http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55354
--- Comment #24 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-11-23
08:13:11 UTC ---
When I rebuild libtsan with -fPIE instead of -fPIC in the Makefile, and
g++ -shared -Wl,--whole-archive -o libtsanx.so libtsan.a -ldl -lpthread
(note that .libs/*.o are still built with -fPIC because libtool overrides those
flags and adds its -fPIC at the end), then this link fails with:
/usr/bin/ld: libtsan.a(tsan_rtl.o): relocation R_X86_64_TPOFF32 against
`_ZN6__tsan22cur_thread_placeholderE' can not be used when making a shared
object; recompile with -fPIC
libtsan.a(tsan_rtl.o): could not read symbols: Bad value
collect2: error: ld returned 1 exit status
(obviously, local-exec model would need to patch the insn at dynamic linking
time, making the library DT_TEXTREL (not acceptable for SELinux, not allowed
for x86_64 at all)).
Yes, I see the code generation differences, but the functions are huge anyway,
is it really so crucial that you'd want to make another libtsan_pie.a for it?
BTW, the tsan that was added to GCC yesterday doesn't have
-ftls-model=initial-exec even, so it is even slower.
-ftls-model=initial-exec can only be done for *-*-linux* targets btw, I don't
think other dynamic linkers support dlopening IE model shared libraries.
E.g. libgomp has in its configure.tgt
if test $gcc_cv_have_tls = yes ; then
case "${target}" in
*-*-linux*)
XCFLAGS="${XCFLAGS} -ftls-model=initial-exec"
;;
esac
fi
so libsanitizer/configure.tgt would need to add it to say TSAN_CXXFLAGS var
that would be substituted by configure.
Would be nice if you could check the numerous warnings from tsan build, e.g. it
seems the ALWAYS_INLINE macro doesn't include the inline keyword, and you are
using it on functions that don't have inline keyword, which gives a warning and
if it is inlined, it is by pure luck. Either you should add inline keywords
manually, or put inline keyword into ALWAYS_INLINE macro. There are other
warnings...
