[cfe-dev] -fsanitize=undefined and shared libraries

[Martin Martin]

Yes, otherwise it wouldn't work when statically linked.


On Wed, Jan 9, 2013 at 6:47 AM, Devchandra L Meetei <dlmeetei at gmail.com>wrote:

> Did you got compiler-rt?
>
>
> On Wed, Jan 9, 2013 at 3:53 AM, Martin Martin <
> martin at silverliningsystems.com> wrote:
>
>> When trying to use -fsanitize=undefined with shared libraries, I get:
>>
>> /usr/bin/ld: a.out: hidden symbol `__ubsan_handle_float_cast_overflow' in
>> /home/clang/build-cmake/bin/../lib/clang/3.2/lib/linux/libclang_rt.ubsan-x86_64.a(ubsan_handlers.cc.o)
>> is referenced by DSO
>> /usr/bin/ld: final link failed: Bad value
>> clang-3: error: linker command failed with exit code 1 (use -v to see
>> invocation)
>>
>> This is with Clang 3.2 compiled from sources using cmake, on Ubuntu 12.10.
>>
>> I'm compiling my files like this:
>>
>> clang++ -fPIC -fsanitize=undefined undefined.cpp -c -o undefined.o
>> clang++ -shared -Wl,-soname,libfoo.so undefined.o -o libfoo.so
>> clang++ -fsanitize=undefined main.cpp -c -o main.o
>> clang++ -fsanitize=undefined main.o -L. -lfoo
>>
>> $ cat undefined.cpp
>> int cast(float x) {
>>     return int(x);
>> }
>>
>> $ cat main.cpp
>> #include <cstdlib>
>>
>> extern int cast(float x);
>>
>> int main(int argc, char *argv[])
>> {
>>     if (argc > 1) {
>>         return cast(atof(argv[1]));
>>     }
>>
>>     return 1;
>> }
>>
>> If I don't use shared libraries, but instead like the two .o files
>> (without the -fPIC), it works fine, I get:
>>
>> ./a.out 1e10
>> <unknown>: fatal error: value 1e+10 is outside the range of representable
>> values of type 'int'
>> Illegal instruction (core dumped)
>>
>>
>> Any idea what I'm doing wrong?
>>
>> Thanks,
>> Martin
>>
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>
>>
>
>
> --
> Warm Regards
> --Dev
> OpenPegasus Developer
> "It's Always better to try and fail instead of not doing/trying anything"
>
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