[FFmpeg-devel] libavcodec/blockdsp : add AVX version

[James Almer]

On 10/1/2017 8:46 PM, Martin Vignali wrote:
> Hello,
> 
> After taking a look on blockdsp
> ./tests/checkasm/checkasm --test=blockdsp --bench
> 
> the result of clear_blocks is slower on my computer than the C version
> except if we add an avx version
> 
> In attach patch to add avx version
> for clear_block and clear_blocks
> 
> result : (Kaby Lake, Mac os 10.12)
> checkasm: all 6 tests passed
> blockdsp.clear_block_c: 15.9
> blockdsp.clear_block_mmx: 16.4
> blockdsp.clear_block_sse: 7.4
> blockdsp.clear_block_avx: 3.9
> 
> blockdsp.clear_blocks_c: 29.6
> blockdsp.clear_blocks_mmx: 99.1
> blockdsp.clear_blocks_sse: 48.4
> blockdsp.clear_blocks_avx: 24.4

On a Haswell Windows x64 I get

benchmarking with native FFmpeg timers
blockdsp.clear_block_c: 28.0
blockdsp.clear_block_mmx: 14.0
blockdsp.clear_block_sse: 6.0
blockdsp.clear_block_avx: 4.0
blockdsp.clear_blocks_c: 77.0
blockdsp.clear_blocks_mmx: 94.0
blockdsp.clear_blocks_sse: 46.0
blockdsp.clear_blocks_avx: 23.0

I used GCC 7.2. clear_blocks_mmx is slower than c for me as well, but
not the rest.
Your compiler seems to have done a much better job than mine. Is it
Clang? Does it somehow have vectorization enabled perhaps? Because
that's not supposed to happen.

> 
> I also modify several decoder/encoder, in order to fix the DECLARE_ALIGNED
> from 16 to 32
> 
> I run make fate SAMPLES=fate-suite/
> i have several errors, but after a check, these errors
> doesn't seems to be related to this patch

Make sure to clean your build folder if you recently pulled new commits
from the git repository. Reconfigure if necessary.

> 
> Martin
> 
> 
> 
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