[compiler-rt] r201545 - [asan] Make __cxa_demangle non-weak symbol on Android.

[Hans Wennborg]

Hi Evgeniy,

Trying to build the Clang package for Linux/Android in Chromium, I now
fail to link the Android ASan run-time. I suspect this commit might
have something to do with it. This is the error I'm getting:

  SO:   clang_linux/asan-arm-android/arm-android:
/usr/local/google/work/chromium/src/third_party/llvm-build/tools/clang/runtime/compiler-rt/clang_linux/asan-arm-android/arm-android/libcompiler_rt.so
../../../llvm-build/android-toolchain/lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld:
/usr/local/google/work/chromium/src/third_party/llvm-build/tools/clang/runtime/compiler-rt/clang_linux/asan-arm-android/arm-android/SubDir.lib__sanitizer_common/sanitizer_symbolizer_posix_libcdep.o:
in function __sanitizer::POSIXSymbolizer::Demangle(char
const*):/usr/local/google/work/chromium/src/third_party/llvm/projects/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc(.text._ZN11__sanitizer15POSIXSymbolizer8DemangleEPKc+0xd0):
error: undefined reference to '__cxa_demangle'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [/usr/local/google/work/chromium/src/third_party/llvm-build/tools/clang/runtime/compiler-rt/clang_linux/asan-arm-android/arm-android/libcompiler_rt.so]
Error 1

Any ideas?

Thanks,
Hans

On Mon, Feb 17, 2014 at 11:34 PM, Evgeniy Stepanov
<eugeni.stepanov at gmail.com> wrote:
> Author: eugenis
> Date: Tue Feb 18 01:34:52 2014
> New Revision: 201545
>
> URL: http://llvm.org/viewvc/llvm-project?rev=201545&view=rev
> Log:
> [asan] Make __cxa_demangle non-weak symbol on Android.
>
> This fixes global-demangle.cc test on Android.
>
> https://code.google.com/p/address-sanitizer/issues/detail?id=264
>
> Modified:
>     compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
>
> Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc?rev=201545&r1=201544&r2=201545&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc (original)
> +++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc Tue Feb 18 01:34:52 2014
> @@ -32,10 +32,18 @@
>  // C++ demangling function, as required by Itanium C++ ABI. This is weak,
>  // because we do not require a C++ ABI library to be linked to a program
>  // using sanitizers; if it's not present, we'll just use the mangled name.
> +//
> +// On Android, this is not weak, because we are using shared runtime library
> +// AND static libstdc++, and there is no good way to conditionally export
> +// __cxa_demangle. By making this a non-weak symbol, we statically link
> +// __cxa_demangle into ASan runtime library.
>  namespace __cxxabiv1 {
> -  extern "C" SANITIZER_WEAK_ATTRIBUTE
> -  char *__cxa_demangle(const char *mangled, char *buffer,
> -                                  size_t *length, int *status);
> +  extern "C"
> +#if !SANITIZER_ANDROID
> +  SANITIZER_WEAK_ATTRIBUTE
> +#endif
> +  char *__cxa_demangle(const char *mangled, char *buffer, size_t *length,
> +                       int *status);
>  }
>
>  namespace __sanitizer {
> @@ -47,7 +55,7 @@ static const char *DemangleCXXABI(const
>    // own demangler (libc++abi's implementation could be adapted so that
>    // it does not allocate). For now, we just call it anyway, and we leak
>    // the returned value.
> -  if (__cxxabiv1::__cxa_demangle)
> +  if (SANITIZER_ANDROID || &__cxxabiv1::__cxa_demangle)
>      if (const char *demangled_name =
>            __cxxabiv1::__cxa_demangle(name, 0, 0, 0))
>        return demangled_name;
>
>
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