Re: [cfe-users] Using llvm-ar & llvm-ranlib vs ar & ranlib for creating static libraries when thinLTO is enabled.
(Teresa, perhaps you can correct me if I'm wrong here)
On Thu, Aug 9, 2018 at 2:21 PM Mateusz Zych via cfe-users <
cfe-users@lists.llvm.org> wrote:
> Hi :)
>
> I am trying to compile simple project consisting of an executable "app"
> and static library "bar".
> Note that I'm enabling thinLTO for both "app" and "bar".
>
>
> // bar.h//
>
> #ifndef BAR
> #define BAR
>
> void bar ();
>
> #endif
>
>
>
> // bar.cpp //
>
> #include "bar.h"
> #include
>
> void bar ()
> {
> std::cout << "Bar" << std::endl;
> }
>
>
>
> // app.cpp //
>
> #include "bar.h"
> #include
>
> int main()
> {
> std::cout << "App" << std::endl;
> bar();
> }
>
>
>
> When I'm using llvm-ar and llvm-ranlib to create static library everything
> works fine:
>
> $ clang++ -flto=thin -c bar.cpp -o bar.o
> $ llvm-ar cr bar.a bar.o
> $ llvm-ranlib bar.a
> $ clang++ -flto=thin -c app.cpp -o app.o
> $ clang++ -flto=thin -o app app.o bar.a
>
>
> However using default ar and ranlib provided by my GNU/Linux distribution
> results in linking failure:
>
> $ clang++ -flto=thin -c bar.cpp -o bar.o
> $ ar cr bar.a bar.o
> $ ranlib bar.a
> $ clang++ -flto=thin -c app.cpp -o app.o
> $ clang++ -flto=thin -o app app.o bar.a
> bar.a: *error adding symbols: Archive has no index; run ranlib to add one*
> clang: error: linker command failed with exit code 1 (use -v to see
> invocation)
>
>
> Note that for GCC using default ar and ranlib works fine:
>
> $ g++ -flto -c bar.cpp -o bar.o
> $ ar cr bar.a bar.o
> $ ranlib bar.a
> $ g++ -flto -c app.cpp -o app.o
> $ g++ -flto -o app app.o bar.a
>
>
> Obviously using gcc-ar and gcc-ranlib also works fine:
>
> $ g++ -flto -c bar.cpp -o bar.o
> $ gcc-ar cr bar.a bar.o
> $ gcc-ranlib bar.a
> $ g++ -flto -c app.cpp -o app.o
> $ g++ -flto -o app app.o bar.a
>
>
> My question is: *Can I use ar and ranlib provided by GNU/Linux with
> clang++?*
>
Not when using LTO, so far as I know. Otherwise, yes. (no idea if
llvm-ar/llvm-ranlib are totally general purpose replacements for those
tools, but I guess they are roughly/generally so)
>
> If not, then to properly setup clang as a default compiler on GNU/Linux
> machine,
> I should not only run update-alternatives for cc and c++ commands,
> but also somehow do that for ar and ranlib commands?
>
> $ sudo update-alternatives --config cc
> $ sudo update-alternatives --config c++
>
>
> That's very problematic since update-alternatives doesn't work with ar and
> ranlib:
>
> $ sudo update-alternatives --config ar
> update-alternatives: error: no alternatives for ar
> $ sudo update-alternatives --config ranlib
> update-alternatives: error: no alternatives for ranlib
>
>
Looks like you can teach update-alternatives to support new commands with
the --install option?
>
> If default ar and ranlib is expected to not work with clang++,
> then how should I setup Clang as a default compiler on GNU/Linux?
>
> Thanks, Mateusz Zych
> ___
> cfe-users mailing list
> cfe-users@lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
>
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Re: [cfe-users] Using llvm-ar & llvm-ranlib vs ar & ranlib for creating static libraries when thinLTO is enabled.
That's correct, we recommend use of the llvm tools for working with
bitcode. Note, however, that the GNU ar and ranlib do accept a plugin via
--plugin, so you could try using those with the LLVM gold plugin to work
with bitcode. I personally use the llvm-ar/llvm-ranlib however.
Teresa
On Mon, Aug 13, 2018 at 8:38 AM David Blaikie wrote:
> (Teresa, perhaps you can correct me if I'm wrong here)
>
> On Thu, Aug 9, 2018 at 2:21 PM Mateusz Zych via cfe-users <
> cfe-users@lists.llvm.org> wrote:
>
>> Hi :)
>>
>> I am trying to compile simple project consisting of an executable "app"
>> and static library "bar".
>> Note that I'm enabling thinLTO for both "app" and "bar".
>>
>>
>> // bar.h//
>>
>> #ifndef BAR
>> #define BAR
>>
>> void bar ();
>>
>> #endif
>>
>>
>>
>> // bar.cpp //
>>
>> #include "bar.h"
>> #include
>>
>> void bar ()
>> {
>> std::cout << "Bar" << std::endl;
>> }
>>
>>
>>
>> // app.cpp //
>>
>> #include "bar.h"
>> #include
>>
>> int main()
>> {
>> std::cout << "App" << std::endl;
>> bar();
>> }
>>
>>
>>
>> When I'm using llvm-ar and llvm-ranlib to create static library
>> everything works fine:
>>
>> $ clang++ -flto=thin -c bar.cpp -o bar.o
>> $ llvm-ar cr bar.a bar.o
>> $ llvm-ranlib bar.a
>> $ clang++ -flto=thin -c app.cpp -o app.o
>> $ clang++ -flto=thin -o app app.o bar.a
>>
>>
>> However using default ar and ranlib provided by my GNU/Linux distribution
>> results in linking failure:
>>
>> $ clang++ -flto=thin -c bar.cpp -o bar.o
>> $ ar cr bar.a bar.o
>> $ ranlib bar.a
>> $ clang++ -flto=thin -c app.cpp -o app.o
>> $ clang++ -flto=thin -o app app.o bar.a
>> bar.a: *error adding symbols: Archive has no index; run ranlib to add
>> one*
>> clang: error: linker command failed with exit code 1 (use -v to see
>> invocation)
>>
>>
>> Note that for GCC using default ar and ranlib works fine:
>>
>> $ g++ -flto -c bar.cpp -o bar.o
>> $ ar cr bar.a bar.o
>> $ ranlib bar.a
>> $ g++ -flto -c app.cpp -o app.o
>> $ g++ -flto -o app app.o bar.a
>>
>>
>> Obviously using gcc-ar and gcc-ranlib also works fine:
>>
>> $ g++ -flto -c bar.cpp -o bar.o
>> $ gcc-ar cr bar.a bar.o
>> $ gcc-ranlib bar.a
>> $ g++ -flto -c app.cpp -o app.o
>> $ g++ -flto -o app app.o bar.a
>>
>>
>> My question is: *Can I use ar and ranlib provided by GNU/Linux with
>> clang++?*
>>
>
> Not when using LTO, so far as I know. Otherwise, yes. (no idea if
> llvm-ar/llvm-ranlib are totally general purpose replacements for those
> tools, but I guess they are roughly/generally so)
>
>
>>
>> If not, then to properly setup clang as a default compiler on GNU/Linux
>> machine,
>> I should not only run update-alternatives for cc and c++ commands,
>> but also somehow do that for ar and ranlib commands?
>>
>> $ sudo update-alternatives --config cc
>> $ sudo update-alternatives --config c++
>>
>>
>> That's very problematic since update-alternatives doesn't work with ar
>> and ranlib:
>>
>> $ sudo update-alternatives --config ar
>> update-alternatives: error: no alternatives for ar
>> $ sudo update-alternatives --config ranlib
>> update-alternatives: error: no alternatives for ranlib
>>
>>
> Looks like you can teach update-alternatives to support new commands with
> the --install option?
>
>
>>
>> If default ar and ranlib is expected to not work with clang++,
>> then how should I setup Clang as a default compiler on GNU/Linux?
>>
>> Thanks, Mateusz Zych
>> ___
>> cfe-users mailing list
>> cfe-users@lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
>>
>
--
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
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Re: [cfe-users] Using llvm-ar & llvm-ranlib vs ar & ranlib for creating static libraries when thinLTO is enabled.
I believe if you install LLVMgold.so into /usr/lib/bfd-plugins, the default
ar and ranlib should pick it up without --plugin. See the info under Usage
at https://llvm.org/docs/GoldPlugin.html.
Teresa
On Mon, Aug 13, 2018 at 8:46 AM Teresa Johnson wrote:
> That's correct, we recommend use of the llvm tools for working with
> bitcode. Note, however, that the GNU ar and ranlib do accept a plugin via
> --plugin, so you could try using those with the LLVM gold plugin to work
> with bitcode. I personally use the llvm-ar/llvm-ranlib however.
> Teresa
>
> On Mon, Aug 13, 2018 at 8:38 AM David Blaikie wrote:
>
>> (Teresa, perhaps you can correct me if I'm wrong here)
>>
>> On Thu, Aug 9, 2018 at 2:21 PM Mateusz Zych via cfe-users <
>> cfe-users@lists.llvm.org> wrote:
>>
>>> Hi :)
>>>
>>> I am trying to compile simple project consisting of an executable "app"
>>> and static library "bar".
>>> Note that I'm enabling thinLTO for both "app" and "bar".
>>>
>>>
>>> // bar.h//
>>>
>>> #ifndef BAR
>>> #define BAR
>>>
>>> void bar ();
>>>
>>> #endif
>>>
>>>
>>>
>>> // bar.cpp //
>>>
>>> #include "bar.h"
>>> #include
>>>
>>> void bar ()
>>> {
>>> std::cout << "Bar" << std::endl;
>>> }
>>>
>>>
>>>
>>> // app.cpp //
>>>
>>> #include "bar.h"
>>> #include
>>>
>>> int main()
>>> {
>>> std::cout << "App" << std::endl;
>>> bar();
>>> }
>>>
>>>
>>>
>>> When I'm using llvm-ar and llvm-ranlib to create static library
>>> everything works fine:
>>>
>>> $ clang++ -flto=thin -c bar.cpp -o bar.o
>>> $ llvm-ar cr bar.a bar.o
>>> $ llvm-ranlib bar.a
>>> $ clang++ -flto=thin -c app.cpp -o app.o
>>> $ clang++ -flto=thin -o app app.o bar.a
>>>
>>>
>>> However using default ar and ranlib provided by my GNU/Linux
>>> distribution results in linking failure:
>>>
>>> $ clang++ -flto=thin -c bar.cpp -o bar.o
>>> $ ar cr bar.a bar.o
>>> $ ranlib bar.a
>>> $ clang++ -flto=thin -c app.cpp -o app.o
>>> $ clang++ -flto=thin -o app app.o bar.a
>>> bar.a: *error adding symbols: Archive has no index; run ranlib to add
>>> one*
>>> clang: error: linker command failed with exit code 1 (use -v to see
>>> invocation)
>>>
>>>
>>> Note that for GCC using default ar and ranlib works fine:
>>>
>>> $ g++ -flto -c bar.cpp -o bar.o
>>> $ ar cr bar.a bar.o
>>> $ ranlib bar.a
>>> $ g++ -flto -c app.cpp -o app.o
>>> $ g++ -flto -o app app.o bar.a
>>>
>>>
>>> Obviously using gcc-ar and gcc-ranlib also works fine:
>>>
>>> $ g++ -flto -c bar.cpp -o bar.o
>>> $ gcc-ar cr bar.a bar.o
>>> $ gcc-ranlib bar.a
>>> $ g++ -flto -c app.cpp -o app.o
>>> $ g++ -flto -o app app.o bar.a
>>>
>>>
>>> My question is: *Can I use ar and ranlib provided by GNU/Linux with
>>> clang++?*
>>>
>>
>> Not when using LTO, so far as I know. Otherwise, yes. (no idea if
>> llvm-ar/llvm-ranlib are totally general purpose replacements for those
>> tools, but I guess they are roughly/generally so)
>>
>>
>>>
>>> If not, then to properly setup clang as a default compiler on GNU/Linux
>>> machine,
>>> I should not only run update-alternatives for cc and c++ commands,
>>> but also somehow do that for ar and ranlib commands?
>>>
>>> $ sudo update-alternatives --config cc
>>> $ sudo update-alternatives --config c++
>>>
>>>
>>> That's very problematic since update-alternatives doesn't work with ar
>>> and ranlib:
>>>
>>> $ sudo update-alternatives --config ar
>>> update-alternatives: error: no alternatives for ar
>>> $ sudo update-alternatives --config ranlib
>>> update-alternatives: error: no alternatives for ranlib
>>>
>>>
>> Looks like you can teach update-alternatives to support new commands with
>> the --install option?
>>
>>
>>>
>>> If default ar and ranlib is expected to not work with clang++,
>>> then how should I setup Clang as a default compiler on GNU/Linux?
>>>
>>> Thanks, Mateusz Zych
>>> ___
>>> cfe-users mailing list
>>> cfe-users@lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
>>>
>>
>
> --
> Teresa Johnson | Software Engineer | tejohn...@google.com |
> 408-460-2413
>
--
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
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