[llvm-dev] ld.lld on MacOS question

Tue May 16 13:39:40 PDT 2017

Lang - I think there has perhaps been a regression in that case, because I
have an example of a trivial IR module that fails to be linked correctly:
https://bugs.llvm.org/show_bug.cgi?id=32376

Kevin provided some clues about this but I was not able to find a fix.

On Tue, May 16, 2017 at 12:24 PM, Lang Hames <lhames at gmail.com> wrote:

> Hi Guys,
>
> As I left it, lld on Darwin could compile Clang / LLVM and the nightly
> test suite, so we were definitely making progress. There were still plenty
> of bug fixes to get through though. If anyone's interested in contributing
> to MachO support in lld I'm happy to translate some of the radars into
> llvm.org bugs.
>
> Cheers,
> Lang.
>
>
> On Thu, May 11, 2017 at 11:34 PM, Peter Kriens <peter.kriens at aqute.biz>
> wrote:
>
>> Sounds like a fantastic goal, and enticingly close …
>>
>> Kind regards,
>>
>> Peter Kriens
>>
>> On 11 May 2017, at 20:53, Andrew Kelley <superjoe30 at gmail.com> wrote:
>>
>> Zig author here in the same boat. Looks like I'm going to have to disable
>> cross compiling for MacOS and when compiling native for MacOS add a
>> dependency on the system linker. Really looking forward to Mach-O support
>> in LLD, because at that point my users will be able to cross compile for
>> any OS out of the box.
>>
>> On Thu, May 11, 2017 at 1:37 PM, Peter Kriens via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Thanks for the answer. However, this means I need a different linker for
>>> MacOS as for Windows/Linux?
>>>
>>> I guess it is a not a major thing but I was hoping to set up a cross
>>> compile env. where only the header files and shared libraries differed :-(
>>> I guess we’re not there yet … :-)
>>>
>>> Kind regards,
>>>
>>> Peter Kriens
>>>
>>> On 6 May 2017, at 19:57, Lang Hames <lhames at gmail.com> wrote:
>>>
>>> LLD work on Darwin is stalled out at the moment. Patches are welcome
>>> (and I'll try to find time to review them), but I'd recommend ld64 for any
>>> real-world linking.
>>>
>>> - Lang.
>>>
>>>
>>> On Thu, Apr 27, 2017 at 11:06 AM, Rui Ueyama <ruiu at google.com> wrote:
>>>
>>>> Cc'ing people who are working on macOS.
>>>>
>>>> On Thu, Apr 27, 2017 at 9:05 AM, Peter Kriens via llvm-dev <
>>>> llvm-dev at lists.llvm.org> wrote:
>>>>
>>>>> Hopefully the right list … otherwise pointers appreciated (I’ve spent
>>>>> days trying to find a solution but could not find sufficient documentation,
>>>>> could not find a proper list of -flavor darwin commands)
>>>>>
>>>>> I am setting up an environment for cross compiling shared libraries
>>>>> using LLVM. Overall this works perfectly for many unix like environments
>>>>> but MacOS is a pain in the ass despite that I am running on MacOS. (I’ve
>>>>> not tried windows yet.)
>>>>>
>>>>> I seem to be able to compile with clang a proper mach object file for
>>>>> a hello function. However, when I link this function into a shared library
>>>>> I (surprisingly for a shared lib?) get undefined symbols like _printf, stub
>>>>> runtime: dyld_stub_binder, _main, etc. Using the flag
>>>>>
>>>>> -undefined dynamic_lookup
>>>>>
>>>>> I get no errors or warnings but then when I try to link the shared
>>>>> library to a main program I get the error:
>>>>>
>>>>> ld: malformed dylib has MH_NO_REEXPORTED_DYLIBS flag
>>>>> but no LC_REEXPORT_DYLIB load commands: ./libhello.dylib file
>>>>> './libhello.dylib'
>>>>>
>>>>> I’ve included the shell file that makes the hello shared lib and the
>>>>> command that I use to link the file.
>>>>>
>>>>> Thanks for any help, this looks like an amazing solution if it can get
>>>>> to work on all supported platforms.
>>>>>
>>>>> Kind regards,
>>>>>
>>>>> Peter Kriens
>>>>>
>>>>> $ /usr/local/Cellar/llvm/4.0.0_1/bin/clang \
>>>>> -target x86_64-apple-darwin16.5.0 \
>>>>> -Ienvs/x86_64/apple/macos/darwin/16.5.0/include  \
>>>>> -v \
>>>>> -nostdinc \
>>>>> -fPIC \
>>>>> -c \
>>>>> -Wno-nullability-completeness \
>>>>> hello.c x.c
>>>>>
>>>>> $ file hello.o
>>>>> hello.o: Mach-O 64-bit object x86_64
>>>>>
>>>>> $ /usr/local/Cellar/llvm/4.0.0_1/bin/ld.lld \
>>>>> -flavor darwin \
>>>>> -v \
>>>>> -sdk_version 10.5.0 \
>>>>> -demangle \
>>>>> -arch x86_64 \
>>>>> -undefined dynamic_lookup \
>>>>> -dylib \
>>>>> -dynamic \
>>>>> -o libhello.dylib \
>>>>> hello.o
>>>>>
>>>>> $ file libhello.dylib
>>>>> libhello.dylib: Mach-O 64-bit dynamically linked shared library x86_64
>>>>>
>>>>> $ gcc x.c -L. -lhello
>>>>> ld: malformed dylib has MH_NO_REEXPORTED_DYLIBS flag but no
>>>>> LC_REEXPORT_DYLIB load commands: ./libhello.dylib file ‘./libhello.dylib'
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> llvm-dev at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>
>>>>>
>>>>
>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
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>>>
>>>
>>
>>
>
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