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ermig1979 / Simd

C++ image processing and machine learning library with using of SIMD: SSE, AVX, AVX-512, AMX for x86/x64, VMX(Altivec) and VSX(Power7) for PowerPC, NEON for ARM.
http://ermig1979.github.io/Simd
MIT License
2.03k stars 406 forks source link

Random segfault issue, possibly in SimdAvx2Interleave #204

Closed s-trinh closed 2 years ago

s-trinh commented 2 years ago

Hi,

We are experiencing some weird random segfault issue. Unfortunately, this is hard to reproduce.

See this post https://github.com/lagadic/visp/issues/1042 for a possible stacktrace. The input data is an array of height=1, width=32, and uchar BGRA data. Function call to Simdlib is Avx2::InterleaveBgra().

I was not able to get a correct stacktrace on my side, but you can find some additional logs here:

About the compiler flags: https://github.com/s-trinh/visp/blob/00709310e5b76b1d0a1011597fd33cdde4c2b1dc/3rdparty/simdlib/CMakeLists.txt

And we are not using aligned vectors.

ermig1979 commented 2 years ago

Thank you for bug report! The bug is caused by the trying of aligned reading of unaligned memory. The alignment checking of input array with alpha channel was missed for SSE4.1, AVX2 and AVX-512BW optimizations of function InterleaveBgra. The error was fixed.

s-trinh commented 2 years ago

Thanks :+1: