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f7c6f42310
This commit fixes a set of -Wmaybe-uninitialized warnings in GDB and
GDBserver, seen with GCC 7.3.1 on F27 at -O2. Specifically, all of
these:
src/gdb/breakpoint.c:5040:4: warning: ‘e’ may be used uninitialized in this function [-Wmaybe-uninitialized]
src/gdb/cli/cli-cmds.c:277:71: warning: ‘tracker’ may be used uninitialized in this function [-Wmaybe-uninitialized]
src/gdb/cli/cli-cmds.c:302:22: warning: ‘word’ may be used uninitialized in this function [-Wmaybe-uninitialized]
src/gdb/gdbserver/server.c:1895:7: warning: ‘result’ may be used uninitialized in this function [-Wmaybe-uninitialized]
src/gdb/gdbserver/server.c:1966:7: warning: ‘result’ may be used uninitialized in this function [-Wmaybe-uninitialized]
For example, looking at one of the gdbserver ones in more detail:
../../../src/gdb/gdbserver/server.c: In function ‘int handle_qxfer_btrace_conf(const char*, gdb_byte*, const gdb_byte*, ULONGEST, LONGEST)’:
../../../src/gdb/gdbserver/server.c:1966:7: warning: ‘result’ may be used uninitialized in this function [-Wmaybe-uninitialized]
if (result != 0)
^~
In this case (like the others), the 'result' variable is assigned in
both TRY and CATCH blocks:
TRY
{
result = target_read_btrace_conf (thread->btrace, &cache);
if (result != 0)
memcpy (own_buf, cache.buffer, cache.used_size);
}
CATCH (exception, RETURN_MASK_ERROR)
{
sprintf (own_buf, "E.%s", exception.message);
result = -1;
}
END_CATCH
if (result != 0)
return -3;
so it would seem like the warning is bogus.
However, END_CATCH is really a catch block in disguise, and that path
indeed does not initialize the variable:
#define END_CATCH \
catch (...) \
{ \
exception_rethrow (); \
} \
}
exception_rethrow does not return normally (it rethrows the current
exception after running cleanups), but the compiler can not see that.
If it could return normally, then indeed 'result' could be used
uninitialized if the TRY block threw some non-gdb exception, which
would be caught by END_CATCH.
The fix it to let the compiler know that the exception_rethrow does
not return normally, using ATTRIBUTE_NORETURN.
gdb/ChangeLog:
2018-05-30 Pedro Alves <palves@redhat.com>
* common/common-exceptions.h (exception_rethrow): Use
ATTRIBUTE_NORETURN.
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.