SSE2 & AVX2 std::find & std::count

stl/CMakeLists.txt

@@ -265,6 +265,7 @@ set(IMPLIB_SOURCES
 set(DLL_SOURCES
     ${CMAKE_CURRENT_LIST_DIR}/src/dllmain.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/instances.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/vector_algorithms.cpp
 )
 
 # Sources that must not be compiled with /GL, since they contain CRT initializers.

stl/inc/algorithm

@@ -485,6 +485,19 @@ namespace ranges {
             _STL_INTERNAL_STATIC_ASSERT(sentinel_for<_Se, _It>);
             _STL_INTERNAL_STATIC_ASSERT(indirect_binary_predicate<ranges::equal_to, projected<_It, _Pj>, const _Ty*>);
 
+#if _USE_STD_VECTOR_ALGORITHMS
+            if (!_STD is_constant_evaluated()) {
+                if constexpr (is_same_v<_Pj, identity> && _Vector_alg_in_find_is_safe<_It, _Ty>) {
+                    if (!_Within_limits(_First, _Val)) {
+                        return 0;
+                    }
+
+                    return static_cast<iter_difference_t<_It>>(
+                        __std_count_trivial(_To_address(_First), _To_address(_Last), _Val));
+                }
+            }
+#endif // _USE_STD_VECTOR_ALGORITHMS
+
             iter_difference_t<_It> _Count = 0;
             for (; _First != _Last; ++_First) {
                 if (_STD invoke(_Proj, *_First) == _Val) {