[FFmpeg-devel] [PATCH] x86/vp9dsp: fix clobbering of xmm6 on IDCT sse2 functions

[James Almer]

On 07/02/15 11:05 PM, Ronald S. Bultje wrote:
> Hi,
> 
> On Sat, Feb 7, 2015 at 8:33 PM, James Almer <jamrial at gmail.com> wrote:
> 
>> Signed-off-by: James Almer <jamrial at gmail.com>
>> ---
>>  libavcodec/x86/vp9itxfm.asm | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/libavcodec/x86/vp9itxfm.asm b/libavcodec/x86/vp9itxfm.asm
>> index 64859a0..bfe427f 100644
>> --- a/libavcodec/x86/vp9itxfm.asm
>> +++ b/libavcodec/x86/vp9itxfm.asm
>> @@ -407,6 +407,9 @@ IDCT_4x4_FN ssse3
>>  %macro IADST4_FN 5
>>  INIT_MMX %5
>>  cglobal vp9_%1_%3_4x4_add, 3, 3, 6 + notcpuflag(ssse3), dst, stride,
>> block, eob
>> +%if WIN64 && notcpuflag(ssse3)
>> +WIN64_SPILL_XMM 7
>> +%endif
>>      movdqa            xmm5, [pd_8192]
>>      mova                m0, [blockq+ 0]
>>      mova                m1, [blockq+ 8]
> 
> 
> Ehw... Well... Crap... OK I guess. (Can't think of anything better.)
> 
> Ronald

We could use INIT_XMM and invert every register alias (xmm -> m; m -> mm).
I just didn't go with that (admittedly cleaner and less hacky) solution because it 
was a bigger patch.