On Tue, 29 Apr 2025 at 13:56, Luc Grosheintz <luc.groshei...@gmail.com> wrote: > > Implements the parts of layout_left that don't depend on any of the > other layouts. > > libstdc++/ChangeLog:
N.B. this needs to be libstdc++-v3/Changelog with "-v3", or the git hooks will reject it. Similarly in patches 6/10 to 10/10. There's a gcc-verify alias you can use to check the commit messages against the hooks, see https://gcc.gnu.org/gitwrite.html#customization# I can fix these (and the other minor review comments) locally before pushing. > > * include/std/mdspan (layout_left): New class. > > Signed-off-by: Luc Grosheintz <luc.groshei...@gmail.com> > --- > libstdc++-v3/include/std/mdspan | 179 ++++++++++++++++++++++++++++++++ > 1 file changed, 179 insertions(+) > > diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan > index 39ced1d6301..e05048a5b93 100644 > --- a/libstdc++-v3/include/std/mdspan > +++ b/libstdc++-v3/include/std/mdspan > @@ -286,6 +286,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > namespace __mdspan > { > + template<typename _Extents> > + constexpr typename _Extents::index_type > + __fwd_prod(const _Extents& __exts, size_t __r) noexcept > + { > + typename _Extents::index_type __fwd = 1; > + for(size_t __i = 0; __i < __r; ++__i) > + __fwd *= __exts.extent(__i); > + return __fwd; > + } > + > + template<typename _Extents> > + constexpr typename _Extents::index_type > + __rev_prod(const _Extents& __exts, size_t __r) noexcept > + { > + typename _Extents::index_type __rev = 1; > + for(size_t __i = __r + 1; __i < __exts.rank(); ++__i) > + __rev *= __exts.extent(__i); > + return __rev; > + } > + > template<typename _IndexType, size_t... _Counts> > auto __build_dextents_type(integer_sequence<size_t, _Counts...>) > -> extents<_IndexType, ((void) _Counts, dynamic_extent)...>; > @@ -304,6 +324,165 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > explicit extents(_Integrals...) -> > extents<size_t, __mdspan::__dynamic_extent<_Integrals>()...>; > > + struct layout_left > + { > + template<typename _Extents> > + class mapping; > + }; > + > + namespace __mdspan > + { > + template<typename _Tp> > + constexpr bool __is_extents = false; > + > + template<typename _IndexType, size_t... _Extents> > + constexpr bool __is_extents<extents<_IndexType, _Extents...>> = true; > + > + template<size_t _Count> > + struct _LinearIndexLeft > + { > + template<typename _Extents, typename... _Indices> > + static constexpr typename _Extents::index_type > + _S_value(const _Extents& __exts, typename _Extents::index_type __idx, > + _Indices... __indices) noexcept > + { > + return __idx + __exts.extent(_Count) > + * _LinearIndexLeft<_Count + 1>::_S_value(__exts, __indices...); > + } > + > + template<typename _Extents> > + static constexpr typename _Extents::index_type > + _S_value(const _Extents&) noexcept > + { return 0; } > + }; > + > + template<typename _Extents, typename... _Indices> > + constexpr typename _Extents::index_type > + __linear_index_left(const _Extents& __exts, _Indices... __indices) > + { > + return _LinearIndexLeft<0>::_S_value(__exts, __indices...); > + } > + > + template<typename _IndexType, typename _Tp, size_t _Nm> > + consteval bool > + __is_representable_product(array<_Tp, _Nm> __factors) > + { > + size_t __rest = numeric_limits<_IndexType>::max(); > + for(size_t __i = 0; __i < _Nm; ++__i) > + { > + if (__factors[__i] == 0) > + return true; > + __rest /= _IndexType(__factors[__i]); > + } > + return __rest > 0; > + } > + > + template<typename _Extents> > + consteval array<typename _Extents::index_type, _Extents::rank()> > + __static_extents_array() > + { > + array<typename _Extents::index_type, _Extents::rank()> __exts; > + for(size_t __i = 0; __i < _Extents::rank(); ++__i) > + __exts[__i] = _Extents::static_extent(__i); > + return __exts; > + } > + > + template<typename _Extents, typename _IndexType> > + concept __representable_size = _Extents::rank_dynamic() != 0 > + || __is_representable_product<_IndexType>( > + __static_extents_array<_Extents>()); > + > + template<typename _Extents> > + concept __layout_extent = __representable_size< > + _Extents, typename _Extents::index_type>; > + } > + > + template<typename _Extents> > + class layout_left::mapping > + { > + static_assert(__mdspan::__layout_extent<_Extents>, > + "The size of extents_type is not representable as index_type."); > + public: > + using extents_type = _Extents; > + using index_type = typename extents_type::index_type; > + using size_type = typename extents_type::size_type; > + using rank_type = typename extents_type::rank_type; > + using layout_type = layout_left; > + > + constexpr > + mapping() noexcept = default; > + > + constexpr > + mapping(const mapping&) noexcept = default; > + > + constexpr > + mapping(const extents_type& __extents) noexcept > + : _M_extents(__extents) > + { } > + > + template<typename _OExtents> > + requires (is_constructible_v<extents_type, _OExtents>) > + constexpr explicit(!is_convertible_v<_OExtents, extents_type>) > + mapping(const mapping<_OExtents>& __other) noexcept > + : _M_extents(__other.extents()) > + { } > + > + constexpr mapping& > + operator=(const mapping&) noexcept = default; > + > + constexpr const extents_type& > + extents() const noexcept { return _M_extents; } > + > + constexpr index_type > + required_span_size() const noexcept > + { return __mdspan::__fwd_prod(_M_extents, _M_extents.rank()); } > + > + template<__mdspan::__valid_index_type<index_type>... _Indices> > + requires (sizeof...(_Indices) == extents_type::rank()) > + constexpr index_type > + operator()(_Indices... __indices) const noexcept > + { > + return __mdspan::__linear_index_left( > + _M_extents, static_cast<index_type>(__indices)...); > + } > + > + static constexpr bool > + is_always_unique() noexcept { return true; } > + > + static constexpr bool > + is_always_exhaustive() noexcept { return true; } > + > + static constexpr bool > + is_always_strided() noexcept { return true; } > + > + static constexpr bool > + is_unique() noexcept { return true; } > + > + static constexpr bool > + is_exhaustive() noexcept { return true; } > + > + static constexpr bool > + is_strided() noexcept { return true; } > + > + constexpr index_type > + stride(rank_type __i) const noexcept > + requires (extents_type::rank() > 0) > + { > + __glibcxx_assert(__i < extents_type::rank()); > + return __mdspan::__fwd_prod(_M_extents, __i); > + } > + > + template<typename _OExtents> > + requires (extents_type::rank() == _OExtents::rank()) > + friend constexpr bool > + operator==(const mapping& __self, const mapping<_OExtents>& __other) > + noexcept > + { return __self.extents() == __other.extents(); } > + > + private: > + [[no_unique_address]] extents_type _M_extents; > + }; > + > _GLIBCXX_END_NAMESPACE_VERSION > } > #endif > -- > 2.49.0 >
