[AArch64] Unroll and use TBL in ScaleRowDown34_NEON

ST3 is known to be slow on a number of modern micro-architectures. By
unrolling the code we are able to use TBL to shuffle elements into the
correct indices without needing to use LD4 and ST3, giving a good
improvement in performance across the board.

Reduction in runtimes observed compared to the existing Neon
implementation:

 Cortex-A55: -14.4%
Cortex-A510: -66.0%
Cortex-A520: -50.8%
 Cortex-A76: -60.5%
Cortex-A715: -63.9%
Cortex-A720: -64.2%
  Cortex-X1: -74.3%
  Cortex-X2: -75.4%
  Cortex-X3: -75.5%
  Cortex-X4: -48.1%

Bug: b/42280945
Change-Id: Ia1efb03af2d6ec00bc5a4b72168963fede9f0c83
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/5785971
Reviewed-by: Frank Barchard <fbarchard@chromium.org>
2 files changed
tree: fd7ecddc12795171aaa2ff817161be0124ec6f1f
  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.