The discussion on gdb-patches which led to this patch may be found
here:
https://www.sourceware.org/ml/gdb-patches/2019-05/msg00018.html
Here's a brief synopsis/analysis:
Eli Zaretskii, while debugging a Windows emacs executable, found
that functions comprised of more than one (non-contiguous)
address range were not being displayed correctly in a backtrace. This
is the example that Eli provided:
(gdb) bt
#0 0x76a63227 in KERNELBASE!DebugBreak ()
from C:\Windows\syswow64\KernelBase.dll
#1 0x012e7b89 in emacs_abort () at w32fns.c:10768
#2 0x012e1f3b in print_vectorlike.cold () at print.c:1824
#3 0x011d2dec in print_object (obj=<optimized out>, printcharfun=XIL(0),
escapeflag=true) at print.c:2150
The function print_vectorlike consists of two address ranges, one of
which contains "cold" code which is expected to not execute very often.
There is a minimal symbol, print_vectorlike.cold.65, which is the address
of the "cold" range.
GDB is prefering this minsym over the the name provided by the
DWARF info due to some really old code in GDB which handles
"certain pathological cases". This comment reads as follows:
/* In certain pathological cases, the symtabs give the wrong
function (when we are in the first function in a file which
is compiled without debugging symbols, the previous function
is compiled with debugging symbols, and the "foo.o" symbol
that is supposed to tell us where the file with debugging
symbols ends has been truncated by ar because it is longer
than 15 characters). This also occurs if the user uses asm()
to create a function but not stabs for it (in a file compiled
with -g).
So look in the minimal symbol tables as well, and if it comes
up with a larger address for the function use that instead.
I don't think this can ever cause any problems; there
shouldn't be any minimal symbols in the middle of a function;
if this is ever changed many parts of GDB will need to be
changed (and we'll create a find_pc_minimal_function or some
such). */
In an earlier version of this patch, I had left the code for the
pathological case intact, but those who reviwed that patch recommended
removing it. So that's what I've done - I've removed it.
gdb/ChangeLog:
* stack.c (find_frame_funname): Remove code which preferred
minsym over symtab sym in "certain pathological cases".
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README for GDB release
This is GDB, the GNU source-level debugger.
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More Documentation
******************
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**************
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make
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==================================
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make
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======================================
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% sh config.sub sun4
sparc-sun-sunos4.1.1
% sh config.sub sun3
m68k-sun-sunos4.1.1
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mips-dec-ultrix4.2
% sh config.sub hp300bsd
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% sh config.sub i786v
Invalid configuration `i786v': machine `i786v' not recognized
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`configure' options
===================
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*note : (autoconf.info)Running configure scripts, for a full
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configure [--help]
[--prefix=DIR]
[--srcdir=PATH]
[--target=TARGET]
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[HOST]
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Display a quick summary of how to invoke `configure'.
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Configure the source to install programs and files under directory
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Enable (i.e., include) support for unit tests when compiling GDB
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`configure' accepts other options, for compatibility with configuring
other GNU tools recursively.
Remote debugging
=================
The files m68k-stub.c, i386-stub.c, and sparc-stub.c are examples
of remote stubs to be used with remote.c. They are designed to run
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The directory gdb/gdbserver/ contains `gdbserver', a program that
allows remote debugging for Unix applications. GDBserver is only
supported for some native configurations, including Sun 3, Sun 4, and
Linux.
The file gdb/gdbserver/README includes further notes on GDBserver; in
particular, it explains how to build GDBserver for cross-debugging
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architecture than the host machine running GDB).
Reporting Bugs in GDB
=====================
There are several ways of reporting bugs in GDB. The prefered
method is to use the World Wide Web:
http://www.gnu.org/software/gdb/bugs/
As an alternative, the bug report can be submitted, via e-mail, to the
address "bug-gdb@gnu.org".
When submitting a bug, please include the GDB version number, and
how you configured it (e.g., "sun4" or "mach386 host,
i586-intel-synopsys target"). Since GDB supports so many
different configurations, it is important that you be precise about
this. The simplest way to do this is to include the output from these
commands:
% gdb --version
% gdb --config
For more information on how/whether to report bugs, see the
Reporting Bugs chapter of the GDB manual (gdb/doc/gdb.texinfo).
Graphical interface to GDB -- X Windows, MS Windows
==========================
Several graphical interfaces to GDB are available. You should
check:
https://sourceware.org/gdb/wiki/GDB%20Front%20Ends
for an up-to-date list.
Emacs users will very likely enjoy the Grand Unified Debugger mode;
try typing `M-x gdb RET'.
Writing Code for GDB
=====================
There is information about writing code for GDB in the file
`CONTRIBUTE' and at the website:
http://www.gnu.org/software/gdb/
in particular in the wiki.
If you are pondering writing anything but a short patch, especially
take note of the information about copyrights and copyright assignment.
It can take quite a while to get all the paperwork done, so
we encourage you to start that process as soon as you decide you are
planning to work on something, or at least well ahead of when you
think you will be ready to submit the patches.
GDB Testsuite
=============
Included with the GDB distribution is a DejaGNU based testsuite
that can either be used to test your newly built GDB, or for
regression testing a GDB with local modifications.
Running the testsuite requires the prior installation of DejaGNU,
which is generally available via ftp. The directory
ftp://sources.redhat.com/pub/dejagnu/ will contain a recent snapshot.
Once DejaGNU is installed, you can run the tests in one of the
following ways:
(1) cd gdb-VERSION
make check-gdb
or
(2) cd gdb-VERSION/gdb
make check
or
(3) cd gdb-VERSION/gdb/testsuite
make site.exp (builds the site specific file)
runtest -tool gdb GDB=../gdb (or GDB=<somepath> as appropriate)
When using a `make'-based method, you can use the Makefile variable
`RUNTESTFLAGS' to pass flags to `runtest', e.g.:
make RUNTESTFLAGS=--directory=gdb.cp check
If you use GNU make, you can use its `-j' option to run the testsuite
in parallel. This can greatly reduce the amount of time it takes for
the testsuite to run. In this case, if you set `RUNTESTFLAGS' then,
by default, the tests will be run serially even under `-j'. You can
override this and force a parallel run by setting the `make' variable
`FORCE_PARALLEL' to any non-empty value. Note that the parallel `make
check' assumes that you want to run the entire testsuite, so it is not
compatible with some dejagnu options, like `--directory'.
The last method gives you slightly more control in case of problems
with building one or more test executables or if you are using the
testsuite `standalone', without it being part of the GDB source tree.
See the DejaGNU documentation for further details.
Copyright and License Notices
=============================
Most files maintained by the GDB Project contain a copyright notice
as well as a license notice, usually at the start of the file.
To reduce the length of copyright notices, consecutive years in the
copyright notice can be combined into a single range. For instance,
the following list of copyright years...
1986, 1988, 1989, 1991-1993, 1999, 2000, 2007, 2008, 2009, 2010, 2011
... is abbreviated into:
1986, 1988-1989, 1991-1993, 1999-2000, 2007-2011
Every year of each range, inclusive, is a copyrightable year that
could be listed individually.
(this is for editing this file with GNU emacs)
Local Variables:
mode: text
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