[FFmpeg-devel] Optimize Mpeg4 decoding for loongarch

[Hao Chen]

./ffmpeg -i 8_mpeg4_1080p_24fps_12Mbps.avi -f rawvideo -y /dev/null -an
before:376fps
after :552fps

V2: Revised PATCH 1/3 according to the comments.
V3: Resubmit these patches due to miss PATCH v2 1/3.

[PATCH v3 1/3] avcodec: [loongarch] Optimize hpeldsp with LASX.
[PATCH v3 2/3] avcodec: [loongarch] Optimize idctdstp with LASX.
[PATCH v3 3/3] avcodec: [loongarch] Optimize prefetch with loongarch.