llvm dev - Nov 2009 - [LLVMdev] Compilation error while cross compiling LLVM for ARM - the __clear_cache issue - now the __sync_val_compare_and_swap issue

Prasanth J skrev:
> Hi,
>
> i am a newbie to llvm architecture. i have been trying to port llvm on
> ARM target. i am using the following configuration for cross compiling
> llvm.
>
> ../llvm/configure --host=arm-linux --target=arm-linux
> --build=i686-linux --prefix=/opt/llvm-arm/ --enable-optimized
> --disable-debug \
>  --disable-expensive-checks --disable-doxygen \
>  --disable-threads --enable-targets=cbe,cpp,arm
>
> using this configuration i am facing the following compilation error.
> pls help me how to resolve this error..
>
> /make[1]: Entering directory
> `/home/prasanth/LLVM_ARM/llvm-target/obj-new/lib/System'
> llvm[1]: Compiling Alarm.cpp for Release build
> llvm[1]: Compiling Atomic.cpp for Release build
> llvm[1]: Compiling Disassembler.cpp for Release build
> llvm[1]: Compiling DynamicLibrary.cpp for Release build
> llvm[1]: Compiling Errno.cpp for Release build
> llvm[1]: Compiling Host.cpp for Release build
> llvm[1]: Compiling IncludeFile.cpp for Release build
> llvm[1]: Compiling Memory.cpp for Release build
> /home/prasanth/LLVM_ARM/llvm-target/llvm/lib/System/Memory.cpp: In
> static member function ‘static void
> llvm::sys::Memory::InvalidateInstructionCache(const void*, size_t)’:
> /home/prasanth/LLVM_ARM/llvm-target/llvm/lib/System/Memory.cpp:67:
> error: ‘__clear_cache’ was not declared in this scope
> make[1]: ***
> [/home/prasanth/LLVM_ARM/llvm-target/obj-new/lib/System/Release/Memory.o]
> Error 1
> make[1]: Leaving directory
> `/home/prasanth/LLVM_ARM/llvm-target/obj-new/lib/System'
> make: *** [all] Error 1//
>
> /i can able to compile by commenting the line in Memory.cpp but i am
> not sure whether it will affect anything while running llvm on target.
> After cross-compilation i copied the binaries to target and i tried to
> compile and run a simple helloworld.c application. As clang requires a
> working gcc on target i used to "-ccc-clang-archs" options to
skip the
> need for gcc on target. But still i am getting the following error.
By commenting out that line will make your llvm version crash
sporadically since you would recreate llvm PR4960 if using the llvm JIT.
http://llvm.org/bugs/show_bug.cgi?id=4960

__clear_cache are needed to clear the instructioncache after jitting a
function and this gcc builtin are found in gcc 4.3.3 and later or
CodeSourcery's 2007Q3/2008Q1 compiler releases and later.

Try updating you cross compiler!

Cheers
Xerxes

Prasanth J wrote:
>
> Hi all,
> with reference to the reply below, I downloaded toolchain from
> codesourcery (arm-2009q1-203-arm-none-linux-gnueabi) with gcc 4.3.3...
> when i compile llvm+clang with this toolchain i am getting the
> following error
>
> make[4]: Entering directory
>
`/home/prasanth/LLVM_ARM/llvm-with-armgcc433/llvm-obj/tools/clang/tools/c-index-test'
> llvm[4]: Linking Release executable c-index-test (without symbols)
>
/home/prasanth/arm-toolchain/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.3/../../../../arm-none-linux-gnueabi/bin/ld:
>
/home/prasanth/LLVM_ARM/llvm-with-armgcc433/llvm-obj/Release/bin/c-index-test:
> hidden symbol `__sync_val_compare_and_swap_4' in
>
/home/prasanth/arm-toolchain/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.3/libgcc.a(linux-atomic.o)
> is referenced by DSO
>
/home/prasanth/arm-toolchain/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.3/../../../../arm-none-linux-gnueabi/bin/ld:
> final link failed: Nonrepresentable section on output
> collect2: ld returned 1 exit status
> make[4]: ***
>
[/home/prasanth/LLVM_ARM/llvm-with-armgcc433/llvm-obj/Release/bin/c-index-test]
> Error 1
> make[4]: Leaving directory
>
`/home/prasanth/LLVM_ARM/llvm-with-armgcc433/llvm-obj/tools/clang/tools/c-index-test'
> make[3]: *** [all] Error 1
> make[3]: Leaving directory
>
`/home/prasanth/LLVM_ARM/llvm-with-armgcc433/llvm-obj/tools/clang/tools'
> make[2]: *** [all] Error 1
> make[2]: Leaving directory
> `/home/prasanth/LLVM_ARM/llvm-with-armgcc433/llvm-obj/tools/clang'
> make[1]: *** [clang/.makeall] Error 2
> make[1]: Leaving directory
> `/home/prasanth/LLVM_ARM/llvm-with-armgcc433/llvm-obj/tools'
> make: *** [all] Error 1
>
> can anyone please tell me why am i getting this error and how can i
> resolve this?
>
> Thanks and Regards,
> Prasanth J
>
>
You get this linking error because the code contains a gcc atomic
intrinsic calls using __sync_val_compare_and_swap . These are GCC
built-ins and have only been implemented on ARM using GCC 4.4.
http://gcc.gnu.org/onlinedocs/gcc-4.4.2/gcc/Atomic-Builtins.html
If you want to use GCC 4.3.3 then you have to implement the
__sync_val_compare_and_swap_4 function yourself.

Ubuntu Jaunty ARM toolchains have been patched to contains the atomic
intrinsics support in GCC 4.3.3

So to solve this issue do one of the following:
a) update your code sourcery cross compiler to arm-2009q3 that are using
GCC 4.4
b) use the Ubuntu gcc 4.3.3 provided toolchain (i use this when
compiling llvm natively on a arm machine without cross compilation)
c) implement the __sync_val_compare_and_swap_4 function and patch llvm
to enable compilation using older toolchains.

Cheers
Xerxes