mirror of
https://forge.sourceware.org/marek/gcc.git
synced 2026-02-22 03:47:02 -05:00
ead579d3c5
Implements `submdspan` and `submdspan_mapping` for layout_left as described in P3663 (Future proofing mdspan). When computing the offset of the submdspan, one must check that the lower bound of the slice range isn't out-of-range. There's a few cases when the lower bound is never out-of-range: - full_extent and exts.extent(k) != 0, - collapsing slice types. If those conditions are known to hold, no checks are generated. Similarly, if all slices are full_extent, there's no need to call mapping(0,...,0) for standardized mappings. The implementation prepares to use the symmetry between layout_left and layout_right and introduces concepts like a "layout side", i.e. left, right or unknown/strided. The tests use an iterator to replace nested for-loops. Which also makes it easier to write the core test logic in a rank-independent manner. PR libstdc++/110352 libstdc++-v3/ChangeLog: * include/std/mdspan (__mdspan::__is_submdspan_mapping_result) (__mdspan::__submdspan_mapping_result, __mdspan::__fwd_prod) (__mdspan::__acceptable_slice_type, __mdspan::__slice_begin) (__mdspan::__suboffset, __mdspan::_LayoutSide, __mdspan::__mapping_side) (__mdspan::_StridesTrait, __mdspan::__substrides_generic) (__mdspan::__substrides_standardized, __mdspan::__substrides) (__mdspan::__is_unit_stride_slice, __mdspan::_SliceKind) (__mdspan::__make_slice_kind, __mdspan::__make_slice_kind_array) (__mdspan::__is_block, __mdspan::__padded_block_begin_generic) (__mdspan::__padded_block_begin, __mpdspan::_SubMdspanMapping) (__mdspan::__submdspan_mapping_impl): Define. (__mdspan::__dynamic_slice_extent, __mdspan::__static_slice_extent) (__mdspan::__subextents): Move earlier in the file. (layout_left::mapping::submdspan_mapping, __mdspan::__sliceable_mapping) (__mdspan::__submapping, submdspan): Define. * src/c++23/std.cc.in: Add submdspan. * testsuite/23_containers/mdspan/submdspan/generic.cc: New test. * testsuite/23_containers/mdspan/submdspan/selections/left.cc: Instantiate selection tests for layout_left. * testsuite/23_containers/mdspan/submdspan/selections/testcases.h: Generic tests different selections. * testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc: New test. * testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc: New test. Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com> Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>