Clang's thread sanitizer (part of libcompiler-rt) does not seem to work

[Grimler91]

Problem description

Compiling a minimal c file on aarch64 or x86_64 with -fsanitize=thread does not work (arm and i686 do not support -fsanitize=thread).

Steps to reproduce

test.c:

int main()
{
  return 0;
}

Compile with clang -fsanitize=thread test.c -o test $PREFIX/lib/clang/10.0.1/lib/android/libclang_rt.tsan-aarch64-android.a gives

/data/data/com.termux/files/usr/bin/aarch64-linux-android-ld: /data/data/com.termux/files/usr/lib/clang/10.0.1/lib/android/libclang_rt.tsan-aarch64-android.a(tsan_interceptors_posix.cpp.o): in function `__interceptor_lgamma':
/home/builder/.termux-build/libllvm/src/projects/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4969: undefined reference to `signgam'
/data/data/com.termux/files/usr/bin/aarch64-linux-android-ld: /home/builder/.termux-build/libllvm/src/projects/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4969: undefined reference to `signgam'
/data/data/com.termux/files/usr/bin/aarch64-linux-android-ld: /data/data/com.termux/files/usr/lib/clang/10.0.1/lib/android/libclang_rt.tsan-aarch64-android.a(tsan_interceptors_posix.cpp.o): in function `__interceptor_lgammaf':
/home/builder/.termux-build/libllvm/src/projects/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4976: undefined reference to `signgam'
/data/data/com.termux/files/usr/bin/aarch64-linux-android-ld: /home/builder/.termux-build/libllvm/src/projects/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4976: undefined reference to `signgam'
/data/data/com.termux/files/usr/bin/aarch64-linux-android-ld: /data/data/com.termux/files/usr/lib/clang/10.0.1/lib/android/libclang_rt.tsan-aarch64-android.a(tsan_interceptors_posix.cpp.o): in function `__interceptor_lgammal':
/home/builder/.termux-build/libllvm/src/projects/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4991: undefined reference to `signgam'
/data/data/com.termux/files/usr/bin/aarch64-linux-android-ld: /data/data/com.termux/files/usr/lib/clang/10.0.1/lib/android/libclang_rt.tsan-aarch64-android.a(tsan_interceptors_posix.cpp.o):/home/builder/.termux-build/libllvm/src/projects/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:4991: more undefined references to `signgam' follow
clang-10: error: linker command failed with exit code 1 (use -v to see invocation)

Expected behavior

It should compile without errors about missing symbols.

Additional information

Packages CPU architecture:
aarch64
Subscribed repositories:
# sources.list
deb https://grimler.se/termux-packages-24 stable main
# root-repo (sources.list.d/root.list)
deb https://grimler.se/termux-root-packages-24 root stable
# sources.list.d/science.list.dpkg-dist
deb https://dl.bintray.com/grimler/science-packages-24 science stable
# sources.list.d/game.list.dpkg-dist
deb https://dl.bintray.com/grimler/game-packages-24 games stable
# science-repo (sources.list.d/science.list)
deb https://grimler.se/science-packages-24 science stable
# game-repo (sources.list.d/game.list)
deb https://grimler.se/game-packages-24 games stable
# unstable-repo (sources.list.d/unstable.list)
deb https://grimler.se/unstable-packages unstable main
# sources.list.d/pointless.list
deb https://its-pointless.github.io/files/24 termux extras
# sources.list.d/x11.list
deb https://grimler.se/x11-packages x11 main
Updatable packages:
apache2/stable 2.4.46-4 aarch64 [upgradable from: 2.4.46-3]
texlive-bin/stable 20200406-6 aarch64 [upgradable from: 20200406-6]
Android version:
10
Kernel build information:
Linux localhost 4.4.111-ga215b80be236 #3 SMP PREEMPT Fri Sep 4 09:51:01 CEST 2020 aarch64 Android
Device manufacturer:
samsung
Device model:
SM-G955F

[nikey02]

I don't know solution and know one has answered so may time to upgrade clang-11 is released.

[its-pointless]

try linking against libm so
clang -fsanitize=thread test.c -o test $PREFIX/lib/clang/10.0.1/lib/android/libclang_rt.tsan-aarch64-android.a -lm

[thunder-coding]

clang seems to now incorrectly try linking to shared library

$ clang x.c -fsanitize=thread $PREFIX/lib/clang/13.0.0/lib/android/libclang_rt.tsan-aarch64-android.a
ld.lld: error: cannot open /data/data/com.termux/files/usr/lib/clang/13.0.0/lib/android/libclang_rt.tsan-aarch64-android.so: No such file or directory
clang-13: error: linker command failed with exit code 1 (use -v to see invocation)

Probably some problem due to we just changed the default linker to ld.lld ?

[Grimler91]

@buttaface do you have any guess why it looks for libclang_rt.tsan-aarch64-android.so as in above comment?

[finagolfin]

It's probably required to actually use the thread sanitizer, which is not implemented for Android yet, android/ndk#1041. This has nothing to do with lld, as clang chooses the libraries to link against.

I guess this never worked before, but might once they finish that work upstream.

[Grimler91]

Aha, closing this then since it is not really a bug with our clang