[AArch64] Unroll {I422,I422Alpha}ToARGBRow_SVE2

Since the UV components are duplicated in I422 we end up wasting half of
the vector bandwidth processing the same elements twice. By unrolling
the kernel to process two vectors of Y per iteration we can fill a whole
vector of U/V components.

Rather than packing RGBA components into pairs during the narrowing we
now just narrow into individual component vectors and use ST4B instead.
This by itself is slower on some micro-architectures like Cortex-A510
but the benefit from unrolling significantly outweights this.

            | I422AlphaToARGBRow_SVE2 | I422ToARGBRow_SVE2
Cortex-A510 |                  -46.2% |             -48.8%
Cortex-A720 |                  -20.8% |             -21.0%
  Cortex-X2 |                  -11.3% |              -7.5%
  Cortex-X4 |                  -15.4% |             -15.5%

Bug: libyuv:973
Change-Id: I69389c4279861f7a460ae0c28186f023c728c4e8
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/5725173
Reviewed-by: Frank Barchard <fbarchard@chromium.org>
1 file changed
tree: 693312ce83a0836003e6f60bc2e068281e183581
  1. build_overrides/
  2. docs/
  3. include/
  4. infra/
  5. riscv_script/
  6. source/
  7. tools_libyuv/
  8. unit_test/
  9. util/
  10. .clang-format
  11. .gitignore
  12. .gn
  13. .vpython
  14. .vpython3
  15. Android.bp
  16. Android.mk
  17. AUTHORS
  18. BUILD.gn
  19. CM_linux_packages.cmake
  20. CMakeLists.txt
  21. codereview.settings
  22. DEPS
  23. DIR_METADATA
  24. download_vs_toolchain.py
  25. libyuv.gni
  26. libyuv.gyp
  27. libyuv.gypi
  28. LICENSE
  29. linux.mk
  30. OWNERS
  31. PATENTS
  32. PRESUBMIT.py
  33. public.mk
  34. pylintrc
  35. README.chromium
  36. README.md
  37. winarm.mk
README.md

libyuv is an open source project that includes YUV scaling and conversion functionality.

  • Scale YUV to prepare content for compression, with point, bilinear or box filter.
  • Convert to YUV from webcam formats for compression.
  • Convert to RGB formats for rendering/effects.
  • Rotate by 90/180/270 degrees to adjust for mobile devices in portrait mode.
  • Optimized for SSSE3/AVX2 on x86/x64.
  • Optimized for Neon on Arm.
  • Optimized for MSA on Mips.
  • Optimized for RVV on RISC-V.

Development

See Getting started for instructions on how to get started developing.

You can also browse the docs directory for more documentation.