[llvm-dev] (Thin)LTO llvm build

[Xinliang David Li via llvm-dev]

In  uint64_t
RTDyldMemoryManager::getSymbolAddressInProcess(const std::string &Name)  {

there is reference to morestack:



#if defined(__i386__) || defined(__x86_64__)
  // __morestack lives in libgcc, a static library.
  if (&__morestack && Name == "__morestack")
    return (uint64_t)&__morestack;
#endif
#endif // __linux__ && __GLIBC__


On Mon, Oct 3, 2016 at 3:32 PM, Teresa Johnson <tejohnson at google.com> wrote:

>
>
> On Mon, Oct 3, 2016 at 2:59 PM, Xinliang David Li <xinliangli at gmail.com>
> wrote:
>
>> Is -fsplit-stack option used anywhere? My wild guess is that with ld.bfd,
>> the thinLTO link for the DSO does not bring in morestack.o from libgcc.a,
>> but the hidden symbol is defined in lldb binary.
>>
>
> AFAICT, no - I had done "ninja -v" so I have all of the intermediate build
> commands, and it doesn't show up in that.
>
> I'll have to do some more digging to figure out why it is referenced from
> liblldb.so in the ld.bfd case and not when using ld.gold
>
> Teresa
>
> David
>>
>> On Mon, Oct 3, 2016 at 1:54 PM, Teresa Johnson via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Aha - finally reproduced! The difference is using ld.bfd not ld.gold.
>>> With that I get the same failure (using 3.9 to build 3.9 sources):
>>>
>>> /usr/local/google/home/tejohnson/binutils_build/install/bin/ld:
>>> bin/lldb-3.9.1: hidden symbol `__morestack' in
>>> /usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc.a(morestack.o) is referenced
>>> by DSO
>>> /usr/local/google/home/tejohnson/binutils_build/install/bin/ld: final
>>> link failed: Bad value
>>> clang-3.9: error: linker command failed with exit code 1 (use -v to see
>>> invocation)
>>> ninja: build stopped: subcommand failed.
>>>
>>> I am not sure what the official support story is for LLVMgold.so and
>>> ld.bfd. As mentioned earlier, the LLVM site indicates it should use the
>>> gold linker. Can you use that while I try to figure out whether this is
>>> something that should be supported/working?
>>>
>>> Thanks,
>>> Teresa
>>>
>>> On Mon, Oct 3, 2016 at 9:56 AM, Carsten Mattner <
>>> carstenmattner at gmail.com> wrote:
>>>
>>>> On Mon, Oct 3, 2016 at 3:50 PM, Teresa Johnson <tejohnson at google.com>
>>>> wrote:
>>>> >
>>>> > On Sun, Oct 2, 2016 at 4:02 AM, Carsten Mattner <
>>>> carstenmattner at gmail.com> wrote:
>>>> >>
>>>> >> On Sun, Oct 2, 2016 at 6:41 AM, Teresa Johnson <tejohnson at google.com>
>>>> wrote:
>>>> > >
>>>> > > > I use trunk, but it depends on how close to the bleeding edge you
>>>> > > > are comfortable with. But like I said, I also tried bootstrapping
>>>> > > > with 3.9 (both trunk as well as 3.9 sources) and couldn't
>>>> reproduce.
>>>> >>
>>>> >> Hmm, so you're saying neither fails for you, right?
>>>> >
>>>> > Yes
>>>>
>>>> Okay. Do you mind focusing on the 3.9 branch? It's less of a moving
>>>> target
>>>> and lends itself more to figuring out what's failing for me.
>>>>
>>>> As soon as I get around to it, I'll send you my full configure and build
>>>> steps as a shell script. Need to streamline it.
>>>>
>>>
>>>
>>>
>>> --
>>> Teresa Johnson |  Software Engineer |  tejohnson at google.com |
>>> 408-460-2413
>>>
>>> _______________________________________________
>>> 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
>
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