forked from Imagelibrary/binutils-gdb
22347e554c
When the user writes or reads a variable whose location is described
with DWARF pieces (DW_OP_piece or DW_OP_bit_piece), GDB's helper
function copy_bitwise is invoked for each piece. The implementation of
this function has a bug that may result in a corrupted copy, depending
on alignment and bit size. (Full-byte copies are not affected.)
This rewrites copy_bitwise, replacing its algorithm by a fixed version,
and adding an appropriate test case. Without the fix the new test case
fails, e.g.:
print def_t
$2 = {a = 0, b = 4177919}
(gdb) FAIL: gdb.dwarf2/nonvar-access.exp: print def_t
Written in binary, the wrong result above looks like this:
01111111011111111111111
Which means that two zero bits have sneaked into the copy of the
original all-one bit pattern. The test uses this simple all-one value
in order to avoid another GDB bug that causes the DWARF piece of a
DW_OP_stack_value to be taken from the wrong end on big-endian
architectures.
gdb/ChangeLog:
* dwarf2loc.c (extract_bits_primitive): Remove.
(extract_bits): Remove.
(copy_bitwise): Rewrite. Fixes a possible corruption that may
occur for non-byte-aligned copies.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/nonvar-access.exp: Add a test for accessing
non-byte-aligned bit fields.
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.