[LLVMdev] Customize Standard C Library Using LLVM (to support llvm backend optimization)

Jonathan Roelofs jonathan at codesourcery.com
Sat Mar 28 06:53:13 PDT 2015

On 3/27/15 8:07 PM, Chao Yan wrote:
> 2015-03-12 15:07 GMT-05:00 Jonathan Roelofs <jonathan at codesourcery.com
> <mailto:jonathan at codesourcery.com>>:
>     This isn't a gcc support mailing list... If you have questions
>     pertaining to llvm/clang, we'd be happy to answer them.
>     That being said, that symbol should be part of the compiler's
>     runtime library (or maybe in the libc?). llvm provides that symbol
>     as part of libclangrt/libcompiler_rt.
> The problem is basically caused by llvm. I cross-compile the musl-libc
> to arm binaries using clang. However, the cross-compiled musl-libc needs
> runtime support from libcompiler_rt. The arm version of this static
> runtime library cannot be obtained by cross compiling.

Where did you read that? Because it's plainly not true.

libcompiler_rt is *designed* to be cross-built, and building the ARM 
version of it from x86 Linux/Darwin is well exercised by several members 
of the community, myself included.

> Do I need to build llvm on an arm host machine?

No. LLVM/Clang is a cross compiler. Building host binaries is just a 
special, easier case of that.


> Thanks,
> Chao

Jon Roelofs
jonathan at codesourcery.com
CodeSourcery / Mentor Embedded

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