION));
      error = gfc_finish_block (&set_status_block);
    }

  gfc_start_block (&elseblock);

  /* Allocate memory to store the data.  */
  pointer = gfc_conv_descriptor_data_get (se->expr);
  STRIP_NOPS (pointer);

  if (coarray && gfc_option.coarray == GFC_FCOARRAY_LIB)
    token = gfc_build_addr_expr (NULL_TREE,
                                 gfc_conv_descriptor_token (se->expr));

  /* The allocatable variant takes the old pointer as first argument.  */
  if (allocatable)
    gfc_allocate_allocatable (&elseblock, pointer, size, token,
                              status, errmsg, errlen, expr);
  else
    gfc_allocate_using_malloc (&elseblock, pointer, size, status);

  if (dimension)
    {
      cond = gfc_unlikely (fold_build2_loc (input_location, NE_EXPR,
                           boolean_type_node, var_overflow, integer_zero_node));
      tmp = fold_build3_loc (input_location, COND_EXPR, void_type_node, cond, 
                             error, gfc_finish_block (&elseblock));
    }
  else
    tmp = gfc_finish_block (&elseblock);

  gfc_add_expr_to_block (&se->pre, tmp);

  /* Update the array descriptors. */
  if (dimension)
    gfc_conv_descriptor_offset_set (&set_descriptor_block, se->expr, offset);
  
  set_descriptor = gfc_finish_block (&set_descriptor_block);
  if (status != NULL_TREE)
    {
      cond = fold_build2_loc (input_location, EQ_EXPR,
                          boolean_type_node, status,
                          build_int_cst (TREE_TYPE (status), 0));
      gfc_add_expr_to_block (&se->pre,
                 fold_build3_loc (input_location, COND_EXPR, void_type_node,
                                  gfc_likely (cond), set_descriptor,
                                  build_empty_stmt (input_location))); 
    }
  else
      gfc_add_expr_to_block (&se->pre, set_descriptor);

  if ((expr->ts.type == BT_DERIVED || expr->ts.type == BT_CLASS)
        && expr->ts.u.derived->attr.alloc_comp)
    {
      tmp = gfc_nullify_alloc_comp (expr->ts.u.derived, se->expr,
                                    ref->u.ar.as->rank);
      gfc_add_expr_to_block (&se->pre, tmp);
    }

  return true;
}


/* Deallocate an array variable.  Also used when an allocated variable goes
   out of scope.  */
/*GCC ARRAYS*/

tree
gfc_array_deallocate (tree descriptor, tree pstat, gfc_expr* expr)
{
  tree var;
  tree tmp;
  stmtblock_t block;

  gfc_start_block (&block);
  /* Get a pointer to the data.  */
  var = gfc_conv_descriptor_data_get (descriptor);
  STRIP_NOPS (var);

  /* Parameter is the address of the data component.  */
  tmp = gfc_deallocate_with_status (var, pstat, false, expr);
  gfc_add_expr_to_block (&block, tmp);

  /* Zero the data pointer.  */
  tmp = fold_build2_loc (input_location, MODIFY_EXPR, void_type_node,
                         var, build_int_cst (TREE_TYPE (var), 0));
  gfc_add_expr_to_block (&block, tmp);

  return gfc_finish_block (&block);
}


/* Create an array constructor from an initialization expression.
   We assume the frontend already did any expansions and conversions.  */

tree
gfc_conv_array_initializer (tree type, gfc_expr * expr)
{
  gfc_constructor *c;
  tree tmp;
  gfc_se se;
  HOST_WIDE_INT hi;
  unsigned HOST_WIDE_INT lo;
  tree index, range;
  VEC(constructor_elt,gc) *v = NULL;

  switch (expr->expr_type)
    {
    case EXPR_CONSTANT:
    case EXPR_STRUCTURE:
      /* A single scalar or derived type value.  Create an array with all
         elements equal to that value.  */
      gfc_init_se (&se, NULL);
      
      if (expr->expr_type == EXPR_CONSTANT)
        gfc_conv_constant (&se, expr);
      else
        gfc_conv_structure (&se, expr, 1);

      tmp = TYPE_MAX_VALUE (TYPE_DOMAIN (type));
      gcc_assert (tmp && INTEGER_CST_P (tmp));
      hi = TREE_INT_CST_HIGH (tmp);
      lo = TREE_INT_CST_LOW (tmp);
      lo++;
      if (lo == 0)
        hi++;
      /* This will probably eat buckets of memory for large arrays.  */
      while (hi != 0 || lo != 0)
        {
          CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, se.expr);
          if (lo == 0)
            hi--;
          lo--;
        }
      break;

    case EXPR_ARRAY:
      /* Create a vector of all the elements.  */
      for (c = gfc_constructor_first (expr->value.constructor);
           c; c = gfc_constructor_next (c))
        {
          if (c->iterator)
            {
              /* Problems occur when we get something like
                 integer :: a(lots) = (/(i, i=1, lots)/)  */
              gfc_fatal_error ("The number of elements in the array constructor "
                               "at %L requires an increase of the allowed %d "
                               "upper limit.   See -fmax-array-constructor "
                               "option", &expr->where,
                               gfc_option.flag_max_array_constructor);
              return NULL_TREE;
            }
          if (mpz_cmp_si (c->offset, 0) != 0)
            index = gfc_conv_mpz_to_tree (c->offset, gfc_index_integer_kind);
          else
            index = NULL_TREE;

          if (mpz_cmp_si (c->repeat, 1) > 0)
            {
              tree tmp1, tmp2;
              mpz_t maxval;

              mpz_init (maxval);
              mpz_add (maxval, c->offset, c->repeat);
              mpz_sub_ui (maxval, maxval, 1);
              tmp2 = gfc_conv_mpz_to_tree (maxval, gfc_index_integer_kind);
              if (mpz_cmp_si (c->offset, 0) != 0)
                {
                  mpz_add_ui (maxval, c->offset, 1);
                  tmp1 = gfc_conv_mpz_to_tree (maxval, gfc_index_integer_kind);
                }
              else
                tmp1 = gfc_conv_mpz_to_tree (c->offset, gfc_index_integer_kind);

              range = fold_build2 (RANGE_EXPR, gfc_array_index_type, tmp1, tmp2);
              mpz_clear (maxval);
            }
          else
            range = NULL;

          gfc_init_se (&se, NULL);
          switch (c->expr->expr_type)
            {
            case EXPR_CONSTANT:
              gfc_conv_constant (&se, c->expr);
              break;

            case EXPR_STRUCTURE:
              gfc_conv_structure (&se, c->expr, 1);
              break;

            default:
              /* Catch those occasional beasts that do not simplify
                 for one reason or another, assuming that if they are
                 standard defying the frontend will catch them.  */
              gfc_conv_expr (&se, c->expr);
              break;
            }

          if (range == NULL_TREE)
            CONSTRUCTOR_APPEND_ELT (v, index, se.expr);
          else
            {
              if (index != NULL_TREE)
                CONSTRUCTOR_APPEND_ELT (v, index, se.expr);
              CONSTRUCTOR_APPEND_ELT (v, range, se.expr);
            }
        }
      break;

    case EXPR_NULL:
      return gfc_build_null_descriptor (type);

    default:
      gcc_unreachable ();
    }

  /* Create a constructor from the list of elements.  */
  tmp = build_constructor (type, v);
  TREE_CONSTANT (tmp) = 1;
  return tmp;
}


/* Generate code to evaluate non-constant coarray cobounds.  */

void
gfc_trans_array_cobounds (tree type, stmtblock_t * pblock,
                          const gfc_symbol *sym)
{
  int dim;
  tree ubound;
  tree lbound;
  gfc_se se;
  gfc_array_spec *as;

  as = sym->as;

  for (dim = as->rank; dim < as->rank + as->corank; dim++)
    {
      /* Evaluate non-constant array bound expressions.  */
      lbound = GFC_TYPE_ARRAY_LBOUND (type, dim);
      if (as->lower[dim] && !INTEGER_CST_P (lbound))
        {
          gfc_init_se (&se, NULL);
          gfc_conv_expr_type (&se, as->lower[dim], gfc_array_index_type);
          gfc_add_block_to_block (pblock, &se.pre);
          gfc_add_modify (pblock, lbound, se.expr);
        }
      ubound = GFC_TYPE_ARRAY_UBOUND (type, dim);
      if (as->upper[dim] && !INTEGER_CST_P (ubound))
        {
          gfc_init_se (&se, NULL);
          gfc_conv_expr_type (&se, as->upper[dim], gfc_array_index_type);
          gfc_add_block_to_block (pblock, &se.pre);
          gfc_add_modify (pblock, ubound, se.expr);
        }
    }
}


/* Generate code to evaluate non-constant array bounds.  Sets *poffset and
   returns the size (in elements) of the array.  */

static tree
gfc_trans_array_bounds (tree type, gfc_symbol * sym, tree * poffset,
                        stmtblock_t * pblock)
{
  gfc_array_spec *as;
  tree size;
  tree stride;
  tree offset;
  tree ubound;
  tree lbound;
  tree tmp;
  gfc_se se;

  int dim;

  as = sym->as;

  size = gfc_index_one_node;
  offset = gfc_index_zero_node;
  for (dim = 0; dim < as->rank; dim++)
    {
      /* Evaluate non-constant array bound expressions.  */
      lbound = GFC_TYPE_ARRAY_LBOUND (type, dim);
      if (as->lower[dim] && !INTEGER_CST_P (lbound))
        {
          gfc_init_se (&se, NULL);
          gfc_conv_expr_type (&se, as->lower[dim], gfc_array_index_type);
          gfc_add_block_to_block (pblock, &se.pre);
          gfc_add_modify (pblock, lbound, se.expr);
        }
      ubound = GFC_TYPE_ARRAY_UBOUND (type, dim);
      if (as->upper[dim] && !INTEGER_CST_P (ubound))
        {
          gfc_init_se (&se, NULL);
          gfc_conv_expr_type (&se, as->upper[dim], gfc_array_index_type);
          gfc_add_block_to_block (pblock, &se.pre);
          gfc_add_modify (pblock, ubound, se.expr);
        }
      /* The offset of this dimension.  offset = offset - lbound * stride.  */
      tmp = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                             lbound, size);
      offset = fold_build2_loc (input_location, MINUS_EXPR, gfc_array_index_type,
                                offset, tmp);

      /* The size of this dimension, and the stride of the next.  */
      if (dim + 1 < as->rank)
        stride = GFC_TYPE_ARRAY_STRIDE (type, dim + 1);
      else
        stride = GFC_TYPE_ARRAY_SIZE (type);

      if (ubound != NULL_TREE && !(stride && INTEGER_CST_P (stride)))
        {
          /* Calculate stride = size * (ubound + 1 - lbound).  */
          tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                 gfc_array_index_type,
                                 gfc_index_one_node, lbound);
          tmp = fold_build2_loc (input_location, PLUS_EXPR,
                                 gfc_array_index_type, ubound, tmp);
          tmp = fold_build2_loc (input_location, MULT_EXPR,
                                 gfc_array_index_type, size, tmp);
          if (stride)
            gfc_add_modify (pblock, stride, tmp);
          else
            stride = gfc_evaluate_now (tmp, pblock);

          /* Make sure that negative size arrays are translated
             to being zero size.  */
          tmp = fold_build2_loc (input_location, GE_EXPR, boolean_type_node,
                                 stride, gfc_index_zero_node);
          tmp = fold_build3_loc (input_location, COND_EXPR,
                                 gfc_array_index_type, tmp,
                                 stride, gfc_index_zero_node);
          gfc_add_modify (pblock, stride, tmp);
        }

      size = stride;
    }

  gfc_trans_array_cobounds (type, pblock, sym);
  gfc_trans_vla_type_sizes (sym, pblock);

  *poffset = offset;
  return size;
}


/* Generate code to initialize/allocate an array variable.  */

void
gfc_trans_auto_array_allocation (tree decl, gfc_symbol * sym,
                                 gfc_wrapped_block * block)
{
  stmtblock_t init;
  tree type;
  tree tmp = NULL_TREE;
  tree size;
  tree offset;
  tree space;
  tree inittree;
  bool onstack;

  gcc_assert (!(sym->attr.pointer || sym->attr.allocatable));

  /* Do nothing for USEd variables.  */
  if (sym->attr.use_assoc)
    return;

  type = TREE_TYPE (decl);
  gcc_assert (GFC_ARRAY_TYPE_P (type));
  onstack = TREE_CODE (type) != POINTER_TYPE;

  gfc_init_block (&init);

  /* Evaluate character string length.  */
  if (sym->ts.type == BT_CHARACTER
      && onstack && !INTEGER_CST_P (sym->ts.u.cl->backend_decl))
    {
      gfc_conv_string_length (sym->ts.u.cl, NULL, &init);

      gfc_trans_vla_type_sizes (sym, &init);

      /* Emit a DECL_EXPR for this variable, which will cause the
         gimplifier to allocate storage, and all that good stuff.  */
      tmp = fold_build1_loc (input_location, DECL_EXPR, TREE_TYPE (decl), decl);
      gfc_add_expr_to_block (&init, tmp);
    }

  if (onstack)
    {
      gfc_add_init_cleanup (block, gfc_finish_block (&init), NULL_TREE);
      return;
    }

  type = TREE_TYPE (type);

  gcc_assert (!sym->attr.use_assoc);
  gcc_assert (!TREE_STATIC (decl));
  gcc_assert (!sym->module);

  if (sym->ts.type == BT_CHARACTER
      && !INTEGER_CST_P (sym->ts.u.cl->backend_decl))
    gfc_conv_string_length (sym->ts.u.cl, NULL, &init);

  size = gfc_trans_array_bounds (type, sym, &offset, &init);

  /* Don't actually allocate space for Cray Pointees.  */
  if (sym->attr.cray_pointee)
    {
      if (TREE_CODE (GFC_TYPE_ARRAY_OFFSET (type)) == VAR_DECL)
        gfc_add_modify (&init, GFC_TYPE_ARRAY_OFFSET (type), offset);

      gfc_add_init_cleanup (block, gfc_finish_block (&init), NULL_TREE);
      return;
    }

  if (gfc_option.flag_stack_arrays)
    {
      gcc_assert (TREE_CODE (TREE_TYPE (decl)) == POINTER_TYPE);
      space = build_decl (sym->declared_at.lb->location,
                          VAR_DECL, create_tmp_var_name ("A"),
                          TREE_TYPE (TREE_TYPE (decl)));
      gfc_trans_vla_type_sizes (sym, &init);
    }
  else
    {
      /* The size is the number of elements in the array, so multiply by the
         size of an element to get the total size.  */
      tmp = TYPE_SIZE_UNIT (gfc_get_element_type (type));
      size = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                              size, fold_convert (gfc_array_index_type, tmp));

      /* Allocate memory to hold the data.  */
      tmp = gfc_call_malloc (&init, TREE_TYPE (decl), size);
      gfc_add_modify (&init, decl, tmp);

      /* Free the temporary.  */
      tmp = gfc_call_free (convert (pvoid_type_node, decl));
      space = NULL_TREE;
    }

  /* Set offset of the array.  */
  if (TREE_CODE (GFC_TYPE_ARRAY_OFFSET (type)) == VAR_DECL)
    gfc_add_modify (&init, GFC_TYPE_ARRAY_OFFSET (type), offset);

  /* Automatic arrays should not have initializers.  */
  gcc_assert (!sym->value);

  inittree = gfc_finish_block (&init);

  if (space)
    {
      tree addr;
      pushdecl (space);

      /* Don't create new scope, emit the DECL_EXPR in exactly the scope
         where also space is located.  */
      gfc_init_block (&init);
      tmp = fold_build1_loc (input_location, DECL_EXPR,
                             TREE_TYPE (space), space);
      gfc_add_expr_to_block (&init, tmp);
      addr = fold_build1_loc (sym->declared_at.lb->location,
                              ADDR_EXPR, TREE_TYPE (decl), space);
      gfc_add_modify (&init, decl, addr);
      gfc_add_init_cleanup (block, gfc_finish_block (&init), NULL_TREE);
      tmp = NULL_TREE;
    }
  gfc_add_init_cleanup (block, inittree, tmp);
}


/* Generate entry and exit code for g77 calling convention arrays.  */

void
gfc_trans_g77_array (gfc_symbol * sym, gfc_wrapped_block * block)
{
  tree parm;
  tree type;
  locus loc;
  tree offset;
  tree tmp;
  tree stmt;
  stmtblock_t init;

  gfc_save_backend_locus (&loc);
  gfc_set_backend_locus (&sym->declared_at);

  /* Descriptor type.  */
  parm = sym->backend_decl;
  type = TREE_TYPE (parm);
  gcc_assert (GFC_ARRAY_TYPE_P (type));

  gfc_start_block (&init);

  if (sym->ts.type == BT_CHARACTER
      && TREE_CODE (sym->ts.u.cl->backend_decl) == VAR_DECL)
    gfc_conv_string_length (sym->ts.u.cl, NULL, &init);

  /* Evaluate the bounds of the array.  */
  gfc_trans_array_bounds (type, sym, &offset, &init);

  /* Set the offset.  */
  if (TREE_CODE (GFC_TYPE_ARRAY_OFFSET (type)) == VAR_DECL)
    gfc_add_modify (&init, GFC_TYPE_ARRAY_OFFSET (type), offset);

  /* Set the pointer itself if we aren't using the parameter directly.  */
  if (TREE_CODE (parm) != PARM_DECL)
    {
      tmp = convert (TREE_TYPE (parm), GFC_DECL_SAVED_DESCRIPTOR (parm));
      gfc_add_modify (&init, parm, tmp);
    }
  stmt = gfc_finish_block (&init);

  gfc_restore_backend_locus (&loc);

  /* Add the initialization code to the start of the function.  */

  if (sym->attr.optional || sym->attr.not_always_present)
    {
      tmp = gfc_conv_expr_present (sym);
      stmt = build3_v (COND_EXPR, tmp, stmt, build_empty_stmt (input_location));
    }
  
  gfc_add_init_cleanup (block, stmt, NULL_TREE);
}


/* Modify the descriptor of an array parameter so that it has the
   correct lower bound.  Also move the upper bound accordingly.
   If the array is not packed, it will be copied into a temporary.
   For each dimension we set the new lower and upper bounds.  Then we copy the
   stride and calculate the offset for this dimension.  We also work out
   what the stride of a packed array would be, and see it the two match.
   If the array need repacking, we set the stride to the values we just
   calculated, recalculate the offset and copy the array data.
   Code is also added to copy the data back at the end of the function.
   */

void
gfc_trans_dummy_array_bias (gfc_symbol * sym, tree tmpdesc,
                            gfc_wrapped_block * block)
{
  tree size;
  tree type;
  tree offset;
  locus loc;
  stmtblock_t init;
  tree stmtInit, stmtCleanup;
  tree lbound;
  tree ubound;
  tree dubound;
  tree dlbound;
  tree dumdesc;
  tree tmp;
  tree stride, stride2;
  tree stmt_packed;
  tree stmt_unpacked;
  tree partial;
  gfc_se se;
  int n;
  int checkparm;
  int no_repack;
  bool optional_arg;

  /* Do nothing for pointer and allocatable arrays.  */
  if (sym->attr.pointer || sym->attr.allocatable)
    return;

  if (sym->attr.dummy && gfc_is_nodesc_array (sym))
    {
      gfc_trans_g77_array (sym, block);
      return;
    }

  gfc_save_backend_locus (&loc);
  gfc_set_backend_locus (&sym->declared_at);

  /* Descriptor type.  */
  type = TREE_TYPE (tmpdesc);
  gcc_assert (GFC_ARRAY_TYPE_P (type));
  dumdesc = GFC_DECL_SAVED_DESCRIPTOR (tmpdesc);
  dumdesc = build_fold_indirect_ref_loc (input_location, dumdesc);
  gfc_start_block (&init);

  if (sym->ts.type == BT_CHARACTER
      && TREE_CODE (sym->ts.u.cl->backend_decl) == VAR_DECL)
    gfc_conv_string_length (sym->ts.u.cl, NULL, &init);

  checkparm = (sym->as->type == AS_EXPLICIT
               && (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS));

  no_repack = !(GFC_DECL_PACKED_ARRAY (tmpdesc)
                || GFC_DECL_PARTIAL_PACKED_ARRAY (tmpdesc));

  if (GFC_DECL_PARTIAL_PACKED_ARRAY (tmpdesc))
    {
      /* For non-constant shape arrays we only check if the first dimension
         is contiguous.  Repacking higher dimensions wouldn't gain us
         anything as we still don't know the array stride.  */
      partial = gfc_create_var (boolean_type_node, "partial");
      TREE_USED (partial) = 1;
      tmp = gfc_conv_descriptor_stride_get (dumdesc, gfc_rank_cst[0]);
      tmp = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node, tmp,
                             gfc_index_one_node);
      gfc_add_modify (&init, partial, tmp);
    }
  else
    partial = NULL_TREE;

  /* The naming of stmt_unpacked and stmt_packed may be counter-intuitive
     here, however I think it does the right thing.  */
  if (no_repack)
    {
      /* Set the first stride.  */
      stride = gfc_conv_descriptor_stride_get (dumdesc, gfc_rank_cst[0]);
      stride = gfc_evaluate_now (stride, &init);

      tmp = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node,
                             stride, gfc_index_zero_node);
      tmp = fold_build3_loc (input_location, COND_EXPR, gfc_array_index_type,
                             tmp, gfc_index_one_node, stride);
      stride = GFC_TYPE_ARRAY_STRIDE (type, 0);
      gfc_add_modify (&init, stride, tmp);

      /* Allow the user to disable array repacking.  */
      stmt_unpacked = NULL_TREE;
    }
  else
    {
      gcc_assert (integer_onep (GFC_TYPE_ARRAY_STRIDE (type, 0)));
      /* A library call to repack the array if necessary.  */
      tmp = GFC_DECL_SAVED_DESCRIPTOR (tmpdesc);
      stmt_unpacked = build_call_expr_loc (input_location,
                                       gfor_fndecl_in_pack, 1, tmp);

      stride = gfc_index_one_node;

      if (gfc_option.warn_array_temp)
        gfc_warning ("Creating array temporary at %L", &loc);
    }

  /* This is for the case where the array data is used directly without
     calling the repack function.  */
  if (no_repack || partial != NULL_TREE)
    stmt_packed = gfc_conv_descriptor_data_get (dumdesc);
  else
    stmt_packed = NULL_TREE;

  /* Assign the data pointer.  */
  if (stmt_packed != NULL_TREE && stmt_unpacked != NULL_TREE)
    {
      /* Don't repack unknown shape arrays when the first stride is 1.  */
      tmp = fold_build3_loc (input_location, COND_EXPR, TREE_TYPE (stmt_packed),
                             partial, stmt_packed, stmt_unpacked);
    }
  else
    tmp = stmt_packed != NULL_TREE ? stmt_packed : stmt_unpacked;
  gfc_add_modify (&init, tmpdesc, fold_convert (type, tmp));

  offset = gfc_index_zero_node;
  size = gfc_index_one_node;

  /* Evaluate the bounds of the array.  */
  for (n = 0; n < sym->as->rank; n++)
    {
      if (checkparm || !sym->as->upper[n])
        {
          /* Get the bounds of the actual parameter.  */
          dubound = gfc_conv_descriptor_ubound_get (dumdesc, gfc_rank_cst[n]);
          dlbound = gfc_conv_descriptor_lbound_get (dumdesc, gfc_rank_cst[n]);
        }
      else
        {
          dubound = NULL_TREE;
          dlbound = NULL_TREE;
        }

      lbound = GFC_TYPE_ARRAY_LBOUND (type, n);
      if (!INTEGER_CST_P (lbound))
        {
          gfc_init_se (&se, NULL);
          gfc_conv_expr_type (&se, sym->as->lower[n],
                              gfc_array_index_type);
          gfc_add_block_to_block (&init, &se.pre);
          gfc_add_modify (&init, lbound, se.expr);
        }

      ubound = GFC_TYPE_ARRAY_UBOUND (type, n);
      /* Set the desired upper bound.  */
      if (sym->as->upper[n])
        {
          /* We know what we want the upper bound to be.  */
          if (!INTEGER_CST_P (ubound))
            {
              gfc_init_se (&se, NULL);
              gfc_conv_expr_type (&se, sym->as->upper[n],
                                  gfc_array_index_type);
              gfc_add_block_to_block (&init, &se.pre);
              gfc_add_modify (&init, ubound, se.expr);
            }

          /* Check the sizes match.  */
          if (checkparm)
            {
              /* Check (ubound(a) - lbound(a) == ubound(b) - lbound(b)).  */
              char * msg;
              tree temp;

              temp = fold_build2_loc (input_location, MINUS_EXPR,
                                      gfc_array_index_type, ubound, lbound);
              temp = fold_build2_loc (input_location, PLUS_EXPR,
                                      gfc_array_index_type,
                                      gfc_index_one_node, temp);
              stride2 = fold_build2_loc (input_location, MINUS_EXPR,
                                         gfc_array_index_type, dubound,
                                         dlbound);
              stride2 = fold_build2_loc (input_location, PLUS_EXPR,
                                         gfc_array_index_type,
                                         gfc_index_one_node, stride2);
              tmp = fold_build2_loc (input_location, NE_EXPR,
                                     gfc_array_index_type, temp, stride2);
              asprintf (&msg, "Dimension %d of array '%s' has extent "
                        "%%ld instead of %%ld", n+1, sym->name);

              gfc_trans_runtime_check (true, false, tmp, &init, &loc, msg, 
                        fold_convert (long_integer_type_node, temp),
                        fold_convert (long_integer_type_node, stride2));

              free (msg);
            }
        }
      else
        {
          /* For assumed shape arrays move the upper bound by the same amount
             as the lower bound.  */
          tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                 gfc_array_index_type, dubound, dlbound);
          tmp = fold_build2_loc (input_location, PLUS_EXPR,
                                 gfc_array_index_type, tmp, lbound);
          gfc_add_modify (&init, ubound, tmp);
        }
      /* The offset of this dimension.  offset = offset - lbound * stride.  */
      tmp = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                             lbound, stride);
      offset = fold_build2_loc (input_location, MINUS_EXPR,
                                gfc_array_index_type, offset, tmp);

      /* The size of this dimension, and the stride of the next.  */
      if (n + 1 < sym->as->rank)
        {
          stride = GFC_TYPE_ARRAY_STRIDE (type, n + 1);

          if (no_repack || partial != NULL_TREE)
            stmt_unpacked =
              gfc_conv_descriptor_stride_get (dumdesc, gfc_rank_cst[n+1]);

          /* Figure out the stride if not a known constant.  */
          if (!INTEGER_CST_P (stride))
            {
              if (no_repack)
                stmt_packed = NULL_TREE;
              else
                {
                  /* Calculate stride = size * (ubound + 1 - lbound).  */
                  tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                         gfc_array_index_type,
                                         gfc_index_one_node, lbound);
                  tmp = fold_build2_loc (input_location, PLUS_EXPR,
                                         gfc_array_index_type, ubound, tmp);
                  size = fold_build2_loc (input_location, MULT_EXPR,
                                          gfc_array_index_type, size, tmp);
                  stmt_packed = size;
                }

              /* Assign the stride.  */
              if (stmt_packed != NULL_TREE && stmt_unpacked != NULL_TREE)
                tmp = fold_build3_loc (input_location, COND_EXPR,
                                       gfc_array_index_type, partial,
                                       stmt_unpacked, stmt_packed);
              else
                tmp = (stmt_packed != NULL_TREE) ? stmt_packed : stmt_unpacked;
              gfc_add_modify (&init, stride, tmp);
            }
        }
      else
        {
          stride = GFC_TYPE_ARRAY_SIZE (type);

          if (stride && !INTEGER_CST_P (stride))
            {
              /* Calculate size = stride * (ubound + 1 - lbound).  */
              tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                     gfc_array_index_type,
                                     gfc_index_one_node, lbound);
              tmp = fold_build2_loc (input_location, PLUS_EXPR,
                                     gfc_array_index_type,
                                     ubound, tmp);
              tmp = fold_build2_loc (input_location, MULT_EXPR,
                                     gfc_array_index_type,
                                     GFC_TYPE_ARRAY_STRIDE (type, n), tmp);
              gfc_add_modify (&init, stride, tmp);
            }
        }
    }

  gfc_trans_array_cobounds (type, &init, sym);

  /* Set the offset.  */
  if (TREE_CODE (GFC_TYPE_ARRAY_OFFSET (type)) == VAR_DECL)
    gfc_add_modify (&init, GFC_TYPE_ARRAY_OFFSET (type), offset);

  gfc_trans_vla_type_sizes (sym, &init);

  stmtInit = gfc_finish_block (&init);

  /* Only do the entry/initialization code if the arg is present.  */
  dumdesc = GFC_DECL_SAVED_DESCRIPTOR (tmpdesc);
  optional_arg = (sym->attr.optional
                  || (sym->ns->proc_name->attr.entry_master
                      && sym->attr.dummy));
  if (optional_arg)
    {
      tmp = gfc_conv_expr_present (sym);
      stmtInit = build3_v (COND_EXPR, tmp, stmtInit,
                           build_empty_stmt (input_location));
    }

  /* Cleanup code.  */
  if (no_repack)
    stmtCleanup = NULL_TREE;
  else
    {
      stmtblock_t cleanup;
      gfc_start_block (&cleanup);

      if (sym->attr.intent != INTENT_IN)
        {
          /* Copy the data back.  */
          tmp = build_call_expr_loc (input_location,
                                 gfor_fndecl_in_unpack, 2, dumdesc, tmpdesc);
          gfc_add_expr_to_block (&cleanup, tmp);
        }

      /* Free the temporary.  */
      tmp = gfc_call_free (tmpdesc);
      gfc_add_expr_to_block (&cleanup, tmp);

      stmtCleanup = gfc_finish_block (&cleanup);
        
      /* Only do the cleanup if the array was repacked.  */
      tmp = build_fold_indirect_ref_loc (input_location, dumdesc);
      tmp = gfc_conv_descriptor_data_get (tmp);
      tmp = fold_build2_loc (input_location, NE_EXPR, boolean_type_node,
                             tmp, tmpdesc);
      stmtCleanup = build3_v (COND_EXPR, tmp, stmtCleanup,
                              build_empty_stmt (input_location));

      if (optional_arg)
        {
          tmp = gfc_conv_expr_present (sym);
          stmtCleanup = build3_v (COND_EXPR, tmp, stmtCleanup,
                                  build_empty_stmt (input_location));
        }
    }

  /* We don't need to free any memory allocated by internal_pack as it will
     be freed at the end of the function by pop_context.  */
  gfc_add_init_cleanup (block, stmtInit, stmtCleanup);

  gfc_restore_backend_locus (&loc);
}


/* Calculate the overall offset, including subreferences.  */
static void
gfc_get_dataptr_offset (stmtblock_t *block, tree parm, tree desc, tree offset,
                        bool subref, gfc_expr *expr)
{
  tree tmp;
  tree field;
  tree stride;
  tree index;
  gfc_ref *ref;
  gfc_se start;
  int n;

  /* If offset is NULL and this is not a subreferenced array, there is
     nothing to do.  */
  if (offset == NULL_TREE)
    {
      if (subref)
        offset = gfc_index_zero_node;
      else
        return;
    }

  tmp = gfc_conv_array_data (desc);
  tmp = build_fold_indirect_ref_loc (input_location,
                                 tmp);
  tmp = gfc_build_array_ref (tmp, offset, NULL);

  /* Offset the data pointer for pointer assignments from arrays with
     subreferences; e.g. my_integer => my_type(:)%integer_component.  */
  if (subref)
    {
      /* Go past the array reference.  */
      for (ref = expr->ref; ref; ref = ref->next)
        if (ref->type == REF_ARRAY &&
              ref->u.ar.type != AR_ELEMENT)
          {
            ref = ref->next;
            break;
          }

      /* Calculate the offset for each subsequent subreference.  */
      for (; ref; ref = ref->next)
        {
          switch (ref->type)
            {
            case REF_COMPONENT:
              field = ref->u.c.component->backend_decl;
              gcc_assert (field && TREE_CODE (field) == FIELD_DECL);
              tmp = fold_build3_loc (input_location, COMPONENT_REF,
                                     TREE_TYPE (field),
                                     tmp, field, NULL_TREE);
              break;

            case REF_SUBSTRING:
              gcc_assert (TREE_CODE (TREE_TYPE (tmp)) == ARRAY_TYPE);
              gfc_init_se (&start, NULL);
              gfc_conv_expr_type (&start, ref->u.ss.start, gfc_charlen_type_node);
              gfc_add_block_to_block (block, &start.pre);
              tmp = gfc_build_array_ref (tmp, start.expr, NULL);
              break;

            case REF_ARRAY:
              gcc_assert (TREE_CODE (TREE_TYPE (tmp)) == ARRAY_TYPE
                            && ref->u.ar.type == AR_ELEMENT);

              /* TODO - Add bounds checking.  */
              stride = gfc_index_one_node;
              index = gfc_index_zero_node;
              for (n = 0; n < ref->u.ar.dimen; n++)
                {
                  tree itmp;
                  tree jtmp;

                  /* Update the index.  */
                  gfc_init_se (&start, NULL);
                  gfc_conv_expr_type (&start, ref->u.ar.start[n], gfc_array_index_type);
                  itmp = gfc_evaluate_now (start.expr, block);
                  gfc_init_se (&start, NULL);
                  gfc_conv_expr_type (&start, ref->u.ar.as->lower[n], gfc_array_index_type);
                  jtmp = gfc_evaluate_now (start.expr, block);
                  itmp = fold_build2_loc (input_location, MINUS_EXPR,
                                          gfc_array_index_type, itmp, jtmp);
                  itmp = fold_build2_loc (input_location, MULT_EXPR,
                                          gfc_array_index_type, itmp, stride);
                  index = fold_build2_loc (input_location, PLUS_EXPR,
                                          gfc_array_index_type, itmp, index);
                  index = gfc_evaluate_now (index, block);

                  /* Update the stride.  */
                  gfc_init_se (&start, NULL);
                  gfc_conv_expr_type (&start, ref->u.ar.as->upper[n], gfc_array_index_type);
                  itmp =  fold_build2_loc (input_location, MINUS_EXPR,
                                           gfc_array_index_type, start.expr,
                                           jtmp);
                  itmp =  fold_build2_loc (input_location, PLUS_EXPR,
                                           gfc_array_index_type,
                                           gfc_index_one_node, itmp);
                  stride =  fold_build2_loc (input_location, MULT_EXPR,
                                             gfc_array_index_type, stride, itmp);
                  stride = gfc_evaluate_now (stride, block);
                }

              /* Apply the index to obtain the array element.  */
              tmp = gfc_build_array_ref (tmp, index, NULL);
              break;

            default:
              gcc_unreachable ();
              break;
            }
        }
    }

  /* Set the target data pointer.  */
  offset = gfc_build_addr_expr (gfc_array_dataptr_type (desc), tmp);
  gfc_conv_descriptor_data_set (block, parm, offset);
}


/* gfc_conv_expr_descriptor needs the string length an expression
   so that the size of the temporary can be obtained.  This is done
   by adding up the string lengths of all the elements in the
   expression.  Function with non-constant expressions have their
   string lengths mapped onto the actual arguments using the
   interface mapping machinery in trans-expr.c.  */
static void
get_array_charlen (gfc_expr *expr, gfc_se *se)
{
  gfc_interface_mapping mapping;
  gfc_formal_arglist *formal;
  gfc_actual_arglist *arg;
  gfc_se tse;

  if (expr->ts.u.cl->length
        && gfc_is_constant_expr (expr->ts.u.cl->length))
    {
      if (!expr->ts.u.cl->backend_decl)
        gfc_conv_string_length (expr->ts.u.cl, expr, &se->pre);
      return;
    }

  switch (expr->expr_type)
    {
    case EXPR_OP:
      get_array_charlen (expr->value.op.op1, se);

      /* For parentheses the expression ts.u.cl is identical.  */
      if (expr->value.op.op == INTRINSIC_PARENTHESES)
        return;

     expr->ts.u.cl->backend_decl =
                gfc_create_var (gfc_charlen_type_node, "sln");

      if (expr->value.op.op2)
        {
          get_array_charlen (expr->value.op.op2, se);

          gcc_assert (expr->value.op.op == INTRINSIC_CONCAT);

          /* Add the string lengths and assign them to the expression
             string length backend declaration.  */
          gfc_add_modify (&se->pre, expr->ts.u.cl->backend_decl,
                          fold_build2_loc (input_location, PLUS_EXPR,
                                gfc_charlen_type_node,
                                expr->value.op.op1->ts.u.cl->backend_decl,
                                expr->value.op.op2->ts.u.cl->backend_decl));
        }
      else
        gfc_add_modify (&se->pre, expr->ts.u.cl->backend_decl,
                        expr->value.op.op1->ts.u.cl->backend_decl);
      break;

    case EXPR_FUNCTION:
      if (expr->value.function.esym == NULL
            || expr->ts.u.cl->length->expr_type == EXPR_CONSTANT)
        {
          gfc_conv_string_length (expr->ts.u.cl, expr, &se->pre);
          break;
        }

      /* Map expressions involving the dummy arguments onto the actual
         argument expressions.  */
      gfc_init_interface_mapping (&mapping);
      formal = expr->symtree->n.sym->formal;
      arg = expr->value.function.actual;

      /* Set se = NULL in the calls to the interface mapping, to suppress any
         backend stuff.  */
      for (; arg != NULL; arg = arg->next, formal = formal ? formal->next : NULL)
        {
          if (!arg->expr)
            continue;
          if (formal->sym)
          gfc_add_interface_mapping (&mapping, formal->sym, NULL, arg->expr);
        }

      gfc_init_se (&tse, NULL);

      /* Build the expression for the character length and convert it.  */
      gfc_apply_interface_mapping (&mapping, &tse, expr->ts.u.cl->length);

      gfc_add_block_to_block (&se->pre, &tse.pre);
      gfc_add_block_to_block (&se->post, &tse.post);
      tse.expr = fold_convert (gfc_charlen_type_node, tse.expr);
      tse.expr = fold_build2_loc (input_location, MAX_EXPR,
                                  gfc_charlen_type_node, tse.expr,
                                  build_int_cst (gfc_charlen_type_node, 0));
      expr->ts.u.cl->backend_decl = tse.expr;
      gfc_free_interface_mapping (&mapping);
      break;

    default:
      gfc_conv_string_length (expr->ts.u.cl, expr, &se->pre);
      break;
    }
}


/* Helper function to check dimensions.  */
static bool
transposed_dims (gfc_ss *ss)
{
  int n;

  for (n = 0; n < ss->dimen; n++)
    if (ss->dim[n] != n)
      return true;
  return false;
}

/* Convert an array for passing as an actual argument.  Expressions and
   vector subscripts are evaluated and stored in a temporary, which is then
   passed.  For whole arrays the descriptor is passed.  For array sections
   a modified copy of the descriptor is passed, but using the original data.

   This function is also used for array pointer assignments, and there
   are three cases:

     - se->want_pointer && !se->direct_byref
         EXPR is an actual argument.  On exit, se->expr contains a
         pointer to the array descriptor.

     - !se->want_pointer && !se->direct_byref
         EXPR is an actual argument to an intrinsic function or the
         left-hand side of a pointer assignment.  On exit, se->expr
         contains the descriptor for EXPR.

     - !se->want_pointer && se->direct_byref
         EXPR is the right-hand side of a pointer assignment and
         se->expr is the descriptor for the previously-evaluated
         left-hand side.  The function creates an assignment from
         EXPR to se->expr.  


   The se->force_tmp flag disables the non-copying descriptor optimization
   that is used for transpose. It may be used in cases where there is an
   alias between the transpose argument and another argument in the same
   function call.  */

void
gfc_conv_expr_descriptor (gfc_se * se, gfc_expr * expr, gfc_ss * ss)
{
  gfc_ss_type ss_type;
  gfc_ss_info *ss_info;
  gfc_loopinfo loop;
  gfc_array_info *info;
  int need_tmp;
  int n;
  tree tmp;
  tree desc;
  stmtblock_t block;
  tree start;
  tree offset;
  int full;
  bool subref_array_target = false;
  gfc_expr *arg, *ss_expr;

  gcc_assert (ss != NULL);
  gcc_assert (ss != gfc_ss_terminator);

  ss_info = ss->info;
  ss_type = ss_info->type;
  ss_expr = ss_info->expr;

  /* Special case things we know we can pass easily.  */
  switch (expr->expr_type)
    {
    case EXPR_VARIABLE:
      /* If we have a linear array section, we can pass it directly.
         Otherwise we need to copy it into a temporary.  */

      gcc_assert (ss_type == GFC_SS_SECTION);
      gcc_assert (ss_expr == expr);
      info = &ss_info->data.array;

      /* Get the descriptor for the array.  */
      gfc_conv_ss_descriptor (&se->pre, ss, 0);
      desc = info->descriptor;

      subref_array_target = se->direct_byref && is_subref_array (expr);
      need_tmp = gfc_ref_needs_temporary_p (expr->ref)
                        && !subref_array_target;

      if (se->force_tmp)
        need_tmp = 1;

      if (need_tmp)
        full = 0;
      else if (GFC_ARRAY_TYPE_P (TREE_TYPE (desc)))
        {
          /* Create a new descriptor if the array doesn't have one.  */
          full = 0;
        }
      else if (info->ref->u.ar.type == AR_FULL)
        full = 1;
      else if (se->direct_byref)
        full = 0;
      else
        full = gfc_full_array_ref_p (info->ref, NULL);

      if (full && !transposed_dims (ss))
        {
          if (se->direct_byref && !se->byref_noassign)
            {
              /* Copy the descriptor for pointer assignments.  */
              gfc_add_modify (&se->pre, se->expr, desc);

              /* Add any offsets from subreferences.  */
              gfc_get_dataptr_offset (&se->pre, se->expr, desc, NULL_TREE,
                                      subref_array_target, expr);
            }
          else if (se->want_pointer)
            {
              /* We pass full arrays directly.  This means that pointers and
                 allocatable arrays should also work.  */
              se->expr = gfc_build_addr_expr (NULL_TREE, desc);
            }
          else
            {
              se->expr = desc;
            }

          if (expr->ts.type == BT_CHARACTER)
            se->string_length = gfc_get_expr_charlen (expr);

          return;
        }
      break;
      
    case EXPR_FUNCTION:

      /* We don't need to copy data in some cases.  */
      arg = gfc_get_noncopying_intrinsic_argument (expr);
      if (arg)
        {
          /* This is a call to transpose...  */
          gcc_assert (expr->value.function.isym->id == GFC_ISYM_TRANSPOSE);
          /* ... which has already been handled by the scalarizer, so
             that we just need to get its argument's descriptor.  */
          gfc_conv_expr_descriptor (se, expr->value.function.actual->expr, ss);
          return;
        }

      /* A transformational function return value will be a temporary
         array descriptor.  We still need to go through the scalarizer
         to create the descriptor.  Elemental functions ar handled as
         arbitrary expressions, i.e. copy to a temporary.  */

      if (se->direct_byref)
        {
          gcc_assert (ss_type == GFC_SS_FUNCTION && ss_expr == expr);

          /* For pointer assignments pass the descriptor directly.  */
          if (se->ss == NULL)
            se->ss = ss;
          else
            gcc_assert (se->ss == ss);
          se->expr = gfc_build_addr_expr (NULL_TREE, se->expr);
          gfc_conv_expr (se, expr);
          return;
        }

      if (ss_expr != expr || ss_type != GFC_SS_FUNCTION)
        {
          if (ss_expr != expr)
            /* Elemental function.  */
            gcc_assert ((expr->value.function.esym != NULL
                         && expr->value.function.esym->attr.elemental)
                        || (expr->value.function.isym != NULL
                            && expr->value.function.isym->elemental));
          else
            gcc_assert (ss_type == GFC_SS_INTRINSIC);

          need_tmp = 1;
          if (expr->ts.type == BT_CHARACTER
                && expr->ts.u.cl->length->expr_type != EXPR_CONSTANT)
            get_array_charlen (expr, se);

          info = NULL;
        }
      else
        {
          /* Transformational function.  */
          info = &ss_info->data.array;
          need_tmp = 0;
        }
      break;

    case EXPR_ARRAY:
      /* Constant array constructors don't need a temporary.  */
      if (ss_type == GFC_SS_CONSTRUCTOR
          && expr->ts.type != BT_CHARACTER
          && gfc_constant_array_constructor_p (expr->value.constructor))
        {
          need_tmp = 0;
          info = &ss_info->data.array;
        }
      else
        {
          need_tmp = 1;
          info = NULL;
        }
      break;

    default:
      /* Something complicated.  Copy it into a temporary.  */
      need_tmp = 1;
      info = NULL;
      break;
    }

  /* If we are creating a temporary, we don't need to bother about aliases
     anymore.  */
  if (need_tmp)
    se->force_tmp = 0;

  gfc_init_loopinfo (&loop);

  /* Associate the SS with the loop.  */
  gfc_add_ss_to_loop (&loop, ss);

  /* Tell the scalarizer not to bother creating loop variables, etc.  */
  if (!need_tmp)
    loop.array_parameter = 1;
  else
    /* The right-hand side of a pointer assignment mustn't use a temporary.  */
    gcc_assert (!se->direct_byref);

  /* Setup the scalarizing loops and bounds.  */
  gfc_conv_ss_startstride (&loop);

  if (need_tmp)
    {
      if (expr->ts.type == BT_CHARACTER && !expr->ts.u.cl->backend_decl)
        get_array_charlen (expr, se);

      /* Tell the scalarizer to make a temporary.  */
      loop.temp_ss = gfc_get_temp_ss (gfc_typenode_for_spec (&expr->ts),
                                      ((expr->ts.type == BT_CHARACTER)
                                       ? expr->ts.u.cl->backend_decl
                                       : NULL),
                                      loop.dimen);

      se->string_length = loop.temp_ss->info->string_length;
      gcc_assert (loop.temp_ss->dimen == loop.dimen);
      gfc_add_ss_to_loop (&loop, loop.temp_ss);
    }

  gfc_conv_loop_setup (&loop, & expr->where);

  if (need_tmp)
    {
      /* Copy into a temporary and pass that.  We don't need to copy the data
         back because expressions and vector subscripts must be INTENT_IN.  */
      /* TODO: Optimize passing function return values.  */
      gfc_se lse;
      gfc_se rse;

      /* Start the copying loops.  */
      gfc_mark_ss_chain_used (loop.temp_ss, 1);
      gfc_mark_ss_chain_used (ss, 1);
      gfc_start_scalarized_body (&loop, &block);

      /* Copy each data element.  */
      gfc_init_se (&lse, NULL);
      gfc_copy_loopinfo_to_se (&lse, &loop);
      gfc_init_se (&rse, NULL);
      gfc_copy_loopinfo_to_se (&rse, &loop);

      lse.ss = loop.temp_ss;
      rse.ss = ss;

      gfc_conv_scalarized_array_ref (&lse, NULL);
      if (expr->ts.type == BT_CHARACTER)
        {
          gfc_conv_expr (&rse, expr);
          if (POINTER_TYPE_P (TREE_TYPE (rse.expr)))
            rse.expr = build_fold_indirect_ref_loc (input_location,
                                                rse.expr);
        }
      else
        gfc_conv_expr_val (&rse, expr);

      gfc_add_block_to_block (&block, &rse.pre);
      gfc_add_block_to_block (&block, &lse.pre);

      lse.string_length = rse.string_length;
      tmp = gfc_trans_scalar_assign (&lse, &rse, expr->ts, true,
                                     expr->expr_type == EXPR_VARIABLE
                                     || expr->expr_type == EXPR_ARRAY, true);
      gfc_add_expr_to_block (&block, tmp);

      /* Finish the copying loops.  */
      gfc_trans_scalarizing_loops (&loop, &block);

      desc = loop.temp_ss->info->data.array.descriptor;
    }
  else if (expr->expr_type == EXPR_FUNCTION && !transposed_dims (ss))
    {
      desc = info->descriptor;
      se->string_length = ss_info->string_length;
    }
  else
    {
      /* We pass sections without copying to a temporary.  Make a new
         descriptor and point it at the section we want.  The loop variable
         limits will be the limits of the section.
         A function may decide to repack the array to speed up access, but
         we're not bothered about that here.  */
      int dim, ndim, codim;
      tree parm;
      tree parmtype;
      tree stride;
      tree from;
      tree to;
      tree base;

      ndim = info->ref ? info->ref->u.ar.dimen : ss->dimen;

      if (se->want_coarray)
        {
          gfc_array_ref *ar = &info->ref->u.ar;

          codim = gfc_get_corank (expr);
          for (n = 0; n < codim - 1; n++)
            {
              /* Make sure we are not lost somehow.  */
              gcc_assert (ar->dimen_type[n + ndim] == DIMEN_THIS_IMAGE);

              /* Make sure the call to gfc_conv_section_startstride won't
                 generate unnecessary code to calculate stride.  */
              gcc_assert (ar->stride[n + ndim] == NULL);

              gfc_conv_section_startstride (&loop, ss, n + ndim);
              loop.from[n + loop.dimen] = info->start[n + ndim];
              loop.to[n + loop.dimen]   = info->end[n + ndim];
            }

          gcc_assert (n == codim - 1);
          evaluate_bound (&loop.pre, info->start, ar->start,
                          info->descriptor, n + ndim, true);
          loop.from[n + loop.dimen] = info->start[n + ndim];
        }
      else
        codim = 0;

      /* Set the string_length for a character array.  */
      if (expr->ts.type == BT_CHARACTER)
        se->string_length =  gfc_get_expr_charlen (expr);

      desc = info->descriptor;
      if (se->direct_byref && !se->byref_noassign)
        {
          /* For pointer assignments we fill in the destination.  */
          parm = se->expr;
          parmtype = TREE_TYPE (parm);
        }
      else
        {
          /* Otherwise make a new one.  */
          parmtype = gfc_get_element_type (TREE_TYPE (desc));
          parmtype = gfc_get_array_type_bounds (parmtype, loop.dimen, codim,
                                                loop.from, loop.to, 0,
                                                GFC_ARRAY_UNKNOWN, false);
          parm = gfc_create_var (parmtype, "parm");
        }

      offset = gfc_index_zero_node;

      /* The following can be somewhat confusing.  We have two
         descriptors, a new one and the original array.
         {parm, parmtype, dim} refer to the new one.
         {desc, type, n, loop} refer to the original, which maybe
         a descriptorless array.
         The bounds of the scalarization are the bounds of the section.
         We don't have to worry about numeric overflows when calculating
         the offsets because all elements are within the array data.  */

      /* Set the dtype.  */
      tmp = gfc_conv_descriptor_dtype (parm);
      gfc_add_modify (&loop.pre, tmp, gfc_get_dtype (parmtype));

      /* Set offset for assignments to pointer only to zero if it is not
         the full array.  */
      if (se->direct_byref
          && info->ref && info->ref->u.ar.type != AR_FULL)
        base = gfc_index_zero_node;
      else if (GFC_ARRAY_TYPE_P (TREE_TYPE (desc)))
        base = gfc_evaluate_now (gfc_conv_array_offset (desc), &loop.pre);
      else
        base = NULL_TREE;

      for (n = 0; n < ndim; n++)
        {
          stride = gfc_conv_array_stride (desc, n);

          /* Work out the offset.  */
          if (info->ref
              && info->ref->u.ar.dimen_type[n] == DIMEN_ELEMENT)
            {
              gcc_assert (info->subscript[n]
                          && info->subscript[n]->info->type == GFC_SS_SCALAR);
              start = info->subscript[n]->info->data.scalar.value;
            }
          else
            {
              /* Evaluate and remember the start of the section.  */
              start = info->start[n];
              stride = gfc_evaluate_now (stride, &loop.pre);
            }

          tmp = gfc_conv_array_lbound (desc, n);
          tmp = fold_build2_loc (input_location, MINUS_EXPR, TREE_TYPE (tmp),
                                 start, tmp);
          tmp = fold_build2_loc (input_location, MULT_EXPR, TREE_TYPE (tmp),
                                 tmp, stride);
          offset = fold_build2_loc (input_location, PLUS_EXPR, TREE_TYPE (tmp),
                                    offset, tmp);

          if (info->ref
              && info->ref->u.ar.dimen_type[n] == DIMEN_ELEMENT)
            {
              /* For elemental dimensions, we only need the offset.  */
              continue;
            }

          /* Vector subscripts need copying and are handled elsewhere.  */
          if (info->ref)
            gcc_assert (info->ref->u.ar.dimen_type[n] == DIMEN_RANGE);
 
          /* look for the corresponding scalarizer dimension: dim.  */
          for (dim = 0; dim < ndim; dim++)
            if (ss->dim[dim] == n)
              break;

          /* loop exited early: the DIM being looked for has been found.  */
          gcc_assert (dim < ndim);

          /* Set the new lower bound.  */
          from = loop.from[dim];
          to = loop.to[dim];

          /* If we have an array section or are assigning make sure that
             the lower bound is 1.  References to the full
             array should otherwise keep the original bounds.  */
          if ((!info->ref
                  || info->ref->u.ar.type != AR_FULL)
              && !integer_onep (from))
            {
              tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                     gfc_array_index_type, gfc_index_one_node,
                                     from);
              to = fold_build2_loc (input_location, PLUS_EXPR,
                                    gfc_array_index_type, to, tmp);
              from = gfc_index_one_node;
            }
          gfc_conv_descriptor_lbound_set (&loop.pre, parm,
                                          gfc_rank_cst[dim], from);

          /* Set the new upper bound.  */
          gfc_conv_descriptor_ubound_set (&loop.pre, parm,
                                          gfc_rank_cst[dim], to);

          /* Multiply the stride by the section stride to get the
             total stride.  */
          stride = fold_build2_loc (input_location, MULT_EXPR,
                                    gfc_array_index_type,
                                    stride, info->stride[n]);

          if (se->direct_byref
              && info->ref
              && info->ref->u.ar.type != AR_FULL)
            {
              base = fold_build2_loc (input_location, MINUS_EXPR,
                                      TREE_TYPE (base), base, stride);
            }
          else if (GFC_ARRAY_TYPE_P (TREE_TYPE (desc)))
            {
              tmp = gfc_conv_array_lbound (desc, n);
              tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                     TREE_TYPE (base), tmp, loop.from[dim]);
              tmp = fold_build2_loc (input_location, MULT_EXPR,
                                     TREE_TYPE (base), tmp,
                                     gfc_conv_array_stride (desc, n));
              base = fold_build2_loc (input_location, PLUS_EXPR,
                                     TREE_TYPE (base), tmp, base);
            }

          /* Store the new stride.  */
          gfc_conv_descriptor_stride_set (&loop.pre, parm,
                                          gfc_rank_cst[dim], stride);
        }

      for (n = loop.dimen; n < loop.dimen + codim; n++)
        {
          from = loop.from[n];
          to = loop.to[n];
          gfc_conv_descriptor_lbound_set (&loop.pre, parm,
                                          gfc_rank_cst[n], from);
          if (n < loop.dimen + codim - 1)
            gfc_conv_descriptor_ubound_set (&loop.pre, parm,
                                            gfc_rank_cst[n], to);
        }

      if (se->data_not_needed)
        gfc_conv_descriptor_data_set (&loop.pre, parm,
                                      gfc_index_zero_node);
      else
        /* Point the data pointer at the 1st element in the section.  */
        gfc_get_dataptr_offset (&loop.pre, parm, desc, offset,
                                subref_array_target, expr);

      if ((se->direct_byref || GFC_ARRAY_TYPE_P (TREE_TYPE (desc)))
          && !se->data_not_needed)
        {
          /* Set the offset.  */
          gfc_conv_descriptor_offset_set (&loop.pre, parm, base);
        }
      else
        {
          /* Only the callee knows what the correct offset it, so just set
             it to zero here.  */
          gfc_conv_descriptor_offset_set (&loop.pre, parm, gfc_index_zero_node);
        }
      desc = parm;
    }

  if (!se->direct_byref || se->byref_noassign)
    {
      /* Get a pointer to the new descriptor.  */
      if (se->want_pointer)
        se->expr = gfc_build_addr_expr (NULL_TREE, desc);
      else
        se->expr = desc;
    }

  gfc_add_block_to_block (&se->pre, &loop.pre);
  gfc_add_block_to_block (&se->post, &loop.post);

  /* Cleanup the scalarizer.  */
  gfc_cleanup_loop (&loop);
}

/* Helper function for gfc_conv_array_parameter if array size needs to be
   computed.  */

static void
array_parameter_size (tree desc, gfc_expr *expr, tree *size)
{
  tree elem;
  if (GFC_ARRAY_TYPE_P (TREE_TYPE (desc)))
    *size = GFC_TYPE_ARRAY_SIZE (TREE_TYPE (desc));
  else if (expr->rank > 1)
    *size = build_call_expr_loc (input_location,
                             gfor_fndecl_size0, 1,
                             gfc_build_addr_expr (NULL, desc));
  else
    {
      tree ubound = gfc_conv_descriptor_ubound_get (desc, gfc_index_zero_node);
      tree lbound = gfc_conv_descriptor_lbound_get (desc, gfc_index_zero_node);

      *size = fold_build2_loc (input_location, MINUS_EXPR,
                               gfc_array_index_type, ubound, lbound);
      *size = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                               *size, gfc_index_one_node);
      *size = fold_build2_loc (input_location, MAX_EXPR, gfc_array_index_type,
                               *size, gfc_index_zero_node);
    }
  elem = TYPE_SIZE_UNIT (gfc_get_element_type (TREE_TYPE (desc)));
  *size = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                           *size, fold_convert (gfc_array_index_type, elem));
}

/* Convert an array for passing as an actual parameter.  */
/* TODO: Optimize passing g77 arrays.  */

void
gfc_conv_array_parameter (gfc_se * se, gfc_expr * expr, gfc_ss * ss, bool g77,
                          const gfc_symbol *fsym, const char *proc_name,
                          tree *size)
{
  tree ptr;
  tree desc;
  tree tmp = NULL_TREE;
  tree stmt;
  tree parent = DECL_CONTEXT (current_function_decl);
  bool full_array_var;
  bool this_array_result;
  bool contiguous;
  bool no_pack;
  bool array_constructor;
  bool good_allocatable;
  bool ultimate_ptr_comp;
  bool ultimate_alloc_comp;
  gfc_symbol *sym;
  stmtblock_t block;
  gfc_ref *ref;

  ultimate_ptr_comp = false;
  ultimate_alloc_comp = false;

  for (ref = expr->ref; ref; ref = ref->next)
    {
      if (ref->next == NULL)
        break;

      if (ref->type == REF_COMPONENT)
        {
          ultimate_ptr_comp = ref->u.c.component->attr.pointer;
          ultimate_alloc_comp = ref->u.c.component->attr.allocatable;
        }
    }

  full_array_var = false;
  contiguous = false;

  if (expr->expr_type == EXPR_VARIABLE && ref && !ultimate_ptr_comp)
    full_array_var = gfc_full_array_ref_p (ref, &contiguous);

  sym = full_array_var ? expr->symtree->n.sym : NULL;

  /* The symbol should have an array specification.  */
  gcc_assert (!sym || sym->as || ref->u.ar.as);

  if (expr->expr_type == EXPR_ARRAY && expr->ts.type == BT_CHARACTER)
    {
      get_array_ctor_strlen (&se->pre, expr->value.constructor, &tmp);
      expr->ts.u.cl->backend_decl = tmp;
      se->string_length = tmp;
    }

  /* Is this the result of the enclosing procedure?  */
  this_array_result = (full_array_var && sym->attr.flavor == FL_PROCEDURE);
  if (this_array_result
        && (sym->backend_decl != current_function_decl)
        && (sym->backend_decl != parent))
    this_array_result = false;

  /* Passing address of the array if it is not pointer or assumed-shape.  */
  if (full_array_var && g77 && !this_array_result)
    {
      tmp = gfc_get_symbol_decl (sym);

      if (sym->ts.type == BT_CHARACTER)
        se->string_length = sym->ts.u.cl->backend_decl;

      if (sym->ts.type == BT_DERIVED || sym->ts.type == BT_CLASS)
        {
          gfc_conv_expr_descriptor (se, expr, ss);
          se->expr = gfc_conv_array_data (se->expr);
          return;
        }

      if (!sym->attr.pointer
            && sym->as
            && sym->as->type != AS_ASSUMED_SHAPE 
            && !sym->attr.allocatable)
        {
          /* Some variables are declared directly, others are declared as
             pointers and allocated on the heap.  */
          if (sym->attr.dummy || POINTER_TYPE_P (TREE_TYPE (tmp)))
            se->expr = tmp;
          else
            se->expr = gfc_build_addr_expr (NULL_TREE, tmp);
          if (size)
            array_parameter_size (tmp, expr, size);
          return;
        }

      if (sym->attr.allocatable)
        {
          if (sym->attr.dummy || sym->attr.result)
            {
              gfc_conv_expr_descriptor (se, expr, ss);
              tmp = se->expr;
            }
          if (size)
            array_parameter_size (tmp, expr, size);
          se->expr = gfc_conv_array_data (tmp);
          return;
        }
    }

  /* A convenient reduction in scope.  */
  contiguous = g77 && !this_array_result && contiguous;

  /* There is no need to pack and unpack the array, if it is contiguous
     and not a deferred- or assumed-shape array, or if it is simply
     contiguous.  */
  no_pack = ((sym && sym->as
                  && !sym->attr.pointer
                  && sym->as->type != AS_DEFERRED
                  && sym->as->type != AS_ASSUMED_SHAPE)
                      ||
             (ref && ref->u.ar.as
                  && ref->u.ar.as->type != AS_DEFERRED
                  && ref->u.ar.as->type != AS_ASSUMED_SHAPE)
                      ||
             gfc_is_simply_contiguous (expr, false));

  no_pack = contiguous && no_pack;

  /* Array constructors are always contiguous and do not need packing.  */
  array_constructor = g77 && !this_array_result && expr->expr_type == EXPR_ARRAY;

  /* Same is true of contiguous sections from allocatable variables.  */
  good_allocatable = contiguous
                       && expr->symtree
                       && expr->symtree->n.sym->attr.allocatable;

  /* Or ultimate allocatable components.  */
  ultimate_alloc_comp = contiguous && ultimate_alloc_comp; 

  if (no_pack || array_constructor || good_allocatable || ultimate_alloc_comp)
    {
      gfc_conv_expr_descriptor (se, expr, ss);
      if (expr->ts.type == BT_CHARACTER)
        se->string_length = expr->ts.u.cl->backend_decl;
      if (size)
        array_parameter_size (se->expr, expr, size);
      se->expr = gfc_conv_array_data (se->expr);
      return;
    }

  if (this_array_result)
    {
      /* Result of the enclosing function.  */
      gfc_conv_expr_descriptor (se, expr, ss);
      if (size)
        array_parameter_size (se->expr, expr, size);
      se->expr = gfc_build_addr_expr (NULL_TREE, se->expr);

      if (g77 && TREE_TYPE (TREE_TYPE (se->expr)) != NULL_TREE
              && GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (TREE_TYPE (se->expr))))
        se->expr = gfc_conv_array_data (build_fold_indirect_ref_loc (input_location,
                                                                 se->expr));

      return;
    }
  else
    {
      /* Every other type of array.  */
      se->want_pointer = 1;
      gfc_conv_expr_descriptor (se, expr, ss);
      if (size)
        array_parameter_size (build_fold_indirect_ref_loc (input_location,
                                                       se->expr),
                                  expr, size);
    }

  /* Deallocate the allocatable components of structures that are
     not variable.  */
  if ((expr->ts.type == BT_DERIVED || expr->ts.type == BT_CLASS)
        && expr->ts.u.derived->attr.alloc_comp
        && expr->expr_type != EXPR_VARIABLE)
    {
      tmp = build_fold_indirect_ref_loc (input_location, se->expr);
      tmp = gfc_deallocate_alloc_comp (expr->ts.u.derived, tmp, expr->rank);

      /* The components shall be deallocated before their containing entity.  */
      gfc_prepend_expr_to_block (&se->post, tmp);
    }

  if (g77 || (fsym && fsym->attr.contiguous
              && !gfc_is_simply_contiguous (expr, false)))
    {
      tree origptr = NULL_TREE;

      desc = se->expr;

      /* For contiguous arrays, save the original value of the descriptor.  */
      if (!g77)
        {
          origptr = gfc_create_var (pvoid_type_node, "origptr");
          tmp = build_fold_indirect_ref_loc (input_location, desc);
          tmp = gfc_conv_array_data (tmp);
          tmp = fold_build2_loc (input_location, MODIFY_EXPR,
                                 TREE_TYPE (origptr), origptr,
                                 fold_convert (TREE_TYPE (origptr), tmp));
          gfc_add_expr_to_block (&se->pre, tmp);
        }

      /* Repack the array.  */
      if (gfc_option.warn_array_temp)
        {
          if (fsym)
            gfc_warning ("Creating array temporary at %L for argument '%s'",
                         &expr->where, fsym->name);
          else
            gfc_warning ("Creating array temporary at %L", &expr->where);
        }

      ptr = build_call_expr_loc (input_location,
                             gfor_fndecl_in_pack, 1, desc);

      if (fsym && fsym->attr.optional && sym && sym->attr.optional)
        {
          tmp = gfc_conv_expr_present (sym);
          ptr = build3_loc (input_location, COND_EXPR, TREE_TYPE (se->expr),
                        tmp, fold_convert (TREE_TYPE (se->expr), ptr),
                        fold_convert (TREE_TYPE (se->expr), null_pointer_node));
        }

      ptr = gfc_evaluate_now (ptr, &se->pre);

      /* Use the packed data for the actual argument, except for contiguous arrays,
         where the descriptor's data component is set.  */
      if (g77)
        se->expr = ptr;
      else
        {
          tmp = build_fold_indirect_ref_loc (input_location, desc);
          gfc_conv_descriptor_data_set (&se->pre, tmp, ptr);
        }

      if (gfc_option.rtcheck & GFC_RTCHECK_ARRAY_TEMPS)
        {
          char * msg;

          if (fsym && proc_name)
            asprintf (&msg, "An array temporary was created for argument "
                      "'%s' of procedure '%s'", fsym->name, proc_name);
          else
            asprintf (&msg, "An array temporary was created");

          tmp = build_fold_indirect_ref_loc (input_location,
                                         desc);
          tmp = gfc_conv_array_data (tmp);
          tmp = fold_build2_loc (input_location, NE_EXPR, boolean_type_node,
                                 fold_convert (TREE_TYPE (tmp), ptr), tmp);

          if (fsym && fsym->attr.optional && sym && sym->attr.optional)
            tmp = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                                   boolean_type_node,
                                   gfc_conv_expr_present (sym), tmp);

          gfc_trans_runtime_check (false, true, tmp, &se->pre,
                                   &expr->where, msg);
          free (msg);
        }

      gfc_start_block (&block);

      /* Copy the data back.  */
      if (fsym == NULL || fsym->attr.intent != INTENT_IN)
        {
          tmp = build_call_expr_loc (input_location,
                                 gfor_fndecl_in_unpack, 2, desc, ptr);
          gfc_add_expr_to_block (&block, tmp);
        }

      /* Free the temporary.  */
      tmp = gfc_call_free (convert (pvoid_type_node, ptr));
      gfc_add_expr_to_block (&block, tmp);

      stmt = gfc_finish_block (&block);

      gfc_init_block (&block);
      /* Only if it was repacked.  This code needs to be executed before the
         loop cleanup code.  */
      tmp = build_fold_indirect_ref_loc (input_location,
                                     desc);
      tmp = gfc_conv_array_data (tmp);
      tmp = fold_build2_loc (input_location, NE_EXPR, boolean_type_node,
                             fold_convert (TREE_TYPE (tmp), ptr), tmp);

      if (fsym && fsym->attr.optional && sym && sym->attr.optional)
        tmp = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                               boolean_type_node,
                               gfc_conv_expr_present (sym), tmp);

      tmp = build3_v (COND_EXPR, tmp, stmt, build_empty_stmt (input_location));

      gfc_add_expr_to_block (&block, tmp);
      gfc_add_block_to_block (&block, &se->post);

      gfc_init_block (&se->post);

      /* Reset the descriptor pointer.  */
      if (!g77)
        {
          tmp = build_fold_indirect_ref_loc (input_location, desc);
          gfc_conv_descriptor_data_set (&se->post, tmp, origptr);
        }

      gfc_add_block_to_block (&se->post, &block);
    }
}


/* Generate code to deallocate an array, if it is allocated.  */

tree
gfc_trans_dealloc_allocated (tree descriptor)
{ 
  tree tmp;
  tree var;
  stmtblock_t block;

  gfc_start_block (&block);

  var = gfc_conv_descriptor_data_get (descriptor);
  STRIP_NOPS (var);

  /* Call array_deallocate with an int * present in the second argument.
     Although it is ignored here, it's presence ensures that arrays that
     are already deallocated are ignored.  */
  tmp = gfc_deallocate_with_status (var, NULL_TREE, true, NULL);
  gfc_add_expr_to_block (&block, tmp);

  /* Zero the data pointer.  */
  tmp = fold_build2_loc (input_location, MODIFY_EXPR, void_type_node,
                         var, build_int_cst (TREE_TYPE (var), 0));
  gfc_add_expr_to_block (&block, tmp);

  return gfc_finish_block (&block);
}


/* This helper function calculates the size in words of a full array.  */

static tree
get_full_array_size (stmtblock_t *block, tree decl, int rank)
{
  tree idx;
  tree nelems;
  tree tmp;
  idx = gfc_rank_cst[rank - 1];
  nelems = gfc_conv_descriptor_ubound_get (decl, idx);
  tmp = gfc_conv_descriptor_lbound_get (decl, idx);
  tmp = fold_build2_loc (input_location, MINUS_EXPR, gfc_array_index_type,
                         nelems, tmp);
  tmp = fold_build2_loc (input_location, PLUS_EXPR, gfc_array_index_type,
                         tmp, gfc_index_one_node);
  tmp = gfc_evaluate_now (tmp, block);

  nelems = gfc_conv_descriptor_stride_get (decl, idx);
  tmp = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                         nelems, tmp);
  return gfc_evaluate_now (tmp, block);
}


/* Allocate dest to the same size as src, and copy src -> dest.
   If no_malloc is set, only the copy is done.  */

static tree
duplicate_allocatable (tree dest, tree src, tree type, int rank,
                       bool no_malloc)
{
  tree tmp;
  tree size;
  tree nelems;
  tree null_cond;
  tree null_data;
  stmtblock_t block;

  /* If the source is null, set the destination to null.  Then,
     allocate memory to the destination.  */
  gfc_init_block (&block);

  if (rank == 0)
    {
      tmp = null_pointer_node;
      tmp = fold_build2_loc (input_location, MODIFY_EXPR, type, dest, tmp);
      gfc_add_expr_to_block (&block, tmp);
      null_data = gfc_finish_block (&block);

      gfc_init_block (&block);
      size = TYPE_SIZE_UNIT (TREE_TYPE (type));
      if (!no_malloc)
        {
          tmp = gfc_call_malloc (&block, type, size);
          tmp = fold_build2_loc (input_location, MODIFY_EXPR, void_type_node,
                                 dest, fold_convert (type, tmp));
          gfc_add_expr_to_block (&block, tmp);
        }

      tmp = builtin_decl_explicit (BUILT_IN_MEMCPY);
      tmp = build_call_expr_loc (input_location, tmp, 3,
                                 dest, src, size);
    }
  else
    {
      gfc_conv_descriptor_data_set (&block, dest, null_pointer_node);
      null_data = gfc_finish_block (&block);

      gfc_init_block (&block);
      nelems = get_full_array_size (&block, src, rank);
      tmp = fold_convert (gfc_array_index_type,
                          TYPE_SIZE_UNIT (gfc_get_element_type (type)));
      size = fold_build2_loc (input_location, MULT_EXPR, gfc_array_index_type,
                              nelems, tmp);
      if (!no_malloc)
        {
          tmp = TREE_TYPE (gfc_conv_descriptor_data_get (src));
          tmp = gfc_call_malloc (&block, tmp, size);
          gfc_conv_descriptor_data_set (&block, dest, tmp);
        }

      /* We know the temporary and the value will be the same length,
         so can use memcpy.  */
      tmp = builtin_decl_explicit (BUILT_IN_MEMCPY);
      tmp = build_call_expr_loc (input_location,
                        tmp, 3, gfc_conv_descriptor_data_get (dest),
                        gfc_conv_descriptor_data_get (src), size);
    }

  gfc_add_expr_to_block (&block, tmp);
  tmp = gfc_finish_block (&block);

  /* Null the destination if the source is null; otherwise do
     the allocate and copy.  */
  if (rank == 0)
    null_cond = src;
  else
    null_cond = gfc_conv_descriptor_data_get (src);

  null_cond = convert (pvoid_type_node, null_cond);
  null_cond = fold_build2_loc (input_location, NE_EXPR, boolean_type_node,
                               null_cond, null_pointer_node);
  return build3_v (COND_EXPR, null_cond, tmp, null_data);
}


/* Allocate dest to the same size as src, and copy data src -> dest.  */

tree
gfc_duplicate_allocatable (tree dest, tree src, tree type, int rank)
{
  return duplicate_allocatable (dest, src, type, rank, false);
}


/* Copy data src -> dest.  */

tree
gfc_copy_allocatable_data (tree dest, tree src, tree type, int rank)
{
  return duplicate_allocatable (dest, src, type, rank, true);
}


/* Recursively traverse an object of derived type, generating code to
   deallocate, nullify or copy allocatable components.  This is the work horse
   function for the functions named in this enum.  */

enum {DEALLOCATE_ALLOC_COMP = 1, NULLIFY_ALLOC_COMP, COPY_ALLOC_COMP,
      COPY_ONLY_ALLOC_COMP};

static tree
structure_alloc_comps (gfc_symbol * der_type, tree decl,
                       tree dest, int rank, int purpose)
{
  gfc_component *c;
  gfc_loopinfo loop;
  stmtblock_t fnblock;
  stmtblock_t loopbody;
  tree decl_type;
  tree tmp;
  tree comp;
  tree dcmp;
  tree nelems;
  tree index;
  tree var;
  tree cdecl;
  tree ctype;
  tree vref, dref;
  tree null_cond = NULL_TREE;

  gfc_init_block (&fnblock);

  decl_type = TREE_TYPE (decl);

  if ((POINTER_TYPE_P (decl_type) && rank != 0)
        || (TREE_CODE (decl_type) == REFERENCE_TYPE && rank == 0))

    decl = build_fold_indirect_ref_loc (input_location,
                                    decl);

  /* Just in case in gets dereferenced.  */
  decl_type = TREE_TYPE (decl);

  /* If this an array of derived types with allocatable components
     build a loop and recursively call this function.  */
  if (TREE_CODE (decl_type) == ARRAY_TYPE
        || GFC_DESCRIPTOR_TYPE_P (decl_type))
    {
      tmp = gfc_conv_array_data (decl);
      var = build_fold_indirect_ref_loc (input_location,
                                     tmp);
        
      /* Get the number of elements - 1 and set the counter.  */
      if (GFC_DESCRIPTOR_TYPE_P (decl_type))
        {
          /* Use the descriptor for an allocatable array.  Since this
             is a full array reference, we only need the descriptor
             information from dimension = rank.  */
          tmp = get_full_array_size (&fnblock, decl, rank);
          tmp = fold_build2_loc (input_location, MINUS_EXPR,
                                 gfc_array_index_type, tmp,
                                 gfc_index_one_node);

          null_cond = gfc_conv_descriptor_data_get (decl);
          null_cond = fold_build2_loc (input_location, NE_EXPR,
                                       boolean_type_node, null_cond,
                                       build_int_cst (TREE_TYPE (null_cond), 0));
        }
      else
        {
          /*  Otherwise use the TYPE_DOMAIN information.  */
          tmp =  array_type_nelts (decl_type);
          tmp = fold_convert (gfc_array_index_type, tmp);
        }

      /* Remember that this is, in fact, the no. of elements - 1.  */
      nelems = gfc_evaluate_now (tmp, &fnblock);
      index = gfc_create_var (gfc_array_index_type, "S");

      /* Build the body of the loop.  */
      gfc_init_block (&loopbody);

      vref = gfc_build_array_ref (var, index, NULL);

      if (purpose == COPY_ALLOC_COMP)
        {
          if (GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (dest)))
            {
              tmp = gfc_duplicate_allocatable (dest, decl, decl_type, rank);
              gfc_add_expr_to_block (&fnblock, tmp);
            }
          tmp = build_fold_indirect_ref_loc (input_location,
                                         gfc_conv_array_data (dest));
          dref = gfc_build_array_ref (tmp, index, NULL);
          tmp = structure_alloc_comps (der_type, vref, dref, rank, purpose);
        }
      else if (purpose == COPY_ONLY_ALLOC_COMP)
        {
          tmp = build_fold_indirect_ref_loc (input_location,
                                         gfc_conv_array_data (dest));
          dref = gfc_build_array_ref (tmp, index, NULL);
          tmp = structure_alloc_comps (der_type, vref, dref, rank,
                                       COPY_ALLOC_COMP);
        }
      else
        tmp = structure_alloc_comps (der_type, vref, NULL_TREE, rank, purpose);

      gfc_add_expr_to_block (&loopbody, tmp);

      /* Build the loop and return.  */
      gfc_init_loopinfo (&loop);
      loop.dimen = 1;
      loop.from[0] = gfc_index_zero_node;
      loop.loopvar[0] = index;
      loop.to[0] = nelems;
      gfc_trans_scalarizing_loops (&loop, &loopbody);
      gfc_add_block_to_block (&fnblock, &loop.pre);

      tmp = gfc_finish_block (&fnblock);
      if (null_cond != NULL_TREE)
        tmp = build3_v (COND_EXPR, null_cond, tmp,
                        build_empty_stmt (input_location));

      return tmp;
    }

  /* Otherwise, act on the components or recursively call self to
     act on a chain of components.  */
  for (c = der_type->components; c; c = c->next)
    {
      bool cmp_has_alloc_comps = (c->ts.type == BT_DERIVED
                                  || c->ts.type == BT_CLASS)
                                    && c->ts.u.derived->attr.alloc_comp;
      cdecl = c->backend_decl;
      ctype = TREE_TYPE (cdecl);

      switch (purpose)
        {
        case DEALLOCATE_ALLOC_COMP:
          if (cmp_has_alloc_comps && !c->attr.pointer)
            {
              /* Do not deallocate the components of ultimate pointer
                 components.  */
              comp = fold_build3_loc (input_location, COMPONENT_REF, ctype,
                                      decl, cdecl, NULL_TREE);
              rank = c->as ? c->as->rank : 0;
              tmp = structure_alloc_comps (c->ts.u.derived, comp, NULL_TREE,
                                           rank, purpose);
              gfc_add_expr_to_block (&fnblock, tmp);
            }

          if (c->attr.allocatable
              && (c->attr.dimension || c->attr.codimension))
            {
              comp = fold_build3_loc (input_location, COMPONENT_REF, ctype,
                                      decl, cdecl, NULL_TREE);
              tmp = gfc_trans_dealloc_allocated (comp);
              gfc_add_expr_to_block (&fnblock, tmp);
            }
          else if (c->attr.allocatable)
            {
              /* Allocatable scalar components.  */
              comp = fold_build3_loc (input_location, COMPONENT_REF, ctype,
                                      decl, cdecl, NULL_TREE);

              tmp = gfc_deallocate_scalar_with_status (comp, NULL, true, NULL,
                                                       c->ts);
              gfc_add_expr_to_block (&fnblock, tmp);

              tmp = fold_build2_loc (input_location, MODIFY_EXPR,
                                     void_type_node, comp,
                                     build_int_cst (TREE_TYPE (comp), 0));
              gfc_add_expr_to_block (&fnblock, tmp);
            }
          else if (c->ts.type == BT_CLASS && CLASS_DATA (c)->attr.allocatable)
            {
              /* Allocatable scalar CLASS components.  */
              comp = fold_build3_loc (input_location, COMPONENT_REF, ctype,
                                      decl, cdecl, NULL_TREE);
              
              /* Add reference to '_data' component.  */
              tmp = CLASS_DATA (c)->backend_decl;
              comp = fold_build3_loc (input_location, COMPONENT_REF,
                                      TREE_TYPE (tmp), comp, tmp, NULL_TREE);

              tmp = gfc_deallocate_scalar_with_status (comp, NULL, true, NULL,
                                                       CLASS_DATA (c)->ts);
              gfc_add_expr_to_block (&fnblock, tmp);

              tmp = fold_build2_loc (input_location, MODIFY_EXPR,
                                     void_type_node, comp,
                                     build_int_cst (TREE_TYPE (comp), 0));
              gfc_add_expr_to_block (&fnblock, tmp);
            }
          break;

        case NULLIFY_ALLOC_COMP:
          if (c->attr.pointer)
            continue;
          else if (c->attr.allocatable
                   && (c->attr.dimension|| c->attr.codimension))
            {
              comp = fold_build3_loc (input_location, COMPONENT_REF, ctype,
                                      decl, cdecl, NULL_TREE);
              gfc_conv_descriptor_data_set (&fnblock, comp, null_pointer_node);
            }
          else if (c->attr.allocatable)
            {
              /* Allocatable scalar components.  */
              comp = fold_build3_loc (input_location, COMPONENT_REF, ctype,
                                      decl, cdecl, NULL_TREE);
              tmp = fold_build2_loc (input_location, MODIFY_EXPR,
                                     void_type_node, comp,
                                     build_int_cst (TREE_TYPE (comp), 0));
              gfc_add_expr_to_block (&fnblock, tmp);
            }
          else if (c->ts.type == BT_CLASS && CLASS_DATA (c)->attr.allocatable)
            {
              /* Allocatable scalar CLASS components.  */
              comp = fold_build3_loc (input_location, COMPONENT_REF, ctype,
                                      decl, cdecl, NULL_TREE);
              /* Add reference to '_data' component.  */
              tmp = CLASS_DATA (c)->backend_decl;
              comp = fold_build3_loc (input_location, COMPONENT_REF,
                                      TREE_TYPE (tmp), comp, tmp, NULL_TREE);
              tmp = fold_build2_loc (input_location, MODIFY_EXPR,
                                     void_type_node, comp,
                                     build_int_cst (TREE_TYPE (comp), 0));
              gfc_add_expr_to_block (&fnblock, tmp);
            }
          else if (cmp_has_alloc_comps)
            {
              comp = fold_build3_loc (input_location, COMPONENT_REF, ctype,
                                      decl, cdecl, NULL_TREE);
              rank = c->as ? c->as->rank : 0;
              tmp = structure_alloc_comps (c->ts.u.derived, comp, NULL_TREE,
                                           rank, purpose);
              gfc_add_expr_to_block (&fnblock, tmp);
            }
          break;

        case COPY_ALLOC_COMP:
          if (c->attr.pointer)
            continue;

          /* We need source and destination components.  */
          comp = fold_build3_loc (input_location, COMPONENT_REF, ctype, decl,
                                  cdecl, NULL_TREE);
          dcmp = fold_build3_loc (input_location, COMPONENT_REF, ctype, dest,
                                  cdecl, NULL_TREE);
          dcmp = fold_convert (TREE_TYPE (comp), dcmp);

          if (c->attr.allocatable && !cmp_has_alloc_comps)
            {
              rank = c->as ? c->as->rank : 0;
              tmp = gfc_duplicate_allocatable (dcmp, comp, ctype, rank);
              gfc_add_expr_to_block (&fnblock, tmp);
            }

          if (cmp_has_alloc_comps)
            {
              rank = c->as ? c->as->rank : 0;
              tmp = fold_convert (TREE_TYPE (dcmp), comp);
              gfc_add_modify (&fnblock, dcmp, tmp);
              tmp = structure_alloc_comps (c->ts.u.derived, comp, dcmp,
                                           rank, purpose);
              gfc_add_expr_to_block (&fnblock, tmp);
            }
          break;

        default:
          gcc_unreachable ();
          break;
        }
    }

  return gfc_finish_block (&fnblock);
}

/* Recursively traverse an object of derived type, generating code to
   nullify allocatable components.  */

tree
gfc_nullify_alloc_comp (gfc_symbol * der_type, tree decl, int rank)
{
  return structure_alloc_comps (der_type, decl, NULL_TREE, rank,
                                NULLIFY_ALLOC_COMP);
}


/* Recursively traverse an object of derived type, generating code to
   deallocate allocatable components.  */

tree
gfc_deallocate_alloc_comp (gfc_symbol * der_type, tree decl, int rank)
{
  return structure_alloc_comps (der_type, decl, NULL_TREE, rank,
                                DEALLOCATE_ALLOC_COMP);
}


/* Recursively traverse an object of derived type, generating code to
   copy it and its allocatable components.  */

tree
gfc_copy_alloc_comp (gfc_symbol * der_type, tree decl, tree dest, int rank)
{
  return structure_alloc_comps (der_type, decl, dest, rank, COPY_ALLOC_COMP);
}


/* Recursively traverse an object of derived type, generating code to
   copy only its allocatable components.  */

tree
gfc_copy_only_alloc_comp (gfc_symbol * der_type, tree decl, tree dest, int rank)
{
  return structure_alloc_comps (der_type, decl, dest, rank, COPY_ONLY_ALLOC_COMP);
}


/* Returns the value of LBOUND for an expression.  This could be broken out
   from gfc_conv_intrinsic_bound but this seemed to be simpler.  This is
   called by gfc_alloc_allocatable_for_assignment.  */
static tree
get_std_lbound (gfc_expr *expr, tree desc, int dim, bool assumed_size)
{
  tree lbound;
  tree ubound;
  tree stride;
  tree cond, cond1, cond3, cond4;
  tree tmp;
  gfc_ref *ref;

  if (GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (desc)))
    {
      tmp = gfc_rank_cst[dim];
      lbound = gfc_conv_descriptor_lbound_get (desc, tmp);
      ubound = gfc_conv_descriptor_ubound_get (desc, tmp);
      stride = gfc_conv_descriptor_stride_get (desc, tmp);
      cond1 = fold_build2_loc (input_location, GE_EXPR, boolean_type_node,
                               ubound, lbound);
      cond3 = fold_build2_loc (input_location, GE_EXPR, boolean_type_node,
                               stride, gfc_index_zero_node);
      cond3 = fold_build2_loc (input_location, TRUTH_AND_EXPR,
                               boolean_type_node, cond3, cond1);
      cond4 = fold_build2_loc (input_location, LT_EXPR, boolean_type_node,
                               stride, gfc_index_zero_node);
      if (assumed_size)
        cond = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node,
                                tmp, build_int_cst (gfc_array_index_type,
                                                    expr->rank - 1));
      else
        cond = boolean_false_node;

      cond1 = fold_build2_loc (input_location, TRUTH_OR_EXPR,
                               boolean_type_node, cond3, cond4);
      cond = fold_build2_loc (input_location, TRUTH_OR_EXPR,
                              boolean_type_node, cond, cond1);

      return fold_build3_loc (input_location, COND_EXPR,
                              gfc_array_index_type, cond,
                              lbound, gfc_index_one_node);
    }
  else if (expr->expr_type == EXPR_VARIABLE)
    {
      tmp = TREE_TYPE (expr->symtree->n.sym->backend_decl);
      for (ref = expr->ref; ref; ref = ref->next)
        {
          if (ref->type == REF_COMPONENT
                && ref->u.c.component->as
                && ref->next
                && ref->next->u.ar.type == AR_FULL)
            tmp = TREE_TYPE (ref->u.c.component->backend_decl);
        }
      return GFC_TYPE_ARRAY_LBOUND(tmp, dim);
    }
  else if (expr->expr_type == EXPR_FUNCTION)
    {
      /* A conversion function, so use the argument.  */
      expr = expr->value.function.actual->expr;
      if (expr->expr_type != EXPR_VARIABLE)
        return gfc_index_one_node;
      desc = TREE_TYPE (expr->symtree->n.sym->backend_decl);
      return get_std_lbound (expr, desc, dim, assumed_size);
    }

  return gfc_index_one_node;
}


/* Returns true if an expression represents an lhs that can be reallocated
   on assignment.  */

bool
gfc_is_reallocatable_lhs (gfc_expr *expr)
{
  gfc_ref * ref;

  if (!expr->ref)
    return false;

  /* An allocatable variable.  */
  if (expr->symtree->n.sym->attr.allocatable
        && expr->ref
        && expr->ref->type == REF_ARRAY
        && expr->ref->u.ar.type == AR_FULL)
    return true;

  /* All that can be left are allocatable components.  */
  if ((expr->symtree->n.sym->ts.type != BT_DERIVED
       && expr->symtree->n.sym->ts.type != BT_CLASS)
        || !expr->symtree->n.sym->ts.u.derived->attr.alloc_comp)
    return false;

  /* Find a component ref followed by an array reference.  */
  for (ref = expr->ref; ref; ref = ref->next)
    if (ref->next
          && ref->type == REF_COMPONENT
          && ref->next->type == REF_ARRAY
          && !ref->next->next)
      break;

  if (!ref)
    return false;

  /* Return true if valid reallocatable lhs.  */
  if (ref->u.c.component->attr.allocatable
        && ref->next->u.ar.type == AR_FULL)
    return true;

  return false;
}


/* Allocate the lhs of an assignment to an allocatable array, otherwise
   reallocate it.  */

tree
gfc_alloc_allocatable_for_assignment (gfc_loopinfo *loop,
                                      gfc_expr *expr1,
                                      gfc_expr *expr2)
{
  stmtblock_t realloc_block;
  stmtblock_t alloc_block;
  stmtblock_t fblock;
  gfc_ss *rss;
  gfc_ss *lss;
  gfc_array_info *linfo;
  tree realloc_expr;
  tree alloc_expr;
  tree size1;
  tree size2;
  tree array1;
  tree cond;
  tree tmp;
  tree tmp2;
  tree lbound;
  tree ubound;
  tree desc;
  tree desc2;
  tree offset;
  tree jump_label1;
  tree jump_label2;
  tree neq_size;
  tree lbd;
  int n;
  int dim;
  gfc_array_spec * as;

  /* x = f(...) with x allocatable.  In this case, expr1 is the rhs.
     Find the lhs expression in the loop chain and set expr1 and
     expr2 accordingly.  */
  if (expr1->expr_type == EXPR_FUNCTION && expr2 == NULL)
    {
      expr2 = expr1;
      /* Find the ss for the lhs.  */
      lss = loop->ss;
      for (; lss && lss != gfc_ss_terminator; lss = lss->loop_chain)
        if (lss->info->expr && lss->info->expr->expr_type == EXPR_VARIABLE)
          break;
      if (lss == gfc_ss_terminator)
        return NULL_TREE;
      expr1 = lss->info->expr;
    }

  /* Bail out if this is not a valid allocate on assignment.  */
  if (!gfc_is_reallocatable_lhs (expr1)
        || (expr2 && !expr2->rank))
    return NULL_TREE;

  /* Find the ss for the lhs.  */
  lss = loop->ss;
  for (; lss && lss != gfc_ss_terminator; lss = lss->loop_chain)
    if (lss->info->expr == expr1)
      break;

  if (lss == gfc_ss_terminator)
    return NULL_TREE;

  linfo = &lss->info->data.array;

  /* Find an ss for the rhs. For operator expressions, we see the
     ss's for the operands. Any one of these will do.  */
  rss = loop->ss;
  for (; rss && rss != gfc_ss_terminator; rss = rss->loop_chain)
    if (rss->info->expr != expr1 && rss != loop->temp_ss)
      break;

  if (expr2 && rss == gfc_ss_terminator)
    return NULL_TREE;

  gfc_start_block (&fblock);

  /* Since the lhs is allocatable, this must be a descriptor type.
     Get the data and array size.  */
  desc = linfo->descriptor;
  gcc_assert (GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (desc)));
  array1 = gfc_conv_descriptor_data_get (desc);

  /* 7.4.1.3 "If variable is an allocated allocatable variable, it is
     deallocated if expr is an array of different shape or any of the
     corresponding length type parameter values of variable and expr
     differ."  This assures F95 compatibility.  */
  jump_label1 = gfc_build_label_decl (NULL_TREE);
  jump_label2 = gfc_build_label_decl (NULL_TREE);

  /* Allocate if data is NULL.  */
  cond = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node,
                         array1, build_int_cst (TREE_TYPE (array1), 0));
  tmp = build3_v (COND_EXPR, cond,
                  build1_v (GOTO_EXPR, jump_label1),
                  build_empty_stmt (input_location));
  gfc_add_expr_to_block (&fblock, tmp);

  /* Get arrayspec if expr is a full array.  */
  if (expr2 && expr2->expr_type == EXPR_FUNCTION
        && expr2->value.function.isym
        && expr2->value.function.isym->conversion)
    {
      /* For conversion functions, take the arg.  */
      gfc_expr *arg = expr2->value.function.actual->expr;
      as = gfc_get_full_arrayspec_from_expr (arg);
    }
  else if (expr2)
    as = gfc_get_full_arrayspec_from_expr (expr2);
  else
    as = NULL;

  /* If the lhs shape is not the same as the rhs jump to setting the
     bounds and doing the reallocation.......  */ 
  for (n = 0; n < expr1->rank; n++)
    {
      /* Check the shape.  */
      lbound = gfc_conv_descriptor_lbound_get (desc, gfc_rank_cst[n]);
      ubound = gfc_conv_descriptor_ubound_get (desc, gfc_rank_cst[n]);
      tmp = fold_build2_loc (input_location, MINUS_EXPR,
                             gfc_array_index_type,
                             loop->to[n], loop->from[n]);
      tmp = fold_build2_loc (input_location, PLUS_EXPR,
                             gfc_array_index_type,
                             tmp, lbound);
      tmp = fold_build2_loc (input_location, MINUS_EXPR,
                             gfc_array_index_type,
                             tmp, ubound);
      cond = fold_build2_loc (input_location, NE_EXPR,
                              boolean_type_node,
                              tmp, gfc_index_zero_node);
      tmp = build3_v (COND_EXPR, cond,
                      build1_v (GOTO_EXPR, jump_label1),
                      build_empty_stmt (input_location));
      gfc_add_expr_to_block (&fblock, tmp);       
    }

  /* ....else jump past the (re)alloc code.  */
  tmp = build1_v (GOTO_EXPR, jump_label2);
  gfc_add_expr_to_block (&fblock, tmp);
    
  /* Add the label to start automatic (re)allocation.  */
  tmp = build1_v (LABEL_EXPR, jump_label1);
  gfc_add_expr_to_block (&fblock, tmp);

  size1 = gfc_conv_descriptor_size (desc, expr1->rank);

  /* Get the rhs size.  Fix both sizes.  */
  if (expr2)
    desc2 = rss->info->data.array.descriptor;
  else
    desc2 = NULL_TREE;
  size2 = gfc_index_one_node;
  for (n = 0; n < expr2->rank; n++)
    {
      tmp = fold_build2_loc (input_location, MINUS_EXPR,
                             gfc_array_index_type,
                             loop->to[n], loop->from[n]);
      tmp = fold_build2_loc (input_location, PLUS_EXPR,
                             gfc_array_index_type,
                             tmp, gfc_index_one_node);
      size2 = fold_build2_loc (input_location, MULT_EXPR,
                               gfc_array_index_type,
                               tmp, size2);
    }

  size1 = gfc_evaluate_now (size1, &fblock);
  size2 = gfc_evaluate_now (size2, &fblock);

  cond = fold_build2_loc (input_location, NE_EXPR, boolean_type_node,
                          size1, size2);
  neq_size = gfc_evaluate_now (cond, &fblock);


  /* Now modify the lhs descriptor and the associated scalarizer
     variables. F2003 7.4.1.3: "If variable is or becomes an
     unallocated allocatable variable, then it is allocated with each
     deferred type parameter equal to the corresponding type parameters
     of expr , with the shape of expr , and with each lower bound equal
     to the corresponding element of LBOUND(expr)."  
     Reuse size1 to keep a dimension-by-dimension track of the
     stride of the new array.  */
  size1 = gfc_index_one_node;
  offset = gfc_index_zero_node;

  for (n = 0; n < expr2->rank; n++)
    {
      tmp = fold_build2_loc (input_location, MINUS_EXPR,
                             gfc_array_index_type,
                             loop->to[n], loop->from[n]);
      tmp = fold_build2_loc (input_location, PLUS_EXPR,
                             gfc_array_index_type,
                             tmp, gfc_index_one_node);

      lbound = gfc_index_one_node;
      ubound = tmp;

      if (as)
        {
          lbd = get_std_lbound (expr2, desc2, n,
                                as->type == AS_ASSUMED_SIZE);
          ubound = fold_build2_loc (input_location,
                                    MINUS_EXPR,
                                    gfc_array_index_type,
                                    ubound, lbound);
          ubound = fold_build2_loc (input_location,
                                    PLUS_EXPR,
                                    gfc_array_index_type,
                                    ubound, lbd);
          lbound = lbd;
        }

      gfc_conv_descriptor_lbound_set (&fblock, desc,
                                      gfc_rank_cst[n],
                                      lbound);
      gfc_conv_descriptor_ubound_set (&fblock, desc,
                                      gfc_rank_cst[n],
                                      ubound);
      gfc_conv_descriptor_stride_set (&fblock, desc,
                                      gfc_rank_cst[n],
                                      size1);
      lbound = gfc_conv_descriptor_lbound_get (desc,
                                               gfc_rank_cst[n]);
      tmp2 = fold_build2_loc (input_location, MULT_EXPR,
                              gfc_array_index_type,
                              lbound, size1);
      offset = fold_build2_loc (input_location, MINUS_EXPR,
                                gfc_array_index_type,
                                offset, tmp2);
      size1 = fold_build2_loc (input_location, MULT_EXPR,
                               gfc_array_index_type,
                               tmp, size1);
    }

  /* Set the lhs descriptor and scalarizer offsets.  For rank > 1,
     the array offset is saved and the info.offset is used for a
     running offset.  Use the saved_offset instead.  */
  tmp = gfc_conv_descriptor_offset (desc);
  gfc_add_modify (&fblock, tmp, offset);
  if (linfo->saved_offset
      && TREE_CODE (linfo->saved_offset) == VAR_DECL)
    gfc_add_modify (&fblock, linfo->saved_offset, tmp);

  /* Now set the deltas for the lhs.  */
  for (n = 0; n < expr1->rank; n++)
    {
      tmp = gfc_conv_descriptor_lbound_get (desc, gfc_rank_cst[n]);
      dim = lss->dim[n];
      tmp = fold_build2_loc (input_location, MINUS_EXPR,
                             gfc_array_index_type, tmp,
                             loop->from[dim]);
      if (linfo->delta[dim]
          && TREE_CODE (linfo->delta[dim]) == VAR_DECL)
        gfc_add_modify (&fblock, linfo->delta[dim], tmp);
    }

  /* Get the new lhs size in bytes.  */
  if (expr1->ts.type == BT_CHARACTER && expr1->ts.deferred)
    {
      tmp = expr2->ts.u.cl->backend_decl;
      gcc_assert (expr1->ts.u.cl->backend_decl);
      tmp = fold_convert (TREE_TYPE (expr1->ts.u.cl->backend_decl), tmp);
      gfc_add_modify (&fblock, expr1->ts.u.cl->backend_decl, tmp);
    }
  else if (expr1->ts.type == BT_CHARACTER && expr1->ts.u.cl->backend_decl)
    {
      tmp = TYPE_SIZE_UNIT (TREE_TYPE (gfc_typenode_for_spec (&expr1->ts)));
      tmp = fold_build2_loc (input_location, MULT_EXPR,
                             gfc_array_index_type, tmp,
                             expr1->ts.u.cl->backend_decl);
    }
  else
    tmp = TYPE_SIZE_UNIT (gfc_typenode_for_spec (&expr1->ts));
  tmp = fold_convert (gfc_array_index_type, tmp);
  size2 = fold_build2_loc (input_location, MULT_EXPR,
                           gfc_array_index_type,
                           tmp, size2);
  size2 = fold_convert (size_type_node, size2);
  size2 = gfc_evaluate_now (size2, &fblock);

  /* Realloc expression.  Note that the scalarizer uses desc.data
     in the array reference - (*desc.data)[<element>]. */
  gfc_init_block (&realloc_block);
  tmp = build_call_expr_loc (input_location,
                             builtin_decl_explicit (BUILT_IN_REALLOC), 2,
                             fold_convert (pvoid_type_node, array1),
                             size2);
  gfc_conv_descriptor_data_set (&realloc_block,
                                desc, tmp);
  realloc_expr = gfc_finish_block (&realloc_block);

  /* Only reallocate if sizes are different.  */
  tmp = build3_v (COND_EXPR, neq_size, realloc_expr,
                  build_empty_stmt (input_location));
  realloc_expr = tmp;


  /* Malloc expression.  */
  gfc_init_block (&alloc_block);
  tmp = build_call_expr_loc (input_location,
                             builtin_decl_explicit (BUILT_IN_MALLOC),
                             1, size2);
  gfc_conv_descriptor_data_set (&alloc_block,
                                desc, tmp);
  tmp = gfc_conv_descriptor_dtype (desc);
  gfc_add_modify (&alloc_block, tmp, gfc_get_dtype (TREE_TYPE (desc)));
  alloc_expr = gfc_finish_block (&alloc_block);

  /* Malloc if not allocated; realloc otherwise.  */
  tmp = build_int_cst (TREE_TYPE (array1), 0);
  cond = fold_build2_loc (input_location, EQ_EXPR,
                          boolean_type_node,
                          array1, tmp);
  tmp = build3_v (COND_EXPR, cond, alloc_expr, realloc_expr);
  gfc_add_expr_to_block (&fblock, tmp);

  /* Make sure that the scalarizer data pointer is updated.  */
  if (linfo->data
      && TREE_CODE (linfo->data) == VAR_DECL)
    {
      tmp = gfc_conv_descriptor_data_get (desc);
      gfc_add_modify (&fblock, linfo->data, tmp);
    }

  /* Add the exit label.  */
  tmp = build1_v (LABEL_EXPR, jump_label2);
  gfc_add_expr_to_block (&fblock, tmp);

  return gfc_finish_block (&fblock);
}


/* NULLIFY an allocatable/pointer array on function entry, free it on exit.
   Do likewise, recursively if necessary, with the allocatable components of
   derived types.  */

void
gfc_trans_deferred_array (gfc_symbol * sym, gfc_wrapped_block * block)
{
  tree type;
  tree tmp;
  tree descriptor;
  stmtblock_t init;
  stmtblock_t cleanup;
  locus loc;
  int rank;
  bool sym_has_alloc_comp;

  sym_has_alloc_comp = (sym->ts.type == BT_DERIVED
                        || sym->ts.type == BT_CLASS)
                          && sym->ts.u.derived->attr.alloc_comp;

  /* Make sure the frontend gets these right.  */
  if (!(sym->attr.pointer || sym->attr.allocatable || sym_has_alloc_comp))
    fatal_error ("Possible front-end bug: Deferred array size without pointer, "
                 "allocatable attribute or derived type without allocatable "
                 "components.");

  gfc_save_backend_locus (&loc);
  gfc_set_backend_locus (&sym->declared_at);
  gfc_init_block (&init);

  gcc_assert (TREE_CODE (sym->backend_decl) == VAR_DECL
                || TREE_CODE (sym->backend_decl) == PARM_DECL);

  if (sym->ts.type == BT_CHARACTER
      && !INTEGER_CST_P (sym->ts.u.cl->backend_decl))
    {
      gfc_conv_string_length (sym->ts.u.cl, NULL, &init);
      gfc_trans_vla_type_sizes (sym, &init);
    }

  /* Dummy, use associated and result variables don't need anything special.  */
  if (sym->attr.dummy || sym->attr.use_assoc || sym->attr.result)
    {
      gfc_add_init_cleanup (block, gfc_finish_block (&init), NULL_TREE);
      gfc_restore_backend_locus (&loc);
      return;
    }

  descriptor = sym->backend_decl;

  /* Although static, derived types with default initializers and
     allocatable components must not be nulled wholesale; instead they
     are treated component by component.  */
  if (TREE_STATIC (descriptor) && !sym_has_alloc_comp)
    {
      /* SAVEd variables are not freed on exit.  */
      gfc_trans_static_array_pointer (sym);

      gfc_add_init_cleanup (block, gfc_finish_block (&init), NULL_TREE);
      gfc_restore_backend_locus (&loc);
      return;
    }

  /* Get the descriptor type.  */
  type = TREE_TYPE (sym->backend_decl);

  if (sym_has_alloc_comp && !(sym->attr.pointer || sym->attr.allocatable))
    {
      if (!sym->attr.save
          && !(TREE_STATIC (sym->backend_decl) && sym->attr.is_main_program))
        {
          if (sym->value == NULL
              || !gfc_has_default_initializer (sym->ts.u.derived))
            {
              rank = sym->as ? sym->as->rank : 0;
              tmp = gfc_nullify_alloc_comp (sym->ts.u.derived,
                                            descriptor, rank);
              gfc_add_expr_to_block (&init, tmp);
            }
          else
            gfc_init_default_dt (sym, &init, false);
        }
    }
  else if (!GFC_DESCRIPTOR_TYPE_P (type))
    {
      /* If the backend_decl is not a descriptor, we must have a pointer
         to one.  */
      descriptor = build_fold_indirect_ref_loc (input_location,
                                                sym->backend_decl);
      type = TREE_TYPE (descriptor);
    }
  
  /* NULLIFY the data pointer.  */
  if (GFC_DESCRIPTOR_TYPE_P (type) && !sym->attr.save)
    gfc_conv_descriptor_data_set (&init, descriptor, null_pointer_node);

  gfc_restore_backend_locus (&loc);
  gfc_init_block (&cleanup);

  /* Allocatable arrays need to be freed when they go out of scope.
     The allocatable components of pointers must not be touched.  */
  if (sym_has_alloc_comp && !(sym->attr.function || sym->attr.result)
      && !sym->attr.pointer && !sym->attr.save)
    {
      int rank;
      rank = sym->as ? sym->as->rank : 0;
      tmp = gfc_deallocate_alloc_comp (sym->ts.u.derived, descriptor, rank);
      gfc_add_expr_to_block (&cleanup, tmp);
    }

  if (sym->attr.allocatable && (sym->attr.dimension || sym->attr.codimension)
      && !sym->attr.save && !sym->attr.result)
    {
      tmp = gfc_trans_dealloc_allocated (sym->backend_decl);
      gfc_add_expr_to_block (&cleanup, tmp);
    }

  gfc_add_init_cleanup (block, gfc_finish_block (&init),
                        gfc_finish_block (&cleanup));
}

/************ Expression Walking Functions ******************/

/* Walk a variable reference.

   Possible extension - multiple component subscripts.
    x(:,:) = foo%a(:)%b(:)
   Transforms to
    forall (i=..., j=...)
      x(i,j) = foo%a(j)%b(i)
    end forall
   This adds a fair amount of complexity because you need to deal with more
   than one ref.  Maybe handle in a similar manner to vector subscripts.
   Maybe not worth the effort.  */


static gfc_ss *
gfc_walk_variable_expr (gfc_ss * ss, gfc_expr * expr)
{
  gfc_ref *ref;

  for (ref = expr->ref; ref; ref = ref->next)
    if (ref->type == REF_ARRAY && ref->u.ar.type != AR_ELEMENT)
      break;

  return gfc_walk_array_ref (ss, expr, ref);
}


gfc_ss *
gfc_walk_array_ref (gfc_ss * ss, gfc_expr * expr, gfc_ref * ref)
{
  gfc_array_ref *ar;
  gfc_ss *newss;
  int n;

  for (; ref; ref = ref->next)
    {
      if (ref->type == REF_SUBSTRING)
        {
          ss = gfc_get_scalar_ss (ss, ref->u.ss.start);
          ss = gfc_get_scalar_ss (ss, ref->u.ss.end);
        }

      /* We're only interested in array sections from now on.  */
      if (ref->type != REF_ARRAY)
        continue;

      ar = &ref->u.ar;

      switch (ar->type)
        {
        case AR_ELEMENT:
          for (n = ar->dimen - 1; n >= 0; n--)
            ss = gfc_get_scalar_ss (ss, ar->start[n]);
          break;

        case AR_FULL:
          newss = gfc_get_array_ss (ss, expr, ar->as->rank, GFC_SS_SECTION);
          newss->info->data.array.ref = ref;

          /* Make sure array is the same as array(:,:), this way
             we don't need to special case all the time.  */
          ar->dimen = ar->as->rank;
          for (n = 0; n < ar->dimen; n++)
            {
              ar->dimen_type[n] = DIMEN_RANGE;

              gcc_assert (ar->start[n] == NULL);
              gcc_assert (ar->end[n] == NULL);
              gcc_assert (ar->stride[n] == NULL);
            }
          ss = newss;
          break;

        case AR_SECTION:
          newss = gfc_get_array_ss (ss, expr, 0, GFC_SS_SECTION);
          newss->info->data.array.ref = ref;

          /* We add SS chains for all the subscripts in the section.  */
          for (n = 0; n < ar->dimen; n++)
            {
              gfc_ss *indexss;

              switch (ar->dimen_type[n])
                {
                case DIMEN_ELEMENT:
                  /* Add SS for elemental (scalar) subscripts.  */
                  gcc_assert (ar->start[n]);
                  indexss = gfc_get_scalar_ss (gfc_ss_terminator, ar->start[n]);
                  indexss->loop_chain = gfc_ss_terminator;
                  newss->info->data.array.subscript[n] = indexss;
                  break;

                case DIMEN_RANGE:
                  /* We don't add anything for sections, just remember this
                     dimension for later.  */
                  newss->dim[newss->dimen] = n;
                  newss->dimen++;
                  break;

                case DIMEN_VECTOR:
                  /* Create a GFC_SS_VECTOR index in which we can store
                     the vector's descriptor.  */
                  indexss = gfc_get_array_ss (gfc_ss_terminator, ar->start[n],
                                              1, GFC_SS_VECTOR);
                  indexss->loop_chain = gfc_ss_terminator;
                  newss->info->data.array.subscript[n] = indexss;
                  newss->dim[newss->dimen] = n;
                  newss->dimen++;
                  break;

                default:
                  /* We should know what sort of section it is by now.  */
                  gcc_unreachable ();
                }
            }
          /* We should have at least one non-elemental dimension,
             unless we are creating a descriptor for a (scalar) coarray.  */
          gcc_assert (newss->dimen > 0
                      || newss->info->data.array.ref->u.ar.as->corank > 0);
          ss = newss;
          break;

        default:
          /* We should know what sort of section it is by now.  */
          gcc_unreachable ();
        }

    }
  return ss;
}


/* Walk an expression operator. If only one operand of a binary expression is
   scalar, we must also add the scalar term to the SS chain.  */

static gfc_ss *
gfc_walk_op_expr (gfc_ss * ss, gfc_expr * expr)
{
  gfc_ss *head;
  gfc_ss *head2;

  head = gfc_walk_subexpr (ss, expr->value.op.op1);
  if (expr->value.op.op2 == NULL)
    head2 = head;
  else
    head2 = gfc_walk_subexpr (head, expr->value.op.op2);

  /* All operands are scalar.  Pass back and let the caller deal with it.  */
  if (head2 == ss)
    return head2;

  /* All operands require scalarization.  */
  if (head != ss && (expr->value.op.op2 == NULL || head2 != head))
    return head2;

  /* One of the operands needs scalarization, the other is scalar.
     Create a gfc_ss for the scalar expression.  */
  if (head == ss)
    {
      /* First operand is scalar.  We build the chain in reverse order, so
         add the scalar SS after the second operand.  */
      head = head2;
      while (head && head->next != ss)
        head = head->next;
      /* Check we haven't somehow broken the chain.  */
      gcc_assert (head);
      head->next = gfc_get_scalar_ss (ss, expr->value.op.op1);
    }
  else                          /* head2 == head */
    {
      gcc_assert (head2 == head);
      /* Second operand is scalar.  */
      head2 = gfc_get_scalar_ss (head2, expr->value.op.op2);
    }

  return head2;
}


/* Reverse a SS chain.  */

gfc_ss *
gfc_reverse_ss (gfc_ss * ss)
{
  gfc_ss *next;
  gfc_ss *head;

  gcc_assert (ss != NULL);

  head = gfc_ss_terminator;
  while (ss != gfc_ss_terminator)
    {
      next = ss->next;
      /* Check we didn't somehow break the chain.  */
      gcc_assert (next != NULL);
      ss->next = head;
      head = ss;
      ss = next;
    }

  return (head);
}


/* Walk the arguments of an elemental function.  */

gfc_ss *
gfc_walk_elemental_function_args (gfc_ss * ss, gfc_actual_arglist *arg,
                                  gfc_ss_type type)
{
  int scalar;
  gfc_ss *head;
  gfc_ss *tail;
  gfc_ss *newss;

  head = gfc_ss_terminator;
  tail = NULL;
  scalar = 1;
  for (; arg; arg = arg->next)
    {
      if (!arg->expr)
        continue;

      newss = gfc_walk_subexpr (head, arg->expr);
      if (newss == head)
        {
          /* Scalar argument.  */
          gcc_assert (type == GFC_SS_SCALAR || type == GFC_SS_REFERENCE);
          newss = gfc_get_scalar_ss (head, arg->expr);
          newss->info->type = type;
        }
      else
        scalar = 0;

      head = newss;
      if (!tail)
        {
          tail = head;
          while (tail->next != gfc_ss_terminator)
            tail = tail->next;
        }
    }

  if (scalar)
    {
      /* If all the arguments are scalar we don't need the argument SS.  */
      gfc_free_ss_chain (head);
      /* Pass it back.  */
      return ss;
    }

  /* Add it onto the existing chain.  */
  tail->next = ss;
  return head;
}


/* Walk a function call.  Scalar functions are passed back, and taken out of
   scalarization loops.  For elemental functions we walk their arguments.
   The result of functions returning arrays is stored in a temporary outside
   the loop, so that the function is only called once.  Hence we do not need
   to walk their arguments.  */

static gfc_ss *
gfc_walk_function_expr (gfc_ss * ss, gfc_expr * expr)
{
  gfc_intrinsic_sym *isym;
  gfc_symbol *sym;
  gfc_component *comp = NULL;

  isym = expr->value.function.isym;

  /* Handle intrinsic functions separately.  */
  if (isym)
    return gfc_walk_intrinsic_function (ss, expr, isym);

  sym = expr->value.function.esym;
  if (!sym)
      sym = expr->symtree->n.sym;

  /* A function that returns arrays.  */
  gfc_is_proc_ptr_comp (expr, &comp);
  if ((!comp && gfc_return_by_reference (sym) && sym->result->attr.dimension)
      || (comp && comp->attr.dimension))
    return gfc_get_array_ss (ss, expr, expr->rank, GFC_SS_FUNCTION);

  /* Walk the parameters of an elemental function.  For now we always pass
     by reference.  */
  if (sym->attr.elemental)
    return gfc_walk_elemental_function_args (ss, expr->value.function.actual,
                                             GFC_SS_REFERENCE);

  /* Scalar functions are OK as these are evaluated outside the scalarization
     loop.  Pass back and let the caller deal with it.  */
  return ss;
}


/* An array temporary is constructed for array constructors.  */

static gfc_ss *
gfc_walk_array_constructor (gfc_ss * ss, gfc_expr * expr)
{
  return gfc_get_array_ss (ss, expr, expr->rank, GFC_SS_CONSTRUCTOR);
}


/* Walk an expression.  Add walked expressions to the head of the SS chain.
   A wholly scalar expression will not be added.  */

gfc_ss *
gfc_walk_subexpr (gfc_ss * ss, gfc_expr * expr)
{
  gfc_ss *head;

  switch (expr->expr_type)
    {
    case EXPR_VARIABLE:
      head = gfc_walk_variable_expr (ss, expr);
      return head;

    case EXPR_OP:
      head = gfc_walk_op_expr (ss, expr);
      return head;

    case EXPR_FUNCTION:
      head = gfc_walk_function_expr (ss, expr);
      return head;

    case EXPR_CONSTANT:
    case EXPR_NULL:
    case EXPR_STRUCTURE:
      /* Pass back and let the caller deal with it.  */
      break;

    case EXPR_ARRAY:
      head = gfc_walk_array_constructor (ss, expr);
      return head;

    case EXPR_SUBSTRING:
      /* Pass back and let the caller deal with it.  */
      break;

    default:
      internal_error ("bad expression type during walk (%d)",
                      expr->expr_type);
    }
  return ss;
}


/* Entry point for expression walking.
   A return value equal to the passed chain means this is
   a scalar expression.  It is up to the caller to take whatever action is
   necessary to translate these.  */

gfc_ss *
gfc_walk_expr (gfc_expr * expr)
{
  gfc_ss *res;

  res = gfc_walk_subexpr (gfc_ss_terminator, expr);
  return gfc_reverse_ss (res);
}