029cb8aff1
This patch fixes an issue in libc++ where `std::copy_backward` and `ranges::copy_backward` incorrectly copy `std::vector<bool>` with small storage types (e.g., `uint8_t`, `uint16_t`). The problem arises from flawed bit mask computations involving integral promotions and sign-bit extension, leading to unintended zeroing of bits. This patch corrects the bitwise operations to ensure correct bit-level copying. Fixes #131718.
269 lines
9.5 KiB
C++
269 lines
9.5 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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// <algorithm>
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// template<BidirectionalIterator InIter, BidirectionalIterator OutIter>
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// requires OutputIterator<OutIter, InIter::reference>
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// constexpr OutIter // constexpr after C++17
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// copy_backward(InIter first, InIter last, OutIter result);
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// XFAIL: FROZEN-CXX03-HEADERS-FIXME
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#include <algorithm>
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#include <cassert>
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#include <vector>
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#include "sized_allocator.h"
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#include "test_macros.h"
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#include "test_iterators.h"
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#include "type_algorithms.h"
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#include "user_defined_integral.h"
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class PaddedBase {
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public:
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TEST_CONSTEXPR PaddedBase(std::int16_t a, std::int8_t b) : a_(a), b_(b) {}
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std::int16_t a_;
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std::int8_t b_;
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};
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class Derived : public PaddedBase {
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public:
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TEST_CONSTEXPR Derived(std::int16_t a, std::int8_t b, std::int8_t c) : PaddedBase(a, b), c_(c) {}
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std::int8_t c_;
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};
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struct TestIterators {
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template <class InIter>
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TEST_CONSTEXPR_CXX20 void operator()() {
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types::for_each(types::bidirectional_iterator_list<int*>(), TestImpl<InIter>());
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}
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template <class InIter>
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struct TestImpl {
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template <class OutIter>
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TEST_CONSTEXPR_CXX20 void operator()() {
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const unsigned N = 1000;
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int ia[N] = {};
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for (unsigned i = 0; i < N; ++i)
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ia[i] = i;
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int ib[N] = {0};
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OutIter r = std::copy_backward(InIter(ia), InIter(ia + N), OutIter(ib + N));
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assert(base(r) == ib);
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for (unsigned i = 0; i < N; ++i)
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assert(ia[i] == ib[i]);
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}
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};
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};
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TEST_CONSTEXPR_CXX20 bool test_vector_bool(std::size_t N) {
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std::vector<bool> in(N, false);
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for (std::size_t i = 0; i < N; i += 2)
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in[i] = true;
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{ // Test copy_backward with aligned bytes
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std::vector<bool> out(N);
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std::copy_backward(in.begin(), in.end(), out.end());
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assert(in == out);
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}
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{ // Test copy_backward with unaligned bytes
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std::vector<bool> out(N + 8);
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std::copy_backward(in.begin(), in.end(), out.end() - 4);
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for (std::size_t i = 0; i < N; ++i)
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assert(out[i + 4] == in[i]);
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}
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return true;
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}
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TEST_CONSTEXPR_CXX20 bool test() {
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types::for_each(types::bidirectional_iterator_list<const int*>(), TestIterators());
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{ // Make sure that padding bits aren't copied
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Derived src(1, 2, 3);
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Derived dst(4, 5, 6);
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std::copy_backward(
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static_cast<PaddedBase*>(&src), static_cast<PaddedBase*>(&src) + 1, static_cast<PaddedBase*>(&dst) + 1);
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assert(dst.a_ == 1);
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assert(dst.b_ == 2);
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assert(dst.c_ == 6);
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}
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{ // Make sure that overlapping ranges can be copied
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int a[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
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std::copy_backward(a, a + 7, a + 10);
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int expected[] = {1, 2, 3, 1, 2, 3, 4, 5, 6, 7};
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assert(std::equal(a, a + 10, expected));
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}
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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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// Validate std::copy_backward with std::vector<bool> iterators and custom storage types.
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// Ensure that assigned bits hold the intended values, while unassigned bits stay unchanged.
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// Related issue: https://github.com/llvm/llvm-project/issues/131718.
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{
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//// Tests for std::copy_backward with aligned bits
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{ // Test the first (partial) word for uint8_t
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using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
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std::vector<bool, Alloc> in(7, false, Alloc(1));
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std::vector<bool, Alloc> out(8, true, Alloc(1));
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std::copy_backward(in.begin(), in.begin() + 1, out.begin() + 1);
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assert(out[0] == false);
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for (std::size_t i = 1; i < out.size(); ++i)
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assert(out[i] == true);
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}
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{ // Test the last (partial) word for uint8_t
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using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
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std::vector<bool, Alloc> in(8, false, Alloc(1));
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for (std::size_t i = 0; i < in.size(); i += 2)
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in[i] = true;
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std::vector<bool, Alloc> out(8, true, Alloc(1));
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std::copy_backward(in.end() - 4, in.end(), out.end());
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for (std::size_t i = 0; i < static_cast<std::size_t>(in.size() - 4); ++i)
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assert(out[i] == true);
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for (std::size_t i = in.size() + 4; i < out.size(); ++i)
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assert(in[i] == out[i]);
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}
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{ // Test the middle (whole) words for uint8_t
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using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
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std::vector<bool, Alloc> in(17, false, Alloc(1));
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for (std::size_t i = 0; i < in.size(); i += 2)
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in[i] = true;
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std::vector<bool, Alloc> out(24, true, Alloc(1));
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std::copy_backward(in.begin(), in.end(), out.begin() + in.size());
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for (std::size_t i = 0; i < in.size(); ++i)
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assert(in[i] == out[i]);
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for (std::size_t i = in.size(); i < out.size(); ++i)
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assert(out[i] == true);
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}
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{ // Test the first (partial) word for uint16_t
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using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
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std::vector<bool, Alloc> in(14, false, Alloc(1));
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std::vector<bool, Alloc> out(16, true, Alloc(1));
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std::copy_backward(in.begin(), in.begin() + 2, out.begin() + 2);
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assert(out[0] == false);
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assert(out[1] == false);
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for (std::size_t i = 2; i < out.size(); ++i)
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assert(out[i] == true);
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}
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{ // Test the last (partial) word for uint16_t
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using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
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std::vector<bool, Alloc> in(16, false, Alloc(1));
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for (std::size_t i = 0; i < in.size(); i += 2)
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in[i] = true;
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std::vector<bool, Alloc> out(16, true, Alloc(1));
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std::copy_backward(in.end() - 8, in.end(), out.end());
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for (std::size_t i = 0; i < static_cast<std::size_t>(in.size() - 8); ++i)
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assert(out[i] == true);
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for (std::size_t i = in.size() + 8; i < out.size(); ++i)
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assert(in[i] == out[i]);
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}
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{ // Test the middle (whole) words for uint16_t
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using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
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std::vector<bool, Alloc> in(34, false, Alloc(1));
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for (std::size_t i = 0; i < in.size(); i += 2)
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in[i] = true;
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std::vector<bool, Alloc> out(48, true, Alloc(1));
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std::copy_backward(in.begin(), in.end(), out.begin() + in.size());
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for (std::size_t i = 0; i < in.size(); ++i)
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assert(in[i] == out[i]);
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for (std::size_t i = in.size(); i < out.size(); ++i)
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assert(out[i] == true);
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}
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//// Tests for std::copy_backward with unaligned bits
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{ // Test the first (partial) word for uint8_t
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using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
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std::vector<bool, Alloc> in(8, false, Alloc(1));
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std::vector<bool, Alloc> out(8, true, Alloc(1));
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std::copy_backward(in.begin(), in.begin() + 1, out.begin() + 1);
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assert(out[0] == false);
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for (std::size_t i = 1; i < out.size(); ++i)
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assert(out[i] == true);
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}
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{ // Test the last (partial) word for uint8_t
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using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
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std::vector<bool, Alloc> in(8, false, Alloc(1));
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std::vector<bool, Alloc> out(8, true, Alloc(1));
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std::copy_backward(in.end() - 1, in.end(), out.begin() + 1);
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assert(out[0] == false);
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for (std::size_t i = 1; i < out.size(); ++i)
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assert(out[i] == true);
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}
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{ // Test the middle (whole) words for uint8_t
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using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
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std::vector<bool, Alloc> in(16, false, Alloc(1));
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for (std::size_t i = 0; i < in.size(); i += 2)
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in[i] = true;
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std::vector<bool, Alloc> out(17, true, Alloc(1));
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std::copy_backward(in.begin(), in.end(), out.end());
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assert(out[0] == true);
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for (std::size_t i = 0; i < in.size(); ++i)
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assert(in[i] == out[i + 1]);
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}
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{ // Test the first (partial) word for uint16_t
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using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
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std::vector<bool, Alloc> in(16, false, Alloc(1));
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std::vector<bool, Alloc> out(16, true, Alloc(1));
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std::copy_backward(in.begin(), in.begin() + 2, out.begin() + 2);
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assert(out[0] == false);
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assert(out[1] == false);
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for (std::size_t i = 2; i < out.size(); ++i)
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assert(out[i] == true);
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}
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{ // Test the last (partial) word for uint16_t
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using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
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std::vector<bool, Alloc> in(16, false, Alloc(1));
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std::vector<bool, Alloc> out(16, true, Alloc(1));
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std::copy_backward(in.end() - 2, in.end(), out.begin() + 2);
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assert(out[0] == false);
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assert(out[1] == false);
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for (std::size_t i = 2; i < out.size(); ++i)
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assert(out[i] == true);
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}
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{ // Test the middle (whole) words for uint16_t
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using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
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std::vector<bool, Alloc> in(32, false, Alloc(1));
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for (std::size_t i = 0; i < in.size(); i += 2)
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in[i] = true;
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std::vector<bool, Alloc> out(33, true, Alloc(1));
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std::copy_backward(in.begin(), in.end(), out.end());
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assert(out[0] == true);
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for (std::size_t i = 0; i < in.size(); ++i)
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assert(in[i] == out[i + 1]);
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}
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}
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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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#if TEST_STD_VER > 17
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static_assert(test());
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#endif
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return 0;
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}
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