[6.40] [mathcore] Work around libstdc++ \<experimental/simd>\ AVX-512 bug#22456
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guitargeek merged 1 commit intoJun 2, 2026
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The `libstdc++`'s `_VecBltnBtmsk` (AVX-512 mask) ABI fails to compile with non-GCC front ends (Clang, Intel icpx) due to a static_assert requiring `long long` and `long` to be the same type, reproducible at least with GCC 15 and 16. Detect this in CMake and, when the AVX-512 path is broken but the 256-bit AVX path compiles, pin ROOT's SIMD alias in `Math/Types.h` to `simd_abi::__avx` (which corresponds to AVX-256). ABI stays consistent across all translation units and interpreted contexts, no `-mno-avx512f` is needed, and the rest of ROOT keeps native AVX-512 codegen. Closes root-project#22370. (cherry picked from commit 83dd2e4)
Test Results 22 files 22 suites 3d 9h 56m 8s ⏱️ Results for commit 0b93453. |
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Backport of #22437, requested by @guitargeek.