llvm dev - May 2018 - lld + ThinLTO + fprofile-generate causes duplicate symbol errors

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
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
>
> --
> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>  408-460-2413
>

-- 
Teresa Johnson |  Software Engineer |  tejohnson at google.com |  408-460-2413
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20180509/d6c95e84/attachment-0001.html>

Hi Teresa,

Thanks for looking into this.  I hadn't initially tried ToT, but it
reproduces in ToT as well when I tried.

$ ./clang --version

clang version 7.0.0 (trunk 331879) (llvm/trunk 331888)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /ssd2/pirama/llvm-upstream/llvm-release/bin/.

$ ./ld.lld --version
LLD 7.0.0 (https://git.llvm.org/git/lld.git
dc4977e104c7f33758ac6119d1528aafcd8a94dc) (compatible with GNU
linkers)


On Wed, May 9, 2018 at 6:44 AM Teresa Johnson <tejohnson at google.com>
wrote:
>
>
> 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
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>
>>
>> --
>> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>>  408-460-2413
>>
>
>
> --
> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>  408-460-2413
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20180509/2f859579/attachment.html>

LLD revision is r331862.  To add, I had initially tried it on r328903,
which also reproduced the issue.

On Wed, May 9, 2018 at 9:26 AM Pirama Arumuga Nainar <pirama at
google.com>
wrote:
> Hi Teresa,
>
> Thanks for looking into this.  I hadn't initially tried ToT, but it
> reproduces in ToT as well when I tried.
>
> $ ./clang --version
>
> clang version 7.0.0 (trunk 331879) (llvm/trunk 331888)
> Target: x86_64-unknown-linux-gnu
> Thread model: posix
> InstalledDir: /ssd2/pirama/llvm-upstream/llvm-release/bin/.
>
> $ ./ld.lld --version
> LLD 7.0.0 (https://git.llvm.org/git/lld.git
dc4977e104c7f33758ac6119d1528aafcd8a94dc) (compatible with GNU linkers)
>
>
> On Wed, May 9, 2018 at 6:44 AM Teresa Johnson <tejohnson at
google.com>
> wrote:
>
>>
>>
>> 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
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> llvm-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>
>>>
>>>
>>> --
>>> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>>>  408-460-2413
>>>
>>
>>
>> --
>> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>>  408-460-2413
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20180509/75e9a8b3/attachment.html>