[LLVMdev] linux mixed 32/64 systems

[Nick Lewycky]

Nathan Keynes wrote:
> 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])

Fantastic, thank you! This is exactly the sort of thing I was looking for!

I've applied this, basically verbatim, to LLVM's configure system in r66765.

Nick