[llvm-dev] Compilation issue "unsupported relocation on symbol" with clang 3.7.1

Peter Smith via llvm-dev llvm-dev at lists.llvm.org
Tue Nov 28 05:23:41 PST 2017 

The file builtins/assembly.h has code to define things like
USE_THUMB_1. Depending on how old your version of compiler-rt is, the
chances are that you don't have an up to date assembly.h so
USE_THUMB_1 isn't going to be defined. Are you able to take the latest
version of compiler-rt? That would minimise your chances of running
into problems like this. If you must keep the existing version of
compiler-rt that you have I suggest that you either adapt USE_THUMB_1
to the defines in your assembly.h or add USE_THUMB_1 to your
assembly.h in the appropriate place.

Peter

On 28 November 2017 at 08:04,  <shiftag at nanotek.info> wrote:
> Hi again,
>
> So I applied the patch but I have still the same issue.
>
> ---
>
> -- Build files have been written to: /tmp/aki/llvm-5.0.0.src/build
> [1465/5024] Creating library symlink lib/libc++.so.1 lib/libc++.so
> GENERATING SCRIPT: 'INPUT(libc++.so.1 -lc++abi)' as file /tmp/aki/llvm-5.0.0.src/build/lib/libc++.so
> [1588/5024] Building C object projects/compiler-rt/lib...ins/CMakeFiles/clang_rt.builtins-arm.dir/cpu_model.c.o
> ../projects/compiler-rt/lib/builtins/cpu_model.c:596:7: warning: ISO C requires a translation unit to contain at least one declaration [-Wempty-translation-unit]
> #endif
>      ^
> 1 warning generated.
> [1786/5024] Building C object projects/compiler-rt/lib.../CMakeFiles/clang_rt.builtins-armv6m.dir/cpu_model.c.o
> ../projects/compiler-rt/lib/builtins/cpu_model.c:596:7: warning: ISO C requires a translation unit to contain at least one declaration [-Wempty-translation-unit]
> #endif
>      ^
> 1 warning generated.
> [1915/5024] Building ASM object projects/compiler-rt/l...iles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o
> FAILED: projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o
> /usr/bin/clang -DLLVM_BUILD_GLOBAL_ISEL -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Iprojects/compiler-rt/lib/builtins -I../projects/compiler-rt/lib/builtins -Iinclude -I../include -fPIC -O3 -DNDEBUG    -march=armv6m -mfloat-abi=soft -fno-lto -MD -MT projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o -MF projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o.d -o projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o -c ../projects/compiler-rt/lib/builtins/arm/aeabi_memcmp.S
> clang -cc1as: fatal error: error in backend: unsupported relocation on symbol
> [1917/5024] Building ASM object projects/compiler-rt/l...iles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o
> FAILED: projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o
> /usr/bin/clang -DLLVM_BUILD_GLOBAL_ISEL -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Iprojects/compiler-rt/lib/builtins -I../projects/compiler-rt/lib/builtins -Iinclude -I../include -fPIC -O3 -DNDEBUG    -march=armv6m -mfloat-abi=soft -fno-lto -MD -MT projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o -MF projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o.d -o projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o -c ../projects/compiler-rt/lib/builtins/arm/aeabi_memcpy.S
> clang -cc1as: fatal error: error in backend: unsupported relocation on symbol
> [1918/5024] Building ASM object projects/compiler-rt/l...les/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o
> FAILED: projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o
> /usr/bin/clang -DLLVM_BUILD_GLOBAL_ISEL -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Iprojects/compiler-rt/lib/builtins -I../projects/compiler-rt/lib/builtins -Iinclude -I../include -fPIC -O3 -DNDEBUG    -march=armv6m -mfloat-abi=soft -fno-lto -MD -MT projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o -MF projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o.d -o projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o -c ../projects/compiler-rt/lib/builtins/arm/aeabi_memmove.S
> clang -cc1as: fatal error: error in backend: unsupported relocation on symbol
> [1920/5024] Building CXX object lib/Target/ARM/MCTargetDesc/CMakeFiles/LLVMARMDesc.dir/ARMMCTargetDesc.cpp.o
> ninja: build stopped: subcommand failed
>
> ---
>
>
> So if we check the content of the following file :
>
>    projects/compiler-rt/lib/builtins/arm/aeabi_memcmp.S
>
> ---
>
> //===-- aeabi_memcmp.S - EABI memcmp implementation -----------------------===//
> //
> //                     The LLVM Compiler Infrastructure
> //
> // This file is dual licensed under the MIT and the University of Illinois Open
> // Source Licenses. See LICENSE.TXT for details.
> //
> //===----------------------------------------------------------------------===//
>
> #include "../assembly.h"
>
> //  void __aeabi_memcmp(void *dest, void *src, size_t n) { memcmp(dest, src, n); }
>
>         .syntax unified
>         .p2align 2
> DEFINE_COMPILERRT_FUNCTION(__aeabi_memcmp)
> #ifdef USE_THUMB_1
>         push    {r7, lr}
>         bl      memcmp
>         pop     {r7, pc}
> #else
>         b       memcmp
> #endif
> END_COMPILERRT_FUNCTION(__aeabi_memcmp)
>
> DEFINE_AEABI_FUNCTION_ALIAS(__aeabi_memcmp4, __aeabi_memcmp)
> DEFINE_AEABI_FUNCTION_ALIAS(__aeabi_memcmp8, __aeabi_memcmp)
>
> NO_EXEC_STACK_DIRECTIVE
>
> ---
>
> The file has been correctly patch but do I need to provide a switch to the pre-processor
> for USE_THUMB_1 like "-DUSE_THUMB_1" ?
>
> Cheers
>
>
>
> November 27, 2017 3:36 PM, "via llvm-dev" <llvm-dev at lists.llvm.org> wrote:
>
>> Thank you Peter, I will try to patch instead.
>>
>> Cheers
>>
>> November 27, 2017 3:12 PM, "Peter Smith" <peter.smith at linaro.org> wrote:
>>
>>> A very recent change to compiler-rt https://reviews.llvm.org/D39700
>>> recently the unconditional branch for v6-m in some of the aeabi_
>>> functions, if you are able to use compiler-rt from trunk or alter the
>>> compiler-rt source yourself you may be able to work around the problem
>>> without changing versions of llvm.
>>>
>>> I'm not sure what to recommend otherwise, you may be able to turn off
>>> the integrated assembler and use arm-non-eabi-as for the files with
>>> unconditional branches, but I couldn't guarantee that would wouldn't
>>> result in other problems.
>>>
>>> Peter
>>>
>>> On 27 November 2017 at 11:02, <shiftag at nanotek.info> wrote:
>>
>> November 27, 2017 2:43 PM, "Peter Smith" <peter.smith at linaro.org> wrote:
>>> My best guess is that this is PR30279
>>> https://bugs.llvm.org/show_bug.cgi?id=30279 which was fixed in r280651
>>> in September 2016. Can you try again with a version of clang/llvm from
>>> after that point? Some versions of aeabi_memcpy.S contain an
>>> unconditional branch to memcpy (a branch out of section that can't be
>>> resolved at assembly time). The v6m unconditional branch has a very
>>> short range and earlier versions of llvm did not support the
>>> relocation.
>>>
>>> Hope this helps
>>
>> Hi Peter,
>>
>> Thank you for your answer. I saw that pages before but I didn't find any
>> information about how to fix this. And unfortunately, I can't use a different
>> version of clang/llvm.
>>
>> Thanks
>>> On 26 November 2017 at 12:09, via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>>
>> Hi List,
>>
>> I'm trying to build llvm-5.0.0 with clang-3.7.1 on ARM (native building). At
>> some point I have the following issue :
>>
>> ----
>>
>> [1588/5024] Building C object
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/cpu_model.c.o
>> ../projects/compiler-rt/lib/builtins/cpu_model.c:596:7: warning: ISO C
>> requires a translation unit to contain at least one declaration
>> [-Wempty-translation-unit]
>> #endif
>> ^
>> 1 warning generated.
>> [1786/5024] Building C object
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/cpu_model.c.o
>> ../projects/compiler-rt/lib/builtins/cpu_model.c:596:7: warning: ISO C
>> requires a translation unit to contain at least one declaration
>> [-Wempty-translation-unit]
>> #endif
>> ^
>> 1 warning generated.
>> [1915/5024] Building ASM object
>> projects/compiler-rt/lib/built...s/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o
>> FAILED:
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o
>> /usr/bin/clang -DLLVM_BUILD_GLOBAL_ISEL -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE
>> -D_LARGEFILE_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS
>> -D__STDC_LIMIT_MACROS -Iprojects/compiler-rt/lib/builtins
>> -I../projects/compiler-rt/lib/builtins -Iinclude -I../include -fPIC -O3
>> -DNDEBUG -march=armv6m -mfloat-abi=soft -fno-lto -MD -MT
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o
>> -MF
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o.d
>> -o
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcmp.S.o
>> -c ../projects/compiler-rt/lib/builtins/arm/aeabi_memcmp.S
>> clang -cc1as: fatal error: error in backend: unsupported relocation on
>> symbol
>> [1917/5024] Building ASM object
>> projects/compiler-rt/lib/built.../CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o
>> FAILED:
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o
>> /usr/bin/clang -DLLVM_BUILD_GLOBAL_ISEL -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE
>> -D_LARGEFILE_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS
>> -D__STDC_LIMIT_MACROS -Iprojects/compiler-rt/lib/builtins
>> -I../projects/compiler-rt/lib/builtins -Iinclude -I../include -fPIC -O3
>> -DNDEBUG -march=armv6m -mfloat-abi=soft -fno-lto -MD -MT
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o
>> -MF
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memmove.S.o.d
>> -o
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins----armv6m.dir/arm/aeabi_memmove.S.o
>> -c ../projects/compiler-rt/lib/builtins/arm/aeabi_memmove.S
>> clang -cc1as: fatal error: error in backend: unsupported relocation on
>> symbol
>> [1918/5024] Building ASM object
>> projects/compiler-rt/lib/built...s/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o
>> FAILED:
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o
>> /usr/bin/clang -DLLVM_BUILD_GLOBAL_ISEL -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE
>> -D_LARGEFILE_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS
>> -D__STDC_LIMIT_MACROS -Iprojects/compiler-rt/lib/builtins
>> -I../projects/compiler-rt/lib/builtins -Iinclude -I../include -fPIC -O3
>> -DNDEBUG -march=armv6m -mfloat-abi=soft -fno-lto -MD -MT
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o
>> -MF
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o.d
>> -o
>> projects/compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins-armv6m.dir/arm/aeabi_memcpy.S.o
>> -c ../projects/compiler-rt/lib/builtins/arm/aeabi_memcpy.S
>> clang -cc1as: fatal error: error in backend: unsupported relocation on
>> symbol
>> [1920/5024] Building CXX object
>> lib/Target/ARM/MCTargetDesc/CMakeFiles/LLVMARMDesc.dir/ARMMCTargetDesc.cpp.o
>> ninja: build stopped: subcommand failed.
>>
>> ----
>>
>> Relevant stuff:
>> clang -cc1as: fatal error: error in backend: unsupported relocation on
>> symbol
>>
>> Well, I don't know how to fix that. Any ideas ?
>>
>> Let me know if you need further info.
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>> _______________________________________________
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