Support for cc -m32

[Warner Losh]

On 11/17/2010 15:18, John Baldwin wrote:
> On Wednesday, November 17, 2010 2:57:51 pm Tijl Coosemans wrote:
>> cc-m32-3.diff:
>>      Modify amd64 headers to include i386 headers when compiling 32 bit code.
>>
>>      All amd64 headers follow the following format:
>>
>>      #ifndef _AMD64_HEADER_H_
>>      #define _AMD64_HEADER_H_
>>
>>      #ifdef __i386__
>>      #include<i386/header.h>
>>      #else
>>
>>      /* Amd64 declarations go here. */
>>
>>      #endif /* __i386__ */
>>      #endif /* !_AMD64_HEADER_H_ */
> I find this to be really ugly, and error prone (since it is a manual process).
> I'd prefer something that autogenerated headers in /usr/include/machine that
> #include the appropriate version similar to what Warner suggested.
>
> However, one issue with that approach (and this one) are headers that only
> exist for one platform.  The end result would be that that header would now
> exist for both platforms (in that if you do 'if [ -r
> /usr/include/machine/foo.h ]' it will be true).  We can make it #error or
> otherwise fail (by including a non-existing file for example), but if there
> was some way to have cc -m32 "magically" substitute "i386/" for "machine",
> that is what I would most prefer.  (This has problems too in that #include
> <machine/foo.h>  would work with -m32 even though /usr/include/machine/foo.h
> doesn't exist, but /usr/include/i386/foo.h does.
"magically" converting machine -> i386 requires cpp hacking.

However, the if [] test is beyond the scope of the API that we support.  
Scripts that use -m32 will have to cope with other issues.

We could 'solve' this by having an /usr/include32, but even that still 
isn't complete.

I contend that the least bad solution is to auto generate the machine 
directory from the sys/{i386,amd64}/include.  If we do that, we could 
implement -m64 on i386 too, but that needs a lot more infrastructure.

Warner