Re: Why is __i686 undefined for x86_64 -m32 (in mainline)

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, Mar 16, 2010 at 1:13 PM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
> On 03/16/2010 08:53 PM, H.J. Lu wrote:
>> The question is what processor macros should "-march=x86-64" define. There
>> is
>>
>> ? ? ? {"x86-64", PROCESSOR_K8, CPU_K8,
>> ? ? ? ? PTA_64BIT | PTA_MMX | PTA_SSE | PTA_SSE2 | PTA_NO_SAHF},
>>
>> For -march=x86-64, __k8 is defined. ?However, real K8 supports:
>>
>> ? ? ? {"k8", PROCESSOR_K8, CPU_K8,
>> ? ? ? ? PTA_64BIT | PTA_MMX | PTA_3DNOW | PTA_3DNOW_A | PTA_SSE
>> ? ? ? ? | PTA_SSE2 | PTA_NO_SAHF},
>>
>> It isn't an issue in i386.c since PROCESSOR_K8 isn't used to check
>> ISAs. But using __k8 to check ISAs is a problem.
>>
> I'm not sure to follow the gory details of your reply, but to me, it
> seems *really* strange that *now*, on x86_64, "-m32" is not the same as
> "-m32 -march=-i686" as far as __i686 is concerned...
>

We never defined __i686 for -m32 by default on x86_64. Here is
a patch to define __i686 for -m32 if the processor supports it.

-- 
H.J.

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