[libcxx-commits] [libcxx] [libc++] Speed-up vector<bool> range-based operations [3/3] (PR #120134)
Peng Liu via libcxx-commits
libcxx-commits at lists.llvm.org
Mon Jan 20 19:58:15 PST 2025
https://github.com/winner245 updated https://github.com/llvm/llvm-project/pull/120134
>From 05c18a3495e91719049a40e020a9b1cc6b84ee98 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Mon, 16 Dec 2024 13:30:56 -0500
Subject: [PATCH] Speed-up range operations in vector<bool>
---
libcxx/include/__algorithm/copy.h | 55 ++++++++++++++++++
libcxx/include/__bit_reference | 12 ++++
.../containers/ContainerBenchmarks.h | 58 +++++++++++++++++++
.../vector_bool_operations.bench.cpp | 37 ++++++++++++
.../alg.copy/copy.pass.cpp | 33 +++++++++++
5 files changed, 195 insertions(+)
create mode 100644 libcxx/test/benchmarks/containers/vector_bool_operations.bench.cpp
diff --git a/libcxx/include/__algorithm/copy.h b/libcxx/include/__algorithm/copy.h
index 962aa90059d574..4727afcc7fcd3d 100644
--- a/libcxx/include/__algorithm/copy.h
+++ b/libcxx/include/__algorithm/copy.h
@@ -13,10 +13,13 @@
#include <__algorithm/for_each_segment.h>
#include <__algorithm/min.h>
#include <__config>
+#include <__fwd/bit_reference.h>
+#include <__iterator/distance.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/segmented_iterator.h>
#include <__type_traits/common_type.h>
#include <__type_traits/enable_if.h>
+#include <__type_traits/is_convertible.h>
#include <__utility/move.h>
#include <__utility/pair.h>
@@ -95,6 +98,58 @@ struct __copy_impl {
}
}
+ template <class _InIter,
+ class _Cp,
+ __enable_if_t<__has_forward_iterator_category<_InIter>::value &&
+ is_convertible<typename iterator_traits<_InIter>::value_type, bool>::value,
+ int> = 0>
+ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_InIter, __bit_iterator<_Cp, false> >
+ operator()(_InIter __first, _InIter __last, __bit_iterator<_Cp, false> __result) const {
+ using _It = __bit_iterator<_Cp, false>;
+ using __storage_type = typename _It::__storage_type;
+ __storage_type __n = static_cast<__storage_type>(std::distance(__first, __last));
+ const unsigned __bits_per_word = _It::__bits_per_word;
+
+ if (__n) {
+ // do first partial word, if present
+ if (__result.__ctz_ != 0) {
+ __storage_type __clz = static_cast<__storage_type>(__bits_per_word - __result.__ctz_);
+ __storage_type __dn = std::min(__clz, __n);
+ __storage_type __w = *__result.__seg_;
+ __storage_type __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
+ __w &= ~__m;
+ for (__storage_type __i = 0; __i < __dn; ++__i, ++__first)
+ __w |= static_cast<__storage_type>(*__first) << __result.__ctz_++;
+ *__result.__seg_ = __w;
+ if (__result.__ctz_ == __bits_per_word) {
+ __result.__ctz_ = 0;
+ ++__result.__seg_;
+ }
+ __n -= __dn;
+ }
+ }
+ // do middle whole words, if present
+ __storage_type __nw = __n / __bits_per_word;
+ __n -= __nw * __bits_per_word;
+ for (; __nw; --__nw) {
+ __storage_type __w = 0;
+ for (__storage_type __i = 0; __i < __bits_per_word; ++__i, ++__first)
+ __w |= static_cast<__storage_type>(*__first) << __i;
+ *__result.__seg_++ = __w;
+ }
+ // do last partial word, if present
+ if (__n) {
+ __storage_type __w = 0;
+ for (__storage_type __i = 0; __i < __n; ++__i, ++__first)
+ __w |= static_cast<__storage_type>(*__first) << __i;
+ __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
+ *__result.__seg_ &= ~__m;
+ *__result.__seg_ |= __w;
+ __result.__ctz_ = __n;
+ }
+ return std::make_pair(std::move(__first), std::move(__result));
+ }
+
// At this point, the iterators have been unwrapped so any `contiguous_iterator` has been unwrapped to a pointer.
template <class _In, class _Out, __enable_if_t<__can_lower_copy_assignment_to_memmove<_In, _Out>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*>
diff --git a/libcxx/include/__bit_reference b/libcxx/include/__bit_reference
index 67abb023122edf..c76686c01cdb7a 100644
--- a/libcxx/include/__bit_reference
+++ b/libcxx/include/__bit_reference
@@ -10,6 +10,7 @@
#ifndef _LIBCPP___BIT_REFERENCE
#define _LIBCPP___BIT_REFERENCE
+#include <__algorithm/copy.h>
#include <__algorithm/copy_n.h>
#include <__algorithm/min.h>
#include <__bit/countr.h>
@@ -22,8 +23,11 @@
#include <__memory/construct_at.h>
#include <__memory/pointer_traits.h>
#include <__type_traits/conditional.h>
+#include <__type_traits/enable_if.h>
#include <__type_traits/is_constant_evaluated.h>
+#include <__type_traits/is_convertible.h>
#include <__type_traits/void_t.h>
+#include <__utility/pair.h>
#include <__utility/swap.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -978,6 +982,14 @@ private:
template <class _Dp>
friend struct __bit_array;
+ template <class _InIter,
+ class _Dp,
+ __enable_if_t<__has_forward_iterator_category<_InIter>::value &&
+ is_convertible<typename iterator_traits<_InIter>::value_type, bool>::value,
+ int> >
+ _LIBCPP_CONSTEXPR_SINCE_CXX14 friend pair<_InIter, __bit_iterator<_Dp, false> >
+ __copy_impl::operator()(_InIter __first, _InIter __last, __bit_iterator<_Dp, false> __result) const;
+
template <bool _FillVal, class _Dp>
_LIBCPP_CONSTEXPR_SINCE_CXX20 friend void
__fill_n_bool(__bit_iterator<_Dp, false> __first, typename __size_difference_type_traits<_Dp>::size_type __n);
diff --git a/libcxx/test/benchmarks/containers/ContainerBenchmarks.h b/libcxx/test/benchmarks/containers/ContainerBenchmarks.h
index 5fc8981619672c..aa22e1cfed1735 100644
--- a/libcxx/test/benchmarks/containers/ContainerBenchmarks.h
+++ b/libcxx/test/benchmarks/containers/ContainerBenchmarks.h
@@ -51,6 +51,30 @@ void BM_Assignment(benchmark::State& st, Container) {
}
}
+template <class Container, class GenInputs>
+void BM_assign_iter_iter(benchmark::State& st, Container c, GenInputs gen) {
+ auto in = gen(st.range(0));
+ auto beg = in.begin();
+ auto end = in.end();
+ for (auto _ : st) {
+ c.assign(beg, end);
+ DoNotOptimizeData(c);
+ DoNotOptimizeData(in);
+ benchmark::ClobberMemory();
+ }
+}
+
+template <std::size_t... sz, typename Container, typename GenInputs>
+void BM_assign_range(benchmark::State& st, Container c, GenInputs gen) {
+ auto in = gen(st.range(0));
+ for (auto _ : st) {
+ c.assign_range(in);
+ DoNotOptimizeData(c);
+ DoNotOptimizeData(in);
+ benchmark::ClobberMemory();
+ }
+}
+
template <std::size_t... sz, typename Container, typename GenInputs>
void BM_AssignInputIterIter(benchmark::State& st, Container c, GenInputs gen) {
auto v = gen(1, sz...);
@@ -108,6 +132,40 @@ void BM_Pushback_no_grow(benchmark::State& state, Container c) {
}
}
+template <class Container, class GenInputs>
+void BM_insert_iter_iter_iter(benchmark::State& st, Container c, GenInputs gen) {
+ auto in = gen(st.range(0));
+ const auto beg = in.begin();
+ const auto end = in.end();
+ for (auto _ : st) {
+ c.resize(100);
+ c.insert(c.begin() + 50, beg, end);
+ DoNotOptimizeData(c);
+ benchmark::ClobberMemory();
+ }
+}
+
+template <class Container, class GenInputs>
+void BM_insert_range(benchmark::State& st, Container c, GenInputs gen) {
+ auto in = gen(st.range(0));
+ for (auto _ : st) {
+ c.resize(100);
+ c.insert_range(c.begin() + 50, in);
+ DoNotOptimizeData(c);
+ benchmark::ClobberMemory();
+ }
+}
+
+template <class Container, class GenInputs>
+void BM_append_range(benchmark::State& st, Container c, GenInputs gen) {
+ auto in = gen(st.range(0));
+ for (auto _ : st) {
+ c.append_range(in);
+ DoNotOptimizeData(c);
+ benchmark::ClobberMemory();
+ }
+}
+
template <class Container, class GenInputs>
void BM_InsertValue(benchmark::State& st, Container c, GenInputs gen) {
auto in = gen(st.range(0));
diff --git a/libcxx/test/benchmarks/containers/vector_bool_operations.bench.cpp b/libcxx/test/benchmarks/containers/vector_bool_operations.bench.cpp
new file mode 100644
index 00000000000000..e62f72ab02e72f
--- /dev/null
+++ b/libcxx/test/benchmarks/containers/vector_bool_operations.bench.cpp
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <deque>
+#include <functional>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+#include "ContainerBenchmarks.h"
+#include "../GenerateInput.h"
+
+using namespace ContainerBenchmarks;
+
+BENCHMARK_CAPTURE(BM_ConstructIterIter, vector_bool, std::vector<bool>{}, getRandomIntegerInputs<bool>)->Arg(5140480);
+BENCHMARK_CAPTURE(BM_ConstructFromRange, vector_bool, std::vector<bool>{}, getRandomIntegerInputs<bool>)->Arg(5140480);
+
+BENCHMARK_CAPTURE(BM_assign_iter_iter, vector_bool, std::vector<bool>{}, getRandomIntegerInputs<bool>)->Arg(5140480);
+BENCHMARK_CAPTURE(BM_assign_range, vector_bool, std::vector<bool>{}, getRandomIntegerInputs<bool>)->Arg(5140480);
+
+BENCHMARK_CAPTURE(BM_insert_iter_iter_iter, vector_bool, std::vector<bool>{}, getRandomIntegerInputs<bool>)
+ ->Arg(5140480);
+BENCHMARK_CAPTURE(BM_insert_range, vector_bool, std::vector<bool>{}, getRandomIntegerInputs<bool>)->Arg(5140480);
+BENCHMARK_CAPTURE(BM_append_range, vector_bool, std::vector<bool>{}, getRandomIntegerInputs<bool>)->Arg(5140480);
+
+BENCHMARK_MAIN();
diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy.pass.cpp
index b5f0a32b986a03..179fa25c15c0cd 100644
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy.pass.cpp
@@ -13,7 +13,9 @@
// copy(InIter first, InIter last, OutIter result);
#include <algorithm>
+#include <array>
#include <cassert>
+#include <vector>
#include "test_macros.h"
#include "test_iterators.h"
@@ -59,6 +61,29 @@ struct TestInIters {
}
};
+template <std::size_t N>
+struct TestFwdIterInBitIterOut {
+ std::array<bool, N> in = {};
+ template <class FwdIter>
+ TEST_CONSTEXPR_CXX20 void operator()() {
+ for (std::size_t i = 0; i < in.size(); i += 2)
+ in[i] = true;
+
+ { // Test with full bytes
+ std::vector<bool> out(N);
+ std::copy(FwdIter(in.data()), FwdIter(in.data() + N), out.begin());
+ for (std::size_t i = 0; i < N; ++i)
+ assert(out[i] == static_cast<bool>(in[i]));
+ }
+ { // Test with partial bytes in both front and back
+ std::vector<bool> out(N + 8);
+ std::copy(FwdIter(in.data()), FwdIter(in.data() + N), out.begin() + 4);
+ for (std::size_t i = 0; i < N; ++i)
+ assert(out[i + 4] == static_cast<bool>(in[i]));
+ }
+ }
+};
+
TEST_CONSTEXPR_CXX20 bool test() {
types::for_each(types::cpp17_input_iterator_list<int*>(), TestInIters());
@@ -78,6 +103,14 @@ TEST_CONSTEXPR_CXX20 bool test() {
assert(std::equal(a, a + 10, expected));
}
+ { // Test std::copy() with forward_iterator-pair input and vector<bool>::iterator output
+ types::for_each(types::forward_iterator_list<bool*>(), TestFwdIterInBitIterOut<8>());
+ types::for_each(types::forward_iterator_list<bool*>(), TestFwdIterInBitIterOut<16>());
+ types::for_each(types::forward_iterator_list<bool*>(), TestFwdIterInBitIterOut<32>());
+ types::for_each(types::forward_iterator_list<bool*>(), TestFwdIterInBitIterOut<64>());
+ types::for_each(types::forward_iterator_list<bool*>(), TestFwdIterInBitIterOut<256>());
+ }
+
return true;
}
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