2018-05-07 Edward Smith-Rowland <3dw4rd@verizon.net>

[official-gcc.git] / gcc / fortran / target-memory.c

/* Simulate storage of variables into target memory.
   Copyright (C) 2007-2018 Free Software Foundation, Inc.
   Contributed by Paul Thomas and Brooks Moses

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/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tree.h"
#include "gfortran.h"
#include "trans.h"
#include "fold-const.h"
#include "stor-layout.h"
#include "arith.h"
#include "constructor.h"
#include "trans-const.h"
#include "trans-types.h"
#include "target-memory.h"

/* --------------------------------------------------------------- */
/* Calculate the size of an expression.  */


static size_t
size_integer (int kind)
{
  return GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (gfc_get_int_type (kind)));
}


static size_t
size_float (int kind)
{
  return GET_MODE_SIZE (SCALAR_FLOAT_TYPE_MODE (gfc_get_real_type (kind)));
}


static size_t
size_complex (int kind)
{
  return 2 * size_float (kind);
}


static size_t
size_logical (int kind)
{
  return GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (gfc_get_logical_type (kind)));
}


static size_t
size_character (gfc_charlen_t length, int kind)
{
  int i = gfc_validate_kind (BT_CHARACTER, kind, false);
  return length * gfc_character_kinds[i].bit_size / 8;
}


/* Return the size of a single element of the given expression.
   Identical to gfc_target_expr_size for scalars.  */

size_t
gfc_element_size (gfc_expr *e)
{
  tree type;

  switch (e->ts.type)
    {
    case BT_INTEGER:
      return size_integer (e->ts.kind);
    case BT_REAL:
      return size_float (e->ts.kind);
    case BT_COMPLEX:
      return size_complex (e->ts.kind);
    case BT_LOGICAL:
      return size_logical (e->ts.kind);
    case BT_CHARACTER:
      if (e->expr_type == EXPR_CONSTANT)
        return size_character (e->value.character.length, e->ts.kind);
      else if (e->ts.u.cl != NULL && e->ts.u.cl->length != NULL
               && e->ts.u.cl->length->expr_type == EXPR_CONSTANT
               && e->ts.u.cl->length->ts.type == BT_INTEGER)
        {
          HOST_WIDE_INT length;

          gfc_extract_hwi (e->ts.u.cl->length, &length);
          return size_character (length, e->ts.kind);
        }
      else
        return 0;

    case BT_HOLLERITH:
      return e->representation.length;
    case BT_DERIVED:
    case BT_CLASS:
    case BT_VOID:
    case BT_ASSUMED:
      {
        /* Determine type size without clobbering the typespec for ISO C
           binding types.  */
        gfc_typespec ts;
        HOST_WIDE_INT size;
        ts = e->ts;
        type = gfc_typenode_for_spec (&ts);
        size = int_size_in_bytes (type);
        gcc_assert (size >= 0);
        return size;
      }
    default:
      gfc_internal_error ("Invalid expression in gfc_element_size.");
      return 0;
    }
}


/* Return the size of an expression in its target representation.  */

size_t
gfc_target_expr_size (gfc_expr *e)
{
  mpz_t tmp;
  size_t asz;

  gcc_assert (e != NULL);

  if (e->rank)
    {
      if (gfc_array_size (e, &tmp))
        asz = mpz_get_ui (tmp);
      else
        asz = 0;
    }
  else
    asz = 1;

  return asz * gfc_element_size (e);
}


/* The encode_* functions export a value into a buffer, and
   return the number of bytes of the buffer that have been
   used.  */

static unsigned HOST_WIDE_INT
encode_array (gfc_expr *expr, unsigned char *buffer, size_t buffer_size)
{
  mpz_t array_size;
  int i;
  int ptr = 0;

  gfc_constructor_base ctor = expr->value.constructor;

  gfc_array_size (expr, &array_size);
  for (i = 0; i < (int)mpz_get_ui (array_size); i++)
    {
      ptr += gfc_target_encode_expr (gfc_constructor_lookup_expr (ctor, i),
                                     &buffer[ptr], buffer_size - ptr);
    }

  mpz_clear (array_size);
  return ptr;
}


static int
encode_integer (int kind, mpz_t integer, unsigned char *buffer,
                size_t buffer_size)
{
  return native_encode_expr (gfc_conv_mpz_to_tree (integer, kind),
                             buffer, buffer_size);
}


static int
encode_float (int kind, mpfr_t real, unsigned char *buffer, size_t buffer_size)
{
  return native_encode_expr (gfc_conv_mpfr_to_tree (real, kind, 0), buffer,
                             buffer_size);
}


static int
encode_complex (int kind, mpc_t cmplx,
                unsigned char *buffer, size_t buffer_size)
{
  int size;
  size = encode_float (kind, mpc_realref (cmplx), &buffer[0], buffer_size);
  size += encode_float (kind, mpc_imagref (cmplx),
                        &buffer[size], buffer_size - size);
  return size;
}


static int
encode_logical (int kind, int logical, unsigned char *buffer, size_t buffer_size)
{
  return native_encode_expr (build_int_cst (gfc_get_logical_type (kind),
                                            logical),
                             buffer, buffer_size);
}


size_t
gfc_encode_character (int kind, size_t length, const gfc_char_t *string,
                      unsigned char *buffer, size_t buffer_size)
{
  size_t elsize = size_character (1, kind);
  tree type = gfc_get_char_type (kind);

  gcc_assert (buffer_size >= size_character (length, kind));

  for (size_t i = 0; i < length; i++)
    native_encode_expr (build_int_cst (type, string[i]), &buffer[i*elsize],
                        elsize);

  return length;
}


static unsigned HOST_WIDE_INT
encode_derived (gfc_expr *source, unsigned char *buffer, size_t buffer_size)
{
  gfc_constructor *c;
  gfc_component *cmp;
  int ptr;
  tree type;
  HOST_WIDE_INT size;

  type = gfc_typenode_for_spec (&source->ts);

  for (c = gfc_constructor_first (source->value.constructor),
       cmp = source->ts.u.derived->components;
       c;
       c = gfc_constructor_next (c), cmp = cmp->next)
    {
      gcc_assert (cmp);
      if (!c->expr)
        continue;
      ptr = TREE_INT_CST_LOW(DECL_FIELD_OFFSET(cmp->backend_decl))
            + TREE_INT_CST_LOW(DECL_FIELD_BIT_OFFSET(cmp->backend_decl))/8;

      if (c->expr->expr_type == EXPR_NULL)
        {
          size = int_size_in_bytes (TREE_TYPE (cmp->backend_decl));
          gcc_assert (size >= 0);
          memset (&buffer[ptr], 0, size);
        }
      else
        gfc_target_encode_expr (c->expr, &buffer[ptr],
                                buffer_size - ptr);
    }

  size = int_size_in_bytes (type);
  gcc_assert (size >= 0);
  return size;
}


/* Write a constant expression in binary form to a buffer.  */
unsigned HOST_WIDE_INT
gfc_target_encode_expr (gfc_expr *source, unsigned char *buffer,
                        size_t buffer_size)
{
  if (source == NULL)
    return 0;

  if (source->expr_type == EXPR_ARRAY)
    return encode_array (source, buffer, buffer_size);

  gcc_assert (source->expr_type == EXPR_CONSTANT
              || source->expr_type == EXPR_STRUCTURE
              || source->expr_type == EXPR_SUBSTRING);

  /* If we already have a target-memory representation, we use that rather
     than recreating one.  */
  if (source->representation.string)
    {
      memcpy (buffer, source->representation.string,
              source->representation.length);
      return source->representation.length;
    }

  switch (source->ts.type)
    {
    case BT_INTEGER:
      return encode_integer (source->ts.kind, source->value.integer, buffer,
                             buffer_size);
    case BT_REAL:
      return encode_float (source->ts.kind, source->value.real, buffer,
                           buffer_size);
    case BT_COMPLEX:
      return encode_complex (source->ts.kind, source->value.complex,
                             buffer, buffer_size);
    case BT_LOGICAL:
      return encode_logical (source->ts.kind, source->value.logical, buffer,
                             buffer_size);
    case BT_CHARACTER:
      if (source->expr_type == EXPR_CONSTANT || source->ref == NULL)
        return gfc_encode_character (source->ts.kind,
                                     source->value.character.length,
                                     source->value.character.string,
                                     buffer, buffer_size);
      else
        {
          HOST_WIDE_INT start, end;

          gcc_assert (source->expr_type == EXPR_SUBSTRING);
          gfc_extract_hwi (source->ref->u.ss.start, &start);
          gfc_extract_hwi (source->ref->u.ss.end, &end);
          return gfc_encode_character (source->ts.kind, MAX(end - start + 1, 0),
                                       &source->value.character.string[start-1],
                                       buffer, buffer_size);
        }

    case BT_DERIVED:
      if (source->ts.u.derived->ts.f90_type == BT_VOID)
        {
          gfc_constructor *c;
          gcc_assert (source->expr_type == EXPR_STRUCTURE);
          c = gfc_constructor_first (source->value.constructor);
          gcc_assert (c->expr->expr_type == EXPR_CONSTANT
                      && c->expr->ts.type == BT_INTEGER);
          return encode_integer (gfc_index_integer_kind, c->expr->value.integer,
                                 buffer, buffer_size);
        }

      return encode_derived (source, buffer, buffer_size);
    default:
      gfc_internal_error ("Invalid expression in gfc_target_encode_expr.");
      return 0;
    }
}


static size_t
interpret_array (unsigned char *buffer, size_t buffer_size, gfc_expr *result)
{
  gfc_constructor_base base = NULL;
  size_t array_size = 1;
  size_t ptr = 0;

  /* Calculate array size from its shape and rank.  */
  gcc_assert (result->rank > 0 && result->shape);

  for (int i = 0; i < result->rank; i++)
    array_size *= mpz_get_ui (result->shape[i]);

  /* Iterate over array elements, producing constructors.  */
  for (size_t i = 0; i < array_size; i++)
    {
      gfc_expr *e = gfc_get_constant_expr (result->ts.type, result->ts.kind,
                                           &result->where);
      e->ts = result->ts;

      if (e->ts.type == BT_CHARACTER)
        e->value.character.length = result->value.character.length;

      gfc_constructor_append_expr (&base, e, &result->where);

      ptr += gfc_target_interpret_expr (&buffer[ptr], buffer_size - ptr, e,
                                        true);
    }

  result->value.constructor = base;
  return ptr;
}


int
gfc_interpret_integer (int kind, unsigned char *buffer, size_t buffer_size,
                   mpz_t integer)
{
  mpz_init (integer);
  gfc_conv_tree_to_mpz (integer,
                        native_interpret_expr (gfc_get_int_type (kind),
                                               buffer, buffer_size));
  return size_integer (kind);
}


int
gfc_interpret_float (int kind, unsigned char *buffer, size_t buffer_size,
                     mpfr_t real)
{
  gfc_set_model_kind (kind);
  mpfr_init (real);
  gfc_conv_tree_to_mpfr (real,
                         native_interpret_expr (gfc_get_real_type (kind),
                                                buffer, buffer_size));

  return size_float (kind);
}


int
gfc_interpret_complex (int kind, unsigned char *buffer, size_t buffer_size,
                       mpc_t complex)
{
  int size;
  size = gfc_interpret_float (kind, &buffer[0], buffer_size,
                              mpc_realref (complex));
  size += gfc_interpret_float (kind, &buffer[size], buffer_size - size,
                               mpc_imagref (complex));
  return size;
}


int
gfc_interpret_logical (int kind, unsigned char *buffer, size_t buffer_size,
                   int *logical)
{
  tree t = native_interpret_expr (gfc_get_logical_type (kind), buffer,
                                  buffer_size);
  *logical = wi::to_wide (t) == 0 ? 0 : 1;
  return size_logical (kind);
}


size_t
gfc_interpret_character (unsigned char *buffer, size_t buffer_size,
                         gfc_expr *result)
{
  if (result->ts.u.cl && result->ts.u.cl->length)
    result->value.character.length =
      gfc_mpz_get_hwi (result->ts.u.cl->length->value.integer);

  gcc_assert (buffer_size >= size_character (result->value.character.length,
                                             result->ts.kind));
  result->value.character.string =
    gfc_get_wide_string (result->value.character.length + 1);

  if (result->ts.kind == gfc_default_character_kind)
    for (size_t i = 0; i < (size_t) result->value.character.length; i++)
      result->value.character.string[i] = (gfc_char_t) buffer[i];
  else
    {
      mpz_t integer;
      size_t bytes = size_character (1, result->ts.kind);
      mpz_init (integer);
      gcc_assert (bytes <= sizeof (unsigned long));

      for (size_t i = 0; i < (size_t) result->value.character.length; i++)
        {
          gfc_conv_tree_to_mpz (integer,
            native_interpret_expr (gfc_get_char_type (result->ts.kind),
                                   &buffer[bytes*i], buffer_size-bytes*i));
          result->value.character.string[i]
            = (gfc_char_t) mpz_get_ui (integer);
        }

      mpz_clear (integer);
    }

  result->value.character.string[result->value.character.length] = '\0';

  return result->value.character.length;
}


int
gfc_interpret_derived (unsigned char *buffer, size_t buffer_size, gfc_expr *result)
{
  gfc_component *cmp;
  int ptr;
  tree type;

  /* The attributes of the derived type need to be bolted to the floor.  */
  result->expr_type = EXPR_STRUCTURE;

  cmp = result->ts.u.derived->components;

  if (result->ts.u.derived->from_intmod == INTMOD_ISO_C_BINDING
      && (result->ts.u.derived->intmod_sym_id == ISOCBINDING_PTR
          || result->ts.u.derived->intmod_sym_id == ISOCBINDING_FUNPTR))
    {
      gfc_constructor *c;
      gfc_expr *e;
      /* Needed as gfc_typenode_for_spec as gfc_typenode_for_spec
         sets this to BT_INTEGER.  */
      result->ts.type = BT_DERIVED;
      e = gfc_get_constant_expr (cmp->ts.type, cmp->ts.kind, &result->where);
      c = gfc_constructor_append_expr (&result->value.constructor, e, NULL);
      c->n.component = cmp;
      gfc_target_interpret_expr (buffer, buffer_size, e, true);
      e->ts.is_iso_c = 1;
      return int_size_in_bytes (ptr_type_node);
    }

  type = gfc_typenode_for_spec (&result->ts);

  /* Run through the derived type components.  */
  for (;cmp; cmp = cmp->next)
    {
      gfc_constructor *c;
      gfc_expr *e = gfc_get_constant_expr (cmp->ts.type, cmp->ts.kind,
                                           &result->where);
      e->ts = cmp->ts;

      /* Copy shape, if needed.  */
      if (cmp->as && cmp->as->rank)
        {
          int n;

          e->expr_type = EXPR_ARRAY;
          e->rank = cmp->as->rank;

          e->shape = gfc_get_shape (e->rank);
          for (n = 0; n < e->rank; n++)
             {
               mpz_init_set_ui (e->shape[n], 1);
               mpz_add (e->shape[n], e->shape[n],
                        cmp->as->upper[n]->value.integer);
               mpz_sub (e->shape[n], e->shape[n],
                        cmp->as->lower[n]->value.integer);
             }
        }

      c = gfc_constructor_append_expr (&result->value.constructor, e, NULL);

      /* The constructor points to the component.  */
      c->n.component = cmp;

      /* Calculate the offset, which consists of the FIELD_OFFSET in
         bytes, which appears in multiples of DECL_OFFSET_ALIGN-bit-sized,
         and additional bits of FIELD_BIT_OFFSET. The code assumes that all
         sizes of the components are multiples of BITS_PER_UNIT,
         i.e. there are, e.g., no bit fields.  */

      gcc_assert (cmp->backend_decl);
      ptr = TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (cmp->backend_decl));
      gcc_assert (ptr % 8 == 0);
      ptr = ptr/8 + TREE_INT_CST_LOW (DECL_FIELD_OFFSET (cmp->backend_decl));

      gcc_assert (e->ts.type != BT_VOID || cmp->attr.caf_token);
      gfc_target_interpret_expr (&buffer[ptr], buffer_size - ptr, e, true);
    }

  return int_size_in_bytes (type);
}


/* Read a binary buffer to a constant expression.  */
size_t
gfc_target_interpret_expr (unsigned char *buffer, size_t buffer_size,
                           gfc_expr *result, bool convert_widechar)
{
  if (result->expr_type == EXPR_ARRAY)
    return interpret_array (buffer, buffer_size, result);

  switch (result->ts.type)
    {
    case BT_INTEGER:
      result->representation.length =
        gfc_interpret_integer (result->ts.kind, buffer, buffer_size,
                               result->value.integer);
      break;

    case BT_REAL:
      result->representation.length =
        gfc_interpret_float (result->ts.kind, buffer, buffer_size,
                             result->value.real);
      break;

    case BT_COMPLEX:
      result->representation.length =
        gfc_interpret_complex (result->ts.kind, buffer, buffer_size,
                               result->value.complex);
      break;

    case BT_LOGICAL:
      result->representation.length =
        gfc_interpret_logical (result->ts.kind, buffer, buffer_size,
                               &result->value.logical);
      break;

    case BT_CHARACTER:
      result->representation.length =
        gfc_interpret_character (buffer, buffer_size, result);
      break;

    case BT_CLASS:
      result->ts = CLASS_DATA (result)->ts;
      /* Fall through.  */
    case BT_DERIVED:
      result->representation.length =
        gfc_interpret_derived (buffer, buffer_size, result);
      gcc_assert (result->representation.length >= 0);
      break;

    case BT_VOID:
      /* This deals with caf_tokens.  */
      result->representation.length =
        gfc_interpret_integer (result->ts.kind, buffer, buffer_size,
                               result->value.integer);
      break;

    default:
      gfc_internal_error ("Invalid expression in gfc_target_interpret_expr.");
      break;
    }

  if (result->ts.type == BT_CHARACTER && convert_widechar)
    result->representation.string
      = gfc_widechar_to_char (result->value.character.string,
                              result->value.character.length);
  else
    {
      result->representation.string =
        XCNEWVEC (char, result->representation.length + 1);
      memcpy (result->representation.string, buffer,
              result->representation.length);
      result->representation.string[result->representation.length] = '\0';
    }

  return result->representation.length;
}


/* --------------------------------------------------------------- */
/* Two functions used by trans-common.c to write overlapping
   equivalence initializers to a buffer.  This is added to the union
   and the original initializers freed.  */


/* Writes the values of a constant expression to a char buffer. If another
   unequal initializer has already been written to the buffer, this is an
   error.  */

static size_t
expr_to_char (gfc_expr *e, locus *loc,
              unsigned char *data, unsigned char *chk, size_t len)
{
  int i;
  int ptr;
  gfc_constructor *c;
  gfc_component *cmp;
  unsigned char *buffer;

  if (e == NULL)
    return 0;

  /* Take a derived type, one component at a time, using the offsets from the backend
     declaration.  */
  if (e->ts.type == BT_DERIVED)
    {
      for (c = gfc_constructor_first (e->value.constructor),
           cmp = e->ts.u.derived->components;
           c; c = gfc_constructor_next (c), cmp = cmp->next)
        {
          gcc_assert (cmp && cmp->backend_decl);
          if (!c->expr)
            continue;
          ptr = TREE_INT_CST_LOW(DECL_FIELD_OFFSET(cmp->backend_decl))
            + TREE_INT_CST_LOW(DECL_FIELD_BIT_OFFSET(cmp->backend_decl))/8;
          expr_to_char (c->expr, loc, &data[ptr], &chk[ptr], len);
        }
      return len;
    }

  /* Otherwise, use the target-memory machinery to write a bitwise image, appropriate
     to the target, in a buffer and check off the initialized part of the buffer.  */
  len = gfc_target_expr_size (e);
  buffer = (unsigned char*)alloca (len);
  len = gfc_target_encode_expr (e, buffer, len);

  for (i = 0; i < (int)len; i++)
    {
      if (chk[i] && (buffer[i] != data[i]))
        {
          if (loc)
            gfc_error ("Overlapping unequal initializers in EQUIVALENCE "
                        "at %L", loc);
          else
            gfc_error ("Overlapping unequal initializers in EQUIVALENCE "
                        "at %C");
          return 0;
        }
      chk[i] = 0xFF;
    }

  memcpy (data, buffer, len);
  return len;
}


/* Writes the values from the equivalence initializers to a char* array
   that will be written to the constructor to make the initializer for
   the union declaration.  */

size_t
gfc_merge_initializers (gfc_typespec ts, gfc_expr *e, locus *loc,
                        unsigned char *data,
                        unsigned char *chk, size_t length)
{
  size_t len = 0;
  gfc_constructor * c;

  switch (e->expr_type)
    {
    case EXPR_CONSTANT:
    case EXPR_STRUCTURE:
      len = expr_to_char (e, loc, &data[0], &chk[0], length);
      break;

    case EXPR_ARRAY:
      for (c = gfc_constructor_first (e->value.constructor);
           c; c = gfc_constructor_next (c))
        {
          size_t elt_size = gfc_target_expr_size (c->expr);

          if (mpz_cmp_si (c->offset, 0) != 0)
            len = elt_size * (size_t)mpz_get_si (c->offset);

          len = len + gfc_merge_initializers (ts, c->expr, loc, &data[len],
                                              &chk[len], length - len);
        }
      break;

    default:
      return 0;
    }

  return len;
}


/* Transfer the bitpattern of a (integer) BOZ to real or complex variables.
   When successful, no BOZ or nothing to do, true is returned.  */

bool
gfc_convert_boz (gfc_expr *expr, gfc_typespec *ts)
{
  size_t buffer_size, boz_bit_size, ts_bit_size;
  int index;
  unsigned char *buffer;

  if (!expr->is_boz)
    return true;

  gcc_assert (expr->expr_type == EXPR_CONSTANT
              && expr->ts.type == BT_INTEGER);

  /* Don't convert BOZ to logical, character, derived etc.  */
  if (ts->type == BT_REAL)
    {
      buffer_size = size_float (ts->kind);
      ts_bit_size = buffer_size * 8;
    }
  else if (ts->type == BT_COMPLEX)
    {
      buffer_size = size_complex (ts->kind);
      ts_bit_size = buffer_size * 8 / 2;
    }
  else
    return true;

  /* Convert BOZ to the smallest possible integer kind.  */
  boz_bit_size = mpz_sizeinbase (expr->value.integer, 2);

  if (boz_bit_size > ts_bit_size)
    {
      gfc_error_now ("BOZ constant at %L is too large (%ld vs %ld bits)",
                     &expr->where, (long) boz_bit_size, (long) ts_bit_size);
      return false;
    }

  for (index = 0; gfc_integer_kinds[index].kind != 0; ++index)
    if ((unsigned) gfc_integer_kinds[index].bit_size >= ts_bit_size)
      break;

  expr->ts.kind = gfc_integer_kinds[index].kind;
  buffer_size = MAX (buffer_size, size_integer (expr->ts.kind));

  buffer = (unsigned char*)alloca (buffer_size);
  encode_integer (expr->ts.kind, expr->value.integer, buffer, buffer_size);
  mpz_clear (expr->value.integer);

  if (ts->type == BT_REAL)
    {
      mpfr_init (expr->value.real);
      gfc_interpret_float (ts->kind, buffer, buffer_size, expr->value.real);
    }
  else
    {
      mpc_init2 (expr->value.complex, mpfr_get_default_prec());
      gfc_interpret_complex (ts->kind, buffer, buffer_size,
                             expr->value.complex);
    }
  expr->is_boz = 0;
  expr->ts.type = ts->type;
  expr->ts.kind = ts->kind;

  return true;
}