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Tom Tromey 7d79de9a4b Add support for variable field offsets
In Ada, a field can have a variable offset.  This patch adds support
for this case to gdb, using the existing dynamic type resolution code.

Doing just this, though, would break C++ virtual base handling.

It turns out that virtual base handling only worked by the ugliest of
hacks.  In particular, the DWARF reader would call decode_locdesc for
a virtual base location.  Here's an example of such an expression from
gdb's m-static test case:

    <241>   DW_AT_data_member_location: 6 byte block: 12 6 48 1c 6 22 	(DW_OP_dup; DW_OP_deref; DW_OP_lit24; DW_OP_minus; DW_OP_deref; DW_OP_plus)

When examining this, decode_locdesc would treat DW_OP_deref as a no-op
and compute some answer (here, -24).  This would be stored as the
offset.

Later, in gnu-v3-abi.c, the real offset would be computed by digging
around in the vtable.

This patch cleans up this area.  In particular, it now evaluates the
location expression on demand.

Note there is a new FIXME in gnu-v3-abi.c.  I think some of the
callers are incorrect here, and have only worked because this member
is unused.  I will file a bug for this.  I didn't fix this problem in
this series because I felt it was already too complex.

gdb/ChangeLog
2020-04-24  Tom Tromey  <tromey@adacore.com>

	* dwarf2/read.c (handle_data_member_location): New overload.
	(dwarf2_add_field): Use it.
	(decode_locdesc): Add "computed" parameter.  Update comment.
	* gdbtypes.c (is_dynamic_type_internal): Also look for
	FIELD_LOC_KIND_DWARF_BLOCK.
	(resolve_dynamic_struct): Handle FIELD_LOC_KIND_DWARF_BLOCK.
	* gdbtypes.c (is_dynamic_type_internal): Add special case for C++
	virtual base classes.
	* gnu-v3-abi.c (gnuv3_baseclass_offset): Handle
	FIELD_LOC_KIND_DWARF_BLOCK.

gdb/testsuite/ChangeLog
2020-04-24  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/variant.exp: Add dynamic field offset tests.
	* gdb.ada/variant/pck.ads (Nested_And_Variable): New type.
	* gdb.ada/variant/pkg.adb: Add new variables.
2020-04-24 13:40:32 -06:00
bfd Automatic date update in version.in 2020-04-24 00:00:20 +00:00
binutils readelf: memory leaks in process_dynamic_section 2020-04-24 10:52:26 +09:30
config
contrib
cpu cpu,gas,opcodes: support for eBPF JMP32 instruction class 2020-04-16 09:52:57 +02:00
elfcpp
etc
gas xtensa: fix PR ld/25861 2020-04-22 18:46:45 -07:00
gdb Add support for variable field offsets 2020-04-24 13:40:32 -06:00
gdbserver Fix search of large memory area in gdbserver 2020-04-22 21:23:39 +02:00
gdbsupport Mark move constructors as "noexcept" 2020-04-20 11:45:06 -06:00
gnulib
gold Add support for --no-rosegment option. 2020-03-19 15:54:38 -07:00
gprof Updated Serbian translation for the gprof subdirectory 2020-04-01 14:37:02 +01:00
include arc: Add support for ARC HS extra registers in core files 2020-04-23 11:09:09 +03:00
intl
ld xtensa: fix PR ld/25861 2020-04-22 18:46:45 -07:00
libctf libctf: Mark bswap_identity_64 inline function as static. 2020-03-11 17:48:49 +10:30
libdecnumber
libiberty Import latest fixes to libiberty from GCC 2020-03-02 03:56:36 -08:00
opcodes Disallow PC relative for CMPI on MC68000/10 2020-04-21 16:53:36 +02:00
readline
sim sim: ppc: netbsd: Sync signal names with NetBSD 9.99.49 2020-03-12 16:07:37 +01:00
texinfo
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ar-lib
ChangeLog Since the pdp11-aout target does not support gdb, gdbserver or gprof these should be excluded in configure. 2020-04-21 10:27:50 +01:00
compile
config-ml.in
config.guess
config.rpath
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configure Since the pdp11-aout target does not support gdb, gdbserver or gprof these should be excluded in configure. 2020-04-21 10:27:50 +01:00
configure.ac Since the pdp11-aout target does not support gdb, gdbserver or gprof these should be excluded in configure. 2020-04-21 10:27:50 +01:00
COPYING
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MAINTAINERS
Makefile.def Change gdbserver to use existing gdbsupport 2020-03-12 13:32:16 -06:00
Makefile.in Change gdbserver to use existing gdbsupport 2020-03-12 13:32:16 -06:00
Makefile.tpl
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		   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.