data.c

/* Supporting functions for resolving DATA statement.
   Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   Contributed by Lifang Zeng <zlf605@hotmail.com>

This file is part of GCC.

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

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

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


/* Notes for DATA statement implementation:
                                                                               
   We first assign initial value to each symbol by gfc_assign_data_value
   during resolveing DATA statement. Refer to check_data_variable and
   traverse_data_list in resolve.c.
                                                                               
   The complexity exists in the handling of array section, implied do
   and array of struct appeared in DATA statement.
                                                                               
   We call gfc_conv_structure, gfc_con_array_array_initializer,
   etc., to convert the initial value. Refer to trans-expr.c and
   trans-array.c.  */

#include "config.h"
#include "gfortran.h"

static void formalize_init_expr (gfc_expr *);

/* Calculate the array element offset.  */

static void
get_array_index (gfc_array_ref * ar, mpz_t * offset)
{
  gfc_expr *e;
  int i;
  try re;
  mpz_t delta;
  mpz_t tmp;

  mpz_init (tmp);
  mpz_set_si (*offset, 0);
  mpz_init_set_si (delta, 1);
  for (i = 0; i < ar->dimen; i++)
    {
      e = gfc_copy_expr (ar->start[i]);
      re = gfc_simplify_expr (e, 1);

      if ((gfc_is_constant_expr (ar->as->lower[i]) == 0)
	  || (gfc_is_constant_expr (ar->as->upper[i]) == 0)
	  || (gfc_is_constant_expr (e) == 0))
	gfc_error ("non-constant array in DATA statement %L.", &ar->where);        
      mpz_set (tmp, e->value.integer);
      mpz_sub (tmp, tmp, ar->as->lower[i]->value.integer);
      mpz_mul (tmp, tmp, delta);
      mpz_add (*offset, tmp, *offset);

      mpz_sub (tmp, ar->as->upper[i]->value.integer,
      ar->as->lower[i]->value.integer);
      mpz_add_ui (tmp, tmp, 1);
      mpz_mul (delta, tmp, delta);
    }
  mpz_clear (delta);
  mpz_clear (tmp);
}


/* Find if there is a constructor which offset is equal to OFFSET.  */

static gfc_constructor *
find_con_by_offset (mpz_t offset, gfc_constructor *con)
{
  mpz_t tmp;
  gfc_constructor *ret = NULL;

  mpz_init (tmp);

  for (; con; con = con->next)
    {
      int cmp = mpz_cmp (offset, con->n.offset);

      /* We retain a sorted list, so if we're too large, we're done.  */
      if (cmp < 0)
	break;

      /* Yaye for exact matches.  */
      if (cmp == 0)
	{
          ret = con;
	  break;
	}

      /* If the constructor element is a range, match any element.  */
      if (mpz_cmp_ui (con->repeat, 1) > 0)
	{
	  mpz_add (tmp, con->n.offset, con->repeat);
	  if (mpz_cmp (offset, tmp) < 0)
	    {
	      ret = con;
	      break;
	    }
	}
    }

  mpz_clear (tmp);
  return ret;
}


/* Find if there is a constructor which component is equal to COM.  */

static gfc_constructor *
find_con_by_component (gfc_component *com, gfc_constructor *con)
{
  for (; con; con = con->next)
    {
      if (com == con->n.component)
        return con;
    }
  return NULL;
}


/* Create a character type initialization expression from RVALUE.
   TS [and REF] describe [the substring of] the variable being initialized.
   INIT is thh existing initializer, not NULL.  Initialization is performed
   according to normal assignment rules.  */

static gfc_expr *
create_character_intializer (gfc_expr * init, gfc_typespec * ts,
			     gfc_ref * ref, gfc_expr * rvalue)
{
  int len;
  int start;
  int end;
  char *dest;
	    
  gfc_extract_int (ts->cl->length, &len);

  if (init == NULL)
    {
      /* Create a new initializer.  */
      init = gfc_get_expr ();
      init->expr_type = EXPR_CONSTANT;
      init->ts = *ts;
      
      dest = gfc_getmem (len);
      init->value.character.length = len;
      init->value.character.string = dest;
      /* Blank the string if we're only setting a substring.  */
      if (ref != NULL)
	memset (dest, ' ', len);
    }
  else
    dest = init->value.character.string;

  if (ref)
    {
      gcc_assert (ref->type == REF_SUBSTRING);

      /* Only set a substring of the destination.  Fortran substring bounds
         are one-based [start, end], we want zero based [start, end).  */
      gfc_extract_int (ref->u.ss.start, &start);
      start--;
      gfc_extract_int (ref->u.ss.end, &end);
    }
  else
    {
      /* Set the whole string.  */
      start = 0;
      end = len;
    }

  /* Copy the initial value.  */
  len = rvalue->value.character.length;
  if (len > end - start)
    len = end - start;
  memcpy (&dest[start], rvalue->value.character.string, len);

  /* Pad with spaces.  Substrings will already be blanked.  */
  if (len < end - start && ref == NULL)
    memset (&dest[start + len], ' ', end - (start + len));

  return init;
}

/* Assign the initial value RVALUE to  LVALUE's symbol->value. If the
   LVALUE already has an initialization, we extend this, otherwise we
   create a new one.  */

void
gfc_assign_data_value (gfc_expr * lvalue, gfc_expr * rvalue, mpz_t index)
{
  gfc_ref *ref;
  gfc_expr *init;
  gfc_expr *expr;
  gfc_constructor *con;
  gfc_constructor *last_con;
  gfc_symbol *symbol;
  gfc_typespec *last_ts;
  mpz_t offset;

  symbol = lvalue->symtree->n.sym;
  init = symbol->value;
  last_ts = &symbol->ts;
  last_con = NULL;
  mpz_init_set_si (offset, 0);

  /* Find/create the parent expressions for subobject references.  */
  for (ref = lvalue->ref; ref; ref = ref->next)
    {
      /* Break out of the loop if we find a substring.  */
      if (ref->type == REF_SUBSTRING)
	{
	  /* A substring should always br the last subobject reference.  */
	  gcc_assert (ref->next == NULL);
	  break;
	}

      /* Use the existing initializer expression if it exists.  Otherwise
         create a new one.  */
      if (init == NULL)
	expr = gfc_get_expr ();
      else
	expr = init;

      /* Find or create this element.  */
      switch (ref->type)
	{
	case REF_ARRAY:
	  if (init == NULL)
	    {
	      /* The element typespec will be the same as the array
		 typespec.  */
	      expr->ts = *last_ts;
	      /* Setup the expression to hold the constructor.  */
	      expr->expr_type = EXPR_ARRAY;
	      expr->rank = ref->u.ar.as->rank;
	    }
	  else
	    gcc_assert (expr->expr_type == EXPR_ARRAY);

	  if (ref->u.ar.type == AR_ELEMENT)
	    get_array_index (&ref->u.ar, &offset);
	  else
	    mpz_set (offset, index);

	  /* Find the same element in the existing constructor.  */
	  con = expr->value.constructor;
	  con = find_con_by_offset (offset, con);

	  if (con == NULL)
	    {
	      /* Create a new constructor.  */
	      con = gfc_get_constructor ();
	      mpz_set (con->n.offset, offset);
	      gfc_insert_constructor (expr, con);
	    }
	  break;

	case REF_COMPONENT:
	  if (init == NULL)
	    {
	      /* Setup the expression to hold the constructor.  */
	      expr->expr_type = EXPR_STRUCTURE;
	      expr->ts.type = BT_DERIVED;
	      expr->ts.derived = ref->u.c.sym;
	    }
	  else
	    gcc_assert (expr->expr_type == EXPR_STRUCTURE);
	  last_ts = &ref->u.c.component->ts;

	  /* Find the same element in the existing constructor.  */
	  con = expr->value.constructor;
	  con = find_con_by_component (ref->u.c.component, con);

	  if (con == NULL)
	    {
	      /* Create a new constructor.  */
	      con = gfc_get_constructor ();
	      con->n.component = ref->u.c.component;
	      con->next = expr->value.constructor;
	      expr->value.constructor = con;
	    }
	  break;

	default:
	  gcc_unreachable ();
	}

      if (init == NULL)
	{
	  /* Point the container at the new expression.  */
	  if (last_con == NULL)
	    symbol->value = expr;
	  else
	    last_con->expr = expr;
	}
      init = con->expr;
      last_con = con;
    }

  if (ref || last_ts->type == BT_CHARACTER)
    expr = create_character_intializer (init, last_ts, ref, rvalue);
  else
    {
      /* Overwriting an existing initializer is non-standard but usually only
	 provokes a warning from other compilers.  */
      if (init != NULL)
	{
	  /* Order in which the expressions arrive here depends on whether they
	     are from data statements or F95 style declarations. Therefore,
	     check which is the most recent.  */
	  expr = (init->where.lb->linenum > rvalue->where.lb->linenum) ?
		    init : rvalue;
	  gfc_notify_std (GFC_STD_GNU, "Extension: re-initialization "
			  "of '%s' at %L",  symbol->name, &expr->where);
	  return;
	}

      expr = gfc_copy_expr (rvalue);
      if (!gfc_compare_types (&lvalue->ts, &expr->ts))
	gfc_convert_type (expr, &lvalue->ts, 0);
    }

  if (last_con == NULL)
    symbol->value = expr;
  else
    last_con->expr = expr;
}

/* Similarly, but initialize REPEAT consecutive values in LVALUE the same
   value in RVALUE.  For the nonce, LVALUE must refer to a full array, not
   an array section.  */

void
gfc_assign_data_value_range (gfc_expr * lvalue, gfc_expr * rvalue,
			     mpz_t index, mpz_t repeat)
{
  gfc_ref *ref;
  gfc_expr *init, *expr;
  gfc_constructor *con, *last_con;
  gfc_symbol *symbol;
  gfc_typespec *last_ts;
  mpz_t offset;

  symbol = lvalue->symtree->n.sym;
  init = symbol->value;
  last_ts = &symbol->ts;
  last_con = NULL;
  mpz_init_set_si (offset, 0);

  /* Find/create the parent expressions for subobject references.  */
  for (ref = lvalue->ref; ref; ref = ref->next)
    {
      /* Use the existing initializer expression if it exists.
	 Otherwise create a new one.  */
      if (init == NULL)
	expr = gfc_get_expr ();
      else
	expr = init;

      /* Find or create this element.  */
      switch (ref->type)
	{
	case REF_ARRAY:
	  if (init == NULL)
	    {
	      /* The element typespec will be the same as the array
		 typespec.  */
	      expr->ts = *last_ts;
	      /* Setup the expression to hold the constructor.  */
	      expr->expr_type = EXPR_ARRAY;
	      expr->rank = ref->u.ar.as->rank;
	    }
	  else
	    gcc_assert (expr->expr_type == EXPR_ARRAY);

	  if (ref->u.ar.type == AR_ELEMENT)
	    {
	      get_array_index (&ref->u.ar, &offset);

	      /* This had better not be the bottom of the reference.
		 We can still get to a full array via a component.  */
	      gcc_assert (ref->next != NULL);
	    }
	  else
	    {
	      mpz_set (offset, index);

	      /* We're at a full array or an array section.  This means
		 that we've better have found a full array, and that we're
		 at the bottom of the reference.  */
	      gcc_assert (ref->u.ar.type == AR_FULL);
	      gcc_assert (ref->next == NULL);
	    }

	  /* Find the same element in the existing constructor.  */
	  con = expr->value.constructor;
	  con = find_con_by_offset (offset, con);

	  /* Create a new constructor.  */
	  if (con == NULL)
	    {
	      con = gfc_get_constructor ();
	      mpz_set (con->n.offset, offset);
	      if (ref->next == NULL)
		mpz_set (con->repeat, repeat);
	      gfc_insert_constructor (expr, con);
	    }
	  else
	    gcc_assert (ref->next != NULL);
	  break;

	case REF_COMPONENT:
	  if (init == NULL)
	    {
	      /* Setup the expression to hold the constructor.  */
	      expr->expr_type = EXPR_STRUCTURE;
	      expr->ts.type = BT_DERIVED;
	      expr->ts.derived = ref->u.c.sym;
	    }
	  else
	    gcc_assert (expr->expr_type == EXPR_STRUCTURE);
	  last_ts = &ref->u.c.component->ts;

	  /* Find the same element in the existing constructor.  */
	  con = expr->value.constructor;
	  con = find_con_by_component (ref->u.c.component, con);

	  if (con == NULL)
	    {
	      /* Create a new constructor.  */
	      con = gfc_get_constructor ();
	      con->n.component = ref->u.c.component;
	      con->next = expr->value.constructor;
	      expr->value.constructor = con;
	    }

	  /* Since we're only intending to initialize arrays here,
	     there better be an inner reference.  */
	  gcc_assert (ref->next != NULL);
	  break;

	case REF_SUBSTRING:
	default:
	  gcc_unreachable ();
	}

      if (init == NULL)
	{
	  /* Point the container at the new expression.  */
	  if (last_con == NULL)
	    symbol->value = expr;
	  else
	    last_con->expr = expr;
	}
      init = con->expr;
      last_con = con;
    }

  if (last_ts->type == BT_CHARACTER)
    expr = create_character_intializer (init, last_ts, NULL, rvalue);
  else
    {
      /* We should never be overwriting an existing initializer.  */
      gcc_assert (!init);

      expr = gfc_copy_expr (rvalue);
      if (!gfc_compare_types (&lvalue->ts, &expr->ts))
	gfc_convert_type (expr, &lvalue->ts, 0);
    }

  if (last_con == NULL)
    symbol->value = expr;
  else
    last_con->expr = expr;
}

/* Modify the index of array section and re-calculate the array offset.  */

void 
gfc_advance_section (mpz_t *section_index, gfc_array_ref *ar,
		     mpz_t *offset_ret)
{
  int i;
  mpz_t delta;
  mpz_t tmp; 
  bool forwards;
  int cmp;

  for (i = 0; i < ar->dimen; i++)
    {
      if (ar->dimen_type[i] != DIMEN_RANGE)
	continue;

      if (ar->stride[i])
	{
	  mpz_add (section_index[i], section_index[i],
		   ar->stride[i]->value.integer);
	if (mpz_cmp_si (ar->stride[i]->value.integer, 0) >= 0)
	  forwards = true;
	else
	  forwards = false;
	}
      else
	{
	  mpz_add_ui (section_index[i], section_index[i], 1);
	  forwards = true;
	}
      
      if (ar->end[i])
	cmp = mpz_cmp (section_index[i], ar->end[i]->value.integer);
      else
	cmp = mpz_cmp (section_index[i], ar->as->upper[i]->value.integer);

      if ((cmp > 0 && forwards)
	  || (cmp < 0 && ! forwards))
	{
          /* Reset index to start, then loop to advance the next index.  */
	  if (ar->start[i])
	    mpz_set (section_index[i], ar->start[i]->value.integer);
	  else
	    mpz_set (section_index[i], ar->as->lower[i]->value.integer);
	}
      else
	break;
    }

  mpz_set_si (*offset_ret, 0);
  mpz_init_set_si (delta, 1);
  mpz_init (tmp);
  for (i = 0; i < ar->dimen; i++)
    {
      mpz_sub (tmp, section_index[i], ar->as->lower[i]->value.integer);
      mpz_mul (tmp, tmp, delta);
      mpz_add (*offset_ret, tmp, *offset_ret);

      mpz_sub (tmp, ar->as->upper[i]->value.integer, 
               ar->as->lower[i]->value.integer);
      mpz_add_ui (tmp, tmp, 1);
      mpz_mul (delta, tmp, delta);
    }
  mpz_clear (tmp);
  mpz_clear (delta);
}


/* Rearrange a structure constructor so the elements are in the specified
   order.  Also insert NULL entries if necessary.  */

static void
formalize_structure_cons (gfc_expr * expr)
{
  gfc_constructor *head;
  gfc_constructor *tail;
  gfc_constructor *cur;
  gfc_constructor *last;
  gfc_constructor *c;
  gfc_component *order;

  c = expr->value.constructor;

  /* Constructor is already formalized.  */
  if (c->n.component == NULL)
    return;

  head = tail = NULL;
  for (order = expr->ts.derived->components; order; order = order->next)
    {
      /* Find the next component.  */
      last = NULL;
      cur = c;
      while (cur != NULL && cur->n.component != order)
	{
	  last = cur;
	  cur = cur->next;
	}

      if (cur == NULL)
	{
	  /* Create a new one.  */
	  cur = gfc_get_constructor ();
	}
      else
	{
	  /* Remove it from the chain.  */
	  if (last == NULL)
	    c = cur->next;
	  else
	    last->next = cur->next;
	  cur->next = NULL;

	  formalize_init_expr (cur->expr);
	}

      /* Add it to the new constructor.  */
      if (head == NULL)
	head = tail = cur;
      else
	{
	  tail->next = cur;
	  tail = tail->next;
	}
    }
  gcc_assert (c == NULL);
  expr->value.constructor = head;
}


/* Make sure an initialization expression is in normalized form.  Ie. all
   elements of the constructors are in the correct order.  */

static void
formalize_init_expr (gfc_expr * expr)
{
  expr_t type;
  gfc_constructor *c;

  if (expr == NULL)
    return;

  type = expr->expr_type;
  switch (type)
    {
    case EXPR_ARRAY:
      c = expr->value.constructor;
      while (c)
	{
	  formalize_init_expr (c->expr);
	  c = c->next;
	}
      break;

    case EXPR_STRUCTURE:
      formalize_structure_cons (expr);
      break;

    default:
      break;
    }
}


/* Resolve symbol's initial value after all data statement.  */

void
gfc_formalize_init_value (gfc_symbol *sym)
{
  formalize_init_expr (sym->value);
}


/* Get the integer value into RET_AS and SECTION from AS and AR, and return
   offset.  */
 
void
gfc_get_section_index (gfc_array_ref *ar, mpz_t *section_index, mpz_t *offset)
{
  int i;
  mpz_t delta;
  mpz_t tmp;

  mpz_set_si (*offset, 0);
  mpz_init (tmp);
  mpz_init_set_si (delta, 1);
  for (i = 0; i < ar->dimen; i++)
    {
      mpz_init (section_index[i]);
      switch (ar->dimen_type[i])
	{
	case DIMEN_ELEMENT:
	case DIMEN_RANGE:
	  if (ar->start[i])
	    {
	      mpz_sub (tmp, ar->start[i]->value.integer,
		       ar->as->lower[i]->value.integer);
	      mpz_mul (tmp, tmp, delta);
	      mpz_add (*offset, tmp, *offset);
	      mpz_set (section_index[i], ar->start[i]->value.integer);
	    }
	  else
	      mpz_set (section_index[i], ar->as->lower[i]->value.integer);
	  break;

	case DIMEN_VECTOR:
	  gfc_internal_error ("TODO: Vector sections in data statements");

	default:
	  gcc_unreachable ();
	}

      mpz_sub (tmp, ar->as->upper[i]->value.integer, 
               ar->as->lower[i]->value.integer);
      mpz_add_ui (tmp, tmp, 1);
      mpz_mul (delta, tmp, delta);
    }

  mpz_clear (tmp);
  mpz_clear (delta);
}