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

[Peter Smith via llvm-dev]

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

Peter

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.
>
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