[LLVMdev] linux mixed 32/64 systems

[Nathan Keynes]

On 10/03/2009, at 1:25 PM, Nick Lewycky wrote:

> Currently the build systems sets ARCH based on the result of 'uname - 
> m'.
> On a mixed 32/64 system (one with a 64-bit kernel and a 32-bit
> userspace) this will result in "x86_64" which is wrong.
>
> We'd like the ARCH variable to represent the userspace we're compiling
> in/for, not what the kernel happens to be.
>
> Does anyone know of a clean way to detect this sort of system  
> configuration?


Cleanest way is probably to explicitly test if __x86_64__ is defined, ie

AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
      [[#ifndef __x86_64__
       error: Not x86-64 even if uname says so!
      #endif
      ]])],
      [ARCH=x86_64],
      [ARCH=i386])

Or in the alternative you can always key off sizeof(void *) == 8.

Cheers,
Nathan