Add `set print array-indexes' handling for Fortran arrays. Currently
the setting is ignored and indices are never shown.
Keep track of the most recent index handled so that any outstanding
repeated elements printed when the limit set by `set print elements' is
hit have the correct index shown.
Output now looks like:
(gdb) set print array-indexes on
(gdb) print array_1d
$1 = ((-2) = 1, (-1) = 1, (0) = 1, (1) = 1, (2) = 1)
(gdb) set print repeats 4
(gdb) set print elements 12
(gdb) print array_2d
$2 = ((-2) = ((-2) = 2, <repeats 5 times>) (-1) = ((-2) = 2, <repeats 5 times>) (0) = ((-2) = 2, (-1) = 2, ...) ...)
(gdb)
for a 5-element vector and a 5 by 5 array filled with the value of 2.
Implement `set print repeats' handling for Fortran arrays. Currently
the setting is ignored and always treated as if no limit was set.
Unlike the generic array walker implemented decades ago the Fortran one
is a proper C++ class. Rather than trying to mimic the old walker then,
which turned out a bit of a challenge where interacting with the `set
print elements' setting, write it entirely from scratch, by adding an
extra specialization handler method for processing dimensions other than
the innermost one and letting the specialization class call the `walk_1'
method from the handler as it sees fit. This way repeats can be tracked
and the next inner dimension recursed into as a need arises only, or
unconditionally in the base class.
Keep track of the dimension number being handled in the class rather as
a parameter to the walker so that it does not have to be passed across
by the specialization class.
Use per-dimension element count tracking, needed to terminate processing
early when the limit set by `set print elements' is hit. This requires
extra care too where the limit triggers exactly where another element
that is a subarray begins. In that case rather than recursing we need
to terminate processing or lone `(...)' would be printed. Additionally
if the skipped element is the last one in the current dimension we need
to print `...' by hand, because `continue_walking' won't print it at the
upper level, because it can see the last element has already been taken
care of.
Preserve the existing semantics of `set print elements' where the total
count of the elements handled is matched against the trigger level which
is unlike with the C/C++ array printer where the per-dimension element
count is used instead.
Output now looks like:
(gdb) set print repeats 4
(gdb) print array_2d
$1 = ((2, <repeats 5 times>) <repeats 5 times>)
(gdb) set print elements 12
(gdb) print array_2d
$2 = ((2, <repeats 5 times>) (2, <repeats 5 times>) (2, 2, ...) ...)
(gdb)
for a 5 by 5 array filled with the value of 2.
Amend existing test cases accordingly that rely on the current incorrect
behavior and explicitly request that there be no limit for printing
repeated elements there.
Add suitable test cases as well covering sliced arrays in particular.
Co-Authored-By: Andrew Burgess <andrew.burgess@embecosm.com>
This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
Move inner dimension's element type determination outside the respective
loops in `fortran_array_walker'. The operation is exactly the same with
each iteration, so there is no point in redoing it for each element and
while a smart compiler might be able to move it outside the loop it is
regardless a bad coding style. No functional change.
Following our coding convention initialize the `m_ndimensions' member in
the member initializer list rather than in the body of the constructor
of the `fortran_array_walker' class. No functional change.
This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
get_discrete_bounds currently has three possible return values (see its
current doc for details). It appears that for all callers, it would be
sufficient to have a boolean "worked" / "didn't work" return value.
Change the return type of get_discrete_bounds to bool and adjust all
callers. Doing so simplifies the following patch.
gdb/ChangeLog:
* gdbtypes.h (get_discrete_bounds): Return bool, adjust all
callers.
* gdbtypes.c (get_discrete_bounds): Return bool.
Change-Id: Ie51feee23c75f0cd7939742604282d745db59172
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'.
