From FEDORA_PATCHES Mon Sep 17 00:00:00 2001

From: Kevin Buettner <kevinb@redhat.com>

Date: Mon, 24 May 2021 22:46:21 -0700

Subject: gdb-rhbz1964167-fortran-array-slices-at-prompt.patch

;; [fortran] Backport Andrew Burgess's commit for Fortran array

;; slice support

gdb/fortran: Add support for Fortran array slices at the GDB prompt

This commit brings array slice support to GDB.

WARNING: This patch contains a rather big hack which is limited to

Fortran arrays, this can be seen in gdbtypes.c and f-lang.c.  More

details on this below.

This patch rewrites two areas of GDB's Fortran support, the code to

extract an array slice, and the code to print an array.

After this commit a user can, from the GDB prompt, ask for a slice of

a Fortran array and should get the correct result back.  Slices can

(optionally) have the lower bound, upper bound, and a stride

specified.  Slices can also have a negative stride.

Fortran has the concept of repacking array slices.  Within a compiled

Fortran program if a user passes a non-contiguous array slice to a

function then the compiler may have to repack the slice, this involves

copying the elements of the slice to a new area of memory before the

call, and copying the elements back to the original array after the

call.  Whether repacking occurs will depend on which version of

Fortran is being used, and what type of function is being called.

This commit adds support for both packed, and unpacked array slicing,

with the default being unpacked.

With an unpacked array slice, when the user asks for a slice of an

array GDB creates a new type that accurately describes where the

elements of the slice can be found within the original array, a

value of this type is then returned to the user.  The address of an

element within the slice will be equal to the address of an element

within the original array.

A user can choose to select packed array slices instead using:

  (gdb) set fortran repack-array-slices on|off

  (gdb) show fortran repack-array-slices

With packed array slices GDB creates a new type that reflects how the

elements of the slice would look if they were laid out in contiguous

memory, allocates a value of this type, and then fetches the elements

from the original array and places then into the contents buffer of

the new value.

One benefit of using packed slices over unpacked slices is the memory

usage, taking a small slice of N elements from a large array will

require (in GDB) N * ELEMENT_SIZE bytes of memory, while an unpacked

array will also include all of the "padding" between the

non-contiguous elements.  There are new tests added that highlight

this difference.

There is also a new debugging flag added with this commit that

introduces these commands:

  (gdb) set debug fortran-array-slicing on|off

  (gdb) show debug fortran-array-slicing

This prints information about how the array slices are being built.

As both the repacking, and the array printing requires GDB to walk

through a multi-dimensional Fortran array visiting each element, this

commit adds the file f-array-walk.h, which introduces some

infrastructure to support this process.  This means the array printing

code in f-valprint.c is significantly reduced.

The only slight issue with this commit is the "rather big hack" that I

mentioned above.  This hack allows us to handle one specific case,

array slices with negative strides.  This is something that I don't

believe the current GDB value contents model will allow us to

correctly handle, and rather than rewrite the value contents code

right now, I'm hoping to slip this hack in as a work around.

The problem is that, as I see it, the current value contents model

assumes that an object base address will be the lowest address within

that object, and that the contents of the object start at this base

address and occupy the TYPE_LENGTH bytes after that.

( We do have the embedded_offset, which is used for C++ sub-classes,

such that an object can start at some offset from the content buffer,

however, the assumption that the object then occupies the next

TYPE_LENGTH bytes is still true within GDB. )

The problem is that Fortran arrays with a negative stride don't follow

this pattern.  In this case the base address of the object points to

the element with the highest address, the contents of the array then

start at some offset _before_ the base address, and proceed for one

element _past_ the base address.

As the stride for such an array would be negative then, in theory the

TYPE_LENGTH for this type would also be negative.  However, in many

places a value in GDB will degrade to a pointer + length, and the

length almost always comes from the TYPE_LENGTH.

It is my belief that in order to correctly model this case the value

content handling of GDB will need to be reworked to split apart the

value's content buffer (which is a block of memory with a length), and

the object's in memory base address and length, which could be

negative.

Things are further complicated because arrays with negative strides

like this are always dynamic types.  When a value has a dynamic type

and its base address needs resolving we actually store the address of

the object within the resolved dynamic type, not within the value

object itself.

In short I don't currently see an easy path to cleanly support this

situation within GDB.  And so I believe that leaves two options,

either add a work around, or catch cases where the user tries to make

use of a negative stride, or access an array with a negative stride,

and throw an error.

This patch currently goes with adding a work around, which is that

when we resolve a dynamic Fortran array type, if the stride is

negative, then we adjust the base address to point to the lowest

address required by the array.  The printing and slicing code is aware

of this adjustment and will correctly slice and print Fortran arrays.

Where this hack will show through to the user is if they ask for the

address of an array in their program with a negative array stride, the

address they get from GDB will not match the address that would be

computed within the Fortran program.

gdb/ChangeLog:

	* Makefile.in (HFILES_NO_SRCDIR): Add f-array-walker.h.

	* NEWS: Mention new options.

	* f-array-walker.h: New file.

	* f-lang.c: Include 'gdbcmd.h' and 'f-array-walker.h'.

	(repack_array_slices): New static global.

	(show_repack_array_slices): New function.

	(fortran_array_slicing_debug): New static global.

	(show_fortran_array_slicing_debug): New function.

	(value_f90_subarray): Delete.

	(skip_undetermined_arglist): Delete.

	(class fortran_array_repacker_base_impl): New class.

	(class fortran_lazy_array_repacker_impl): New class.

	(class fortran_array_repacker_impl): New class.

	(fortran_value_subarray): Complete rewrite.

	(set_fortran_list): New static global.

	(show_fortran_list): Likewise.

	(_initialize_f_language): Register new commands.

	(fortran_adjust_dynamic_array_base_address_hack): New function.

	* f-lang.h (fortran_adjust_dynamic_array_base_address_hack):

	Declare.

	* f-valprint.c: Include 'f-array-walker.h'.

	(class fortran_array_printer_impl): New class.

	(f77_print_array_1): Delete.

	(f77_print_array): Delete.

	(fortran_print_array): New.

	(f_value_print_inner): Update to call fortran_print_array.

	* gdbtypes.c: Include 'f-lang.h'.

	(resolve_dynamic_type_internal): Call

	fortran_adjust_dynamic_array_base_address_hack.

gdb/testsuite/ChangeLog:

        * gdb.fortran/array-slices-bad.exp: New file.

        * gdb.fortran/array-slices-bad.f90: New file.

        * gdb.fortran/array-slices-sub-slices.exp: New file.

        * gdb.fortran/array-slices-sub-slices.f90: New file.

        * gdb.fortran/array-slices.exp: Rewrite tests.

        * gdb.fortran/array-slices.f90: Rewrite tests.

        * gdb.fortran/vla-sizeof.exp: Correct expected results.

gdb/doc/ChangeLog:

        * gdb.texinfo (Debugging Output): Document 'set/show debug

        fortran-array-slicing'.

        (Special Fortran Commands): Document 'set/show fortran

        repack-array-slices'.

diff --git a/gdb/Makefile.in b/gdb/Makefile.in

--- a/gdb/Makefile.in

+++ b/gdb/Makefile.in

@@ -1268,6 +1268,7 @@ HFILES_NO_SRCDIR = \

 	expression.h \

 	extension.h \

 	extension-priv.h \

+	f-array-walker.h \

 	f-lang.h \

 	fbsd-nat.h \

 	fbsd-tdep.h \

diff --git a/gdb/NEWS b/gdb/NEWS

--- a/gdb/NEWS

+++ b/gdb/NEWS

@@ -111,6 +111,19 @@ maintenance print core-file-backed-mappings

   Prints file-backed mappings loaded from a core file's note section.

   Output is expected to be similar to that of "info proc mappings".

+set debug fortran-array-slicing on|off

+show debug fortran-array-slicing

+  Print debugging when taking slices of Fortran arrays.

+

+set fortran repack-array-slices on|off

+show fortran repack-array-slices

+  When taking slices from Fortran arrays and strings, if the slice is

+  non-contiguous within the original value then, when this option is

+  on, the new value will be repacked into a single contiguous value.

+  When this option is off, then the value returned will consist of a

+  descriptor that describes the slice within the memory of the

+  original parent value.

+

 * Changed commands

 alias [-a] [--] ALIAS = COMMAND [DEFAULT-ARGS...]

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo

--- a/gdb/doc/gdb.texinfo

+++ b/gdb/doc/gdb.texinfo

@@ -16919,6 +16919,29 @@ This command prints the values contained in the Fortran @code{COMMON}

 block whose name is @var{common-name}.  With no argument, the names of

 all @code{COMMON} blocks visible at the current program location are

 printed.

+@cindex arrays slices (Fortran)

+@kindex set fortran repack-array-slices

+@kindex show fortran repack-array-slices

+@item set fortran repack-array-slices [on|off]

+@item show fortran repack-array-slices

+When taking a slice from an array, a Fortran compiler can choose to

+either produce an array descriptor that describes the slice in place,

+or it may repack the slice, copying the elements of the slice into a

+new region of memory.

+

+When this setting is on, then @value{GDBN} will also repack array

+slices in some situations.  When this setting is off, then

+@value{GDBN} will create array descriptors for slices that reference

+the original data in place.

+

+@value{GDBN} will never repack an array slice if the data for the

+slice is contiguous within the original array.

+

+@value{GDBN} will always repack string slices if the data for the

+slice is non-contiguous within the original string as @value{GDBN}

+does not support printing non-contiguous strings.

+

+The default for this setting is @code{off}.

 @end table

 @node Pascal

@@ -26507,6 +26530,16 @@ Show the current state of FreeBSD LWP debugging messages.

 Turns on or off debugging messages from the FreeBSD native target.

 @item show debug fbsd-nat

 Show the current state of FreeBSD native target debugging messages.

+

+@item set debug fortran-array-slicing

+@cindex fortran array slicing debugging info

+Turns on or off display of @value{GDBN} Fortran array slicing

+debugging info.  The default is off.

+

+@item show debug fortran-array-slicing

+Displays the current state of displaying @value{GDBN} Fortran array

+slicing debugging info.

+

 @item set debug frame

 @cindex frame debugging info

 Turns on or off display of @value{GDBN} frame debugging info.  The

diff --git a/gdb/f-array-walker.h b/gdb/f-array-walker.h

new file mode 100644

--- /dev/null

+++ b/gdb/f-array-walker.h

@@ -0,0 +1,265 @@

+/* Copyright (C) 2020 Free Software Foundation, Inc.

+

+   This file is part of GDB.

+

+   This program 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 of the License, or

+   (at your option) any later version.

+

+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */

+

+/* Support classes to wrap up the process of iterating over a

+   multi-dimensional Fortran array.  */

+

+#ifndef F_ARRAY_WALKER_H

+#define F_ARRAY_WALKER_H

+

+#include "defs.h"

+#include "gdbtypes.h"

+#include "f-lang.h"

+

+/* Class for calculating the byte offset for elements within a single

+   dimension of a Fortran array.  */

+class fortran_array_offset_calculator

+{

+public:

+  /* Create a new offset calculator for TYPE, which is either an array or a

+     string.  */

+  explicit fortran_array_offset_calculator (struct type *type)

+  {

+    /* Validate the type.  */

+    type = check_typedef (type);

+    if (type->code () != TYPE_CODE_ARRAY

+	&& (type->code () != TYPE_CODE_STRING))

+      error (_("can only compute offsets for arrays and strings"));

+

+    /* Get the range, and extract the bounds.  */

+    struct type *range_type = type->index_type ();

+    if (!get_discrete_bounds (range_type, &m_lowerbound, &m_upperbound))

+      error ("unable to read array bounds");

+

+    /* Figure out the stride for this array.  */

+    struct type *elt_type = check_typedef (TYPE_TARGET_TYPE (type));

+    m_stride = type->index_type ()->bounds ()->bit_stride ();

+    if (m_stride == 0)

+      m_stride = type_length_units (elt_type);

+    else

+      {

+	struct gdbarch *arch = get_type_arch (elt_type);

+	int unit_size = gdbarch_addressable_memory_unit_size (arch);

+	m_stride /= (unit_size * 8);

+      }

+  };

+

+  /* Get the byte offset for element INDEX within the type we are working

+     on.  There is no bounds checking done on INDEX.  If the stride is

+     negative then we still assume that the base address (for the array

+     object) points to the element with the lowest memory address, we then

+     calculate an offset assuming that index 0 will be the element at the

+     highest address, index 1 the next highest, and so on.  This is not

+     quite how Fortran works in reality; in reality the base address of

+     the object would point at the element with the highest address, and

+     we would index backwards from there in the "normal" way, however,

+     GDB's current value contents model doesn't support having the base

+     address be near to the end of the value contents, so we currently

+     adjust the base address of Fortran arrays with negative strides so

+     their base address points at the lowest memory address.  This code

+     here is part of working around this weirdness.  */

+  LONGEST index_offset (LONGEST index)

+  {

+    LONGEST offset;

+    if (m_stride < 0)

+      offset = std::abs (m_stride) * (m_upperbound - index);

+    else

+      offset = std::abs (m_stride) * (index - m_lowerbound);

+    return offset;

+  }

+

+private:

+

+  /* The stride for the type we are working with.  */

+  LONGEST m_stride;

+

+  /* The upper bound for the type we are working with.  */

+  LONGEST m_upperbound;

+

+  /* The lower bound for the type we are working with.  */

+  LONGEST m_lowerbound;

+};

+

+/* A base class used by fortran_array_walker.  There's no virtual methods

+   here, sub-classes should just override the functions they want in order

+   to specialise the behaviour to their needs.  The functionality

+   provided in these default implementations will visit every array

+   element, but do nothing for each element.  */

+

+struct fortran_array_walker_base_impl

+{

+  /* Called when iterating between the lower and upper bounds of each

+     dimension of the array.  Return true if GDB should continue iterating,

+     otherwise, return false.

+

+     SHOULD_CONTINUE indicates if GDB is going to stop anyway, and should

+     be taken into consideration when deciding what to return.  If

+     SHOULD_CONTINUE is false then this function must also return false,

+     the function is still called though in case extra work needs to be

+     done as part of the stopping process.  */

+  bool continue_walking (bool should_continue)

+  { return should_continue; }

+

+  /* Called when GDB starts iterating over a dimension of the array.  The

+     argument INNER_P is true for the inner most dimension (the dimension

+     containing the actual elements of the array), and false for more outer

+     dimensions.  For a concrete example of how this function is called

+     see the comment on process_element below.  */

+  void start_dimension (bool inner_p)

+  { /* Nothing.  */ }

+

+  /* Called when GDB finishes iterating over a dimension of the array.  The

+     argument INNER_P is true for the inner most dimension (the dimension

+     containing the actual elements of the array), and false for more outer

+     dimensions.  LAST_P is true for the last call at a particular

+     dimension.  For a concrete example of how this function is called

+     see the comment on process_element below.  */

+  void finish_dimension (bool inner_p, bool last_p)

+  { /* Nothing.  */ }

+

+  /* Called when processing the inner most dimension of the array, for

+     every element in the array.  ELT_TYPE is the type of the element being

+     extracted, and ELT_OFF is the offset of the element from the start of

+     array being walked, and LAST_P is true only when this is the last

+     element that will be processed in this dimension.

+

+     Given this two dimensional array ((1, 2) (3, 4)), the calls to

+     start_dimension, process_element, and finish_dimension look like this:

+

+     start_dimension (false);

+       start_dimension (true);

+         process_element (TYPE, OFFSET, false);

+         process_element (TYPE, OFFSET, true);

+       finish_dimension (true, false);

+       start_dimension (true);

+         process_element (TYPE, OFFSET, false);

+         process_element (TYPE, OFFSET, true);

+       finish_dimension (true, true);

+     finish_dimension (false, true);  */

+  void process_element (struct type *elt_type, LONGEST elt_off, bool last_p)

+  { /* Nothing.  */ }

+};

+

+/* A class to wrap up the process of iterating over a multi-dimensional

+   Fortran array.  IMPL is used to specialise what happens as we walk over

+   the array.  See class FORTRAN_ARRAY_WALKER_BASE_IMPL (above) for the

+   methods than can be used to customise the array walk.  */

+template<typename Impl>

+class fortran_array_walker

+{

+  /* Ensure that Impl is derived from the required base class.  This just

+     ensures that all of the required API methods are available and have a

+     sensible default implementation.  */

+  gdb_static_assert ((std::is_base_of<fortran_array_walker_base_impl,Impl>::value));

+

+public:

+  /* Create a new array walker.  TYPE is the type of the array being walked

+     over, and ADDRESS is the base address for the object of TYPE in

+     memory.  All other arguments are forwarded to the constructor of the

+     template parameter class IMPL.  */

+  template <typename ...Args>

+  fortran_array_walker (struct type *type, CORE_ADDR address,

+			Args... args)

+    : m_type (type),

+      m_address (address),

+      m_impl (type, address, args...)

+  {

+    m_ndimensions =  calc_f77_array_dims (m_type);

+  }

+

+  /* Walk the array.  */

+  void

+  walk ()

+  {

+    walk_1 (1, m_type, 0, false);

+  }

+

+private:

+  /* The core of the array walking algorithm.  NSS is the current

+     dimension number being processed, TYPE is the type of this dimension,

+     and OFFSET is the offset (in bytes) for the start of this dimension.  */

+  void

+  walk_1 (int nss, struct type *type, int offset, bool last_p)

+  {

+    /* Extract the range, and get lower and upper bounds.  */

+    struct type *range_type = check_typedef (type)->index_type ();

+    LONGEST lowerbound, upperbound;

+    if (!get_discrete_bounds (range_type, &lowerbound, &upperbound))

+      error ("failed to get range bounds");

+

+    /* CALC is used to calculate the offsets for each element in this

+       dimension.  */

+    fortran_array_offset_calculator calc (type);

+

+    m_impl.start_dimension (nss == m_ndimensions);

+

+    if (nss != m_ndimensions)

+      {

+	/* For dimensions other than the inner most, walk each element and

+	   recurse while peeling off one more dimension of the array.  */

+	for (LONGEST i = lowerbound;

+	     m_impl.continue_walking (i < upperbound + 1);

+	     i++)

+	  {

+	    /* Use the index and the stride to work out a new offset.  */

+	    LONGEST new_offset = offset + calc.index_offset (i);

+

+	    /* Now print the lower dimension.  */

+	    struct type *subarray_type

+	      = TYPE_TARGET_TYPE (check_typedef (type));

+	    walk_1 (nss + 1, subarray_type, new_offset, (i == upperbound));

+	  }

+      }

+    else

+      {

+	/* For the inner most dimension of the array, process each element

+	   within this dimension.  */

+	for (LONGEST i = lowerbound;

+	     m_impl.continue_walking (i < upperbound + 1);

+	     i++)

+	  {

+	    LONGEST elt_off = offset + calc.index_offset (i);

+

+	    struct type *elt_type = check_typedef (TYPE_TARGET_TYPE (type));

+	    if (is_dynamic_type (elt_type))

+	      {

+		CORE_ADDR e_address = m_address + elt_off;

+		elt_type = resolve_dynamic_type (elt_type, {}, e_address);

+	      }

+

+	    m_impl.process_element (elt_type, elt_off, (i == upperbound));

+	  }

+      }

+

+    m_impl.finish_dimension (nss == m_ndimensions, last_p || nss == 1);

+  }

+

+  /* The array type being processed.  */

+  struct type *m_type;

+

+  /* The address in target memory for the object of M_TYPE being

+     processed.  This is required in order to resolve dynamic types.  */

+  CORE_ADDR m_address;

+

+  /* An instance of the template specialisation class.  */

+  Impl m_impl;

+

+  /* The total number of dimensions in M_TYPE.  */

+  int m_ndimensions;

+};

+

+#endif /* F_ARRAY_WALKER_H */

diff --git a/gdb/f-lang.c b/gdb/f-lang.c

--- a/gdb/f-lang.c

+++ b/gdb/f-lang.c

@@ -36,9 +36,36 @@

 #include "c-lang.h"

 #include "target-float.h"

 #include "gdbarch.h"

+#include "gdbcmd.h"

+#include "f-array-walker.h"

 #include <math.h>

+/* Whether GDB should repack array slices created by the user.  */

+static bool repack_array_slices = false;

+

+/* Implement 'show fortran repack-array-slices'.  */

+static void

+show_repack_array_slices (struct ui_file *file, int from_tty,

+			  struct cmd_list_element *c, const char *value)

+{

+  fprintf_filtered (file, _("Repacking of Fortran array slices is %s.\n"),

+		    value);

+}

+

+/* Debugging of Fortran's array slicing.  */

+static bool fortran_array_slicing_debug = false;

+

+/* Implement 'show debug fortran-array-slicing'.  */

+static void

+show_fortran_array_slicing_debug (struct ui_file *file, int from_tty,

+				  struct cmd_list_element *c,

+				  const char *value)

+{

+  fprintf_filtered (file, _("Debugging of Fortran array slicing is %s.\n"),

+		    value);

+}

+

 /* Local functions */

 /* Return the encoding that should be used for the character type

@@ -114,57 +141,6 @@ enum f_primitive_types {

   nr_f_primitive_types

 };

-/* Called from fortran_value_subarray to take a slice of an array or a

-   string.  ARRAY is the array or string to be accessed.  EXP, POS, and

-   NOSIDE are as for evaluate_subexp_standard.  Return a value that is a

-   slice of the array.  */

-

-static struct value *

-value_f90_subarray (struct value *array,

-		    struct expression *exp, int *pos, enum noside noside)

-{

-  int pc = (*pos) + 1;

-  LONGEST low_bound, high_bound, stride;

-  struct type *range = check_typedef (value_type (array)->index_type ());

-  enum range_flag range_flag

-    = (enum range_flag) longest_to_int (exp->elts[pc].longconst);

-

-  *pos += 3;

-

-  if (range_flag & RANGE_LOW_BOUND_DEFAULT)

-    low_bound = range->bounds ()->low.const_val ();

-  else

-    low_bound = value_as_long (evaluate_subexp (nullptr, exp, pos, noside));

-

-  if (range_flag & RANGE_HIGH_BOUND_DEFAULT)

-    high_bound = range->bounds ()->high.const_val ();

-  else

-    high_bound = value_as_long (evaluate_subexp (nullptr, exp, pos, noside));

-

-  if (range_flag & RANGE_HAS_STRIDE)

-    stride = value_as_long (evaluate_subexp (nullptr, exp, pos, noside));

-  else

-    stride = 1;

-

-  if (stride != 1)

-    error (_("Fortran array strides are not currently supported"));

-

-  return value_slice (array, low_bound, high_bound - low_bound + 1);

-}

-

-/* Helper for skipping all the arguments in an undetermined argument list.

-   This function was designed for use in the OP_F77_UNDETERMINED_ARGLIST

-   case of evaluate_subexp_standard as multiple, but not all, code paths

-   require a generic skip.  */

-

-static void

-skip_undetermined_arglist (int nargs, struct expression *exp, int *pos,

-			   enum noside noside)

-{

-  for (int i = 0; i < nargs; ++i)

-    evaluate_subexp (nullptr, exp, pos, noside);

-}

-

 /* Return the number of dimensions for a Fortran array or string.  */

 int

@@ -189,6 +165,145 @@ calc_f77_array_dims (struct type *array_type)

   return ndimen;

 }

+/* A class used by FORTRAN_VALUE_SUBARRAY when repacking Fortran array

+   slices.  This is a base class for two alternative repacking mechanisms,

+   one for when repacking from a lazy value, and one for repacking from a

+   non-lazy (already loaded) value.  */

+class fortran_array_repacker_base_impl

+  : public fortran_array_walker_base_impl

+{

+public:

+  /* Constructor, DEST is the value we are repacking into.  */

+  fortran_array_repacker_base_impl (struct value *dest)

+    : m_dest (dest),

+      m_dest_offset (0)

+  { /* Nothing.  */ }

+

+  /* When we start processing the inner most dimension, this is where we

+     will be creating values for each element as we load them and then copy

+     them into the M_DEST value.  Set a value mark so we can free these

+     temporary values.  */

+  void start_dimension (bool inner_p)

+  {

+    if (inner_p)

+      {

+	gdb_assert (m_mark == nullptr);

+	m_mark = value_mark ();

+      }

+  }

+

+  /* When we finish processing the inner most dimension free all temporary

+     value that were created.  */

+  void finish_dimension (bool inner_p, bool last_p)

+  {

+    if (inner_p)

+      {

+	gdb_assert (m_mark != nullptr);

+	value_free_to_mark (m_mark);

+	m_mark = nullptr;

+      }

+  }

+

+protected:

+  /* Copy the contents of array element ELT into M_DEST at the next

+     available offset.  */

+  void copy_element_to_dest (struct value *elt)

+  {

+    value_contents_copy (m_dest, m_dest_offset, elt, 0,

+			 TYPE_LENGTH (value_type (elt)));

+    m_dest_offset += TYPE_LENGTH (value_type (elt));

+  }

+

+  /* The value being written to.  */

+  struct value *m_dest;

+

+  /* The byte offset in M_DEST at which the next element should be

+     written.  */

+  LONGEST m_dest_offset;

+

+  /* Set with a call to VALUE_MARK, and then reset after calling

+     VALUE_FREE_TO_MARK.  */

+  struct value *m_mark = nullptr;

+};

+

+/* A class used by FORTRAN_VALUE_SUBARRAY when repacking Fortran array

+   slices.  This class is specialised for repacking an array slice from a

+   lazy array value, as such it does not require the parent array value to

+   be loaded into GDB's memory; the parent value could be huge, while the

+   slice could be tiny.  */

+class fortran_lazy_array_repacker_impl

+  : public fortran_array_repacker_base_impl

+{

+public:

+  /* Constructor.  TYPE is the type of the slice being loaded from the

+     parent value, so this type will correctly reflect the strides required

+     to find all of the elements from the parent value.  ADDRESS is the

+     address in target memory of value matching TYPE, and DEST is the value

+     we are repacking into.  */

+  explicit fortran_lazy_array_repacker_impl (struct type *type,

+					     CORE_ADDR address,

+					     struct value *dest)

+    : fortran_array_repacker_base_impl (dest),

+      m_addr (address)

+  { /* Nothing.  */ }

+

+  /* Create a lazy value in target memory representing a single element,

+     then load the element into GDB's memory and copy the contents into the