[llvm-dev] Orc JIT vs. STL

[Praveen Velliengiri via llvm-dev]

You can add symbols from Archieve via StaticLibrarySearchGenerator. But it
is added recently though

On Tue, 27 Aug 2019 at 21:02, Praveen Velliengiri <
praveenvelliengiri at gmail.com> wrote:

> Hi Geoff,
> I tried it, but I can't able to reproduce it.
>
> Test Program:
> #include <fstream>
> int main()
> {
>  std::ifstream stream1, stream2;
>  stream1.swap(stream2);
>  return 0;
> }
>
> I didn't get undefined symbols error. I used
> DynamicLibrarySearchGenerator::GetForCurrentProcess API to make symbols
> from STL visible to ORC JIT.
>
> On Tue, 27 Aug 2019 at 20:36, Geoff Levner <glevner at gmail.com> wrote:
>
>> On Tue, Aug 27, 2019 at 4:56 PM Praveen Velliengiri
>> <praveenvelliengiri at gmail.com> wrote:
>> >
>> > HI
>> > Did you run the static constructor and destructor? How did you make
>> your process symbols visible to ORC jit?
>>
>> Yes. It's the constructor that generates the undefined symbol error.
>> We use DynamicLibrary::LoadLibraryPermanently(nullptr) to add process
>> symbols.
>>
>> > Could you please share us the for what symbols you get undefined
>> references :-)
>>
>> Certainly! Mangled:
>>
>>     _ZNSi4swapERSi
>>     _ZNSt13basic_filebufIcSt11char_traitsIcEE4swapERS2_
>>
>> And unmangled:
>>
>>     std::basic_istream<char, std::char_traits<char>
>> >::swap(std::basic_istream<char, std::char_traits<char> >&)
>>     std::basic_filebuf<char, std::char_traits<char>
>> >::swap(std::basic_filebuf<char, std::char_traits<char> >&)
>>
>> Incidentally, if I call that STL swap() function in the application,
>> to ensure it is in the process symbols, the second symbol is found,
>> but the first is still undefined.
>>
>>
>> >
>> > On Aug 27, 2019 8:18 PM, "Geoff Levner via llvm-dev" <
>> llvm-dev at lists.llvm.org> wrote:
>> >>
>> >> Greetings, LLVM wizards.
>> >>
>> >> We are using Clang and Orc JIT (v1) to compile and execute C++ code on
>> the fly. If a C++ module calls functions from external libraries, we add
>> them via DynamicLibrary::LoadLibraryPermanently().
>> >>
>> >> The problem we have run into recently is when a module calls a
>> function from the STL -- in particular this swap() function for input
>> streams:
>> >>
>> >> #include <fstream>
>> >> std::ifstream stream1, stream2;
>> >> stream1.swap(stream2);
>> >>
>> >> When we run the constructors for the module, we get two undefined
>> symbols. And explicitly adding libstdc++ doesn't help. It turns out that
>> the missing symbols are defined not in the runtime DSO but in an archive
>> file:
>> >>
>> >>
>> /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/libstdc++.a
>> >>
>> >> So my questions are:
>> >>
>> >> 1. Is there a simple way to get access to all symbols defined in the
>> STL? Intuitively, it seems like we should not need to know about such
>> compiler magic.
>> >>
>> >> 2. If there is no magical solution, is there a way to explicitly add
>> symbols from an archive?
>> >>
>> >> Thanks,
>> >> Geoff
>> >>
>> >>
>> >> _______________________________________________
>> >> LLVM Developers mailing list
>> >> llvm-dev at lists.llvm.org
>> >> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>> >>
>>
>
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