Binutils with MCST patches
b50d69b5aa
For displaying the full view of a class-wide object, GDB relies on
the assumption that this view will have the same address as the
address of the object. In the case of simple inheritance, this
assumption is correct; the proper type is deduced by decoding
the tag of the object and converting the result to this full-view
type.
Consider for example an abstract class Shape, a child Circle
which implements an interface Drawable, and the corresponding
following objects:
My_Circle : Circle := ((1, 2), 3);
My_Shape : Shape'Class := Shape'Class (My_Circle);
My_Drawable : Drawable'Class := Drawable'Class (My_Circle);
To display My_Shape, the debugger first extracts the tag (an internal
field, usually the first one of the record):
(gdb) p my_shape'address
$2 = (system.address) 0x8063e28
(gdb) x/x my_shape'address
0x8063e28 <classes__my_shape>: 0x08059ec4
Then the type specific data and the expanded name of the tag is read
from there:
(gdb) p my_shape'tag
$3 = (access ada.tags.dispatch_table) 0x8059ec4 (classes.circle)
To get the full view, the debugger converts to the corresponding type:
(gdb) p {classes.circle}0x8063e28
$4 = (center => (x => 1, y => 2), radius => 3)
Now, in the case of multiple inheritance, the assumption does not hold
anymore. The address that we have usually points to some
place lower. The offset to the original address is saved in the field
Offset_To_Top of the metadata that are above the tag, at address
obj'tag - 8. In the case of my_shape, this offset is 0:
(gdb) x/x my_shape'tag - 8
0x8059ebc <classes__circleT+12>: 0x00000000
...but in the case of an interface-wide object, it is not null:
(gdb) x/x my_drawable'tag - 8
0x8063b28 <classes__classes__circle_classes__drawable1T56s+12>: 0x00000004
(gdb) p {classes.circle}(my_drawable'address - 4)
$7 = (center => (x => 1, y => 2), radius => 3)
The following change handles this relocation in the most common cases.
Remaining cases that are still to be investigated are signaled by
comments.
gdb/ChangeLog:
* ada-lang.h (ada_tag_value_at_base_address): New function
declaration.
* ada-lang.c (is_ada95_tag, ada_tag_value_at_base_address):
New functions.
(ada_to_fixed_type_1, ada_evaluate_subexp): Let ada_tag_base_address
relocate the class-wide value if need be.
(ada_value_struct_elt, ada_value_ind, ada_coerce_ref):
Let ada_tag_value_at_base_address relocate the class-wide access/ref
before dereferencing it.
* ada-valprint.c (ada_val_print_1): Relocate to base address
before displaying the content of an interface-wide ref.
gdb/testsuite/ChangeLog:
* gdb.ada/ptype_tagged_param.exp: Adjust expected output in
ptype test.
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| bfd | ||
| binutils | ||
| config | ||
| cpu | ||
| elfcpp | ||
| etc | ||
| gas | ||
| gdb | ||
| gold | ||
| gprof | ||
| include | ||
| intl | ||
| ld | ||
| libdecnumber | ||
| libiberty | ||
| opcodes | ||
| readline | ||
| sim | ||
| texinfo | ||
| .cvsignore | ||
| .gitignore | ||
| ChangeLog | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| COPYING.LIB | ||
| COPYING.LIBGLOSS | ||
| COPYING.NEWLIB | ||
| depcomp | ||
| djunpack.bat | ||
| install-sh | ||
| libtool.m4 | ||
| lt~obsolete.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| makefile.vms | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| README | ||
| README-maintainer-mode | ||
| setup.com | ||
| src-release | ||
| symlink-tree | ||
| ylwrap | ||
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.