[libcxx-commits] [libcxx] [libc++] Vectorize std::mismatch with trivially equality comparable types (PR #87716)

[Louis Dionne via libcxx-commits]

================
@@ -116,9 +112,41 @@ __mismatch(_Tp* __first1, _Tp* __last1, _Tp* __first2, _Pred& __pred, _Proj1& __
     } // else loop over the elements individually
   }
 
-  return std::__mismatch_loop(__first1, __last1, __first2, __pred, __proj1, __proj2);
+  __equal_to __pred;
+  __identity __proj;
+  return std::__mismatch_loop(__first1, __last1, __first2, __pred, __proj, __proj);
+}
+
+template <class _Tp,
+          class _Pred,
+          class _Proj1,
+          class _Proj2,
+          __enable_if_t<is_integral<_Tp>::value && __desugars_to_v<__equal_tag, _Pred, _Tp, _Tp> &&
+                            __is_identity<_Proj1>::value && __is_identity<_Proj2>::value,
+                        int> = 0>
+_LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Tp*, _Tp*>
+__mismatch(_Tp* __first1, _Tp* __last1, _Tp* __first2, _Pred&, _Proj1&, _Proj2&) {
+  return std::__mismatch_vectorized(__first1, __last1, __first2);
 }
 
+template <class _Tp,
+          class _Pred,
+          class _Proj1,
+          class _Proj2,
+          __enable_if_t<!is_integral<_Tp>::value && __desugars_to_v<__equal_tag, _Pred, _Tp, _Tp> &&
+                            __is_identity<_Proj1>::value && __is_identity<_Proj2>::value &&
+                            __can_map_to_integer_v<_Tp> && __libcpp_is_trivially_equality_comparable<_Tp, _Tp>::value,
----------------
ldionne wrote:

As a drive-by, I would like us to add this to the documentation for `__libcpp_is_trivially_equality_comparable`:

```
// The following types are not trivially equality comparable:
//  [...]
//   objects with padding bytes: <explain>
```

https://github.com/llvm/llvm-project/pull/87716