libstdc++: Improve and cleanup mdspan related code.

The improvement is that in __index_type_cast, we don't need to check at
runtime if we know that _IndexType is smaller than _OIndexType.

The cleanup is whitespace (overlength lines) in <mdspan>, grouping is_always_foo
and is_foo together, and de-uglifying a variable in test code.

libstdc++-v3/ChangeLog:

	* include/std/mdspan (__mdspan::__index_type_cast): Optimize by
	skipping a __glibcxx_assert if it's know at compile-time.
	(std::layout_left_padded, std::layout_righ_padded): Reorder
	is_always_strided and is_unique member functions.
	* testsuite/23_containers/mdspan/int_like.h: Rename _M_i to
	value.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>

diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index 6714b19a88436d476113d4252f28dc542644e9dc..8d2421819a55946e950f7b3eec3c23104d32463a 100644 (file)
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -77,11 +77,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
        if constexpr (std::is_integral_v<_OIndexType>)
          {
-           __glibcxx_assert(cmp_less_equal(__other,
-               __gnu_cxx::__int_traits<_IndexType>::__max));
+           constexpr _IndexType __index_type_max
+             = __gnu_cxx::__int_traits<_IndexType>::__max;
+           constexpr _OIndexType __oindex_type_max
+             = __gnu_cxx::__int_traits<_OIndexType>::__max;
+
+           if constexpr (__index_type_max < __oindex_type_max)
+             __glibcxx_assert(cmp_less_equal(__other, __index_type_max));
+
            if constexpr (std::is_signed_v<_OIndexType>)
              __glibcxx_assert(__other >= 0);
-           return std::move(__other);
+           return static_cast<_IndexType>(__other);
          }
        else
          {
@@ -821,8 +827,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        mapping(const _LeftpadMapping& __other) noexcept
        : mapping(__other.extents(), __mdspan::__internal_ctor{})
        {
-         constexpr size_t __ostride_sta = __mdspan::__get_static_stride<
-           _LeftpadMapping>();
+         constexpr size_t __ostride_sta
+           = __mdspan::__get_static_stride<_LeftpadMapping>();
 
          if constexpr (extents_type::rank() > 1)
            {
@@ -981,7 +987,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       template<typename _RightPaddedMapping>
        requires __mdspan::__is_right_padded_mapping<_RightPaddedMapping>
                 && is_constructible_v<extents_type,
-                                      typename _RightPaddedMapping::extents_type>
+                     typename _RightPaddedMapping::extents_type>
        constexpr
        explicit(!is_convertible_v<typename _RightPaddedMapping::extents_type,
                                   extents_type>)
@@ -989,8 +995,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        : mapping(__other.extents(), __mdspan::__internal_ctor{})
        {
          constexpr size_t __rank = extents_type::rank();
-         constexpr size_t __ostride_sta = __mdspan::__get_static_stride<
-           _RightPaddedMapping>();
+         constexpr size_t __ostride_sta
+           = __mdspan::__get_static_stride<_RightPaddedMapping>();
 
          if constexpr (__rank > 1)
            {
@@ -1441,7 +1447,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        constexpr static const size_t _S_unpad_end = _Rank;
 
        template<typename _IndexType, size_t _StaticStride, size_t..._Extents>
-         constexpr static auto _S_make_padded_extent(
+         constexpr static auto
+         _S_make_padded_extent(
            extents<_IndexType, _StaticStride> __stride,
            const extents<_IndexType, _Extents...>& __exts)
          {
@@ -1467,7 +1474,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        constexpr static size_t _S_unpad_end = _Rank - 1;
 
        template<typename _IndexType, size_t _StaticStride, size_t..._Extents>
-         constexpr static auto _S_make_padded_extent(
+         constexpr static auto
+         _S_make_padded_extent(
            extents<_IndexType, _StaticStride> __stride,
            const extents<_IndexType, _Extents...>& __exts)
          {
@@ -1792,7 +1800,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        { }
 
        template<__mdspan::__valid_index_type<index_type> _OIndexType>
-         constexpr mapping(const extents_type& __exts, _OIndexType __pad)
+         constexpr
+         mapping(const extents_type& __exts, _OIndexType __pad)
          : _M_storage(__exts,
              __mdspan::__index_type_cast<index_type>(std::move(__pad)))
          { }
@@ -1881,10 +1890,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        is_always_unique() noexcept { return true; }
 
        static constexpr bool
-       is_always_strided() noexcept { return true; }
+       is_unique() noexcept { return true; }
 
        static constexpr bool
-       is_unique() noexcept { return true; }
+       is_always_strided() noexcept { return true; }
 
        static constexpr bool
        is_strided() noexcept { return true; }
@@ -1952,7 +1961,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        { }
 
        template<__mdspan::__valid_index_type<index_type> _OIndexType>
-         constexpr mapping(const extents_type& __exts, _OIndexType __pad)
+         constexpr
+         mapping(const extents_type& __exts, _OIndexType __pad)
          : _M_storage(__exts,
              __mdspan::__index_type_cast<index_type>(std::move(__pad)))
          { }
@@ -2040,10 +2050,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        is_always_unique() noexcept { return true; }
 
        static constexpr bool
-       is_always_strided() noexcept { return true; }
+       is_unique() noexcept { return true; }
 
        static constexpr bool
-       is_unique() noexcept { return true; }
+       is_always_strided() noexcept { return true; }
 
        static constexpr bool
        is_strided() noexcept { return true; }

diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/int_like.h b/libstdc++-v3/testsuite/23_containers/mdspan/int_like.h
index 310dd8ddf207e3cf6dda9988fe94f11c8c528be0..e9172c1345592df06222d81767311d014e31d03b 100644 (file)
--- a/libstdc++-v3/testsuite/23_containers/mdspan/int_like.h
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/int_like.h
@@ -15,7 +15,7 @@ template<CustomIndexKind Kind>
   public:
     explicit
     CustomIndexType(int i)
-    : _M_i(i)
+    : value(i)
     { }
 
     CustomIndexType() = delete;
@@ -31,25 +31,25 @@ template<CustomIndexKind Kind>
     constexpr
     operator int() const noexcept
     requires (Kind == CustomIndexKind::Const)
-    { return _M_i; }
+    { return value; }
 
     constexpr
     operator int() const
     requires (Kind == CustomIndexKind::Throwing)
-    { return _M_i; }
+    { return value; }
 
     constexpr
     operator int() noexcept
     requires (Kind == CustomIndexKind::Mutating)
-    { return _M_i; }
+    { return value; }
 
     constexpr
     operator int() && noexcept
     requires (Kind == CustomIndexKind::RValue)
-    { return _M_i; }
+    { return value; }
 
   private:
-    int _M_i;
+    int value;
   };
 
 using IntLike = CustomIndexType<CustomIndexKind::Const>;