[FFmpeg-devel] [PATCH] avcodec/h264: mmxext 4:2:2 chroma deblock/loop filter

[James Almer]

On 1/15/2016 5:00 PM, James Darnley wrote:
> On 2016-01-15 03:55, James Almer wrote:
>> On 1/14/2016 11:05 PM, James Darnley wrote:
>>> diff --git a/libavcodec/x86/h264_deblock.asm b/libavcodec/x86/h264_deblock.asm
>>> index 5151f3c..20f0814 100644
>>> --- a/libavcodec/x86/h264_deblock.asm
>>> +++ b/libavcodec/x86/h264_deblock.asm
>>> @@ -864,7 +864,47 @@ ff_chroma_inter_body_mmxext:
>>>      DEBLOCK_P0_Q0
>>>      ret
>>>  
>>> +cglobal h264_h_loop_filter_chroma422_8, 5, 7, 8, mmsize + ARCH_X86_64*2*mmsize
>>
>> This will not work with x86_32 compilers that don't have aligned stack (Like msvc)
>> because r6 is needed to store the stack pointer.
> 
> The other chroma deblock function I borrowed most of this from doesn't
> appear to use any guard against that (see a few lines above where my
> patch starts).  Neither in assembly or in the init function.

That's because the other chroma function doesn't allocate stack using x86inc magic.
On x86_32 it uses r#m only and on x86_64 it handles the stack pointer by itself.

> 
>>> +    %if ARCH_X86_64
>>> +        %define buf0 [rsp+16]
>>> +        %define buf1 [rsp+8]
>>> +    %else
>>> +        %define buf0 r0m
>>> +        %define buf1 r2m
>>> +    %endif
>>> +
>>> +    movd m6, [r4]
>>
>> Since r4 is free after this point, you can use it instead of r6 to easily solve
>> the above.
> 
> Noted.
> 
> 
> 
> 
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