Implement submdspan_extents as described in P3663 and adds it to the std
module.
There's one deviation from the standard. Doesn't (under all
circumstances) require:
0 <= begin[k] <= end[k] <= exts.extent(k)
where the k-th slice range is [begin[k], end[k]). Instead, it requires
that the k-th slice ranges is contained in the k-th extent interval. If
the the slice range is empty, then that condition is always satisfied,
even if
begin[k] == end[k] > exts.extent(k)
The deviation is that we enforce the above inequality through
preconditions. This is analogous to what the standard requires if
begin[k] is a constant wrapper.
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 | 142 ++++++++++++++-
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, 368 insertions(+), 5 deletions(-)
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 9b7428c20ac..1d506f0338e 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -959,24 +959,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
static_assert(__valid_canonical_slice_type<_Slice, _IndexType>);
if constexpr (__is_strided_slice<_Slice>)
{
if constexpr (!(__is_constant_wrapper<typename _Slice::extent_type>
&& __is_constant_wrapper<typename
_Slice::stride_type>))
__glibcxx_assert(__slice.extent == 0 || __slice.stride > 0);
// DEVIATION: For empty slices, P3663r3 does not allow us to check
- // that that this is less than or equal to the k-th extent (at
- // runtime). We're only allowed to check if __slice.offset,
- // __slice.extent are constant wrappers and __ext is a static
- // extent.
+ // that this is less than or equal to the k-th extent (at runtime).
+ // We're only allowed to check if __slice.offset, __slice.extent
+ // are constant wrappers and __ext is a static extent.
__assert_valid_index(__ext, __slice.offset);
__assert_valid_index(__ext, __slice.extent);
if constexpr (__is_constant_wrapper<typename _Slice::offset_type>
&& __is_constant_wrapper<typename _Slice::extent_type>
&& _Extent != dynamic_extent)
static_assert(std::cmp_greater_equal(
_Extent - _Slice::offset_type::value,
_Slice::extent_type::value));
else
@@ -2679,20 +2678,155 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typename _MappingType::layout_type>;
template<typename _MappingType, typename _AccessorType>
mdspan(const typename _AccessorType::data_handle_type&, const
_MappingType&,
const _AccessorType&)
-> mdspan<typename _AccessorType::element_type,
typename _MappingType::extents_type,
typename _MappingType::layout_type, _AccessorType>;
#if __glibcxx_submdspan
+ namespace __mdspan
+ {
+ template<typename _Slice>
+ consteval bool
+ __is_statically_empty_strided_slice()
+ {
+ if constexpr (__is_strided_slice<_Slice>)
+ {
+ using _ExtentType = typename _Slice::extent_type;
+ return __detail::__integral_constant_like<_ExtentType>
+ && _ExtentType() == 0;
+ }
+ else
+ return false;
+ }
+
+ template<typename _Slice>
+ consteval bool
+ __is_statically_sized_strided_slice()
+ {
+ if constexpr (__is_strided_slice<_Slice>)
+ {
+ using _ExtentType = typename _Slice::extent_type;
+ using _StrideType = typename _Slice::stride_type;
+ return __detail::__integral_constant_like<_ExtentType>
+ && __detail::__integral_constant_like<_StrideType>;
+ }
+ else
+ return false;
+ }
+
+ template<typename _IndexType, size_t _Extent, typename _Slice>
+ consteval size_t
+ __deduce_static_slice_extent()
+ {
+ if constexpr (same_as<_Slice, full_extent_t>)
+ return _Extent;
+ else if constexpr (__is_statically_empty_strided_slice<_Slice>())
+ return 0;
+ else if constexpr (__is_statically_sized_strided_slice<_Slice>())
+ 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
+ __deduce_dynamic_slice_extent(const _Extents& __exts, _Slice __slice)
+ {
+ using _IndexType = typename _Extents::index_type;
+ if constexpr (__is_strided_slice<_Slice>)
+ return __slice.extent == 0 ? 0 :
+ 1 + (__slice.extent - 1) / __slice.stride;
+ else if constexpr (convertible_to<_Slice, _IndexType>)
+ return 1;
+ else
+ return __exts.extent(_K);
+
+ }
+
+ 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{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;
+ }
+
+ 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::__deduce_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::__deduce_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... _Slices>
+ requires (sizeof...(_Slices) == sizeof...(_Extents))
+ constexpr auto
+ submdspan_extents(const extents<_IndexType, _Extents...>& __exts,
+ _Slices... __raw_slices)
+ {
+ auto [...__slices] = submdspan_canonicalize_slices(__exts,
__raw_slices...);
+ return __mdspan::__subextents(__exts, __slices...);
+ }
+
template<typename _IndexType, size_t... _Extents, typename... _Slices>
requires (sizeof...(_Extents) == sizeof...(_Slices))
constexpr auto
submdspan_canonicalize_slices(const extents<_IndexType, _Extents...>&
__exts,
_Slices... __raw_slices)
{
auto [...__slices]
= make_tuple(__mdspan::__slice_cast<_IndexType>(__raw_slices)...);
__mdspan::__assert_valid_slices(__exts, __slices...);
return make_tuple(__slices...);
diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/std.cc.in
index 6862b4d69c2..2dfdf13f0d1 100644
--- a/libstdc++-v3/src/c++23/std.cc.in
+++ b/libstdc++-v3/src/c++23/std.cc.in
@@ -1868,27 +1868,30 @@ export namespace std
using std::layout_right;
using std::layout_stride;
using std::default_accessor;
#if __glibcxx_aligned_accessor
using std::aligned_accessor;
#endif
using std::mdspan;
#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
// 20.2 <memory>
export namespace std
{
using std::align;
using std::allocator;
using std::allocator_arg;
using std::allocator_arg_t;
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
@@ -62,11 +62,20 @@ template<CustomIndexKind Kind, bool Copyable = false>
};
using IntLike = CustomIndexType<CustomIndexKind::Const>;
using ThrowingInt = CustomIndexType<CustomIndexKind::Throwing>;
using MutatingInt = CustomIndexType<CustomIndexKind::Mutating>;
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" }
--
2.51.2
