libyuv/docs/environment_variables.md
Frank Barchard 2b4453d46f Deprecate MIPS and MSA support.
- Remove *_msa.cc source files
- Update build files
- Update header references, planar ifdefs for row functions
- Update documentation on supported platforms
- Version bumped to 1921
- clang-format applied

Bug: 434383432
Change-Id: I072d6aac4956f0ed668e64614ac8557612171f76
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/7045953
Reviewed-by: Justin Green <greenjustin@google.com>
2025-10-16 12:20:40 -07:00

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Markdown

# Introduction
For test purposes, environment variables can be set to control libyuv behavior. These should only be used for testing, to narrow down bugs or to test performance.
# CPU
By default the cpu is detected and the most advanced form of SIMD is used. But you can disable instruction sets selectively, or completely, falling back on C code. Set the variable to 1 to disable the specified instruction set.
## All CPUs
LIBYUV_DISABLE_ASM
## Intel CPUs
LIBYUV_DISABLE_X86
LIBYUV_DISABLE_SSE2
LIBYUV_DISABLE_SSSE3
LIBYUV_DISABLE_SSE41
LIBYUV_DISABLE_SSE42
LIBYUV_DISABLE_AVX
LIBYUV_DISABLE_AVX2
LIBYUV_DISABLE_ERMS
LIBYUV_DISABLE_FMA3
LIBYUV_DISABLE_F16C
LIBYUV_DISABLE_AVX512BW
LIBYUV_DISABLE_AVX512VL
LIBYUV_DISABLE_AVX512VNNI
LIBYUV_DISABLE_AVX512VBMI
LIBYUV_DISABLE_AVX512VBMI2
LIBYUV_DISABLE_AVX512VBITALG
LIBYUV_DISABLE_AVX10
LIBYUV_DISABLE_AVX10_2
LIBYUV_DISABLE_AVXVNNI
LIBYUV_DISABLE_AVXVNNIINT8
LIBYUV_DISABLE_AMXINT8
## Arm CPUs
LIBYUV_DISABLE_NEON
LIBYUV_DISABLE_NEON_DOTPROD
LIBYUV_DISABLE_NEON_I8MM
LIBYUV_DISABLE_SVE
LIBYUV_DISABLE_SVE2
LIBYUV_DISABLE_SME
## LOONGARCH CPUs
LIBYUV_DISABLE_LSX
LIBYUV_DISABLE_LASX
## RISCV CPUs
LIBYUV_DISABLE_RVV
# Test Width/Height/Repeat
The unittests default to a small image (128x72) to run fast. This can be set by environment variable to test a specific resolutions.
You can also repeat the test a specified number of iterations, allowing benchmarking and profiling.
set LIBYUV_WIDTH=1280
set LIBYUV_HEIGHT=720
set LIBYUV_REPEAT=999
set LIBYUV_FLAGS=-1
set LIBYUV_CPU_INFO=-1