Extend range of min max optimization (#2825)

microsoft · Jul 1, 2022 · e619743 · e619743
1 parent 0e29ddb
commit e619743
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diff --git a/stl/inc/algorithm b/stl/inc/algorithm
@@ -9442,6 +9442,22 @@ namespace ranges {
         _STL_INTERNAL_STATIC_ASSERT(sentinel_for<_Se, _It>);
         _STL_INTERNAL_STATIC_ASSERT(indirect_strict_weak_order<_Pr, projected<_It, _Pj>>);
 
+#if _USE_STD_VECTOR_ALGORITHMS
+        if constexpr (is_same_v<_Pj, identity> && _Is_min_max_optimization_safe<_It, _Pr> //
+                      && sized_sentinel_for<_Se, _It>) {
+            if (!_STD is_constant_evaluated()) {
+                const auto _First_ptr = _STD to_address(_First);
+                const auto _Last_ptr  = _First_ptr + (_Last - _First);
+                const auto _Result    = __std_max_element(_First_ptr, _Last_ptr);
+                if constexpr (is_pointer_v<_It>) {
+                    return _Result;
+                } else {
+                    return _First + (_Result - _First_ptr);
+                }
+            }
+        }
+#endif // _USE_STD_VECTOR_ALGORITHMS
+
         auto _Found = _First;
         if (_First == _Last) {
             return _Found;
@@ -9547,6 +9563,22 @@ namespace ranges {
         _STL_INTERNAL_STATIC_ASSERT(sentinel_for<_Se, _It>);
         _STL_INTERNAL_STATIC_ASSERT(indirect_strict_weak_order<_Pr, projected<_It, _Pj>>);
 
+#if _USE_STD_VECTOR_ALGORITHMS
+        if constexpr (is_same_v<_Pj, identity> && _Is_min_max_optimization_safe<_It, _Pr> //
+                      && sized_sentinel_for<_Se, _It>) {
+            if (!_STD is_constant_evaluated()) {
+                const auto _First_ptr = _STD to_address(_First);
+                const auto _Last_ptr  = _First_ptr + (_Last - _First);
+                const auto _Result    = __std_min_element(_First_ptr, _Last_ptr);
+                if constexpr (is_pointer_v<_It>) {
+                    return _Result;
+                } else {
+                    return _First + (_Result - _First_ptr);
+                }
+            }
+        }
+#endif // _USE_STD_VECTOR_ALGORITHMS
+
         auto _Found = _First;
         if (_First == _Last) {
             return _Found;
@@ -9686,6 +9718,22 @@ namespace ranges {
         _STL_INTERNAL_STATIC_ASSERT(sentinel_for<_Se, _It>);
         _STL_INTERNAL_STATIC_ASSERT(indirect_strict_weak_order<_Pr, projected<_It, _Pj>>);
 
+#if _USE_STD_VECTOR_ALGORITHMS
+        if constexpr (is_same_v<_Pj, identity> && _Is_min_max_optimization_safe<_It, _Pr> //
+                      && sized_sentinel_for<_Se, _It>) {
+            if (!_STD is_constant_evaluated()) {
+                const auto _First_ptr = _STD to_address(_First);
+                const auto _Last_ptr  = _First_ptr + (_Last - _First);
+                const auto _Result    = __std_minmax_element(_First_ptr, _Last_ptr);
+                if constexpr (is_pointer_v<_It>) {
+                    return {_Result.first, _Result.second};
+                } else {
+                    return {_First + (_Result.first - _First_ptr), _First + (_Result.second - _First_ptr)};
+                }
+            }
+        }
+#endif // _USE_STD_VECTOR_ALGORITHMS
+
         min_max_result<_It> _Found{_First, _First};
 
         if (_First == _Last) {

diff --git a/tests/std/tests/VSO_0000000_vector_algorithms/test.cpp b/tests/std/tests/VSO_0000000_vector_algorithms/test.cpp
@@ -15,6 +15,10 @@
 #include <type_traits>
 #include <vector>
 
+#ifdef __cpp_lib_concepts
+#include <ranges>
+#endif
+
 using namespace std;
 
 #pragma warning(disable : 4984) // 'if constexpr' is a C++17 language extension
@@ -194,6 +198,24 @@ void test_case_min_max_element(const vector<T>& input) {
     assert(expected_min == actual_min);
     assert(expected_max == actual_max);
     assert(expected_minmax == actual_minmax);
+#ifdef __cpp_lib_concepts
+    using ranges::views::take;
+
+    auto actual_min_range          = ranges::min_element(input);
+    auto actual_max_range          = ranges::max_element(input);
+    auto actual_minmax_range       = ranges::minmax_element(input);
+    auto actual_min_sized_range    = ranges::min_element(take(input, static_cast<ptrdiff_t>(input.size())));
+    auto actual_max_sized_range    = ranges::max_element(take(input, static_cast<ptrdiff_t>(input.size())));
+    auto actual_minmax_sized_range = ranges::minmax_element(take(input, static_cast<ptrdiff_t>(input.size())));
+    assert(expected_min == actual_min_range);
+    assert(expected_max == actual_max_range);
+    assert(expected_minmax.first == actual_minmax_range.min);
+    assert(expected_minmax.second == actual_minmax_range.max);
+    assert(expected_min == actual_min_sized_range);
+    assert(expected_max == actual_max_sized_range);
+    assert(expected_minmax.first == actual_minmax_sized_range.min);
+    assert(expected_minmax.second == actual_minmax_sized_range.max);
+#endif // __cpp_lib_concepts
 }
 
 template <class T>