[cfe-dev] Cross compiling with clang (and sysroot support)

[Stephen Kelly]

Hi there,

I'm investigating adding sysroot functionality to cmake

 http://thread.gmane.org/gmane.comp.programming.tools.cmake.devel/6613/focus=6702

Does anyone know what version of clang the --sysroot flag was introduced or 
if it was 'a really long time ago'?

I tried to figure out how to cross compile something with clang.

 http://clang.llvm.org/UniversalDriver.html

says that clang is inherently a cross compiler, so I guess that means I 
don't need a separate binary, as I do with g++ based cross compilers?

I tried using clang with the arguments in this page:

 http://wiki.osdev.org/LLVM_Cross-Compiler

without success:

stephen at hal:~/tmp$ cat main.c 

int main(int argc, char **argv)
{
  return 0;
}


stephen at hal:~/tmp$ clang -target armv7--eabi -mcpu=cortex-a9 main.c 
gcc: warning: ‘-mcpu=’ is deprecated; use ‘-mtune=’ or ‘-march=’ instead
/tmp/main-EitGh6.s: Assembler messages:
/tmp/main-EitGh6.s:1: Error: unknown pseudo-op: `.syntax'
/tmp/main-EitGh6.s:2: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:3: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:4: Error: unknown pseudo-op: `.fpu'
/tmp/main-EitGh6.s:5: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:6: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:7: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:8: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:9: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:10: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:11: Error: unknown pseudo-op: `.eabi_attribute'
/tmp/main-EitGh6.s:18: Error: too many memory references for `sub'
/tmp/main-EitGh6.s:19: Error: expecting operand after ','; got nothing
/tmp/main-EitGh6.s:20: Error: invalid char '[' beginning operand 2 `[sp'
/tmp/main-EitGh6.s:21: Error: invalid char '[' beginning operand 2 `[sp'
/tmp/main-EitGh6.s:22: Error: invalid char '[' beginning operand 2 `[sp'
/tmp/main-EitGh6.s:23: Error: invalid char '[' beginning operand 2 `[sp'
/tmp/main-EitGh6.s:24: Error: too many memory references for `mov'
/tmp/main-EitGh6.s:25: Error: invalid char '[' beginning operand 2 `[sp]'
/tmp/main-EitGh6.s:26: Error: too many memory references for `add'                                                                                                                                                 
/tmp/main-EitGh6.s:27: Error: no such instruction: `bx lr'                                                                                                                                                         
clang: error: assembler (via gcc) command failed with exit code 1 (use -v to 
see invocation)                                                                                                                       
                                                                                                                                                                                                                   
stephen at hal:~/tmp$ clang --version                                                                                                                                                                                 
Ubuntu clang version 3.2-1~exp5ubuntu2 (tags/RELEASE_32/final) (based on 
LLVM 3.2)                                                                                                                                 
Target: x86_64-pc-linux-gnu                                                                                                                                                                                        
Thread model: posix 

Am I missing something?

Thanks,

Steve.