[llvm-dev] lld + ThinLTO + fprofile-generate causes duplicate symbol errors

[Teresa Johnson via llvm-dev]

On Wed, May 9, 2018 at 6:43 AM Teresa Johnson <tejohnson at google.com> wrote:

> Hi Pirama,
>
> I can't reproduce with either lld or gold, using a compiler built from
> head. What version is your clang?
>
(and your lld)


>
> Thanks,
> Teresa
>
> On Tue, May 8, 2018 at 7:50 PM Pirama Arumuga Nainar via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> The duplicate symbol errors are for __llvm_profile_filename and __llvm_profile_raw_version.
>> IIUC, these are supposed to be weak symbols but Thin LTO seems to break
>> this in some way.  This does't happen with gold or no LTO or full LTO.
>>
>> $ cat > a.c
>> extern int foo();
>>
>> int main() {
>>   return foo();
>> }
>>
>> $ cat > b.c
>> int foo() {
>>   return 0;
>> }
>>
>> $ clang a.c -fprofile-generate -flto=thin -c
>> $ clang b.c -fprofile-generate -flto=thin -c
>> $ clang a.o b.o -fprofile-generate -flto=thin -fuse-ld=lld
>> ld.lld: error: duplicate symbol: __llvm_profile_filename
>> >>> defined at a.c
>> >>>            lto.tmp:(__llvm_profile_filename)
>> >>> defined at b.c
>> >>>            lto.tmp:(.rodata.__llvm_profile_filename+0x0)
>>
>> ld.lld: error: duplicate symbol: __llvm_profile_raw_version
>> >>> defined at a.c
>> >>>            lto.tmp:(__llvm_profile_raw_version)
>> >>> defined at b.c
>> >>>            lto.tmp:(.rodata.__llvm_profile_raw_version+0x0)
>> clang-7: error: linker command failed with exit code 1 (use -v to see
>> invocation)
>> Makefile:10: recipe for target 'a.out' failed
>> make: *** [a.out] Error 1
>> _______________________________________________
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>> llvm-dev at lists.llvm.org
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>>
>
>
> --
> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>  408-460-2413
>


-- 
Teresa Johnson |  Software Engineer |  tejohnson at google.com |  408-460-2413
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