[PATCH v1 6/6] libstdc++: Implement submdspan_mapping for layout_stride. [PR110352]
Luc Grosheintz
luc.grosheintz@gmail.com
Fri Nov 14 14:09:42 GMT 2025
Add submdspan_mapping for layout_stride as in P3663.
PR libstdc++/110352
libstdc++-v3/ChangeLog:
* include/std/mdspan (layout_stride::mapping::submdspan_mapping): New
friend function.
* testsuite/23_containers/mdspan/submdspan/submdspan.cc:
Instantiate tests for layout_stride.
* testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc:
Ditto.
* testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc:
Add tests for layout_stride.
Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>
---
libstdc++-v3/include/std/mdspan | 25 +++++++++++++++++++
.../mdspan/submdspan/submdspan.cc | 1 +
.../mdspan/submdspan/submdspan_mapping.cc | 18 +++++++++++++
.../mdspan/submdspan/submdspan_neg.cc | 9 +++++++
4 files changed, 53 insertions(+)
diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index b38485ddd3d..35e46b94b27 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -1969,20 +1969,45 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
if (__self.extents() != __other.extents())
return false;
if constexpr (extents_type::rank() > 0)
for (size_t __i = 0; __i < extents_type::rank(); ++__i)
if (!cmp_equal(__self.stride(__i), __other.stride(__i)))
return false;
return __mdspan::__offset(__other) == 0;
}
private:
+#if __glibcxx_submdspan
+ constexpr auto
+ _M_submdspan_mapping_impl() const
+ { return submdspan_mapping_result{*this, 0}; }
+
+ template<typename... _Slices>
+ requires (sizeof...(_Slices) > 0)
+ constexpr auto
+ _M_submdspan_mapping_impl(_Slices... __slices) const
+ {
+ auto __offset = __mdspan::__suboffset(*this, __slices...);
+ auto __sub_exts = submdspan_extents(extents(), __slices...);
+ auto __sub_strides
+ = __mdspan::__substrides<decltype(__sub_exts)>(*this, __slices...);
+ return submdspan_mapping_result{
+ layout_stride::mapping(__sub_exts, __sub_strides), __offset};
+ }
+
+ template<__mdspan::__valid_canonical_slice_type<index_type>... _Slices>
+ requires (extents_type::rank() == sizeof...(_Slices))
+ friend constexpr auto
+ submdspan_mapping(const mapping& __mapping, _Slices... __slices)
+ { return __mapping._M_submdspan_mapping_impl(__slices...); }
+#endif
+
using _Strides = typename __array_traits<index_type,
extents_type::rank()>::_Type;
[[no_unique_address]] extents_type _M_extents;
[[no_unique_address]] _Strides _M_strides;
};
#ifdef __glibcxx_padded_layouts
namespace __mdspan
{
constexpr size_t
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan.cc b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan.cc
index cd6e9454b17..645c4711294 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan.cc
@@ -359,12 +359,13 @@ template<typename Layout>
test_all_cheap<Layout>();
test_all_expensive<Layout>();
return true;
}
int
main()
{
test_all<std::layout_left>();
test_all<std::layout_right>();
+ test_all<std::layout_stride>();
return 0;
}
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc
index cc832cdb415..cf6167dc3b0 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc
@@ -116,27 +116,45 @@ template<typename Layout>
VERIFY(padding_value == expected);
};
check(std::extents(std::cw<3>, std::cw<5>, std::cw<7>, 11, 13), 3*5);
check(std::extents(std::cw<3>, std::cw<5>, 7, 11, 13), 3*5);
check(std::extents(std::cw<3>, 5, 7, 11, 13), dyn);
check(std::extents(3, 5, 7, 11, 13), dyn);
return true;
}
+constexpr bool
+test_layout_stride_return_types()
+{
+ auto exts = std::extents(3, 5);
+ auto m = std::layout_stride::mapping(exts, std::array{2, 12});
+
+ using index_type = decltype(exts)::index_type;
+ auto s1 = std::strided_slice{index_type(2), index_type(2),
+ std::cw<index_type(2)>};
+ auto result = submdspan_mapping(m, index_type(1), s1);
+ using layout_type = decltype(result.mapping)::layout_type;
+ static_assert(std::same_as<layout_type, std::layout_stride>);
+ return true;
+}
+
int
main()
{
test_layout_unpadded_return_types<std::layout_left>();
static_assert(test_layout_unpadded_return_types<std::layout_left>());
test_layout_unpadded_return_types<std::layout_right>();
static_assert(test_layout_unpadded_return_types<std::layout_right>());
+ test_layout_stride_return_types();
+ static_assert(test_layout_stride_return_types());
+
test_layout_unpadded_padding_value<std::layout_left>();
static_assert(test_layout_unpadded_padding_value<std::layout_left>());
test_layout_unpadded_padding_value<std::layout_right>();
static_assert(test_layout_unpadded_padding_value<std::layout_right>());
return 0;
}
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc
index 3d6b0191e17..59688b2330c 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc
@@ -18,94 +18,103 @@ template<typename Layout, typename... Slices>
template<typename Layout>
constexpr bool
test_int_under()
{
check_slice_range<Layout>(1, -1, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_int_under<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_int_under<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_int_under<std::layout_stride>()); // { dg-error "expansion of" }
template<typename Layout>
constexpr bool
test_int_over()
{
check_slice_range<Layout>(1, 5, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_int_over<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_int_over<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_int_over<std::layout_stride>()); // { dg-error "expansion of" }
template<typename Layout>
constexpr bool
test_tuple_under()
{
check_slice_range<Layout>(1, std::tuple{-1, 2}, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_tuple_under<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_tuple_under<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_tuple_under<std::layout_stride>()); // { dg-error "expansion of" }
template<typename Layout>
constexpr bool
test_tuple_reversed()
{
check_slice_range<Layout>(1, std::tuple{3, 2}, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_tuple_reversed<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_tuple_reversed<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_tuple_reversed<std::layout_stride>()); // { dg-error "expansion of" }
template<typename Layout>
constexpr bool
test_tuple_over()
{
check_slice_range<Layout>(1, std::tuple{0, 6}, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_tuple_over<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_tuple_over<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_tuple_over<std::layout_stride>()); // { dg-error "expansion of" }
template<typename Layout>
constexpr bool
test_strided_slice_zero()
{
check_slice_range<Layout>(1, std::strided_slice{1, 1, 0}, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_strided_slice_zero<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_strided_slice_zero<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_strided_slice_zero<std::layout_stride>()); // { dg-error "expansion of" }
template<typename Layout>
constexpr bool
test_strided_slice_offset_under()
{
check_slice_range<Layout>(1, std::strided_slice{-1, 1, 1}, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_strided_slice_offset_under<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_strided_slice_offset_under<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_strided_slice_offset_under<std::layout_stride>()); // { dg-error "expansion of" }
template<typename Layout>
constexpr bool
test_strided_slice_offset_over()
{
check_slice_range<Layout>(1, std::strided_slice{6, 0, 1}, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_strided_slice_offset_over<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_strided_slice_offset_over<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_strided_slice_offset_over<std::layout_stride>()); // { dg-error "expansion of" }
template<typename Layout>
constexpr bool
test_strided_slice_extent_over()
{
check_slice_range<Layout>(1, std::strided_slice{1, 5, 1}, 2); // { dg-error "expansion of" }
return true;
}
static_assert(test_strided_slice_extent_over<std::layout_left>()); // { dg-error "expansion of" }
static_assert(test_strided_slice_extent_over<std::layout_right>()); // { dg-error "expansion of" }
+static_assert(test_strided_slice_extent_over<std::layout_stride>()); // { dg-error "expansion of" }
// { dg-prune-output "static assertion failed" }
// { dg-prune-output "__glibcxx_assert_fail" }
// { dg-prune-output "non-constant condition" }
--
2.51.2
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