CMake fails to detect NEON, etc. support on ARM processor #18244
Description
System information (version)
- OpenCV => 4.4.0
- Operating System / Platform => Ubuntu 18.04 / armv7l
- Compiler => gcc 7.5.0
Detailed description
CMake does not detect that my ARM CPU supports NEON instructions or other features. If I compile the example source code from cmake/checks/cpu_neon.cpp with -mfpu=neon, it builds and runs successfully.
-- Performing Test HAVE_CXX_MFPU_VFPV3
-- Performing Test HAVE_CXX_MFPU_VFPV3 - Success
-- Performing Test HAVE_CPU_NEON_SUPPORT (check file: cmake/checks/cpu_neon.cpp)
-- Performing Test HAVE_CPU_NEON_SUPPORT - Failed
-- Performing Test HAVE_CXX_MFPU_NEON (check file: cmake/checks/cpu_neon.cpp)
-- Performing Test HAVE_CXX_MFPU_NEON - Success
-- Performing Test HAVE_CPU_FP16_SUPPORT (check file: cmake/checks/cpu_fp16.cpp)
-- Performing Test HAVE_CPU_FP16_SUPPORT - Failed
-- Performing Test HAVE_CXX_MFPU_NEON_FP16_MFP16_FORMAT_IEEE (check file: cmake/checks/cpu_fp16.cpp)
-- Performing Test HAVE_CXX_MFPU_NEON_FP16_MFP16_FORMAT_IEEE - Success
-- Performing Test HAVE_CPU_BASELINE_FLAGS
-- Performing Test HAVE_CPU_BASELINE_FLAGS - Success
...
-- CPU/HW features:
-- Baseline:
-- requested: DETECT
-- disabled: VFPV3 NEON
Steps to reproduce
cmake .. \
-DCMAKE_BUILD_TYPE=RelWithDebugInfo \
-DCMAKE_INSTALL_PREFIX="$(cd root; pwd)" \
-DOPENCV_EXTRA_MODULES_PATH=../opencv_contrib/modules \
-DBUILD_JAVA=OFF \
-DBUILD_TESTS=OFF \
-DBUILD_PERF_TESTS=OFF \
-DBUILD_opencv_java=OFF \
-DBUILD_opencv_python2=OFF \
-DBUILD_opencv_python3=ON \
-DPYTHON_DEFAULT_EXECUTABLE="$(command -v python3.7)" \
-DPYTHON3_INCLUDE_DIR="$PYTHON_INCLUDE" \
-DPYTHON3_LIBRARY="$PYTHON_LIBRARY" \
-DPYTHON3_EXECUTABLE="$(command -v python3.7)" \
-DPYTHON3_NUMPY_INCLUDE_DIRS="$NUMPY_INCLUDE" \
-DPYTHON3_PACKAGES_PATH="$PYTHON_PACKAGES" \
-DOPENCV_SKIP_PYTHON_LOADER=ON
Issue submission checklist
- I report the issue, it's not a question
- I checked the problem with documentation, FAQ, open issues,
answers.opencv.org, Stack Overflow, etc and have not found solution - I updated to latest OpenCV version and the issue is still there
- There is reproducer code and related data files: videos, images, onnx, etc