On Tue, Sep 23, 2025 at 3:41 PM Luc Grosheintz <[email protected]>
wrote:
This commit adds the right padded layout as described in N5014, with
LWG4372 (dynamic padding value) and LWG4314 (move in operator()).
libstdc++-v3/ChangeLog:
* include/std/mdspan (_RightPaddedIndices): New class.
(layout_right_padded): New class.
* src/c++23/std.cc.in (layout_right_padded): Add.
* testsuite/23_containers/mdspan/layouts/ctors.cc: Update
test for right padded layout.
* testsuite/23_containers/mdspan/layouts/empty.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/mapping.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/padded.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/padded_neg.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/padded_traits.h: Ditto.
Signed-off-by: Luc Grosheintz <[email protected]>
This also looks good to me, the usage of common storage and the traits
in the test have really paid off.
---
libstdc++-v3/include/std/mdspan | 263 ++++++++++++++++++
libstdc++-v3/src/c++23/std.cc.in | 5 +-
.../23_containers/mdspan/layouts/ctors.cc | 3 +-
.../23_containers/mdspan/layouts/empty.cc | 1 +
.../23_containers/mdspan/layouts/mapping.cc | 6 +-
.../23_containers/mdspan/layouts/padded.cc | 4 +
.../mdspan/layouts/padded_neg.cc | 28 ++
.../mdspan/layouts/padded_traits.h | 135 ++++++++-
8 files changed, 437 insertions(+), 8 deletions(-)
diff --git a/libstdc++-v3/include/std/mdspan
b/libstdc++-v3/include/std/mdspan
index 18782bf0a06..f61931ab8e6 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -954,6 +954,32 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: mapping(__other.extents(), __mdspan::__internal_ctor{})
{ __glibcxx_assert(*this == __other); }
+#if __glibcxx_padded_layouts
+ template<class _RightPaddedMapping>
+ requires __mdspan::__is_right_padded_mapping<_RightPaddedMapping>
+ && is_constructible_v<extents_type,
+ typename
_RightPaddedMapping::extents_type>
+ constexpr
+ explicit(!is_convertible_v<typename
_RightPaddedMapping::extents_type,
+ extents_type>)
+ mapping(const _RightPaddedMapping& __other) noexcept
+ : mapping(__other.extents(), __mdspan::__internal_ctor{})
+ {
+ constexpr size_t __rank = extents_type::rank();
+ constexpr size_t __ostride_sta = __mdspan::__get_static_stride<
+ _RightPaddedMapping>();
+
+ if constexpr (__rank > 1
Same comment about extracting (_rank > 1) first, and then doing
__glibcxx_assert in else.
+ && extents_type::static_extent(__rank - 1) != dynamic_extent
+ && __ostride_sta != dynamic_extent)
+ static_assert(extents_type::static_extent(__rank - 1) ==
__ostride_sta);
+
+ if constexpr (__rank > 1)
+ __glibcxx_assert(__other.stride(__rank - 2)
+ == __other.extents().extent(__rank - 1));
+ }
+#endif
+
constexpr mapping&
operator=(const mapping&) noexcept = default;
@@ -1350,6 +1376,37 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return __res;
}
+ template<typename _Extents, typename _Stride, typename... _Indices>
+ constexpr typename _Extents::index_type
+ __linear_index_rightpad(const _Extents& __exts, _Stride __stride,
+ _Indices... __indices)
+ {
+ // i[n-1] + stride*(i[n-2] + extents.extent(n-2])*...)
+ using _IndexType = typename _Extents::index_type;
+ _IndexType __res = 0;
+ if constexpr (sizeof...(__indices) > 0)
+ {
+ _IndexType __mult = 1;
+ array<_IndexType, sizeof...(__indices)>
__ind_arr{__indices...};
+
+ auto __update_rest = [&, __pos = __exts.rank()-1](_IndexType)
mutable
+ {
+ --__pos;
+ __res += __ind_arr[__pos] * __mult;
+ __mult *= __exts.extent(__pos);
+ };
+
+ auto __update = [&](_IndexType, auto... __rest)
+ {
+ __res += __ind_arr[__exts.rank() - 1];
+ __mult = __stride.extent(0);
+ (__update_rest(__rest), ...);
+ };
+ __update(__indices...);
+ }
+ return __res;
+ }
+
template<size_t _Rank>
struct _LeftPaddedLayoutTraits
{
@@ -1384,6 +1441,39 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
};
+ template<size_t _Rank>
+ struct _RightPaddedLayoutTraits
+ {
+ using _LayoutSame = layout_right;
+ using _LayoutOther = layout_left;
+
+ constexpr static size_t _S_ext_idx = _Rank - 1;
+ constexpr static size_t _S_stride_idx = _Rank - 2;
+ constexpr static size_t _S_unpad_begin = 0;
+ constexpr static size_t _S_unpad_end = _Rank - 1;
+
+ template<typename _Mapping>
+ constexpr static bool _S_is_same_padded_mapping =
+ __is_right_padded_mapping<_Mapping>;
+
+ template<typename _Mapping>
+ constexpr static bool _S_is_other_padded_mapping =
+ __is_left_padded_mapping<_Mapping>;
+
+ template<typename _IndexType, size_t _StaticStride,
size_t..._Extents>
+ constexpr static auto _S_make_padded_extent(
+ extents<_IndexType, _StaticStride> __stride,
+ const extents<_IndexType, _Extents...>& __exts)
+ {
+ auto __impl = [&]<size_t... _Is>(integer_sequence<size_t,
_Is...>)
+ {
+ return extents<_IndexType, (_Extents...[_Is])...,
_StaticStride>{
+ __exts.extent(_Is)..., __stride.extent(0)};
+ };
+ return __impl(make_index_sequence<sizeof...(_Extents) - 1>());
+ }
+ };
+
template<size_t _PaddingValue, typename _Extents, typename
_LayoutTraits>
class _PaddedStorage
{
@@ -1834,6 +1924,179 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__other.stride(1)));
}
};
+
+ template<size_t _PaddingValue>
+ template<typename _Extents>
+ class layout_right_padded<_PaddingValue>::mapping {
+ public:
+ static constexpr size_t padding_value = _PaddingValue;
+ 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_right_padded<_PaddingValue>;
+
+ private:
+ static constexpr size_t _S_rank = extents_type::rank();
+ using _RightPaddedStorage = __mdspan::_PaddedStorage<_PaddingValue,
+ _Extents, __mdspan::_RightPaddedLayoutTraits<_S_rank>>;
The name will become _PaddedStorage, so we can change __get_static_stride.
+ [[no_unique_address]] _RightPaddedStorage _M_storage;
+
+ static constexpr size_t _S_static_stride =
+ _RightPaddedStorage::_S_static_stride;
+
+ consteval friend size_t
+ __mdspan::__get_static_stride<mapping>();
+
+ constexpr index_type
+ _M_extent(size_t __r) const noexcept
+ { return _M_storage._M_extents.extent(__r); }
+
+ constexpr index_type
+ _M_dynamic_padded_stride() const noexcept
+ { return _M_storage._M_stride.extent(0); }
+
+ public:
+ constexpr
+ mapping() noexcept
+ { }
+
+ constexpr
+ mapping(const mapping&) noexcept = default;
+
+ constexpr
+ mapping(const extents_type& __exts)
+ : _M_storage(__exts)
+ { }
+
+ template<__mdspan::__valid_index_type<index_type> _OIndexType>
+ constexpr mapping(const extents_type& __exts, _OIndexType __opad)
+ : _M_storage(__exts, std::move(__opad))
+ { }
+
+ template<typename _OExtents>
+ requires is_constructible_v<extents_type, _OExtents>
+ constexpr explicit(!is_convertible_v<_OExtents, extents_type>)
+ mapping(const layout_right::mapping<_OExtents>& __other)
+ : _M_storage(__other)
+ { }
+
+ template<typename _OExtents>
+ requires is_constructible_v<_OExtents, extents_type>
+ constexpr explicit(_OExtents::rank() > 0)
+ mapping(const typename layout_stride::mapping<_OExtents>&
__other)
+ : _M_storage(__other)
+ { __glibcxx_assert(*this == __other); }
+
+ template<typename _RightPaddedMapping>
+ requires __mdspan::__is_right_padded_mapping<_RightPaddedMapping>
+ && is_constructible_v<extents_type,
+ typename
_RightPaddedMapping::extents_type>
+ constexpr explicit(_S_rank > 1 && (padding_value !=
dynamic_extent
+ || _RightPaddedMapping::padding_value == dynamic_extent))
+ mapping(const _RightPaddedMapping& __other)
+ : _M_storage(__other)
This will pass _M_storage(layout_right{}, _other);l
+ { }
+
+ template<typename _LeftPaddedMapping>
+ requires (__mdspan::__is_left_padded_mapping<_LeftPaddedMapping>
+ || __mdspan::__mapping_of<layout_left, _LeftPaddedMapping>)
+ && (_S_rank <= 1)
+ && is_constructible_v<extents_type,
+ typename
_LeftPaddedMapping::extents_type>
+ constexpr explicit(!is_convertible_v<
+ typename _LeftPaddedMapping::extents_type, extents_type>)
+ mapping(const _LeftPaddedMapping& __other) noexcept
+ : _M_storage(__other)
This will pass _M_storage(layout_left{}, _other);l
+ { }
+
+ constexpr mapping& operator=(const mapping&) noexcept = default;
+
+ constexpr const extents_type&
+ extents() const noexcept { return _M_storage._M_extents; }
+
+ constexpr array<index_type, _S_rank>
+ strides() const noexcept
+ {
+ array<index_type, _S_rank> __ret;
+ if constexpr (_S_rank > 0)
+ __ret[_S_rank - 1] = 1;
+ if constexpr (_S_rank > 1)
+ __ret[_S_rank - 2] = _M_dynamic_padded_stride();
+ if constexpr (_S_rank > 2)
+ for(size_t __i = _S_rank - 2; __i > 0; --__i)
+ __ret[__i - 1] = __ret[__i] * _M_extent(__i);
+ return __ret;
+ }
+
+ constexpr index_type
+ required_span_size() const noexcept
+ { return _M_storage._M_required_span_size(); }
+
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 4314. Missing move in mdspan layout mapping::operator()
+ template<__mdspan::__valid_index_type<index_type>... _Indices>
+ requires (sizeof...(_Indices) == _S_rank)
+ constexpr index_type
+ operator()(_Indices... __indices) const noexcept
+ {
+ return __mdspan::__linear_index_rightpad(
+ extents(), _M_storage._M_stride,
+ static_cast<index_type>(std::move(__indices))...);
+ }
+
+ static constexpr bool
+ is_always_exhaustive() noexcept
+ { return _RightPaddedStorage::_M_is_always_exhaustive(); }
+
+ constexpr bool
+ is_exhaustive() noexcept
+ { return _M_storage._M_is_exhaustive(); }
+
+ static constexpr bool
+ is_always_unique() noexcept { return true; }
+
+ static constexpr bool
+ is_always_strided() noexcept { return true; }
+
+ static constexpr bool
+ is_unique() noexcept { return true; }
+
+ static constexpr bool
+ is_strided() noexcept { return true; }
+
+ constexpr index_type
+ stride(rank_type __r) const noexcept
+ {
+ __glibcxx_assert(__r < _S_rank);
+ if constexpr (_S_rank <= 1)
+ return 1;
+ else
This can be chained with next if without need for subbraces,
I would do that.
+ {
+ if (__r == _S_rank - 1)
+ return 1;
+ else if (__r == _S_rank - 2)
+ return _M_dynamic_padded_stride();
+ else
+ return static_cast<index_type>(
+ static_cast<size_t>(_M_dynamic_padded_stride()) *
+ static_cast<size_t>(__mdspan::__fwd_prod(
+ extents(), __r + 1, _S_rank - 1)));
+ }
+ }
+
+ template<typename _RightPaddedMapping>
+ requires(__mdspan::__is_right_padded_mapping<_RightPaddedMapping>
+ && _RightPaddedMapping::extents_type::rank() == _S_rank)
+ friend constexpr bool
+ operator==(const mapping& __self, const _RightPaddedMapping&
__other)
+ noexcept
+ {
+ return __self.extents() == __other.extents()
+ && (_S_rank < 2 || cmp_equal(__self.stride(_S_rank - 2),
+ __other.stride(_S_rank - 2)));
+ }
+ };
#endif
template<typename _ElementType>
diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/
std.cc.in
index f10bab59e2c..c1b4e4c88b7 100644
--- a/libstdc++-v3/src/c++23/std.cc.in
+++ b/libstdc++-v3/src/c++23/std.cc.in
@@ -1871,9 +1871,10 @@ export namespace std
using std::mdspan;
#if __glibcxx_padded_layouts
using std::layout_left_padded;
+ using std::layout_right_padded;
#endif
- // FIXME layout_right_padded, strided_slice, submdspan_mapping_result,
- // full_extent_t, full_extent, submdspan_extents, mdsubspan
+ // FIXME strided_slice, submdspan_mapping_result, full_extent_t,
full_extent,
+ // submdspan_extents, mdsubspan
}
#endif
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
index 891471467e1..73b161f5979 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
@@ -10,7 +10,7 @@ constexpr size_t dyn = std::dynamic_extent;
#if __glibcxx_padded_layouts
template<typename Layout>
constexpr bool
- is_padded_layout = is_left_padded<Layout>;
+ is_padded_layout = is_left_padded<Layout> || is_right_padded<Layout>;
#else
template<typename>
constexpr bool
@@ -479,6 +479,7 @@ main()
test_all<std::layout_right>();
#ifdef __glibcxx_padded_layouts
test_padded_all<std::layout_left_padded>();
+ test_padded_all<std::layout_right_padded>();
#endif
from_left_or_right::test_all<std::layout_left, std::layout_right>();
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
index 236aca8bc2b..c5519afe34f 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
@@ -142,6 +142,7 @@ main()
static_assert(test_all<std::layout_stride>());
#ifdef __glibcxx_padded_layouts
static_assert(test_padded_all<std::layout_left_padded>());
+ static_assert(test_padded_all<std::layout_right_padded>());
#endif
return 0;
}
diff --git
a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
index 5bf6bf65d3a..57560a6aae7 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
@@ -374,7 +374,7 @@ template<>
#if __glibcxx_padded_layouts
template<typename Layout>
- requires is_left_padded<Layout>
+ requires is_left_padded<Layout> || is_right_padded<Layout>
struct TestStride2D<Layout>
{
static constexpr void
@@ -458,7 +458,7 @@ template<>
#if __glibcxx_padded_layouts
template<typename Layout>
- requires is_left_padded<Layout>
+ requires is_left_padded<Layout> || is_right_padded<Layout>
struct TestStride3D<Layout>
{
static constexpr void
@@ -702,6 +702,7 @@ main()
test_all<std::layout_stride>();
#ifdef __glibcxx_padded_layouts
test_padded_all<std::layout_left_padded>();
+ test_padded_all<std::layout_right_padded>();
#endif
test_has_op_eq<std::layout_right, std::layout_left, false>();
@@ -709,6 +710,7 @@ main()
test_has_op_eq<std::layout_left, std::layout_stride, true>();
#ifdef __glibcxx_padded_layouts
test_padded_has_op_eq<std::layout_left_padded>();
+ test_padded_has_op_eq<std::layout_right_padded>();
#endif
test_has_op_eq_peculiar();
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded.cc
index ea9a8ef3f4b..a607d1ddd02 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded.cc
@@ -670,6 +670,10 @@ main()
test_all<std::layout_left_padded>();
static_assert(test_all<std::layout_left_padded>());
+ test_all<std::layout_right_padded>();
+ static_assert(test_all<std::layout_right_padded>());
+
test_from_pad_all<std::layout_left_padded>();
+ test_from_pad_all<std::layout_right_padded>();
return 0;
}
diff --git
a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_neg.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_neg.cc
index 29f12aa4de2..d0ac31c2810 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_neg.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_neg.cc
@@ -15,6 +15,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_extens_representable_sta<std::layout_left_padded>());
// { dg-error "from here" }
+static_assert(test_from_extens_representable_sta<std::layout_right_padded>());
// { dg-error "from here" }
template<template<size_t> typename Layout>
constexpr bool
@@ -28,6 +29,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_extents_representable_padded_size<std::layout_left_padded>());
// { dg-error "expansion of" }
+static_assert(test_from_extents_representable_padded_size<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -40,6 +42,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_extents_representable_stride<std::layout_left_padded>());
// { dg-error "expansion of" }
+static_assert(test_from_extents_representable_stride<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -51,6 +54,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_pad_representable_stride<std::layout_left_padded>());
// { dg-error "expansion of" }
+static_assert(test_from_pad_representable_stride<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -62,6 +66,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_pad_representable_padded_size<std::layout_left_padded>());
// { dg-error "expansion of" }
+static_assert(test_from_pad_representable_padded_size<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -76,6 +81,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_left<std::layout_left_padded>()); // { dg-error
"required from here" }
+static_assert(test_from_left<std::layout_right_padded>()); // { dg-error
"required from here" }
template<template<size_t> typename Layout>
constexpr bool
@@ -90,6 +96,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_left_bad_runtime_stride<std::layout_left_padded>());
// { dg-error "expansion of" }
+static_assert(test_from_left_bad_runtime_stride<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -103,6 +110,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_left_representable_extents<std::layout_left_padded>());
// { dg-error "expansion of" }
+static_assert(test_from_left_representable_extents<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout, size_t PaddingValue>
constexpr bool
@@ -116,6 +124,8 @@ template<template<size_t> typename Layout, size_t
PaddingValue>
}
static_assert(test_pad_overflow<std::layout_left_padded, 1>()); // {
dg-error "expansion of" }
static_assert(test_pad_overflow<std::layout_left_padded, dyn>()); // {
dg-error "expansion of" }
+static_assert(test_pad_overflow<std::layout_right_padded, 1>()); // {
dg-error "expansion of" }
+static_assert(test_pad_overflow<std::layout_right_padded, dyn>()); // {
dg-error "expansion of" }
template<template<size_t> typename Layout, size_t PaddingValue>
constexpr bool
@@ -128,6 +138,8 @@ template<template<size_t> typename Layout, size_t
PaddingValue>
}
static_assert(test_from_pad_negative<std::layout_left_padded, 1>()); //
{ dg-error "expansion of" }
static_assert(test_from_pad_negative<std::layout_left_padded, dyn>()); //
{ dg-error "expansion of" }
+static_assert(test_from_pad_negative<std::layout_right_padded, 1>());
// { dg-error "expansion of" }
+static_assert(test_from_pad_negative<std::layout_right_padded, dyn>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout, size_t Pad>
constexpr bool
@@ -142,6 +154,8 @@ template<template<size_t> typename Layout, size_t Pad>
}
static_assert(test_static_pad_same<std::layout_left_padded, 1>()); // {
dg-error "expansion of" }
static_assert(test_static_pad_same<std::layout_left_padded, 3>()); // {
dg-error "expansion of" }
+static_assert(test_static_pad_same<std::layout_right_padded, 1>()); // {
dg-error "expansion of" }
+static_assert(test_static_pad_same<std::layout_right_padded, 3>()); // {
dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -156,6 +170,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_stride_wrong_stride0<std::layout_left_padded>());
// { dg-error "expansion of" }
+static_assert(test_from_stride_wrong_stride0<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -170,6 +185,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_stride_wrong_stride1<std::layout_left_padded>());
// { dg-error "expansion of" }
+static_assert(test_from_stride_wrong_stride1<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -184,6 +200,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_stride_wrong_stride2<std::layout_left_padded>());
+static_assert(test_from_stride_wrong_stride2<std::layout_right_padded>());
template<template<size_t> typename Layout>
constexpr bool
@@ -200,6 +217,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_stride_oversized<std::layout_left_padded>()); //
{ dg-error "expansion of" }
+static_assert(test_from_stride_oversized<std::layout_right_padded>()); //
{ dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -213,6 +231,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_samepad_dyn<std::layout_left_padded>()); // {
dg-error "expansion of" }
+static_assert(test_from_samepad_dyn<std::layout_right_padded>()); // {
dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -226,6 +245,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_samepad_sta<std::layout_left_padded>()); // {
dg-error "expansion of" }
+static_assert(test_from_samepad_sta<std::layout_right_padded>()); // {
dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -240,6 +260,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_from_samepad_oversized<std::layout_left_padded>()); //
{ dg-error "expansion of" }
+static_assert(test_from_samepad_oversized<std::layout_right_padded>());
// { dg-error "expansion of" }
template<template<size_t> typename Layout, size_t RunId>
constexpr bool
@@ -278,6 +299,10 @@
static_assert(test_to_same_not_exhaustive<std::layout_left_padded, 0>());
// { d
static_assert(test_to_same_not_exhaustive<std::layout_left_padded, 1>());
// { dg-error "expansion of" }
static_assert(test_to_same_not_exhaustive<std::layout_left_padded, 2>());
// { dg-error "expansion of" }
static_assert(test_to_same_not_exhaustive<std::layout_left_padded, 3>());
// { dg-error "expansion of" }
+static_assert(test_to_same_not_exhaustive<std::layout_right_padded,
0>()); // { dg-error "expansion of" }
+static_assert(test_to_same_not_exhaustive<std::layout_right_padded,
1>()); // { dg-error "expansion of" }
+static_assert(test_to_same_not_exhaustive<std::layout_right_padded,
2>()); // { dg-error "expansion of" }
+static_assert(test_to_same_not_exhaustive<std::layout_right_padded,
3>()); // { dg-error "expansion of" }
template<template<size_t> typename Layout>
constexpr bool
@@ -290,6 +315,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_statically_bad_padding_value1<std::layout_left_padded>());
// { dg-error "required from" }
+static_assert(test_statically_bad_padding_value1<std::layout_right_padded>());
// { dg-error "required from" }
template<template<size_t> typename Layout>
constexpr bool
@@ -301,6 +327,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_statically_bad_padding_value2<std::layout_left_padded>());
// { dg-error "required from" }
+static_assert(test_statically_bad_padding_value2<std::layout_right_padded>());
// { dg-error "required from" }
template<template<size_t> typename Layout>
constexpr bool
@@ -312,6 +339,7 @@ template<template<size_t> typename Layout>
return true;
}
static_assert(test_statically_oversized<std::layout_left_padded>()); // {
dg-error "from here" }
+static_assert(test_statically_oversized<std::layout_right_padded>()); //
{ dg-error "from here" }
// { dg-prune-output "padding_value must be representable as index_type" }
// { dg-prune-output "non-constant condition for static assertion" }
diff --git
a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_traits.h
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_traits.h
index 1f0169d7c02..c267454f467 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_traits.h
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_traits.h
@@ -2,9 +2,86 @@
#define TEST_MDSPAN_PADDED_TRAITS_H
#if __glibcxx_padded_layouts
+template<typename Rev, typename Fwd>
+ struct reverse_impl;
+
+template<size_t... Ir, size_t I0, size_t... I>
+ struct reverse_impl<std::integer_sequence<size_t, Ir...>,
+ std::integer_sequence<size_t, I0, I...>>
+ {
+ using type = typename reverse_impl<std::index_sequence<I0, Ir...>,
+ std::index_sequence<I...>>::type;
+ };
+
+template<size_t... Ir>
+ struct reverse_impl<std::integer_sequence<size_t, Ir...>,
+ std::integer_sequence<size_t>>
+ {
+ using type = std::index_sequence<Ir...>;
+ };
+
+template<typename I>
+ struct reverse;
+
+template<size_t... Ir>
+ struct reverse<std::index_sequence<Ir...>>
+ {
+ using type = typename reverse_impl<std::integer_sequence<size_t>,
+ std::integer_sequence<size_t,
Ir...>>::type;
+ };
+
+template<typename, typename>
+ struct sequence_to_extents;
+
+template<typename IndexType, size_t... I>
+ struct sequence_to_extents<IndexType, std::index_sequence<I...>>
+ {
+ using type = std::extents<IndexType, I...>;
+ };
+
+template<typename IndexType, size_t... I>
+ struct reverse<std::extents<IndexType, I...>>
+ {
+ using type = typename sequence_to_extents<
+ IndexType,
+ typename reverse<std::index_sequence<I...>>::type
+ >::type;
+ };
+
+template<typename Extents>
+ constexpr auto
+ dynamic_extents_array(const Extents& exts)
+ {
+ std::array<typename Extents::index_type, Extents::rank()> ret;
+ for(size_t i = 0; i < Extents::rank(); ++i)
+ ret[i] = exts.extent(i);
+ return ret;
+ }
+
+template<typename T, size_t N>
+ constexpr std::array<T, N>
+ reversed(const std::array<T, N>& fwd)
+ {
+ std::array<T, N> rev;
+ for(size_t i = 0; i < N; ++i)
+ rev[(N-1) - i] = fwd[i];
+ return rev;
+ }
+
+template<typename IndexType, size_t... I>
+ constexpr auto
+ reversed(const std::extents<IndexType, I...>& exts)
+ {
I believe this can be implemented much simpler, something like:
using E = std::extents<IndexType, I...>;
if contexpr (sizeof...(I) == 0) // or separate overload
return E();
{
static constexpr size_t Last = sizeof...(I) - 1;
auto _impl = [&]<template... Idx>(std::index_seqence<Idx...>)
{ return std::extents<IndexType, E::static_extents(Last -
Idx)....>(E::extent(Last - Idx)....); }
return _impl(std::index_sequence_for<I...>);
}
+ using rev_type = typename reverse<std::extents<IndexType,
I...>>::type;
+ return rev_type(reversed(dynamic_extents_array(exts)));
+ }
+
+static_assert(std::array{3, 2, 1} == reversed(std::array{1, 2, 3}));
+
enum class PaddingSide
{
- Left
+ Left,
+ Right
};
template<typename Layout>
@@ -13,17 +90,33 @@ template<typename Layout>
template<size_t PaddingValue>
constexpr static bool
is_left_padded<std::layout_left_padded<PaddingValue>> = true;
+template<typename Layout>
+ constexpr static bool is_right_padded = false;
+
+template<size_t PaddingValue>
+ constexpr static bool
is_right_padded<std::layout_right_padded<PaddingValue>> = true;
+
struct DeducePaddingSide
{
template<template<size_t> typename Layout>
constexpr static PaddingSide
from_template()
- { return PaddingSide::Left; }
+ {
+ if constexpr (std::same_as<Layout<0>, std::layout_left_padded<0>>)
+ return PaddingSide::Left;
+ else
+ return PaddingSide::Right;
+ }
template<typename Layout>
constexpr static PaddingSide
from_typename()
- { return PaddingSide::Left; }
+ {
+ if constexpr (is_left_padded<Layout>)
+ return PaddingSide::Left;
+ else
+ return PaddingSide::Right;
+ }
};
template<PaddingSide Side>
@@ -59,5 +152,41 @@ template<>
{ return exts.extent(0); }
};
+template<>
+ struct LayoutTraits<PaddingSide::Right>
+ {
+ using layout_same = std::layout_right;
+ using layout_other = std::layout_left;
+
+ template<typename Extents>
+ using extents_type = typename reverse<Extents>::type;
+
+ template<typename Extents>
+ constexpr static extents_type<Extents>
+ make_extents(const Extents& exts)
+ { return reversed(exts); }
+
+ template<typename T, size_t N>
+ constexpr static std::array<T, N>
+ make_expected(const std::array<T, N>& expected)
+ { return reversed(expected)
Inline the reversed function here, and use std::ranges::reverse.
; }
+
+ template<typename Mapping>
+ constexpr static auto
+ padded_stride(const Mapping& m)
+ {
+ auto rank = Mapping::extents_type::rank();
+ return m.stride(rank - 2);
+ }
+
+ template<typename Extents>
+ constexpr static auto
+ padded_extent(const Extents& exts)
+ {
+ auto rank = Extents::rank();
+ return exts.extent(rank - 1);
+ }
+ };
+
#endif
#endif
--
2.50.1
