[libcxx-commits] [libcxx] [libc++] Vectorize mismatch (PR #73255)

[Louis Dionne via libcxx-commits]

================
@@ -16,79 +16,133 @@
 // template<InputIterator Iter1, InputIterator Iter2Pred>
 //   constexpr pair<Iter1, Iter2>   // constexpr after c++17
 //   mismatch(Iter1 first1, Iter1 last1, Iter2 first2, Iter2 last2); // C++14
+//
+// template<InputIterator Iter1, InputIterator Iter2,
+//          Predicate<auto, Iter1::value_type, Iter2::value_type> Pred>
+//   requires CopyConstructible<Pred>
+//   constexpr pair<Iter1, Iter2>   // constexpr after c++17
+//   mismatch(Iter1 first1, Iter1 last1, Iter2 first2, Pred pred);
+//
+// template<InputIterator Iter1, InputIterator Iter2, Predicate Pred>
+//   constexpr pair<Iter1, Iter2>   // constexpr after c++17
+//   mismatch(Iter1 first1, Iter1 last1, Iter2 first2, Iter2 last2, Pred pred); // C++14
+
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=50000000
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-ops-limit): -fconstexpr-ops-limit=100000000
 
 #include <algorithm>
+#include <array>
 #include <cassert>
+#include <vector>
 
 #include "test_macros.h"
 #include "test_iterators.h"
-
-#if TEST_STD_VER > 17
-TEST_CONSTEXPR bool test_constexpr() {
-    int ia[] = {1, 3, 6, 7};
-    int ib[] = {1, 3};
-    int ic[] = {1, 3, 5, 7};
-    typedef cpp17_input_iterator<int*>         II;
-    typedef bidirectional_iterator<int*> BI;
-
-    auto p1 = std::mismatch(std::begin(ia), std::end(ia), std::begin(ic));
-    if (p1.first != ia+2 || p1.second != ic+2)
-        return false;
-
-    auto p2 = std::mismatch(std::begin(ia), std::end(ia), std::begin(ic), std::end(ic));
-    if (p2.first != ia+2 || p2.second != ic+2)
-        return false;
-
-    auto p3 = std::mismatch(std::begin(ib), std::end(ib), std::begin(ic));
-    if (p3.first != ib+2 || p3.second != ic+2)
-        return false;
-
-    auto p4 = std::mismatch(std::begin(ib), std::end(ib), std::begin(ic), std::end(ic));
-    if (p4.first != ib+2 || p4.second != ic+2)
-        return false;
-
-    auto p5 = std::mismatch(II(std::begin(ib)), II(std::end(ib)), II(std::begin(ic)));
-    if (p5.first != II(ib+2) || p5.second != II(ic+2))
-        return false;
-    auto p6 = std::mismatch(BI(std::begin(ib)), BI(std::end(ib)), BI(std::begin(ic)), BI(std::end(ic)));
-    if (p6.first != BI(ib+2) || p6.second != BI(ic+2))
-        return false;
-
-    return true;
-    }
+#include "type_algorithms.h"
+
+template <class Iter, class Container1, class Container2>
+TEST_CONSTEXPR_CXX20 void check(Container1 lhs, Container2 rhs, size_t offset) {
+  if (lhs.size() == rhs.size()) {
+    assert(std::mismatch(Iter(lhs.data()), Iter(lhs.data() + lhs.size()), Iter(rhs.data())) ==
+           std::make_pair(Iter(lhs.data() + offset), Iter(rhs.data() + offset)));
+
+    assert(std::mismatch(Iter(lhs.data()), Iter(lhs.data() + lhs.size()), Iter(rhs.data()), std::equal_to<int>()) ==
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ldionne wrote:

We need coverage for the pred version with something other than `std::equal_to`.

https://github.com/llvm/llvm-project/pull/73255