[MPlayer-dev-eng] [PATCH] x86_64 mmx/sse/3dnow optimisation support

[Reimar Döffinger]

Hi,

>>>>-#ifdef ARCH_X86
>>>>+#if defined(ARCH_X86) || defined(ARCH_X86_64)
>>>
>>>There are lots of these. From what I know, I find it incorrect to
>>>define X86_64 as a separate architecture, those are "only" 64bit
>>>extensions after all...
>>>Think you would need to change less if you put the x86_64 case to the
>>>x86 case, and just adding something like:
>>>
>>>if ("$host_arch" == x86_64); then
>>>_def_arch += "#define ARCH_X86_64 1\n$_def_arch"
>>>fi
>>>
>>>so that both ARCH_X86 and ARCH_X86_64 are defined then.
>>
>>Sure I could do this. But I thought It would be clearer to have
>>distinct ARCH.
>>I personnaly prefer considering x86_64 as a really different arch
>>(having 64 bits addressing instead of 32 bits, is a big enough
>>difference IMHO).
>>Any other one with an opinion about diffining or not ARCH_X86 for
>>x86_64 traget ?
> 
> yes, x86_64 is not a superset of x86 (there are some tiny things missing, and 
> theres no binary compatibility), so its no extension and ARCH_X86 shoudl IMO 
> not be defined on ARCH_X86_64

I never cared to really check, but I thought AMD64 can execute any 32 
bit code. In how far that is true when in 64 bit mode I have to admit I 
don't know...

> another way to justify this is that ARCH_X86 code will often not compile or 
> work on X86_64 without a few (tiny) modifications

from what I can see the code will neverthless be 90% the same. My main 
point was actually that it would render quite a part of the 
modifications unneccessary. So whether it is a different architecture or 
not, does it make sense to define it as such?

Greetings,
Reimar Döffinger