Fix inverted NDEBUG logic in mdspan precondition checking - #464
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MDSPAN_IMPL_CHECK_PRECONDITION defaulted to enabled when NDEBUG was defined (Release builds) and disabled when NDEBUG was undefined (Debug builds) -- backwards from the usual assert()/NDEBUG convention. As a result, every View/DynRankView mapping construction paid for O(rank) overflow-checked multiplications in optimized builds, causing a large performance regression relative to the legacy View implementation (observed ~20x slower DynRankView construction in a Release build). Swap the branches so precondition checks are enabled for debug builds and disabled for release builds, matching normal convention. Signed-off-by: Roger Pawlowski <rppawlo@sandia.gov> Assisted-by: Claude
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MDSPAN_IMPL_CHECK_PRECONDITION defaulted to enabled when NDEBUG was defined (Release builds) and disabled when NDEBUG was undefined (Debug builds) -- backwards from the usual assert()/NDEBUG convention. As a result, every View/DynRankView mapping construction paid for O(rank) overflow-checked multiplications in optimized builds, causing a large performance regression relative to the legacy View implementation (observed ~20x slower DynRankView construction in a Release build).
Swap the branches so precondition checks are enabled for debug builds and disabled for release builds, matching normal convention.
Details are in
kokkos/kokkos#9368
kokkos/kokkos#9374