llvm dev - May 2016 - Problem on cross-compiling compiler-rt

Hi.
I'm trying to use Clang/LLVM as a cross-compiling toolchain. In previous
version of LLVM with the old configure/Makefile building system, I'm able to
build Clang/LLVM for target architecture with the host GCC firstly and then use
the generated cross compiler to compile the compiler-rt project, and,
consequently, I can get a cross compiler as well as the compiler-rt library.
However, when I move to version 3.9 which abandoned configure/Makefile and uses
CMake now, it always compile the compiler-rt simultaneously with the host GCC.
The same problem is also existing in 3.5 CMake building system. It seems that in
the CMake building system compiler-rt is not dependent on the generated
toolchain. I also tried to compile the compiler-rt after Clang/LLVM has been
built, and there is another problem that the generated Clang/LLVM cannot pass
the CMake checking without compiler-rt, which is obvious... So is there any way
that I can solve this problem. Thank you.


Lei Wang







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Hi WangLei,

Do you mean that the version 3.9 is LLVM project 3.9 and 3.5 is CMake 3.5?

In the guide[GetStarted.rst], the tutorial says before running CMake
command, you must checkout all the source code.  CMake does not pickup
newly added source directories in incremental builds.

Have you cross-compiled the LLVM/Clang for ARM, or other successfully?

Cheers,
Liyang

2016-05-03 14:42 GMT+08:00 王磊 via llvm-dev <llvm-dev at lists.llvm.org>:
>
> Hi.
> I'm trying to use Clang/LLVM as a cross-compiling toolchain. In
previous
> version of LLVM with the old configure/Makefile building system, I'm
able
> to build Clang/LLVM for target architecture with the host GCC firstly and
> then use the generated cross compiler to compile the compiler-rt project,
> and, consequently, I can get a cross compiler as well as the compiler-rt
> library. However, when I move to version 3.9 which abandoned
> configure/Makefile and uses CMake now, it always compile the compiler-rt
> simultaneously with the host GCC. The same problem is also existing in 3.5
> CMake building system. It seems that in the CMake building system
> compiler-rt is not dependent on the generated toolchain. I also tried to
> compile the compiler-rt after Clang/LLVM has been built, and there is
> another problem that the generated Clang/LLVM cannot pass the CMake
> checking without compiler-rt, which is obvious... So is there any way that
> I can solve this problem. Thank you.
>
> Lei Wang
>
>
> <#m_-2483977491504695984_>
>
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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This is currently a rough area in our build system, but there are two CMake
options you probably need to set.

(1) -DLLVM_BUILD_EXTERNAL_COMPILER_RT=On —> This option causes the build to
use the just-built clang when building compiler-rt
(2) -DCOMPILER_RT_DEFAULT_TARGET_ARCH=??? —> This is where you specify which
architecture you want to build the compiler-rt archives and libraries for

Hopefully in the near future we’ll have a better story for building this
functionality.

Hope this helps,
-Chris

> On May 3, 2016, at 12:09 AM, 李阳 via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi WangLei,
> 
> Do you mean that the version 3.9 is LLVM project 3.9 and 3.5 is CMake 3.5?
> 
> In the guide[GetStarted.rst], the tutorial says before running CMake
command, you must checkout all the source code.  CMake does not pickup newly
added source directories in incremental builds.
> 
> Have you cross-compiled the LLVM/Clang for ARM, or other successfully?
> 
> Cheers,
> Liyang 
> 
> 2016-05-03 14:42 GMT+08:00 王磊 via llvm-dev <llvm-dev at lists.llvm.org
<mailto:llvm-dev at lists.llvm.org>>:
> 
> Hi.
> I'm trying to use Clang/LLVM as a cross-compiling toolchain. In
previous version of LLVM with the old configure/Makefile building system,
I'm able to build Clang/LLVM for target architecture with the host GCC
firstly and then use the generated cross compiler to compile the compiler-rt
project, and, consequently, I can get a cross compiler as well as the
compiler-rt library. However, when I move to version 3.9 which abandoned
configure/Makefile and uses CMake now, it always compile the compiler-rt
simultaneously with the host GCC. The same problem is also existing in 3.5 CMake
building system. It seems that in the CMake building system compiler-rt is not
dependent on the generated toolchain. I also tried to compile the compiler-rt
after Clang/LLVM has been built, and there is another problem that the generated
Clang/LLVM cannot pass the CMake checking without compiler-rt, which is
obvious... So is there any way that I can solve this problem. Thank you.
> 
> Lei Wang
> 
> 
>  <> <> <> <x-msg://106/#m_-2483977491504695984_>
<>
> 
> 
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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