Implement submdspan_extents as described in P3663 and adds it to the std
module.
PR libstdc++/110352
libstdc++-v3/ChangeLog:
* include/std/mdspan (submdspan_extents): New function.
* src/c++23/std.cc.in: Add submdspan_extents.
* testsuite/23_containers/mdspan/int_like.h: Add StructuralInt.
* testsuite/23_containers/mdspan/submdspan/submdspan_extents.cc: New
test.
* testsuite/23_containers/mdspan/submdspan/submdspan_extents_neg.cc:
New test.
Signed-off-by: Luc Grosheintz <[email protected]>
---
libstdc++-v3/include/std/mdspan | 103 +++++++++++
libstdc++-v3/src/c++23/std.cc.in | 5 +-
.../testsuite/23_containers/mdspan/int_like.h | 9 +
.../mdspan/submdspan/submdspan_extents.cc | 169 ++++++++++++++++++
.../mdspan/submdspan/submdspan_extents_neg.cc | 48 +++++
5 files changed, 333 insertions(+), 1 deletion(-)
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents_neg.cc
diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index 4fce6172589..31395b068b9 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -865,6 +865,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return extents<_IndexType, _Extents::static_extent(_Index)>{
__exts.extent(_Index)};
}
+
+ template<typename _IndexType, typename... _Slices>
+ consteval auto
+ __subrank()
+ {
+ return (static_cast<size_t>(!convertible_to<_Slices, _IndexType>)
+ + ... + 0);
+ }
+
+ template<typename _IndexType, typename... _Slices>
+ consteval auto
+ __inv_map_rank()
+ {
+ constexpr auto __rank = sizeof...(_Slices);
+ constexpr auto __sub_rank = __subrank<_IndexType, _Slices...>();
+ auto __map = std::array<size_t, __sub_rank>{};
+ auto __is_int_like = std::array<bool, __rank>{
+ convertible_to<_Slices, _IndexType>...};
+
+ size_t __i = 0;
+ for (size_t __k = 0; __k < __rank; ++__k)
+ if (!__is_int_like[__k])
+ __map[__i++] = __k;
+ return __map;
+ }
#endif // __glibcxx_submdspan
}
@@ -2659,8 +2684,86 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
};
__impl(make_index_sequence<__rank>());
}
+
+ template<typename _IndexType, size_t _Extent, typename _Slice>
+ consteval size_t
+ __static_slice_extent()
+ {
+ if constexpr (same_as<_Slice, full_extent_t>)
+ return _Extent;
+ else if constexpr (same_as<_Slice, constant_wrapper<_IndexType(0)>>)
+ return 0;
+ else if constexpr (__is_constant_wrapper<typename _Slice::extent_type>
+ && __is_constant_wrapper<typename _Slice::stride_type>)
+ return 1 + ((typename _Slice::extent_type{}) - 1)
+ / (typename _Slice::stride_type{});
+ else
+ return dynamic_extent;
+ }
+
+ template<size_t _K, typename _Extents, typename _Slice>
+ constexpr typename _Extents::index_type
+ __dynamic_slice_extent(const _Extents& __exts, _Slice __slice)
+ {
+ if constexpr (__is_strided_slice<_Slice>)
+ return __slice.extent == 0 ? 0 : 1 + (__slice.extent - 1) /
__slice.stride;
+ else
+ return __exts.extent(_K);
+ }
+
+ template<typename _IndexType, size_t... _Extents, typename... _Slices>
+ requires (sizeof...(_Slices) == sizeof...(_Extents))
+ constexpr auto
+ __subextents(const extents<_IndexType, _Extents...>& __exts,
+ _Slices... __slices)
+ {
+ constexpr auto __inv_map = __mdspan::__inv_map_rank<_IndexType,
_Slices...>();
+ auto __impl = [&]<size_t... _Indices>(index_sequence<_Indices...>)
+ {
+ using _SubExtents = extents<_IndexType,
+ (__mdspan::__static_slice_extent<_IndexType,
+ _Extents...[__inv_map[_Indices]],
+ _Slices...[__inv_map[_Indices]]>())...>;
+ if constexpr (_SubExtents::rank_dynamic() == 0)
+ return _SubExtents{};
+ else
+ {
+ using _StaticSubExtents = __mdspan::_StaticExtents<
+ __mdspan::__static_extents<_SubExtents>()>;
+ auto __create = [&]<size_t... _Is>(index_sequence<_Is...>)
+ {
+ constexpr auto __slice_idx = [__inv_map](size_t __i) consteval
+ {
+ return
__inv_map[_StaticSubExtents::_S_dynamic_index_inv(__i)];
+ };
+
+ return _SubExtents{
+ (__mdspan::__dynamic_slice_extent<__slice_idx(_Is)>(
+ __exts, __slices...[__slice_idx(_Is)]))...};
+ };
+ constexpr auto __dyn_subrank = _SubExtents::rank_dynamic();
+ return __create(make_index_sequence<__dyn_subrank>());
+ }
+ };
+
+ return __impl(make_index_sequence<__inv_map.size()>());
+ }
}
+ template<typename _IndexType, size_t... _Extents, typename... _RawSlices>
+ requires (sizeof...(_RawSlices) == sizeof...(_Extents))
+ constexpr auto
+ submdspan_extents(const extents<_IndexType, _Extents...>& __exts,
+ _RawSlices... __raw_slices)
+ {
+ auto __impl = [&__exts](auto... __slices)
+ {
+ __mdspan::__check_valid_slices(__exts, __slices...);
+ return __mdspan::__subextents(__exts, __slices...);
+ };
+ return __impl(__mdspan::__slice_cast<_IndexType>(__raw_slices)...);
+ }
+
template<typename _IndexType, size_t... _Extents, typename... _RawSlices>
requires (sizeof...(_Extents) == sizeof...(_RawSlices))
constexpr auto
diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/std.cc.in
index 63b3d183bf5..c2a9293b05a 100644
--- a/libstdc++-v3/src/c++23/std.cc.in
+++ b/libstdc++-v3/src/c++23/std.cc.in
@@ -1877,13 +1877,16 @@ export namespace std
#if __glibcxx_padded_layouts
using std::layout_left_padded;
using std::layout_right_padded;
+#endif
+#if __glibcxx_submdspan
using std::strided_slice;
using std::full_extent_t;
using std::full_extent;
using std::submdspan_mapping_result;
using std::submdspan_canonicalize_slices;
+ using std::submdspan_extents;
#endif
- // FIXME submdspan_extents, mdsubspan
+ // FIXME mdsubspan
}
#endif
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/int_like.h
b/libstdc++-v3/testsuite/23_containers/mdspan/int_like.h
index 2f79b9dd3b5..b839be73ae9 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/int_like.h
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/int_like.h
@@ -69,4 +69,13 @@ using RValueInt = CustomIndexType<CustomIndexKind::RValue>;
struct NotIntLike
{ };
+struct StructuralInt
+{
+ constexpr
+ operator int() const noexcept
+ { return value; }
+
+ int value;
+};
+
#endif // TEST_MDSPAN_INT_LIKE_H
diff --git
a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents.cc
new file mode 100644
index 00000000000..841910a77c8
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents.cc
@@ -0,0 +1,169 @@
+// { dg-do run { target c++26 } }
+#include <mdspan>
+
+#include "../int_like.h"
+#include <testsuite_hooks.h>
+
+constexpr size_t dyn = std::dynamic_extent;
+constexpr auto all = std::full_extent;
+
+constexpr bool
+test_from_full_extent()
+{
+ auto exts = std::extents<int, 3, dyn, 7>{};
+ auto sub_exts = submdspan_extents(exts, 1, all, all);
+ VERIFY(sub_exts.rank() == 2);
+ VERIFY(sub_exts.static_extent(0) == dyn);
+ VERIFY(sub_exts.extent(0) == exts.extent(1));
+ VERIFY(std::cmp_equal(sub_exts.static_extent(1), exts.extent(2)));
+ return true;
+}
+
+template<template<typename, typename> typename Pair, template<int> typename Cw>
+ constexpr bool
+ test_from_tuple()
+ {
+ auto exts = std::extents<int, 3, 5, 7>{};
+ auto s0 = Cw<1>{};
+ auto s1 = Pair{Cw<1>{}, Cw<2>{}};
+ auto s2 = Pair{Cw<1>{}, 4};
+ auto sub_exts = submdspan_extents(exts, s0, s1, s2);
+ VERIFY(sub_exts.rank() == 2);
+ VERIFY(sub_exts.static_extent(0) == size_t(get<1>(s1) - get<0>(s1)));
+ VERIFY(sub_exts.static_extent(1) == dyn);
+ VERIFY(std::cmp_equal(sub_exts.extent(1), get<1>(s2) - get<0>(s2)));
+ return true;
+ }
+
+template<template<int> typename Cw>
+ constexpr bool
+ test_from_tuple_all()
+ {
+ test_from_tuple<std::tuple, Cw>();
+ test_from_tuple<std::pair, Cw>();
+ return true;
+ }
+
+
+template<typename Int>
+ void
+ test_from_int_like_as_scalar()
+ {
+ auto exts = std::extents<int, 3, 5>{};
+ auto sub_exts = submdspan_extents(exts, Int(1), std::tuple{1, 3});
+ VERIFY(sub_exts.rank() == 1);
+ VERIFY(sub_exts.static_extent(0) == dyn);
+ VERIFY(sub_exts.extent(0) == 2);
+ }
+
+template<template<int> typename Cw>
+ constexpr bool
+ test_from_const_int()
+ {
+ auto exts = std::extents<int, 3, 5>{};
+ auto sub_exts = submdspan_extents(exts, Cw<1>{}, std::tuple{1, 3});
+ VERIFY(sub_exts.rank() == 1);
+ VERIFY(sub_exts.static_extent(0) == dyn);
+ VERIFY(sub_exts.extent(0) == 2);
+ return true;
+ }
+
+template<typename Int>
+ constexpr bool
+ test_from_int_like_in_tuple()
+ {
+ auto exts = std::extents<int, 3, 5>{};
+ auto sub_exts = submdspan_extents(exts, Int(1), std::tuple{Int(1),
Int(3)});
+ VERIFY(sub_exts.rank() == 1);
+ VERIFY(sub_exts.static_extent(0) == dyn);
+ VERIFY(sub_exts.extent(0) == 2);
+ return true;
+ }
+
+template<template<int> typename Cw>
+ constexpr bool
+ test_from_strided_slice()
+ {
+ auto exts = std::extents<int, 5, 7, 11>{};
+ {
+ auto s0 = 1;
+ auto s1 = std::strided_slice{0, 0, 0};
+ auto s2 = std::strided_slice{1, Cw<0>{}, 0};
+ auto sub_exts = submdspan_extents(exts, s0, s1, s2);
+ VERIFY(sub_exts.rank() == 2);
+ VERIFY(sub_exts.static_extent(0) == dyn);
+ VERIFY(sub_exts.extent(0) == 0);
+ VERIFY(sub_exts.static_extent(1) == 0);
+ }
+
+ {
+ auto s0 = 1;
+ auto s1 = std::strided_slice{0, 2, Cw<1>{}};
+ auto s2 = std::strided_slice{1, Cw<2>{}, 1};
+ auto sub_exts = submdspan_extents(exts, s0, s1, s2);
+ VERIFY(sub_exts.rank() == 2);
+ VERIFY(sub_exts.static_extent(0) == dyn);
+ VERIFY(sub_exts.extent(0) == 2);
+ VERIFY(sub_exts.static_extent(1) == dyn);
+ VERIFY(sub_exts.extent(1) == 2);
+ }
+
+ {
+ // selected = 1 x [1, 3] x [1, 4, 7, 10]
+ auto s0 = 1;
+ auto s1 = std::strided_slice{1, Cw<4>{}, 2};
+ auto s2 = std::strided_slice{1, Cw<10>{}, Cw<3>{}};
+ auto sub_exts = submdspan_extents(exts, s0, s1, s2);
+ VERIFY(sub_exts.rank() == 2);
+ VERIFY(sub_exts.static_extent(0) == dyn);
+ VERIFY(sub_exts.extent(0) == 2);
+ VERIFY(sub_exts.static_extent(1) == 4);
+ }
+
+ {
+ // selected = [0, 2] x [1, 3] x [0, 3, 6]
+ auto s0 = std::strided_slice(0, 3, 2);
+ auto s1 = std::strided_slice(1, 4, 2);
+ auto s2 = std::strided_slice(0, 7, 3);
+ auto sub_exts = submdspan_extents(exts, s0, s1, s2);
+ VERIFY(sub_exts.rank() == 3);
+ VERIFY(sub_exts.extent(0) == 2);
+ VERIFY(sub_exts.extent(1) == 2);
+ VERIFY(sub_exts.extent(2) == 3);
+ }
+ return true;
+ }
+
+template<int Value>
+ using CW = std::constant_wrapper<Value, int>;
+
+template<int Value>
+ using IC = std::integral_constant<int, Value>;
+
+constexpr bool
+test_all()
+{
+ test_from_full_extent();
+ test_from_tuple_all<CW>();
+ test_from_tuple_all<IC>();
+ test_from_const_int<CW>();
+ test_from_const_int<IC>();
+ test_from_strided_slice<CW>();
+ test_from_strided_slice<IC>();
+ test_from_int_like_in_tuple<StructuralInt>();
+ return true;
+}
+
+int
+main()
+{
+ test_all();
+ static_assert(test_all());
+
+ test_from_int_like_as_scalar<CustomIndexType<CustomIndexKind::Const,
true>>();
+ test_from_int_like_as_scalar<CustomIndexType<CustomIndexKind::Throwing,
true>>();
+ test_from_int_like_as_scalar<CustomIndexType<CustomIndexKind::Mutating,
true>>();
+ test_from_int_like_as_scalar<CustomIndexType<CustomIndexKind::RValue,
true>>();
+ test_from_int_like_as_scalar<StructuralInt>();
+ return 0;
+}
diff --git
a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents_neg.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents_neg.cc
new file mode 100644
index 00000000000..cf27c0c7e4d
--- /dev/null
+++
b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents_neg.cc
@@ -0,0 +1,48 @@
+// { dg-do compile { target c++26 } }
+#include <mdspan>
+
+#include <cstdint>
+
+struct NotASlice
+{ };
+
+constexpr bool
+test_unrelated_stride_type()
+{
+ auto exts = std::extents(3, 5, 7);
+ auto sub_exts = submdspan_extents(exts, 1, NotASlice{}, 2); // { dg-error
"required from" }
+ return true;
+}
+static_assert(test_unrelated_stride_type());
+
+constexpr bool
+test_invalid_stride_zero()
+{
+ auto exts = std::extents(3, 5, 7);
+ auto s = std::strided_slice{0, 1, 0};
+ auto sub_exts = submdspan_extents(exts, 1, s, 2); // { dg-error "expansion
of" }
+ return true;
+}
+static_assert(test_invalid_stride_zero());
+
+template<typename Slice>
+constexpr bool
+test_out_of_bounds(const Slice& slice)
+{
+ auto exts = std::extents<uint16_t, 3, 5, 7>{};
+ auto sub_exts = submdspan_extents(exts, 1, slice, 2); // { dg-error
"expansion of" }
+ return true;
+}
+static_assert(test_out_of_bounds(std::strided_slice{0, 6, 1})); // { dg-error
"expansion of" }
+static_assert(test_out_of_bounds(std::strided_slice{0, 7, 2})); // { dg-error
"expansion of" }
+static_assert(test_out_of_bounds(std::strided_slice{1, 6, 1})); // { dg-error
"expansion of" }
+static_assert(test_out_of_bounds(std::strided_slice{1, 6, 2})); // { dg-error
"expansion of" }
+static_assert(test_out_of_bounds(std::tuple{1, 6})); // { dg-error
"expansion of" }
+static_assert(test_out_of_bounds(std::tuple{std::cw<1>, std::cw<6>})); // {
dg-error "expansion of" }
+static_assert(test_out_of_bounds(std::strided_slice{-1, 2, 1})); // { dg-error
"expansion of" }
+static_assert(test_out_of_bounds(std::tuple{-1, 2})); // { dg-error
"expansion of" }
+
+// { dg-prune-output "cannot decompose class type 'NotASlice'" }
+// { dg-prune-output "static assertion failed" }
+// { dg-prune-output "__glibcxx_assert_fail" }
+// { dg-prune-output "non-constant condition" }
--
2.52.0
