1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // UNSUPPORTED: c++03
10 
11 // <algorithm>
12 
13 // We optimize std::copy(_backward) and std::move(_backward) into memmove
14 // when the iterator is trivial and contiguous and the type in question
15 // is also trivially (copyable, movable). This test verifies that the
16 // optimization never eliminates an actually non-trivial copy or move.
17 
18 #include <algorithm>
19 #include <iterator>
20 #include <cassert>
21 
22 #include "test_macros.h"
23 #include "test_iterators.h"
24 
25 struct TMBNTC {
26     int *p;
27     constexpr TMBNTC(int& copies) : p(&copies) {}
28     constexpr TMBNTC(const TMBNTC&) = default;
29     TEST_CONSTEXPR_CXX14 TMBNTC& operator=(TMBNTC&&) = default;
30     TEST_CONSTEXPR_CXX14 TMBNTC& operator=(const TMBNTC&) { ++*p; return *this; }
31 };
32 
33 TEST_CONSTEXPR_CXX20 bool
34 test_trivial_moveassign_but_no_trivial_copyassign()
35 {
36     int copies = 0;
37     TMBNTC ia[] = { copies, copies, copies, copies };
38     TMBNTC ib[] = { copies, copies, copies, copies };
39     std::copy(ia, ia+4, ib);
40     assert(copies == 4);
41     copies = 0;
42     std::copy_backward(ia, ia+4, ib+4);
43     assert(copies == 4);
44 
45     copies = 0;
46     std::copy(std::make_move_iterator(ia), std::make_move_iterator(ia+4), ib);
47     assert(copies == 0);
48     std::copy_backward(std::make_move_iterator(ia), std::make_move_iterator(ia+4), ib+4);
49     assert(copies == 0);
50 
51     std::move(ia, ia+4, ib);
52     assert(copies == 0);
53     std::move_backward(ia, ia+4, ib+4);
54     assert(copies == 0);
55 
56     return true;
57 }
58 
59 struct TCBNTM {
60     int *p;
61     constexpr TCBNTM(int& moves) : p(&moves) {}
62     constexpr TCBNTM(const TCBNTM&) = default;
63     TEST_CONSTEXPR_CXX14 TCBNTM& operator=(TCBNTM&&) { ++*p; return *this; }
64     TEST_CONSTEXPR_CXX14 TCBNTM& operator=(const TCBNTM&) = default;
65 };
66 
67 TEST_CONSTEXPR_CXX20 bool
68 test_trivial_copyassign_but_no_trivial_moveassign()
69 {
70     int moves = 0;
71     TCBNTM ia[] = { moves, moves, moves, moves };
72     TCBNTM ib[] = { moves, moves, moves, moves };
73     std::move(ia, ia+4, ib);
74     assert(moves == 4);
75     moves = 0;
76     std::move_backward(ia, ia+4, ib+4);
77     assert(moves == 4);
78 
79     moves = 0;
80     std::copy(std::make_move_iterator(ia), std::make_move_iterator(ia+4), ib);
81     assert(moves == 4);
82     moves = 0;
83     std::copy_backward(std::make_move_iterator(ia), std::make_move_iterator(ia+4), ib+4);
84     assert(moves == 4);
85 
86     moves = 0;
87     std::copy(ia, ia+4, ib);
88     assert(moves == 0);
89     std::copy_backward(ia, ia+4, ib+4);
90     assert(moves == 0);
91 
92     return true;
93 }
94 
95 int main(int, char**)
96 {
97     test_trivial_moveassign_but_no_trivial_copyassign();
98     test_trivial_copyassign_but_no_trivial_moveassign();
99 
100 #if TEST_STD_VER > 17
101     static_assert(test_trivial_moveassign_but_no_trivial_copyassign());
102     static_assert(test_trivial_copyassign_but_no_trivial_moveassign());
103 #endif
104 
105     return 0;
106 }
107