SIMD: Add where and ternary operator#5095
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ax3l wants to merge 6 commits intoAMReX-Codes:developmentfrom
Open
SIMD: Add where and ternary operator#5095ax3l wants to merge 6 commits intoAMReX-Codes:developmentfrom
ax3l wants to merge 6 commits intoAMReX-Codes:developmentfrom
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To write more portable code, add a scalar fallback for `std::simd::where` for non-SIMD code. Expose both as `amrex::simd::stdx`. Add Doxygen string to existing scalar `amrex::simd::std::any_of` fallback. Add a new implementation for a portable tenary operator, inspired by Kokkos https://kokkos.org/kokkos-core-wiki/ProgrammingGuide/SIMD.html#ternary-operator as `amrex::simd::conditional`. Demonstrate usage in doc strings and new test cases.
This is the likely ISO C++26 name.
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Will be there eventually with C++26
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Consistently: Real -> ParticleReal
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@WeiqunZhang oh dang, I force pushed away your last commit. Sorry for this! If you still have it locally feel free to push. Just cleaning up santitizer warnings rn |
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No problems. Very simple change. |
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And your change was actually I wanted to do. But I was not 100 percent sure. So I did the nolint way. If your change works, it's better than nolint. |
WeiqunZhang
approved these changes
Mar 2, 2026
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Summary
To write more portable code, add a scalar fallback for
std::simd::wherefor non-SIMD code. Expose both asamrex::simd::stdx.Add Doxygen string to existing scalar
amrex::simd::std::any_offallback.Add a new implementation for a portable ternary operator, inspired by Kokkos condition as
amrex::simd::stdx::select. (We call itselectbecause that is the likely ISO C++26 name: https://en.cppreference.com/w/cpp/numeric/simd.html )Demonstrate usage in doc strings and new test cases.
Additional background
These are patterns I commonly see needed in BLAST-ImpactX, e.g. here.
This will help to write more complex SIMD code like #4649 in a cleaner way, too.
Follow up to #4520 #4938 #4924
Checklist
The proposed changes: