[mathcore] Work around libstdc++ <experimental/simd> AVX-512 bug#22437
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Test Results 21 files 21 suites 3d 7h 25m 7s ⏱️ For more details on these failures, see this check. Results for commit 76f8a02. ♻️ This comment has been updated with latest results. |
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.
dpiparo
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Jun 2, 2026
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/backport to 6.40 |
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Preparing to backport PR #22437 to branch 6.40 requested by guitargeek |
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This PR has been backported to branch 6.40: #22456 |
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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 requiringlong longandlongto 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.htosimd_abi::__avx(which corresponds to AVX-256). ABI stays consistent across all translation units and interpreted contexts, no-mno-avx512fis needed, and the rest of ROOT keeps native AVX-512 codegen.Closes #22370.