normL1 does not give consistent results with different compilers and optimization levels #27080
Description
System Information
Latest 5.x.
Detailed description
I was working on normL1 on 32s input data and found that the existing kernel
opencv/modules/core/include/opencv2/core/base.hpp
Lines 367 to 374 in 7635d9a
, which calls cv_absdiff<int>
, cannot produce consistent results with different compilers and optimization levels.
Reproducer is attached below. Here is the summary with the reproducer.
- cv_absdiff:
| Compiler | -O0 | -O3 |
|---|---|---|
| x64, gcc-12.3.0 | n=11074883890230.000000 | n=6878700842038.000000 |
| arm64, apple clang 16.0.0 | n=11074883890230.000000 | n=11073593898738.000000 |
| risc-v, gcc-14.2.0 | n=11074883890230.000000 | n=11074883890230.000000 |
| risc-v, clang-18.0.0 | n=11074883890230.000000 | n=8302375796980.000000 |
- A improved version in demo:
| Compiler | -O0 | -O3 |
|---|---|---|
| x64, gcc-12.3.0 | n=11074883890230.000000 | n=11074883890230.000000 |
| arm64, apple clang 16.0.0 | n=11074883890230.000000 | n=11074883890230.000000 |
| risc-v, gcc-14.2.0 | n=11074883890230.000000 | n=11074883890230.000000 |
| risc-v, clang-18.0.0 | n=11074883890230.000000 | n=11074883890230.000000 |
Steps to reproduce
Download
, extract, compile and run with the following commands.
g++ -std=c++11 main.cpp
./a.out
g++ -std=c++11 -O3 main.cpp
./a.out
Note that input data is collected from opencv performance tests.
Issue submission checklist
- I report the issue, it's not a question
- I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution
- I updated to the latest OpenCV version and the issue is still there
- There is reproducer code and related data files (videos, images, onnx, etc)