[Pixman] Building as 64-Bit (i.e. dropping the use of USE_X86_MMX )

[Dave Yeo]

On 09/14/20 01:09 AM, John Emmas wrote:
> On 13/09/2020 12:12, John Emmas wrote:
>>
>> Understandably, USE_X86_MMX doesn't work for a 64-bit build.  I
>> assumed there might be a 64-bit alternative (USE_X64_MMX) but that
>> doesn't seem to exist  :-(
>>
>> So do I just need to stop #defining USE_X86_MMX now?  Or is there some
>> alternative #define that I'll need to use instead?
>>
>
> A quick Google search this morning revealed that MMX was later replaced
> by SSE2 (and then SSE3).
>
> So rather than USE_X86_MMX, should I be #defining something like
> USE_SSE2 - or USE_SSE3 maybe ??

IIRC, MMX's registers were aliased with the FPU registers, making mixing 
MMX and floating point inefficient. Seems that SSE2 would be better as 
it can also do floating point depending on the compiler flags.
All 64 bit processors support SSE2 IIRC, while some old ones may not 
support SSE3
Dave