[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>()) ==
+           std::make_pair(Iter(lhs.data() + offset), Iter(rhs.data() + offset)));
+  }
+
+#if TEST_STD_VER >= 14
+  assert(
+      std::mismatch(Iter(lhs.data()), Iter(lhs.data() + lhs.size()), Iter(rhs.data()), Iter(rhs.data() + rhs.size())) ==
+      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()),
+                       Iter(rhs.data() + rhs.size()),
+                       std::equal_to<int>()) == std::make_pair(Iter(lhs.data() + offset), Iter(rhs.data() + offset)));
 #endif
+}
 
-int main(int, char**)
-{
-    int ia[] = {0, 1, 2, 2, 0, 1, 2, 3};
-    const unsigned sa = sizeof(ia)/sizeof(ia[0]);
-    int ib[] = {0, 1, 2, 3, 0, 1, 2, 3};
-    const unsigned sb = sizeof(ib)/sizeof(ib[0]); ((void)sb); // unused in C++11
-
-    typedef cpp17_input_iterator<const int*> II;
-    typedef random_access_iterator<const int*>  RAI;
-
-    assert(std::mismatch(II(ia), II(ia + sa), II(ib))
-            == (std::pair<II, II>(II(ia+3), II(ib+3))));
-
-    assert(std::mismatch(RAI(ia), RAI(ia + sa), RAI(ib))
-            == (std::pair<RAI, RAI>(RAI(ia+3), RAI(ib+3))));
+template <class Iter>
+TEST_CONSTEXPR_CXX20 bool test() {
----------------
ldionne wrote:

We need to add coverage for non-ints here, since ints are now taking a special codepath.

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