Re: [patch] Smaller gdb: -rdynamic -> -Wl,--dynamic-list

Jan Kratochvil
2010-06-05T12:45:35Z

On Sat, 05 Jun 2010 04:48:33 +0200, Doug Evans wrote:
> "ImportError: /usr/grte/v1/k8-linux/lib/python2.4/lib-dynload/itertools.so:
> undefined symbol: PyExc_StopIteration"
>
> when I did "import itertools".
>
> I was statically linking libpythonX.Y.a.
>
> I'm not sure what the right fix is.

This is an open Python bug: http://bugs.python.org/issue4434
(I was not aware of it.)

I doubt how useful is to depend on .so modules while having .a libpython
linked in but I understand my patch broke compatibility with such case.

With libpythonX.Y.so.1.0 the problem does not happen as all the symbols are
present in its .dynsym. There is an inefficiency Python-2.6.4/Include/pyport.h
uses dllimport and dllimport declarations for the API but it has no support
for gcc __attribute__((visibility)) there and thus libpythonX.Y.so.1.0's
.dynsym is excessively large there.

I was unable to test it as Fedora (13) does not ship libpythonX.Y.a (and it
failed to build one when I tried to). Could you test it, please?

If some existing python tests were already broken I can drop this new one.

No regressions on {x86_64,x86_64-m32,i686}-fedora13-linux-gnu.

Thanks,
Jan

gdb/
2010-06-05 Jan Kratochvil <jan.kratochvil@redhat.com>

* configure.ac <"${have_libpython}" != no>: New workaround of
python#4434.
* configure: Regenerate.

gdb/testsuite/
2010-06-05 Jan Kratochvil <jan.kratochvil@redhat.com>

* gdb.python/python.exp (pythonX.Y/lib-dynload/*.so): New.

--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1470,16 +1470,39 @@ if test ${build} = ${host} -a ${host} = ${target} ; then
# Older GNU ld supports --export-dynamic but --dynamic-list it does not.
RDYNAMIC="-Wl,--dynamic-list=${srcdir}/proc-service.list"
LDFLAGS="$LDFLAGS $RDYNAMIC"
- AC_TRY_LINK([], [],
- [found="-Wl,--dynamic-list"
- RDYNAMIC='-Wl,--dynamic-list=$(srcdir)/proc-service.list'],
- [RDYNAMIC="-rdynamic"
- LDFLAGS="$old_LDFLAGS $RDYNAMIC"
- AC_TRY_LINK([], [],
- [found="-rdynamic"],
- [found="no"
- # Error on its usage by .mh file.
- RDYNAMIC="no-rdynamic-available"])])
+ dynamic_list=false
+ if test "${have_libpython}" = no; then
+ AC_TRY_LINK([], [], [dynamic_list=true])
+ else
+ # Workaround http://bugs.python.org/issue4434 where static
+ # libpythonX.Y.a would get its symbols required for
+ # pythonX.Y/lib-dynload/*.so modules hidden by -Wl,--dynamic-list.
+ # Problem does not happen for the recommended libpythonX.Y.so linkage.
+ old_CFLAGS="$CFLAGS"
+ CFLAGS="$CFLAGS $PYTHON_CFLAGS"
+ AC_RUN_IFELSE(
+ AC_LANG_PROGRAM(
+ [#include "]${have_libpython}[/Python.h"],
+ [int err;
+ Py_Initialize ();
+ err = PyRun_SimpleString ("import itertools\n");
+ Py_Finalize ();
+ return err == 0 ? 0 : 1;]),
+ [dynamic_list=true], [], [true])
+ CFLAGS="$old_CFLAGS"
+ fi
+ if $dynamic_list;then
+ found="-Wl,--dynamic-list"
+ RDYNAMIC='-Wl,--dynamic-list=$(srcdir)/proc-service.list'
+ else
+ RDYNAMIC="-rdynamic"
+ LDFLAGS="$old_LDFLAGS $RDYNAMIC"
+ AC_TRY_LINK([], [],
+ [found="-rdynamic"],
+ [found="no"
+ # Error on its usage by .mh file.
+ RDYNAMIC="no-rdynamic-available"])
+ fi
AC_SUBST(RDYNAMIC)
LDFLAGS="$old_LDFLAGS"
AC_MSG_RESULT($found)
--- a/gdb/configure
+++ b/gdb/configure
@@ -14199,7 +14199,9 @@ $as_echo_n "checking for the dynamic export flag... " >&6; }
# Older GNU ld supports --export-dynamic but --dynamic-list it does not.
RDYNAMIC="-Wl,--dynamic-list=${srcdir}/proc-service.list"
LDFLAGS="$LDFLAGS $RDYNAMIC"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ dynamic_list=false
+ if test "${have_libpython}" = no; then
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */

int
@@ -14211,12 +14213,51 @@ main ()
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
- found="-Wl,--dynamic-list"
- RDYNAMIC='-Wl,--dynamic-list=$(srcdir)/proc-service.list'
+ dynamic_list=true
+fi
+rm -f core conftest.err conftest.$ac_objext \
+ conftest$ac_exeext conftest.$ac_ext
+ else
+ # Workaround http://bugs.python.org/issue4434 where static
+ # libpythonX.Y.a would get its symbols required for
+ # pythonX.Y/lib-dynload/*.so modules hidden by -Wl,--dynamic-list.
+ # Problem does not happen for the recommended libpythonX.Y.so linkage.
+ old_CFLAGS="$CFLAGS"
+ CFLAGS="$CFLAGS $PYTHON_CFLAGS"
+ if test "$cross_compiling" = yes; then :
+ true
else
- RDYNAMIC="-rdynamic"
- LDFLAGS="$old_LDFLAGS $RDYNAMIC"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+#include "${have_libpython}/Python.h"
+int
+main ()
+{
+int err;
+ Py_Initialize ();
+ err = PyRun_SimpleString ("import itertools\n");
+ Py_Finalize ();
+ return err == 0 ? 0 : 1;
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_c_try_run "$LINENO"; then :
+ dynamic_list=true
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
+ conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+
+ CFLAGS="$old_CFLAGS"
+ fi
+ if $dynamic_list;then
+ found="-Wl,--dynamic-list"
+ RDYNAMIC='-Wl,--dynamic-list=$(srcdir)/proc-service.list'
+ else
+ RDYNAMIC="-rdynamic"
+ LDFLAGS="$old_LDFLAGS $RDYNAMIC"
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */

int
@@ -14231,14 +14272,12 @@ if ac_fn_c_try_link "$LINENO"; then :
found="-rdynamic"
else
found="no"
- # Error on its usage by .mh file.
- RDYNAMIC="no-rdynamic-available"
-fi
-rm -f core conftest.err conftest.$ac_objext \
- conftest$ac_exeext conftest.$ac_ext
+ # Error on its usage by .mh file.
+ RDYNAMIC="no-rdynamic-available"
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
+ fi

LDFLAGS="$old_LDFLAGS"
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $found" >&5
--- a/gdb/testsuite/gdb.python/python.exp
+++ b/gdb/testsuite/gdb.python/python.exp
@@ -80,3 +80,6 @@ gdb_test "source $srcdir/$subdir/source2.py" "yes"

gdb_test "python print gdb.current_objfile()" "None"
gdb_test "python print gdb.objfiles()" "\\\[\\\]"
+
+# Test http://bugs.python.org/issue4434 workaround in configure.ac
+gdb_test "python import itertools; print 'IMPOR'+'TED'" "IMPORTED" "pythonX.Y/lib-dynload/*.so"