[cfe-dev] Problem linking in some dataflow sanitizer functions?

[Christian Convey]

Thanks Peter.  That seems to have done the trick for dfsan_get_label_info.

I'm still having trouble with C++ STL functions, though.  Any idea why
I might be getting the following?

I have this simple test program, foo2.c:
>>>>>
#include <iostream>

using namespace std;

int main(void) {
    cout << "Hellow, world!" << endl;
    return 0;
}
<<<<<

When I build it without the dataflow sanitizer, things work fine:
/home/cconvey/dw/clang-llvm-git/build/bin/clang++ -std=c++11  foo2.cpp

However, when I enable the sanitizer, there are a lot of unmet
dependencies.  Any idea if I'm doing something wrong on the command
line?
cconvey at spaceman /tmp $
/home/cconvey/dw/clang-llvm-git/build/bin/clang++ -std=c++11
-fsanitize=dataflow foo2.cpp
/tmp/foo2-8b9f0f.o: In function `main':
foo2.cpp:(.text+0xb): undefined reference to
`dfs$_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_'
foo2.cpp:(.text+0x44): undefined reference to
`dfs$_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc'
foo2.cpp:(.text+0x6a): undefined reference to `dfs$_ZNSolsEPFRSoS_E'
/tmp/foo2-8b9f0f.o: In function `dfs$__cxx_global_var_init':
foo2.cpp:(.text.startup+0x1d): undefined reference to
`dfs$_ZNSt8ios_base4InitC1Ev'
foo2.cpp:(.text.startup+0x24): undefined reference to
`dfs$_ZNSt8ios_base4InitD1Ev'
clang-3.6: error: linker command failed with exit code 1 (use -v to
see invocation)


Thanks,
Christian

On Mon, Jan 12, 2015 at 3:43 PM, Peter Collingbourne <peter at pcc.me.uk> wrote:
> Hi Christian,
>
> There was a bug that prevented clients from using the dfsan_get_label_info
> function. That bug is now fixed in compiler-rt r225692.
>
> Peter
>
> On Mon, Jan 12, 2015 at 12:56:01PM -0500, Christian Convey wrote:
>> Hello, I'm using the dataflow sanitizer in clang 3.6 for the first
>> time, I'm I'm running into some linker errors.  I was wondering if
>> someone could point out my mistake?
>>
>> I downloaded (today) from git the current llvm, clang, and compiler-rt
>> code.  It built without any problem.
>>
>> Using that build of clang/llvm, I'm able to run the example code shown
>> here:  http://clang.llvm.org/docs/DataFlowSanitizer.html#example
>>
>> However, I have a linking problem when I try to extend the example.
>> When I try to call the function "dfsan_get_label_info", the linker
>> can't find it.  This is a bit of a surprise, because it does appear to
>> be defined in my LLVM build:
>>
>> cconvey at spaceman /tmp $ nm
>> /home/cconvey/dw/clang-llvm-git/build/bin/../lib/clang/3.6.0/lib/linux/libclang_rt.dfsan-x86_64.a
>> | grep dfsan_get_label_info
>> 0000000000000990 T _Z20dfsan_get_label_infot
>> cconvey at spaceman /tmp $ c++filt _Z20dfsan_get_label_infot
>> dfsan_get_label_info(unsigned short)
>>
>> And I'm reasonably sure I'm linking in that .a file:
>>
>> cconvey at spaceman /tmp $
>> /home/cconvey/dw/clang-llvm-git/build/bin/clang  -fsanitize=dataflow
>> foo.c -v
>> clang version 3.6.0 (http://llvm.org/git/clang.git
>> 48d2f2367001a51a3253cc34aea4a91c92fd45fb)
>> (http://llvm.org/git/llvm.git
>> ad017096fc8eec5afd256f572d8d0b9d5d8aa09f)
>> ...
>> End of search list.
>>  "/usr/bin/ld" -pie --eh-frame-hdr -m elf_x86_64 -dynamic-linker
>> /lib64/ld-linux-x86-64.so.2 -o a.out
>> /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/Scrt1.o
>> /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o
>> /usr/lib/gcc/x86_64-linux-gnu/4.8/crtbeginS.o
>> -L/usr/lib/gcc/x86_64-linux-gnu/4.8
>> -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu
>> -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu
>> -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../..
>> -L/home/cconvey/dw/clang-llvm-git/build/bin/../lib -L/lib -L/usr/lib
>> -whole-archive /home/cconvey/dw/clang-llvm-git/build/bin/../lib/clang/3.6.0/lib/linux/libclang_rt.dfsan-x86_64.a
>> -no-whole-archive
>> --dynamic-list=/home/cconvey/dw/clang-llvm-git/build/bin/../lib/clang/3.6.0/lib/linux/libclang_rt.dfsan-x86_64.a.syms
>> /tmp/foo-5310a2.o --no-as-needed -lpthread -lrt -lm -ldl -lgcc
>> --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s
>> --no-as-needed /usr/lib/gcc/x86_64-linux-gnu/4.8/crtendS.o
>> /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crtn.o
>> /tmp/foo-5310a2.o: In function `dfs$execute_tree':
>> foo.c:(.text+0xa89): undefined reference to `dfsan_get_label_info'
>> /tmp/foo-5310a2.o: In function `dfsw$dfsan_get_label_info':
>> foo.c:(.text.dfsw$dfsan_get_label_info[dfsw$dfsan_get_label_info]+0xb):
>> undefined reference to `dfsan_get_label_info'
>> clang-3.6: error: linker command failed with exit code 1 (use -v to
>> see invocation)
>> cconvey at spaceman /tmp $
>>
>> (I'm also having linkage problems when my code uses C++ iostreams, but
>> I figured I'd work through this issue first.)
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>>
>
> --
> Peter