Hi,

On Sat, Nov 12, 2011 at 2:18 PM, Martin Storsjö <[email protected]> wrote:
> On Fri, 11 Nov 2011, Ronald S. Bultje wrote:
>
>> Hi,
>>
>> On Fri, Nov 11, 2011 at 3:27 PM, Martin Storsjö <[email protected]> wrote:
>>>
>>> On Fri, 11 Nov 2011, Ronald S. Bultje wrote:
>>>
>>>> As said, this is for the case where we read planar YUV, then
>>>> SwsContext->convertData[] is not used, instead the planar pointer is
>>>> used directly without any conversion. This is used-provided and may
>>>> thus be unaligned (we currently make no alignment requirements).
>>>
>>> Hmm, since this commit last Saturday
>>>
>>>> Commit: c435653627529e22d74214c2266f571255e404d6
>>>>
>>>> Author:    Ronald S. Bultje <[email protected]>
>>>> Committer: Ronald S. Bultje <[email protected]>
>>>> Date:      Sat Nov  5 17:31:40 2011 -0700
>>>>
>>>> swscale: write yuv2plane1 MMX/SSE2/SSE4/AVX functions.
>>>
>>> code that passes unaligned buffers to swscale started crashing. Do I read
>>> the the comment above correctly, this is a bug - calling code shouldn't
>>> need
>>> to provide any particular alignment?
>>
>> Yeah, if you tell me which instruction fails I'll fix it, or a
>> backtrace + disass is fine also.
>
> On one machine, I get this backtrace + disassembly:
>
> #0  ff_yuv2plane1_8_avx.loop_a () at libswscale/x86/scale.asm:804
> #1  0x00000000007acdd1 in swScale (c=0xed3300, src=0x7fffffffe4e0,
>    srcStride=0x7fffffffe500, srcSliceY=0, srcSliceH=<value optimized out>,
>    dst=0x7fffffffe4c0, dstStride=0x7fffffffe510) at
> libswscale/swscale.c:2510
> #2  0x0000000000792d5d in sws_scale (c=0xed3300, srcSlice=0xec5c00,
>    srcStride=<value optimized out>, srcSliceY=0, srcSliceH=19,
>    dst=<value optimized out>, dstStride=0xecb240)
>    at libswscale/swscale_unscaled.c:913
>
> Dump of assembler code for function ff_yuv2plane1_8_avx.loop_a:
>   0x00000000007c264e <+0>:     vpaddsw (%rdi,%rdx,2),%xmm2,%xmm0
>   0x00000000007c2653 <+5>:     vpaddsw 0x10(%rdi,%rdx,2),%xmm3,%xmm1
>   0x00000000007c2659 <+11>:    psraw  $0x7,%xmm0
>   0x00000000007c265e <+16>:    psraw  $0x7,%xmm1
>   0x00000000007c2663 <+21>:    packuswb %xmm1,%xmm0
> => 0x00000000007c2667 <+25>:    movdqa %xmm0,(%rsi,%rdx,1)
>   0x00000000007c266c <+30>:    add    $0x10,%rdx
>   0x00000000007c2670 <+34>:    jl     0x7c264e <ff_yuv2plane1_8_avx.loop_a>
>   0x00000000007c2672 <+36>:    repz retq
> End of assembler dump.

info all-registers? I wonder what rsi/rdx are here.

Ronald
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