ab3d793982
As a follow-up to #121013 (which optimized `ranges::copy`) and #121026 (which optimized `ranges::copy_backward`), this PR enhances the performance of `std::ranges::{move, move_backward}` for `vector<bool>::iterator`, addressing a subtask outlined in issue #64038. The optimizations bring performance improvements analogous to those achieved for the `{copy, copy_backward}` algorithms: up to 2000x for aligned moves and 60x for unaligned moves. Moreover, comprehensive tests covering up to 4 storage words (256 bytes) with odd and even bit sizes are provided, which validate the proposed optimizations in this patch.
420 lines
14 KiB
C++
420 lines
14 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17
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// UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
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// <algorithm>
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// template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
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// requires indirectly_movable<I1, I2>
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// constexpr ranges::move_backward_result<I1, I2>
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// ranges::move_backward(I1 first, S1 last, I2 result);
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// template<bidirectional_range R, bidirectional_iterator I>
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// requires indirectly_movable<iterator_t<R>, I>
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// constexpr ranges::move_backward_result<borrowed_iterator_t<R>, I>
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// ranges::move_backward(R&& r, I result);
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#include <algorithm>
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#include <array>
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#include <cassert>
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#include <deque>
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#include <iterator>
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#include <ranges>
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#include <vector>
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#include "almost_satisfies_types.h"
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#include "MoveOnly.h"
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#include "test_iterators.h"
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#include "test_macros.h"
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template <class In, class Out = In, class Sent = sentinel_wrapper<In>>
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concept HasMoveBackwardIt = requires(In in, Sent sent, Out out) { std::ranges::move_backward(in, sent, out); };
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static_assert(HasMoveBackwardIt<int*>);
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static_assert(!HasMoveBackwardIt<InputIteratorNotDerivedFrom>);
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static_assert(!HasMoveBackwardIt<InputIteratorNotIndirectlyReadable>);
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static_assert(!HasMoveBackwardIt<InputIteratorNotInputOrOutputIterator>);
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static_assert(!HasMoveBackwardIt<int*, WeaklyIncrementableNotMovable>);
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struct NotIndirectlyCopyable {};
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static_assert(!HasMoveBackwardIt<int*, NotIndirectlyCopyable*>);
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static_assert(!HasMoveBackwardIt<int*, int*, SentinelForNotSemiregular>);
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static_assert(!HasMoveBackwardIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
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template <class Range, class Out>
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concept HasMoveBackwardR = requires(Range range, Out out) { std::ranges::move_backward(range, out); };
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static_assert(HasMoveBackwardR<std::array<int, 10>, int*>);
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static_assert(!HasMoveBackwardR<InputRangeNotDerivedFrom, int*>);
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static_assert(!HasMoveBackwardR<InputRangeNotIndirectlyReadable, int*>);
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static_assert(!HasMoveBackwardR<InputRangeNotInputOrOutputIterator, int*>);
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static_assert(!HasMoveBackwardR<WeaklyIncrementableNotMovable, int*>);
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static_assert(!HasMoveBackwardR<UncheckedRange<NotIndirectlyCopyable*>, int*>);
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static_assert(!HasMoveBackwardR<InputRangeNotSentinelSemiregular, int*>);
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static_assert(!HasMoveBackwardR<InputRangeNotSentinelEqualityComparableWith, int*>);
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static_assert(!HasMoveBackwardR<UncheckedRange<int*>, WeaklyIncrementableNotMovable>);
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static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);
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template <class In, class Out, class Sent, int N>
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constexpr void test(std::array<int, N> in) {
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{
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std::array<int, N> out;
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std::same_as<std::ranges::in_out_result<In, Out>> decltype(auto) ret =
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std::ranges::move_backward(In(in.data()), Sent(In(in.data() + in.size())), Out(out.data() + out.size()));
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assert(in == out);
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assert(base(ret.in) == in.data() + in.size());
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assert(base(ret.out) == out.data());
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}
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{
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std::array<int, N> out;
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auto range = std::ranges::subrange(In(in.data()), Sent(In(in.data() + in.size())));
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std::same_as<std::ranges::in_out_result<In, Out>> decltype(auto) ret =
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std::ranges::move_backward(range, Out(out.data() + out.size()));
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assert(in == out);
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assert(base(ret.in) == in.data() + in.size());
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assert(base(ret.out) == out.data());
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}
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}
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template <class In, class Out, class Sent = In>
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constexpr void test_iterators() {
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// simple test
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test<In, Out, Sent, 4>({1, 2, 3, 4});
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// check that an empty range works
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test<In, Out, Sent, 0>({});
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}
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template <class InContainer, class OutContainer, class In, class Out, class Sent = In>
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constexpr void test_containers() {
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{
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InContainer in{1, 2, 3, 4};
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OutContainer out(4);
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std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
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std::ranges::move_backward(In(in.begin()), Sent(In(in.end())), Out(out.end()));
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assert(std::ranges::equal(in, out));
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assert(base(ret.in) == in.end());
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assert(base(ret.out) == out.begin());
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}
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{
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InContainer in{1, 2, 3, 4};
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OutContainer out(4);
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auto range = std::ranges::subrange(In(in.begin()), Sent(In(in.end())));
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std::same_as<std::ranges::in_out_result<In, Out>> auto ret = std::ranges::move_backward(range, Out(out.end()));
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assert(std::ranges::equal(in, out));
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assert(base(ret.in) == in.end());
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assert(base(ret.out) == out.begin());
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}
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}
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template <template <class> class InIter, template <class> class OutIter>
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constexpr void test_sentinels() {
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test_iterators<InIter<int*>, OutIter<int*>, InIter<int*>>();
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test_iterators<InIter<int*>, OutIter<int*>, sentinel_wrapper<InIter<int*>>>();
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test_iterators<InIter<int*>, OutIter<int*>, sized_sentinel<InIter<int*>>>();
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if (!std::is_constant_evaluated()) {
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if constexpr (!std::is_same_v<InIter<int*>, contiguous_iterator<int*>> &&
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!std::is_same_v<OutIter<int*>, contiguous_iterator<int*>> &&
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!std::is_same_v<InIter<int*>, ContiguousProxyIterator<int*>> &&
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!std::is_same_v<OutIter<int*>, ContiguousProxyIterator<int*>>) {
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test_containers<std::deque<int>,
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std::deque<int>,
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InIter<std::deque<int>::iterator>,
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OutIter<std::deque<int>::iterator>>();
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test_containers<std::deque<int>,
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std::vector<int>,
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InIter<std::deque<int>::iterator>,
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OutIter<std::vector<int>::iterator>>();
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test_containers<std::vector<int>,
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std::deque<int>,
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InIter<std::vector<int>::iterator>,
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OutIter<std::deque<int>::iterator>>();
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test_containers<std::vector<int>,
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std::vector<int>,
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InIter<std::vector<int>::iterator>,
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OutIter<std::vector<int>::iterator>>();
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}
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}
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}
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template <template <class> class Out>
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constexpr void test_in_iterators() {
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test_sentinels<bidirectional_iterator, Out>();
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test_sentinels<random_access_iterator, Out>();
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test_sentinels<contiguous_iterator, Out>();
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test_sentinels<std::type_identity_t, Out>();
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}
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template <template <class> class Out>
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constexpr void test_proxy_in_iterators() {
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test_sentinels<BidirectionalProxyIterator, Out>();
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test_sentinels<RandomAccessProxyIterator, Out>();
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test_sentinels<ContiguousProxyIterator, Out>();
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test_sentinels<ProxyIterator, Out>();
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}
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struct IteratorWithMoveIter {
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using value_type = int;
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using difference_type = int;
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explicit IteratorWithMoveIter() = default;
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int* ptr;
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constexpr IteratorWithMoveIter(int* ptr_) : ptr(ptr_) {}
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constexpr int& operator*() const; // iterator with iter_move should not be dereferenced
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constexpr IteratorWithMoveIter& operator++() {
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++ptr;
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return *this;
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}
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constexpr IteratorWithMoveIter operator++(int) {
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auto ret = *this;
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++*this;
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return ret;
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}
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constexpr IteratorWithMoveIter& operator--() {
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--ptr;
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return *this;
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}
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constexpr IteratorWithMoveIter operator--(int) {
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auto ret = *this;
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--*this;
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return ret;
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}
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friend constexpr int iter_move(const IteratorWithMoveIter&) { return 42; }
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constexpr bool operator==(const IteratorWithMoveIter& other) const = default;
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};
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#if TEST_STD_VER >= 23
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constexpr bool test_vector_bool(std::size_t N) {
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std::vector<bool> v(N, false);
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for (std::size_t i = 0; i < N; i += 2)
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v[i] = true;
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{ // Test move_backward with aligned bytes
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std::vector<bool> in{v};
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std::vector<bool> out(N);
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std::ranges::move_backward(in, out.end());
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assert(out == v);
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}
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{ // Test move_backward with unaligned bytes
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std::vector<bool> in{v};
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std::vector<bool> out(N);
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std::ranges::move_backward(std::views::counted(in.begin(), N - 4), out.end());
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assert(std::ranges::equal(v | std::views::take(N - 4), out | std::views::drop(4)));
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}
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return true;
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}
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#endif
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constexpr bool test() {
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test_in_iterators<bidirectional_iterator>();
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test_in_iterators<random_access_iterator>();
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test_in_iterators<contiguous_iterator>();
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test_in_iterators<std::type_identity_t>();
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test_proxy_in_iterators<BidirectionalProxyIterator>();
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test_proxy_in_iterators<RandomAccessProxyIterator>();
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test_proxy_in_iterators<ContiguousProxyIterator>();
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test_proxy_in_iterators<ProxyIterator>();
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{ // check that a move-only type works
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// When non-trivial
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{
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MoveOnly a[] = {1, 2, 3};
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MoveOnly b[3];
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std::ranges::move_backward(a, std::end(b));
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assert(b[0].get() == 1);
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assert(b[1].get() == 2);
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assert(b[2].get() == 3);
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}
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{
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MoveOnly a[] = {1, 2, 3};
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MoveOnly b[3];
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std::ranges::move_backward(std::begin(a), std::end(a), std::end(b));
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assert(b[0].get() == 1);
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assert(b[1].get() == 2);
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assert(b[2].get() == 3);
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}
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// When trivial
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{
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TrivialMoveOnly a[] = {1, 2, 3};
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TrivialMoveOnly b[3];
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std::ranges::move_backward(a, std::end(b));
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assert(b[0].get() == 1);
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assert(b[1].get() == 2);
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assert(b[2].get() == 3);
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}
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{
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TrivialMoveOnly a[] = {1, 2, 3};
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TrivialMoveOnly b[3];
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std::ranges::move_backward(std::begin(a), std::end(a), std::end(b));
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assert(b[0].get() == 1);
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assert(b[1].get() == 2);
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assert(b[2].get() == 3);
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}
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}
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{ // check that a move-only type works for ProxyIterator
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{
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MoveOnly a[] = {1, 2, 3};
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MoveOnly b[3];
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ProxyRange proxyA{a};
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ProxyRange proxyB{b};
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std::ranges::move_backward(proxyA, std::ranges::next(proxyB.begin(), std::end(proxyB)));
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assert(b[0].get() == 1);
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assert(b[1].get() == 2);
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assert(b[2].get() == 3);
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}
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{
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MoveOnly a[] = {1, 2, 3};
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MoveOnly b[3];
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ProxyRange proxyA{a};
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ProxyRange proxyB{b};
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std::ranges::move_backward(
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std::begin(proxyA), std::end(proxyA), std::ranges::next(proxyB.begin(), std::end(proxyB)));
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assert(b[0].get() == 1);
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assert(b[1].get() == 2);
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assert(b[2].get() == 3);
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}
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}
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{ // check that ranges::dangling is returned
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std::array<int, 4> out;
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std::same_as<std::ranges::in_out_result<std::ranges::dangling, int*>> auto ret =
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std::ranges::move_backward(std::array{1, 2, 3, 4}, out.data() + out.size());
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assert(ret.out == out.data());
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assert((out == std::array{1, 2, 3, 4}));
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}
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{ // check that an iterator is returned with a borrowing range
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std::array in{1, 2, 3, 4};
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std::array<int, 4> out;
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std::same_as<std::ranges::in_out_result<std::array<int, 4>::iterator, int*>> auto ret =
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std::ranges::move_backward(std::views::all(in), out.data() + out.size());
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assert(ret.in == in.end());
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assert(ret.out == out.data());
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assert(in == out);
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}
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{ // check that every element is moved exactly once
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struct MoveOnce {
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bool moved = false;
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constexpr MoveOnce() = default;
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constexpr MoveOnce(const MoveOnce& other) = delete;
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constexpr MoveOnce& operator=(const MoveOnce& other) {
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assert(!other.moved);
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moved = true;
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return *this;
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}
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};
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{
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std::array<MoveOnce, 4> in{};
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std::array<MoveOnce, 4> out{};
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auto ret = std::ranges::move_backward(in.begin(), in.end(), out.end());
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assert(ret.in == in.end());
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assert(ret.out == out.begin());
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assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.moved; }));
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}
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{
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std::array<MoveOnce, 4> in{};
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std::array<MoveOnce, 4> out{};
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auto ret = std::ranges::move_backward(in, out.end());
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assert(ret.in == in.end());
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assert(ret.out == out.begin());
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assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.moved; }));
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}
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}
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{ // check that the range is moved backwards
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struct OnlyBackwardsMovable {
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OnlyBackwardsMovable* next = nullptr;
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bool canMove = false;
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OnlyBackwardsMovable() = default;
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constexpr OnlyBackwardsMovable& operator=(const OnlyBackwardsMovable&) {
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assert(canMove);
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if (next != nullptr)
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next->canMove = true;
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return *this;
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}
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};
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{
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std::array<OnlyBackwardsMovable, 3> in{};
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std::array<OnlyBackwardsMovable, 3> out{};
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out[1].next = &out[0];
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out[2].next = &out[1];
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out[2].canMove = true;
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auto ret = std::ranges::move_backward(in, out.end());
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assert(ret.in == in.end());
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assert(ret.out == out.begin());
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assert(out[0].canMove);
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assert(out[1].canMove);
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assert(out[2].canMove);
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}
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{
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std::array<OnlyBackwardsMovable, 3> in{};
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std::array<OnlyBackwardsMovable, 3> out{};
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out[1].next = &out[0];
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out[2].next = &out[1];
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out[2].canMove = true;
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auto ret = std::ranges::move_backward(in.begin(), in.end(), out.end());
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assert(ret.in == in.end());
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assert(ret.out == out.begin());
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assert(out[0].canMove);
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assert(out[1].canMove);
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assert(out[2].canMove);
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}
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}
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{ // check that iter_move is used properly
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{
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int a[] = {1, 2, 3, 4};
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std::array<int, 4> b;
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auto ret = std::ranges::move_backward(IteratorWithMoveIter(a), IteratorWithMoveIter(a + 4), b.data() + b.size());
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assert(ret.in == a + 4);
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assert(ret.out == b.data());
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assert((b == std::array{42, 42, 42, 42}));
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}
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{
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int a[] = {1, 2, 3, 4};
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std::array<int, 4> b;
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auto range = std::ranges::subrange(IteratorWithMoveIter(a), IteratorWithMoveIter(a + 4));
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auto ret = std::ranges::move_backward(range, b.data() + b.size());
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assert(ret.in == a + 4);
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assert(ret.out == b.data());
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assert((b == std::array{42, 42, 42, 42}));
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}
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}
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#if TEST_STD_VER >= 23
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{ // Test vector<bool>::iterator optimization
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assert(test_vector_bool(8));
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assert(test_vector_bool(19));
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assert(test_vector_bool(32));
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assert(test_vector_bool(49));
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assert(test_vector_bool(64));
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assert(test_vector_bool(199));
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assert(test_vector_bool(256));
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}
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#endif
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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