[libcxx-commits] [libcxx] [libc++] Optimize ranges::{for_each, for_each_n} for segmented iterators (PR #132896)
Peng Liu via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Mar 28 20:59:17 PDT 2025
https://github.com/winner245 updated https://github.com/llvm/llvm-project/pull/132896
>From c912407bc1698369fd865fd4e2b0ed3aa0e67b66 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Tue, 25 Mar 2025 03:44:59 -0400
Subject: [PATCH 1/9] Optimize ranges::{for_each, for_each_n} for segmented
iterators
---
libcxx/include/__algorithm/for_each_n.h | 25 +++-
libcxx/include/__algorithm/ranges_for_each.h | 14 +-
.../include/__algorithm/ranges_for_each_n.h | 15 ++-
.../nonmodifying/for_each_n.bench.cpp | 57 +++++++++
.../alg.foreach/for_each_n.pass.cpp | 120 ++++++++++++------
.../alg.foreach/ranges.for_each.pass.cpp | 46 ++++++-
.../alg.foreach/ranges.for_each_n.pass.cpp | 46 ++++++-
7 files changed, 270 insertions(+), 53 deletions(-)
create mode 100644 libcxx/test/benchmarks/algorithms/nonmodifying/for_each_n.bench.cpp
diff --git a/libcxx/include/__algorithm/for_each_n.h b/libcxx/include/__algorithm/for_each_n.h
index fce380b49df3e..3d91124432f56 100644
--- a/libcxx/include/__algorithm/for_each_n.h
+++ b/libcxx/include/__algorithm/for_each_n.h
@@ -10,7 +10,11 @@
#ifndef _LIBCPP___ALGORITHM_FOR_EACH_N_H
#define _LIBCPP___ALGORITHM_FOR_EACH_N_H
+#include <__algorithm/for_each.h>
#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/segmented_iterator.h>
+#include <__type_traits/enable_if.h>
#include <__utility/convert_to_integral.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -21,7 +25,13 @@ _LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 17
-template <class _InputIterator, class _Size, class _Function>
+template <class _InputIterator,
+ class _Size,
+ class _Function,
+ __enable_if_t<!__is_segmented_iterator<_InputIterator>::value ||
+ (__has_input_iterator_category<_InputIterator>::value &&
+ !__has_random_access_iterator_category<_InputIterator>::value),
+ int> = 0>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
@@ -34,6 +44,19 @@ for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
return __first;
}
+template <class _InputIterator,
+ class _Size,
+ class _Function,
+ __enable_if_t<__is_segmented_iterator<_InputIterator>::value &&
+ __has_random_access_iterator_category<_InputIterator>::value,
+ int> = 0>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
+for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
+ _InputIterator __last = __first + __orig_n;
+ std::for_each(__first, __last, __f);
+ return __last;
+}
+
#endif
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/__algorithm/ranges_for_each.h b/libcxx/include/__algorithm/ranges_for_each.h
index de39bc5522753..475f85366188e 100644
--- a/libcxx/include/__algorithm/ranges_for_each.h
+++ b/libcxx/include/__algorithm/ranges_for_each.h
@@ -9,6 +9,7 @@
#ifndef _LIBCPP___ALGORITHM_RANGES_FOR_EACH_H
#define _LIBCPP___ALGORITHM_RANGES_FOR_EACH_H
+#include <__algorithm/for_each.h>
#include <__algorithm/in_fun_result.h>
#include <__config>
#include <__functional/identity.h>
@@ -41,9 +42,16 @@ struct __for_each {
template <class _Iter, class _Sent, class _Proj, class _Func>
_LIBCPP_HIDE_FROM_ABI constexpr static for_each_result<_Iter, _Func>
__for_each_impl(_Iter __first, _Sent __last, _Func& __func, _Proj& __proj) {
- for (; __first != __last; ++__first)
- std::invoke(__func, std::invoke(__proj, *__first));
- return {std::move(__first), std::move(__func)};
+ if constexpr (random_access_iterator<_Iter> && sized_sentinel_for<_Sent, _Iter>) {
+ auto __n = __last - __first;
+ auto __end = __first + __n;
+ std::for_each(__first, __end, [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); });
+ return {std::move(__end), std::move(__func)};
+ } else {
+ for (; __first != __last; ++__first)
+ std::invoke(__func, std::invoke(__proj, *__first));
+ return {std::move(__first), std::move(__func)};
+ }
}
public:
diff --git a/libcxx/include/__algorithm/ranges_for_each_n.h b/libcxx/include/__algorithm/ranges_for_each_n.h
index 603cb723233c8..3108d66001295 100644
--- a/libcxx/include/__algorithm/ranges_for_each_n.h
+++ b/libcxx/include/__algorithm/ranges_for_each_n.h
@@ -9,6 +9,7 @@
#ifndef _LIBCPP___ALGORITHM_RANGES_FOR_EACH_N_H
#define _LIBCPP___ALGORITHM_RANGES_FOR_EACH_N_H
+#include <__algorithm/for_each.h>
#include <__algorithm/in_fun_result.h>
#include <__config>
#include <__functional/identity.h>
@@ -40,11 +41,17 @@ struct __for_each_n {
template <input_iterator _Iter, class _Proj = identity, indirectly_unary_invocable<projected<_Iter, _Proj>> _Func>
_LIBCPP_HIDE_FROM_ABI constexpr for_each_n_result<_Iter, _Func>
operator()(_Iter __first, iter_difference_t<_Iter> __count, _Func __func, _Proj __proj = {}) const {
- while (__count-- > 0) {
- std::invoke(__func, std::invoke(__proj, *__first));
- ++__first;
+ if constexpr (random_access_iterator<_Iter>) {
+ auto __last = __first + __count;
+ std::for_each(__first, __last, [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); });
+ return {std::move(__last), std::move(__func)};
+ } else {
+ while (__count-- > 0) {
+ std::invoke(__func, std::invoke(__proj, *__first));
+ ++__first;
+ }
+ return {std::move(__first), std::move(__func)};
}
- return {std::move(__first), std::move(__func)};
}
};
diff --git a/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_n.bench.cpp b/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_n.bench.cpp
new file mode 100644
index 0000000000000..af46371881577
--- /dev/null
+++ b/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_n.bench.cpp
@@ -0,0 +1,57 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+#include <algorithm>
+#include <cstddef>
+#include <deque>
+#include <list>
+#include <string>
+#include <vector>
+
+#include <benchmark/benchmark.h>
+
+int main(int argc, char** argv) {
+ auto std_for_each_n = [](auto first, auto n, auto f) { return std::for_each_n(first, n, f); };
+
+ // {std,ranges}::for_each_n
+ {
+ auto bm = []<class Container>(std::string name, auto for_each_n) {
+ benchmark::RegisterBenchmark(
+ name,
+ [for_each_n](auto& st) {
+ std::size_t const n = st.range(0);
+ Container c(n, 1);
+ auto first = c.begin();
+
+ for ([[maybe_unused]] auto _ : st) {
+ benchmark::DoNotOptimize(c);
+ auto result = for_each_n(first, n, [](int& x) { x = std::clamp(x, 10, 100); });
+ benchmark::DoNotOptimize(result);
+ }
+ })
+ ->Arg(8)
+ ->Arg(32)
+ ->Arg(50) // non power-of-two
+ ->Arg(8192)
+ ->Arg(1 << 20);
+ };
+ bm.operator()<std::vector<int>>("std::for_each_n(vector<int>)", std_for_each_n);
+ bm.operator()<std::deque<int>>("std::for_each_n(deque<int>)", std_for_each_n);
+ bm.operator()<std::list<int>>("std::for_each_n(list<int>)", std_for_each_n);
+ bm.operator()<std::vector<int>>("rng::for_each_n(vector<int>)", std::ranges::for_each_n);
+ bm.operator()<std::deque<int>>("rng::for_each_n(deque<int>)", std::ranges::for_each_n);
+ bm.operator()<std::list<int>>("rng::for_each_n(list<int>)", std::ranges::for_each_n);
+ }
+
+ benchmark::Initialize(&argc, argv);
+ benchmark::RunSpecifiedBenchmarks();
+ benchmark::Shutdown();
+ return 0;
+}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
index 371f6c92f1ed1..42f1a41a27096 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
@@ -13,69 +13,113 @@
// constexpr InputIterator // constexpr after C++17
// for_each_n(InputIterator first, Size n, Function f);
-
#include <algorithm>
#include <cassert>
+#include <deque>
#include <functional>
+#include <iterator>
+#include <ranges>
+#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 expected[] = {3, 5, 8, 9};
- const std::size_t N = 4;
+struct for_each_test {
+ TEST_CONSTEXPR for_each_test(int c) : count(c) {}
+ int count;
+ TEST_CONSTEXPR_CXX14 void operator()(int& i) {
+ ++i;
+ ++count;
+ }
+};
- auto it = std::for_each_n(std::begin(ia), N, [](int &a) { a += 2; });
- return it == (std::begin(ia) + N)
- && std::equal(std::begin(ia), std::end(ia), std::begin(expected))
- ;
- }
-#endif
+struct deque_test {
+ std::deque<int>* d_;
+ int* i_;
+
+ deque_test(std::deque<int>& d, int& i) : d_(&d), i_(&i) {}
-struct for_each_test
-{
- for_each_test(int c) : count(c) {}
- int count;
- void operator()(int& i) {++i; ++count;}
+ void operator()(int& v) {
+ assert(&(*d_)[*i_] == &v);
+ ++*i_;
+ }
};
-int main(int, char**)
-{
+/*TEST_CONSTEXPR_CXX23*/
+void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
+ // check that segmented iterators work properly
+ int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
+ for (const int size : sizes) {
+ std::deque<int> d(size);
+ int index = 0;
+
+ std::for_each_n(d.begin(), d.size(), deque_test(d, index));
+ }
+}
+
+TEST_CONSTEXPR_CXX20 bool test() {
+ {
typedef cpp17_input_iterator<int*> Iter;
- int ia[] = {0, 1, 2, 3, 4, 5};
- const unsigned s = sizeof(ia)/sizeof(ia[0]);
+ int ia[] = {0, 1, 2, 3, 4, 5};
+ const unsigned s = sizeof(ia) / sizeof(ia[0]);
{
- auto f = for_each_test(0);
- Iter it = std::for_each_n(Iter(ia), 0, std::ref(f));
- assert(it == Iter(ia));
- assert(f.count == 0);
+ auto f = for_each_test(0);
+ Iter it = std::for_each_n(Iter(ia), 0, std::ref(f));
+ assert(it == Iter(ia));
+ assert(f.count == 0);
}
{
- auto f = for_each_test(0);
- Iter it = std::for_each_n(Iter(ia), s, std::ref(f));
+ auto f = for_each_test(0);
+ Iter it = std::for_each_n(Iter(ia), s, std::ref(f));
- assert(it == Iter(ia+s));
- assert(f.count == s);
- for (unsigned i = 0; i < s; ++i)
- assert(ia[i] == static_cast<int>(i+1));
+ assert(it == Iter(ia + s));
+ assert(f.count == s);
+ for (unsigned i = 0; i < s; ++i)
+ assert(ia[i] == static_cast<int>(i + 1));
}
{
- auto f = for_each_test(0);
- Iter it = std::for_each_n(Iter(ia), 1, std::ref(f));
+ auto f = for_each_test(0);
+ Iter it = std::for_each_n(Iter(ia), 1, std::ref(f));
- assert(it == Iter(ia+1));
- assert(f.count == 1);
- for (unsigned i = 0; i < 1; ++i)
- assert(ia[i] == static_cast<int>(i+2));
+ assert(it == Iter(ia + 1));
+ assert(f.count == 1);
+ for (unsigned i = 0; i < 1; ++i)
+ assert(ia[i] == static_cast<int>(i + 2));
}
+ }
+
+#if TEST_STD_VER > 11
+ {
+ int ia[] = {1, 3, 6, 7};
+ int expected[] = {3, 5, 8, 9};
+ const std::size_t N = 4;
+
+ auto it = std::for_each_n(std::begin(ia), N, [](int& a) { a += 2; });
+ assert(it == (std::begin(ia) + N) && std::equal(std::begin(ia), std::end(ia), std::begin(expected)));
+ }
+#endif
+
+ if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_23_OR_RUNTIME_EVALUATED when std::deque is made constexpr
+ test_segmented_deque_iterator();
+
+#if TEST_STD_VER >= 20
+ { // Make sure that the segmented iterator optimization works during constant evaluation
+ std::vector<std::vector<int>> vec = {{0}, {1, 2}, {3, 4, 5}, {6, 7, 8, 9}, {10}, {11, 12, 13}};
+ auto v = vec | std::views::join;
+ std::for_each_n(v.begin(), std::ranges::distance(v), [i = 0](int& a) mutable { assert(a == i++); });
+ }
+#endif
+
+ return true;
+}
+int main(int, char**) {
+ assert(test());
#if TEST_STD_VER > 17
- static_assert(test_constexpr());
+ static_assert(test());
#endif
return 0;
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
index 8b9b6e82cbcb2..2f4bfb9db6dba 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
@@ -20,7 +20,10 @@
#include <algorithm>
#include <array>
+#include <cassert>
+#include <deque>
#include <ranges>
+#include <vector>
#include "almost_satisfies_types.h"
#include "test_iterators.h"
@@ -30,7 +33,7 @@ struct Callable {
};
template <class Iter, class Sent = Iter>
-concept HasForEachIt = requires (Iter iter, Sent sent) { std::ranges::for_each(iter, sent, Callable{}); };
+concept HasForEachIt = requires(Iter iter, Sent sent) { std::ranges::for_each(iter, sent, Callable{}); };
static_assert(HasForEachIt<int*>);
static_assert(!HasForEachIt<InputIteratorNotDerivedFrom>);
@@ -47,7 +50,7 @@ static_assert(!HasForEachItFunc<IndirectUnaryPredicateNotPredicate>);
static_assert(!HasForEachItFunc<IndirectUnaryPredicateNotCopyConstructible>);
template <class Range>
-concept HasForEachR = requires (Range range) { std::ranges::for_each(range, Callable{}); };
+concept HasForEachR = requires(Range range) { std::ranges::for_each(range, Callable{}); };
static_assert(HasForEachR<UncheckedRange<int*>>);
static_assert(!HasForEachR<InputRangeNotDerivedFrom>);
@@ -68,7 +71,7 @@ constexpr void test_iterator() {
{ // simple test
{
auto func = [i = 0](int& a) mutable { a += i++; };
- int a[] = {1, 6, 3, 4};
+ int a[] = {1, 6, 3, 4};
std::same_as<std::ranges::for_each_result<Iter, decltype(func)>> decltype(auto) ret =
std::ranges::for_each(Iter(a), Sent(Iter(a + 4)), func);
assert(a[0] == 1);
@@ -81,8 +84,8 @@ constexpr void test_iterator() {
assert(i == 4);
}
{
- auto func = [i = 0](int& a) mutable { a += i++; };
- int a[] = {1, 6, 3, 4};
+ auto func = [i = 0](int& a) mutable { a += i++; };
+ int a[] = {1, 6, 3, 4};
auto range = std::ranges::subrange(Iter(a), Sent(Iter(a + 4)));
std::same_as<std::ranges::for_each_result<Iter, decltype(func)>> decltype(auto) ret =
std::ranges::for_each(range, func);
@@ -110,6 +113,30 @@ constexpr void test_iterator() {
}
}
+struct deque_test {
+ std::deque<int>* d_;
+ int* i_;
+
+ deque_test(std::deque<int>& d, int& i) : d_(&d), i_(&i) {}
+
+ void operator()(int& v) {
+ assert(&(*d_)[*i_] == &v);
+ ++*i_;
+ }
+};
+
+/*TEST_CONSTEXPR_CXX23*/
+void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
+ // check that segmented iterators work properly
+ int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
+ for (const int size : sizes) {
+ std::deque<int> d(size);
+ int index = 0;
+
+ std::ranges::for_each(d, deque_test(d, index));
+ }
+}
+
constexpr bool test() {
test_iterator<cpp17_input_iterator<int*>, sentinel_wrapper<cpp17_input_iterator<int*>>>();
test_iterator<cpp20_input_iterator<int*>, sentinel_wrapper<cpp20_input_iterator<int*>>>();
@@ -146,6 +173,15 @@ constexpr bool test() {
}
}
+ if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_23_OR_RUNTIME_EVALUATED when std::deque is made constexpr
+ test_segmented_deque_iterator();
+
+ {
+ std::vector<std::vector<int>> vec = {{0}, {1, 2}, {3, 4, 5}, {6, 7, 8, 9}, {10}, {11, 12, 13}};
+ auto v = vec | std::views::join;
+ std::ranges::for_each(v, [i = 0](int x) mutable { assert(x == 2 * i++); }, [](int x) { return 2 * x; });
+ }
+
return true;
}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
index d4b2d053d08ce..ad1447b7348f5 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
@@ -17,7 +17,12 @@
#include <algorithm>
#include <array>
+#include <cassert>
+#include <deque>
+#include <iterator>
#include <ranges>
+#include <ranges>
+#include <vector>
#include "almost_satisfies_types.h"
#include "test_iterators.h"
@@ -27,7 +32,7 @@ struct Callable {
};
template <class Iter>
-concept HasForEachN = requires (Iter iter) { std::ranges::for_each_n(iter, 0, Callable{}); };
+concept HasForEachN = requires(Iter iter) { std::ranges::for_each_n(iter, 0, Callable{}); };
static_assert(HasForEachN<int*>);
static_assert(!HasForEachN<InputIteratorNotDerivedFrom>);
@@ -45,7 +50,7 @@ template <class Iter>
constexpr void test_iterator() {
{ // simple test
auto func = [i = 0](int& a) mutable { a += i++; };
- int a[] = {1, 6, 3, 4};
+ int a[] = {1, 6, 3, 4};
std::same_as<std::ranges::for_each_result<Iter, decltype(func)>> auto ret =
std::ranges::for_each_n(Iter(a), 4, func);
assert(a[0] == 1);
@@ -64,6 +69,30 @@ constexpr void test_iterator() {
}
}
+struct deque_test {
+ std::deque<int>* d_;
+ int* i_;
+
+ deque_test(std::deque<int>& d, int& i) : d_(&d), i_(&i) {}
+
+ void operator()(int& v) {
+ assert(&(*d_)[*i_] == &v);
+ ++*i_;
+ }
+};
+
+/*TEST_CONSTEXPR_CXX23*/
+void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
+ // check that segmented iterators work properly
+ int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
+ for (const int size : sizes) {
+ std::deque<int> d(size);
+ int index = 0;
+
+ std::ranges::for_each_n(d.begin(), d.size(), deque_test(d, index));
+ }
+}
+
constexpr bool test() {
test_iterator<cpp17_input_iterator<int*>>();
test_iterator<cpp20_input_iterator<int*>>();
@@ -89,6 +118,19 @@ constexpr bool test() {
assert(a[2].other == 6);
}
+ if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_23_OR_RUNTIME_EVALUATED when std::deque is made constexpr
+ test_segmented_deque_iterator();
+
+ {
+ std::vector<std::vector<int>> vec = {{0}, {1, 2}, {3, 4, 5}, {6, 7, 8, 9}, {10}, {11, 12, 13}};
+ auto v = vec | std::views::join;
+ std::ranges::for_each_n(
+ v.begin(),
+ std::ranges::distance(v),
+ [i = 0](int x) mutable { assert(x == 2 * i++); },
+ [](int x) { return 2 * x; });
+ }
+
return true;
}
>From 04615867db212b1a4b92072e577677cca3b57d20 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Tue, 25 Mar 2025 21:29:27 -0400
Subject: [PATCH 2/9] Address ldionne's review comments
---
libcxx/include/__algorithm/for_each.h | 17 ++++++++++++-----
libcxx/include/__algorithm/for_each_n.h | 3 ++-
libcxx/include/__algorithm/ranges_for_each.h | 4 +++-
libcxx/include/__algorithm/ranges_for_each_n.h | 4 +++-
.../alg.foreach/for_each_n.pass.cpp | 2 +-
.../alg.foreach/ranges.for_each.pass.cpp | 2 +-
.../alg.foreach/ranges.for_each_n.pass.cpp | 2 +-
7 files changed, 23 insertions(+), 11 deletions(-)
diff --git a/libcxx/include/__algorithm/for_each.h b/libcxx/include/__algorithm/for_each.h
index e08f583504c01..0a03702f982be 100644
--- a/libcxx/include/__algorithm/for_each.h
+++ b/libcxx/include/__algorithm/for_each.h
@@ -11,6 +11,7 @@
#define _LIBCPP___ALGORITHM_FOR_EACH_H
#include <__algorithm/for_each_segment.h>
+#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__iterator/segmented_iterator.h>
#include <__ranges/movable_box.h>
@@ -26,20 +27,20 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
-template <class _InputIterator, class _Function>
+template <class, class _InputIterator, class _Function>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
-for_each(_InputIterator __first, _InputIterator __last, _Function __f) {
+__for_each(_InputIterator __first, _InputIterator __last, _Function& __f) {
for (; __first != __last; ++__first)
__f(*__first);
- return __f;
+ return std::move(__f);
}
// __movable_box is available in C++20, but is actually a copyable-box, so optimization is only correct in C++23
#if _LIBCPP_STD_VER >= 23
-template <class _SegmentedIterator, class _Function>
+template <class, class _SegmentedIterator, class _Function>
requires __is_segmented_iterator<_SegmentedIterator>::value
_LIBCPP_HIDE_FROM_ABI constexpr _Function
-for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function __func) {
+for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function& __func) {
ranges::__movable_box<_Function> __wrapped_func(in_place, std::move(__func));
std::__for_each_segment(__first, __last, [&](auto __lfirst, auto __llast) {
__wrapped_func =
@@ -49,6 +50,12 @@ for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function __func
}
#endif // _LIBCPP_STD_VER >= 23
+template <class _InputIterator, class _Function>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
+for_each(_InputIterator __first, _InputIterator __last, _Function __f) {
+ return __for_each<_ClassicAlgPolicy>(__first, __last, __f);
+}
+
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
diff --git a/libcxx/include/__algorithm/for_each_n.h b/libcxx/include/__algorithm/for_each_n.h
index 3d91124432f56..20e8bcc4b8c76 100644
--- a/libcxx/include/__algorithm/for_each_n.h
+++ b/libcxx/include/__algorithm/for_each_n.h
@@ -11,6 +11,7 @@
#define _LIBCPP___ALGORITHM_FOR_EACH_N_H
#include <__algorithm/for_each.h>
+#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__iterator/segmented_iterator.h>
@@ -53,7 +54,7 @@ template <class _InputIterator,
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
_InputIterator __last = __first + __orig_n;
- std::for_each(__first, __last, __f);
+ std::__for_each<_ClassicAlgPolicy>(__first, __last, __f);
return __last;
}
diff --git a/libcxx/include/__algorithm/ranges_for_each.h b/libcxx/include/__algorithm/ranges_for_each.h
index 475f85366188e..5d27befd9619f 100644
--- a/libcxx/include/__algorithm/ranges_for_each.h
+++ b/libcxx/include/__algorithm/ranges_for_each.h
@@ -11,6 +11,7 @@
#include <__algorithm/for_each.h>
#include <__algorithm/in_fun_result.h>
+#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__functional/identity.h>
#include <__functional/invoke.h>
@@ -45,7 +46,8 @@ struct __for_each {
if constexpr (random_access_iterator<_Iter> && sized_sentinel_for<_Sent, _Iter>) {
auto __n = __last - __first;
auto __end = __first + __n;
- std::for_each(__first, __end, [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); });
+ auto __f = [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); };
+ std::__for_each<_RangeAlgPolicy>(__first, __end, __f);
return {std::move(__end), std::move(__func)};
} else {
for (; __first != __last; ++__first)
diff --git a/libcxx/include/__algorithm/ranges_for_each_n.h b/libcxx/include/__algorithm/ranges_for_each_n.h
index 3108d66001295..8384ba3bb14e6 100644
--- a/libcxx/include/__algorithm/ranges_for_each_n.h
+++ b/libcxx/include/__algorithm/ranges_for_each_n.h
@@ -11,6 +11,7 @@
#include <__algorithm/for_each.h>
#include <__algorithm/in_fun_result.h>
+#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__functional/identity.h>
#include <__functional/invoke.h>
@@ -43,7 +44,8 @@ struct __for_each_n {
operator()(_Iter __first, iter_difference_t<_Iter> __count, _Func __func, _Proj __proj = {}) const {
if constexpr (random_access_iterator<_Iter>) {
auto __last = __first + __count;
- std::for_each(__first, __last, [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); });
+ auto __f = [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); };
+ std::__for_each<_RangeAlgPolicy>(__first, __last, __f);
return {std::move(__last), std::move(__func)};
} else {
while (__count-- > 0) {
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
index 42f1a41a27096..7819c785fc3eb 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
@@ -47,7 +47,7 @@ struct deque_test {
/*TEST_CONSTEXPR_CXX23*/
void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
- // check that segmented iterators work properly
+ // check that segmented deque iterators work properly
int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
for (const int size : sizes) {
std::deque<int> d(size);
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
index 2f4bfb9db6dba..14be4a42f667c 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
@@ -127,7 +127,7 @@ struct deque_test {
/*TEST_CONSTEXPR_CXX23*/
void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
- // check that segmented iterators work properly
+ // check that segmented deque iterators work properly
int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
for (const int size : sizes) {
std::deque<int> d(size);
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
index ad1447b7348f5..ac073d3052170 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
@@ -83,7 +83,7 @@ struct deque_test {
/*TEST_CONSTEXPR_CXX23*/
void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
- // check that segmented iterators work properly
+ // check that segmented deque iterators work properly
int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
for (const int size : sizes) {
std::deque<int> d(size);
>From ee2866d2fd4dcee36ae2352b61251cdc80a92594 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Tue, 25 Mar 2025 23:11:34 -0400
Subject: [PATCH 3/9] Fix test and ADL call
---
libcxx/include/__algorithm/for_each.h | 6 +++++-
.../alg.nonmodifying/alg.foreach/for_each_n.pass.cpp | 6 +++---
.../alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp | 6 +++---
.../alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp | 6 +++---
4 files changed, 14 insertions(+), 10 deletions(-)
diff --git a/libcxx/include/__algorithm/for_each.h b/libcxx/include/__algorithm/for_each.h
index 0a03702f982be..07fa58df55c28 100644
--- a/libcxx/include/__algorithm/for_each.h
+++ b/libcxx/include/__algorithm/for_each.h
@@ -27,6 +27,10 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
+template <class _InputIterator, class _Function>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
+for_each(_InputIterator __first, _InputIterator __last, _Function __f);
+
template <class, class _InputIterator, class _Function>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
__for_each(_InputIterator __first, _InputIterator __last, _Function& __f) {
@@ -53,7 +57,7 @@ for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function& __fun
template <class _InputIterator, class _Function>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
for_each(_InputIterator __first, _InputIterator __last, _Function __f) {
- return __for_each<_ClassicAlgPolicy>(__first, __last, __f);
+ return std::__for_each<_ClassicAlgPolicy>(__first, __last, __f);
}
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
index 7819c785fc3eb..a2b8931a62985 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
@@ -45,8 +45,8 @@ struct deque_test {
}
};
-/*TEST_CONSTEXPR_CXX23*/
-void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
+/*TEST_CONSTEXPR_CXX26*/
+void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX26 once std::deque is constexpr
// check that segmented deque iterators work properly
int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
for (const int size : sizes) {
@@ -102,7 +102,7 @@ TEST_CONSTEXPR_CXX20 bool test() {
}
#endif
- if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_23_OR_RUNTIME_EVALUATED when std::deque is made constexpr
+ if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_26_OR_RUNTIME_EVALUATED when std::deque is made constexpr
test_segmented_deque_iterator();
#if TEST_STD_VER >= 20
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
index 14be4a42f667c..a6d0afde3186a 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each.pass.cpp
@@ -125,8 +125,8 @@ struct deque_test {
}
};
-/*TEST_CONSTEXPR_CXX23*/
-void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
+/*TEST_CONSTEXPR_CXX26*/
+void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX26 once std::deque is constexpr
// check that segmented deque iterators work properly
int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
for (const int size : sizes) {
@@ -173,7 +173,7 @@ constexpr bool test() {
}
}
- if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_23_OR_RUNTIME_EVALUATED when std::deque is made constexpr
+ if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_26_OR_RUNTIME_EVALUATED when std::deque is made constexpr
test_segmented_deque_iterator();
{
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
index ac073d3052170..1578763694231 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/ranges.for_each_n.pass.cpp
@@ -81,8 +81,8 @@ struct deque_test {
}
};
-/*TEST_CONSTEXPR_CXX23*/
-void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX23 once std::deque is constexpr
+/*TEST_CONSTEXPR_CXX26*/
+void test_segmented_deque_iterator() { // TODO: Mark as TEST_CONSTEXPR_CXX26 once std::deque is constexpr
// check that segmented deque iterators work properly
int sizes[] = {0, 1, 2, 1023, 1024, 1025, 2047, 2048, 2049};
for (const int size : sizes) {
@@ -118,7 +118,7 @@ constexpr bool test() {
assert(a[2].other == 6);
}
- if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_23_OR_RUNTIME_EVALUATED when std::deque is made constexpr
+ if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_26_OR_RUNTIME_EVALUATED when std::deque is made constexpr
test_segmented_deque_iterator();
{
>From e104b2c0cd565a10fc076c703cca056b96ec5551 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Wed, 26 Mar 2025 11:10:37 -0400
Subject: [PATCH 4/9] Make for_each segmented iterator optimization valid for
C++03
---
libcxx/include/__algorithm/for_each.h | 43 +++++++++++--------
libcxx/include/__algorithm/for_each_n.h | 10 +++--
.../include/__algorithm/ranges_for_each_n.h | 5 ++-
3 files changed, 33 insertions(+), 25 deletions(-)
diff --git a/libcxx/include/__algorithm/for_each.h b/libcxx/include/__algorithm/for_each.h
index 07fa58df55c28..1260d5204bcf1 100644
--- a/libcxx/include/__algorithm/for_each.h
+++ b/libcxx/include/__algorithm/for_each.h
@@ -14,7 +14,7 @@
#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__iterator/segmented_iterator.h>
-#include <__ranges/movable_box.h>
+#include <__type_traits/enable_if.h>
#include <__utility/in_place.h>
#include <__utility/move.h>
@@ -27,32 +27,37 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
-template <class _InputIterator, class _Function>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
-for_each(_InputIterator __first, _InputIterator __last, _Function __f);
-
-template <class, class _InputIterator, class _Function>
+template <class, class _InputIterator, class _Sent, class _Function>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
-__for_each(_InputIterator __first, _InputIterator __last, _Function& __f) {
+__for_each(_InputIterator __first, _Sent __last, _Function& __f) {
for (; __first != __last; ++__first)
__f(*__first);
return std::move(__f);
}
-// __movable_box is available in C++20, but is actually a copyable-box, so optimization is only correct in C++23
-#if _LIBCPP_STD_VER >= 23
-template <class, class _SegmentedIterator, class _Function>
- requires __is_segmented_iterator<_SegmentedIterator>::value
+template <class _InputIterator, class _Function>
+struct _ForeachSegment {
+ using _Traits _LIBCPP_NODEBUG = __segmented_iterator_traits<_InputIterator>;
+
+ _Function& __func_;
+
+ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit _ForeachSegment(_Function& __func) : __func_(__func) {}
+
+ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
+ operator()(typename _Traits::__local_iterator __lfirst, typename _Traits::__local_iterator __llast) {
+ std::__for_each<_ClassicAlgPolicy>(__lfirst, __llast, __func_);
+ }
+};
+
+template <class,
+ class _SegmentedIterator,
+ class _Function,
+ __enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI constexpr _Function
-for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function& __func) {
- ranges::__movable_box<_Function> __wrapped_func(in_place, std::move(__func));
- std::__for_each_segment(__first, __last, [&](auto __lfirst, auto __llast) {
- __wrapped_func =
- ranges::__movable_box<_Function>(in_place, std::for_each(__lfirst, __llast, std::move(*__wrapped_func)));
- });
- return std::move(*__wrapped_func);
+__for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function& __func) {
+ std::__for_each_segment(__first, __last, _ForeachSegment<_SegmentedIterator, _Function>(__func));
+ return std::move(__func);
}
-#endif // _LIBCPP_STD_VER >= 23
template <class _InputIterator, class _Function>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
diff --git a/libcxx/include/__algorithm/for_each_n.h b/libcxx/include/__algorithm/for_each_n.h
index 20e8bcc4b8c76..8cd136521743c 100644
--- a/libcxx/include/__algorithm/for_each_n.h
+++ b/libcxx/include/__algorithm/for_each_n.h
@@ -14,6 +14,7 @@
#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
#include <__iterator/segmented_iterator.h>
#include <__type_traits/enable_if.h>
#include <__utility/convert_to_integral.h>
@@ -30,8 +31,7 @@ template <class _InputIterator,
class _Size,
class _Function,
__enable_if_t<!__is_segmented_iterator<_InputIterator>::value ||
- (__has_input_iterator_category<_InputIterator>::value &&
- !__has_random_access_iterator_category<_InputIterator>::value),
+ __has_exactly_input_iterator_category<_InputIterator>::value,
int> = 0>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
@@ -49,11 +49,13 @@ template <class _InputIterator,
class _Size,
class _Function,
__enable_if_t<__is_segmented_iterator<_InputIterator>::value &&
- __has_random_access_iterator_category<_InputIterator>::value,
+ __has_forward_iterator_category<_InputIterator>::value,
int> = 0>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
- _InputIterator __last = __first + __orig_n;
+ typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
+ _IntegralSize __n = __orig_n;
+ _InputIterator __last = std::next(__first, __n);
std::__for_each<_ClassicAlgPolicy>(__first, __last, __f);
return __last;
}
diff --git a/libcxx/include/__algorithm/ranges_for_each_n.h b/libcxx/include/__algorithm/ranges_for_each_n.h
index 8384ba3bb14e6..a5c81868c2062 100644
--- a/libcxx/include/__algorithm/ranges_for_each_n.h
+++ b/libcxx/include/__algorithm/ranges_for_each_n.h
@@ -18,6 +18,7 @@
#include <__iterator/concepts.h>
#include <__iterator/incrementable_traits.h>
#include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
#include <__iterator/projected.h>
#include <__ranges/concepts.h>
#include <__utility/move.h>
@@ -42,8 +43,8 @@ struct __for_each_n {
template <input_iterator _Iter, class _Proj = identity, indirectly_unary_invocable<projected<_Iter, _Proj>> _Func>
_LIBCPP_HIDE_FROM_ABI constexpr for_each_n_result<_Iter, _Func>
operator()(_Iter __first, iter_difference_t<_Iter> __count, _Func __func, _Proj __proj = {}) const {
- if constexpr (random_access_iterator<_Iter>) {
- auto __last = __first + __count;
+ if constexpr (forward_iterator<_Iter>) {
+ auto __last = std::ranges::next(__first, __count);
auto __f = [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); };
std::__for_each<_RangeAlgPolicy>(__first, __last, __f);
return {std::move(__last), std::move(__func)};
>From 79f64a68bbff3f9a0476936c101b3801263a3f90 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Wed, 26 Mar 2025 11:25:44 -0400
Subject: [PATCH 5/9] Use _LIBCPP_CONSTEXPR_SINCE_CXX14 in place of constexpr
---
libcxx/include/__algorithm/for_each.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/libcxx/include/__algorithm/for_each.h b/libcxx/include/__algorithm/for_each.h
index 1260d5204bcf1..7e514710122b8 100644
--- a/libcxx/include/__algorithm/for_each.h
+++ b/libcxx/include/__algorithm/for_each.h
@@ -15,7 +15,6 @@
#include <__config>
#include <__iterator/segmented_iterator.h>
#include <__type_traits/enable_if.h>
-#include <__utility/in_place.h>
#include <__utility/move.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -53,7 +52,7 @@ template <class,
class _SegmentedIterator,
class _Function,
__enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0>
-_LIBCPP_HIDE_FROM_ABI constexpr _Function
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Function
__for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function& __func) {
std::__for_each_segment(__first, __last, _ForeachSegment<_SegmentedIterator, _Function>(__func));
return std::move(__func);
>From 6af203b1c475df4ec8967f135d7588d2493a0d2c Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Thu, 27 Mar 2025 11:50:12 -0400
Subject: [PATCH 6/9] Allow transitive include of <optional> in affected
headers
---
libcxx/include/algorithm | 1 +
libcxx/include/array | 1 +
libcxx/include/bitset | 1 +
libcxx/include/codecvt | 1 +
libcxx/include/condition_variable | 1 +
libcxx/include/experimental/iterator | 1 +
libcxx/include/ios | 1 +
libcxx/include/locale | 1 +
libcxx/include/mutex | 1 +
libcxx/include/shared_mutex | 1 +
libcxx/include/streambuf | 1 +
libcxx/include/string | 1 +
libcxx/include/string_view | 1 +
libcxx/include/system_error | 1 +
libcxx/include/vector | 1 +
15 files changed, 15 insertions(+)
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 6ba903ad3ce1e..1ef709082324b 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -2057,6 +2057,7 @@ template <class BidirectionalIterator, class Compare>
# include <cstring>
# include <iterator>
# include <memory>
+# include <optional>
# include <stdexcept>
# include <type_traits>
# include <utility>
diff --git a/libcxx/include/array b/libcxx/include/array
index d536575d41680..099b85b5d222d 100644
--- a/libcxx/include/array
+++ b/libcxx/include/array
@@ -566,6 +566,7 @@ _LIBCPP_POP_MACROS
# include <cstdlib>
# include <iterator>
# include <new>
+# include <optional>
# include <type_traits>
# include <utility>
# endif
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
index 9106080ec1020..bea5c826ac3b5 100644
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -974,6 +974,7 @@ _LIBCPP_POP_MACROS
# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
# include <concepts>
# include <cstdlib>
+# include <optional>
# include <type_traits>
# endif
#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
diff --git a/libcxx/include/codecvt b/libcxx/include/codecvt
index 0526b8512175f..398a777af1333 100644
--- a/libcxx/include/codecvt
+++ b/libcxx/include/codecvt
@@ -597,6 +597,7 @@ _LIBCPP_END_NAMESPACE_STD
# include <limits>
# include <mutex>
# include <new>
+# include <optional>
# include <stdexcept>
# include <type_traits>
# include <typeinfo>
diff --git a/libcxx/include/condition_variable b/libcxx/include/condition_variable
index 81699bf6adbf7..a80627cbf7dec 100644
--- a/libcxx/include/condition_variable
+++ b/libcxx/include/condition_variable
@@ -363,6 +363,7 @@ _LIBCPP_POP_MACROS
# include <initializer_list>
# include <iosfwd>
# include <new>
+# include <optional>
# include <stdexcept>
# include <system_error>
# include <type_traits>
diff --git a/libcxx/include/experimental/iterator b/libcxx/include/experimental/iterator
index 8448654e8d94c..47ad7459e0150 100644
--- a/libcxx/include/experimental/iterator
+++ b/libcxx/include/experimental/iterator
@@ -127,6 +127,7 @@ _LIBCPP_POP_MACROS
# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
# include <cstddef>
# include <iosfwd>
+# include <optional>
# include <type_traits>
# endif
#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
diff --git a/libcxx/include/ios b/libcxx/include/ios
index 98a088266539a..62e94a28d709e 100644
--- a/libcxx/include/ios
+++ b/libcxx/include/ios
@@ -887,6 +887,7 @@ _LIBCPP_POP_MACROS
# include <limits>
# include <mutex>
# include <new>
+# include <optional>
# include <stdexcept>
# include <system_error>
# include <type_traits>
diff --git a/libcxx/include/locale b/libcxx/include/locale
index fa15302223202..2a233ce7c159e 100644
--- a/libcxx/include/locale
+++ b/libcxx/include/locale
@@ -3689,6 +3689,7 @@ _LIBCPP_POP_MACROS
# include <cstdarg>
# include <iterator>
# include <mutex>
+# include <optional>
# include <stdexcept>
# include <type_traits>
# include <typeinfo>
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
index 9b128e8710aae..de196b256201a 100644
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -508,6 +508,7 @@ _LIBCPP_POP_MACROS
# include <initializer_list>
# include <iosfwd>
# include <new>
+# include <optional>
# include <stdexcept>
# include <system_error>
# include <type_traits>
diff --git a/libcxx/include/shared_mutex b/libcxx/include/shared_mutex
index b1e2a5d434400..7200c417995a5 100644
--- a/libcxx/include/shared_mutex
+++ b/libcxx/include/shared_mutex
@@ -461,6 +461,7 @@ _LIBCPP_POP_MACROS
# endif // _LIBCPP_HAS_THREADS
# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
+# include <optional>
# include <system_error>
# endif
#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
diff --git a/libcxx/include/streambuf b/libcxx/include/streambuf
index 3c4e9086e05ec..d688ec76cae3a 100644
--- a/libcxx/include/streambuf
+++ b/libcxx/include/streambuf
@@ -386,6 +386,7 @@ _LIBCPP_POP_MACROS
# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
# include <cstdint>
+# include <optional>
# endif
#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
diff --git a/libcxx/include/string b/libcxx/include/string
index fa87dc2fddb59..ef873f175f70c 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -4101,6 +4101,7 @@ _LIBCPP_POP_MACROS
# include <cstdlib>
# include <iterator>
# include <new>
+# include <optional>
# include <type_traits>
# include <typeinfo>
# include <utility>
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
index c640ae4e79865..b9efaa90ef3e6 100644
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -948,6 +948,7 @@ _LIBCPP_POP_MACROS
# include <concepts>
# include <cstdlib>
# include <iterator>
+# include <optional>
# include <type_traits>
# endif
#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
diff --git a/libcxx/include/system_error b/libcxx/include/system_error
index 4dadc0a6ab483..2b668e5f8f1bc 100644
--- a/libcxx/include/system_error
+++ b/libcxx/include/system_error
@@ -168,6 +168,7 @@ template <> struct hash<std::error_condition>;
# include <cstdint>
# include <cstring>
# include <limits>
+# include <optional>
# include <type_traits>
# endif
#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
diff --git a/libcxx/include/vector b/libcxx/include/vector
index 9fa81dcb7e76e..d2d5fcf4a3199 100644
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -362,6 +362,7 @@ template<class T, class charT> requires is-vector-bool-reference<T> // Since C++
# if _LIBCPP_HAS_LOCALIZATION
# include <locale>
# endif
+# include <optional>
# include <string>
# include <string_view>
# include <tuple>
>From 7b1dbd36c115325709ef7f1bcb9f911bac8b59db Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Thu, 27 Mar 2025 12:00:54 -0400
Subject: [PATCH 7/9] Remove unnecessary _AlgoPolicy template parameter
---
libcxx/include/__algorithm/for_each.h | 10 ++++------
libcxx/include/__algorithm/for_each_n.h | 3 +--
libcxx/include/__algorithm/ranges_for_each.h | 3 +--
libcxx/include/__algorithm/ranges_for_each_n.h | 3 +--
4 files changed, 7 insertions(+), 12 deletions(-)
diff --git a/libcxx/include/__algorithm/for_each.h b/libcxx/include/__algorithm/for_each.h
index 7e514710122b8..a61c2f1fd2420 100644
--- a/libcxx/include/__algorithm/for_each.h
+++ b/libcxx/include/__algorithm/for_each.h
@@ -11,7 +11,6 @@
#define _LIBCPP___ALGORITHM_FOR_EACH_H
#include <__algorithm/for_each_segment.h>
-#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__iterator/segmented_iterator.h>
#include <__type_traits/enable_if.h>
@@ -26,7 +25,7 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
-template <class, class _InputIterator, class _Sent, class _Function>
+template <class _InputIterator, class _Sent, class _Function>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
__for_each(_InputIterator __first, _Sent __last, _Function& __f) {
for (; __first != __last; ++__first)
@@ -44,12 +43,11 @@ struct _ForeachSegment {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
operator()(typename _Traits::__local_iterator __lfirst, typename _Traits::__local_iterator __llast) {
- std::__for_each<_ClassicAlgPolicy>(__lfirst, __llast, __func_);
+ std::__for_each(__lfirst, __llast, __func_);
}
};
-template <class,
- class _SegmentedIterator,
+template <class _SegmentedIterator,
class _Function,
__enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Function
@@ -61,7 +59,7 @@ __for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function& __f
template <class _InputIterator, class _Function>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Function
for_each(_InputIterator __first, _InputIterator __last, _Function __f) {
- return std::__for_each<_ClassicAlgPolicy>(__first, __last, __f);
+ return std::__for_each(__first, __last, __f);
}
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/__algorithm/for_each_n.h b/libcxx/include/__algorithm/for_each_n.h
index 8cd136521743c..ec8fe955ed48f 100644
--- a/libcxx/include/__algorithm/for_each_n.h
+++ b/libcxx/include/__algorithm/for_each_n.h
@@ -11,7 +11,6 @@
#define _LIBCPP___ALGORITHM_FOR_EACH_N_H
#include <__algorithm/for_each.h>
-#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__iterator/next.h>
@@ -56,7 +55,7 @@ for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
_IntegralSize __n = __orig_n;
_InputIterator __last = std::next(__first, __n);
- std::__for_each<_ClassicAlgPolicy>(__first, __last, __f);
+ std::__for_each(__first, __last, __f);
return __last;
}
diff --git a/libcxx/include/__algorithm/ranges_for_each.h b/libcxx/include/__algorithm/ranges_for_each.h
index 5d27befd9619f..096e60683e39d 100644
--- a/libcxx/include/__algorithm/ranges_for_each.h
+++ b/libcxx/include/__algorithm/ranges_for_each.h
@@ -11,7 +11,6 @@
#include <__algorithm/for_each.h>
#include <__algorithm/in_fun_result.h>
-#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__functional/identity.h>
#include <__functional/invoke.h>
@@ -47,7 +46,7 @@ struct __for_each {
auto __n = __last - __first;
auto __end = __first + __n;
auto __f = [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); };
- std::__for_each<_RangeAlgPolicy>(__first, __end, __f);
+ std::__for_each(__first, __end, __f);
return {std::move(__end), std::move(__func)};
} else {
for (; __first != __last; ++__first)
diff --git a/libcxx/include/__algorithm/ranges_for_each_n.h b/libcxx/include/__algorithm/ranges_for_each_n.h
index a5c81868c2062..9c6c2b97a2ad1 100644
--- a/libcxx/include/__algorithm/ranges_for_each_n.h
+++ b/libcxx/include/__algorithm/ranges_for_each_n.h
@@ -11,7 +11,6 @@
#include <__algorithm/for_each.h>
#include <__algorithm/in_fun_result.h>
-#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__functional/identity.h>
#include <__functional/invoke.h>
@@ -46,7 +45,7 @@ struct __for_each_n {
if constexpr (forward_iterator<_Iter>) {
auto __last = std::ranges::next(__first, __count);
auto __f = [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); };
- std::__for_each<_RangeAlgPolicy>(__first, __last, __f);
+ std::__for_each(__first, __last, __f);
return {std::move(__last), std::move(__func)};
} else {
while (__count-- > 0) {
>From f314697d184158f4a8c51c0aef4f3e779d661d7a Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Thu, 27 Mar 2025 23:40:27 -0400
Subject: [PATCH 8/9] Inline tests and remove std::ref
---
.../alg.foreach/for_each_n.pass.cpp | 31 +++++++++++--------
1 file changed, 18 insertions(+), 13 deletions(-)
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
index a2b8931a62985..4d6e4c615c022 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp
@@ -64,34 +64,40 @@ TEST_CONSTEXPR_CXX20 bool test() {
const unsigned s = sizeof(ia) / sizeof(ia[0]);
{
- auto f = for_each_test(0);
- Iter it = std::for_each_n(Iter(ia), 0, std::ref(f));
+ unsigned count = 0;
+ Iter it = std::for_each_n(Iter(ia), 0, [&count](int& i) mutable {
+ ++i;
+ ++count;
+ });
assert(it == Iter(ia));
- assert(f.count == 0);
+ assert(count == 0);
}
{
- auto f = for_each_test(0);
- Iter it = std::for_each_n(Iter(ia), s, std::ref(f));
-
+ unsigned count = 0;
+ Iter it = std::for_each_n(Iter(ia), s, [&count](int& i) mutable {
+ ++i;
+ ++count;
+ });
assert(it == Iter(ia + s));
- assert(f.count == s);
+ assert(count == s);
for (unsigned i = 0; i < s; ++i)
assert(ia[i] == static_cast<int>(i + 1));
}
{
- auto f = for_each_test(0);
- Iter it = std::for_each_n(Iter(ia), 1, std::ref(f));
-
+ unsigned count = 0;
+ Iter it = std::for_each_n(Iter(ia), 1, [&count](int& i) mutable {
+ ++i;
+ ++count;
+ });
assert(it == Iter(ia + 1));
- assert(f.count == 1);
+ assert(count == 1);
for (unsigned i = 0; i < 1; ++i)
assert(ia[i] == static_cast<int>(i + 2));
}
}
-#if TEST_STD_VER > 11
{
int ia[] = {1, 3, 6, 7};
int expected[] = {3, 5, 8, 9};
@@ -100,7 +106,6 @@ TEST_CONSTEXPR_CXX20 bool test() {
auto it = std::for_each_n(std::begin(ia), N, [](int& a) { a += 2; });
assert(it == (std::begin(ia) + N) && std::equal(std::begin(ia), std::end(ia), std::begin(expected)));
}
-#endif
if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_26_OR_RUNTIME_EVALUATED when std::deque is made constexpr
test_segmented_deque_iterator();
>From 5a7b6ebdd3ee77817e62d5174f26c676aff47ebb Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Fri, 28 Mar 2025 20:26:31 -0400
Subject: [PATCH 9/9] Apply optimization for join_view segmented iterators
---
libcxx/docs/ReleaseNotes/21.rst | 4 +
libcxx/include/CMakeLists.txt | 1 +
libcxx/include/__algorithm/for_each.h | 7 +-
libcxx/include/__algorithm/for_each_n.h | 17 +--
.../include/__algorithm/for_each_n_segment.h | 77 +++++++++++
.../include/__algorithm/ranges_for_each_n.h | 5 +-
libcxx/include/module.modulemap | 1 +
.../nonmodifying/for_each.bench.cpp | 23 +++-
.../nonmodifying/for_each_join_view.bench.cpp | 122 ++++++++++++++++++
.../nonmodifying/for_each_n.bench.cpp | 23 +++-
10 files changed, 260 insertions(+), 20 deletions(-)
create mode 100644 libcxx/include/__algorithm/for_each_n_segment.h
create mode 100644 libcxx/test/benchmarks/algorithms/nonmodifying/for_each_join_view.bench.cpp
diff --git a/libcxx/docs/ReleaseNotes/21.rst b/libcxx/docs/ReleaseNotes/21.rst
index 877aa06f8b7e4..c4bbe3aecad90 100644
--- a/libcxx/docs/ReleaseNotes/21.rst
+++ b/libcxx/docs/ReleaseNotes/21.rst
@@ -60,6 +60,10 @@ Improvements and New Features
- Updated formatting library to Unicode 16.0.0.
+- The ``std::ranges::for_each`` and ``std::ranges::for_each_n`` algorithms have been optimized for segmented iterators,
+ resulting in performance improvements of up to 21.2x for ``std::deque::iterator`` segmented inputs and 17.9x for
+ ``join_view`` of ``vector<vector<T>>``.
+
Deprecations and Removals
-------------------------
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index a021b9bb44d67..9803ff8c193c4 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -25,6 +25,7 @@ set(files
__algorithm/find_segment_if.h
__algorithm/for_each.h
__algorithm/for_each_n.h
+ __algorithm/for_each_n_segment.h
__algorithm/for_each_segment.h
__algorithm/generate.h
__algorithm/generate_n.h
diff --git a/libcxx/include/__algorithm/for_each.h b/libcxx/include/__algorithm/for_each.h
index a61c2f1fd2420..e6cb505e35274 100644
--- a/libcxx/include/__algorithm/for_each.h
+++ b/libcxx/include/__algorithm/for_each.h
@@ -33,13 +33,14 @@ __for_each(_InputIterator __first, _Sent __last, _Function& __f) {
return std::move(__f);
}
+// __do_segment acts as a functor for processing individual segments within the __for_each_segment{, _n} algorithms.
template <class _InputIterator, class _Function>
-struct _ForeachSegment {
+struct __do_segment {
using _Traits _LIBCPP_NODEBUG = __segmented_iterator_traits<_InputIterator>;
_Function& __func_;
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit _ForeachSegment(_Function& __func) : __func_(__func) {}
+ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __do_segment(_Function& __func) : __func_(__func) {}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
operator()(typename _Traits::__local_iterator __lfirst, typename _Traits::__local_iterator __llast) {
@@ -52,7 +53,7 @@ template <class _SegmentedIterator,
__enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Function
__for_each(_SegmentedIterator __first, _SegmentedIterator __last, _Function& __func) {
- std::__for_each_segment(__first, __last, _ForeachSegment<_SegmentedIterator, _Function>(__func));
+ std::__for_each_segment(__first, __last, std::__do_segment<_SegmentedIterator, _Function>(__func));
return std::move(__func);
}
diff --git a/libcxx/include/__algorithm/for_each_n.h b/libcxx/include/__algorithm/for_each_n.h
index ec8fe955ed48f..2abb163766dcb 100644
--- a/libcxx/include/__algorithm/for_each_n.h
+++ b/libcxx/include/__algorithm/for_each_n.h
@@ -11,6 +11,7 @@
#define _LIBCPP___ALGORITHM_FOR_EACH_N_H
#include <__algorithm/for_each.h>
+#include <__algorithm/for_each_n_segment.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__iterator/next.h>
@@ -44,19 +45,15 @@ for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
return __first;
}
-template <class _InputIterator,
+template <class _SegmentedIterator,
class _Size,
class _Function,
- __enable_if_t<__is_segmented_iterator<_InputIterator>::value &&
- __has_forward_iterator_category<_InputIterator>::value,
+ __enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value &&
+ __has_forward_iterator_category<_SegmentedIterator>::value,
int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
-for_each_n(_InputIterator __first, _Size __orig_n, _Function __f) {
- typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
- _IntegralSize __n = __orig_n;
- _InputIterator __last = std::next(__first, __n);
- std::__for_each(__first, __last, __f);
- return __last;
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _SegmentedIterator
+for_each_n(_SegmentedIterator __first, _Size __orig_n, _Function __f) {
+ return std::__for_each_n_segment(__first, __orig_n, std::__do_segment<_SegmentedIterator, _Function>(__f));
}
#endif
diff --git a/libcxx/include/__algorithm/for_each_n_segment.h b/libcxx/include/__algorithm/for_each_n_segment.h
new file mode 100644
index 0000000000000..e2e19cb31ecee
--- /dev/null
+++ b/libcxx/include/__algorithm/for_each_n_segment.h
@@ -0,0 +1,77 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FOR_EACH_N_SEGMENT_H
+#define _LIBCPP___ALGORITHM_FOR_EACH_N_SEGMENT_H
+
+#include <__config>
+#include <__iterator/distance.h>
+#include <__iterator/next.h>
+#include <__iterator/segmented_iterator.h>
+#include <__utility/convert_to_integral.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// __for_each_n_segment is a utility function for optimizing iterating over segmented iterators linearly.
+// __first and __orig_n are represent the begining and size of a segmented range. __func is expected to
+// take a range of local iterators. Anything that is returned from __func is ignored.
+
+template <class _SegmentedIterator, class _Size, class _Functor>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator
+__for_each_n_segment(_SegmentedIterator __first, _Size __orig_n, _Functor __func) {
+ if (__orig_n == 0)
+ return __first;
+
+ using _Traits = __segmented_iterator_traits<_SegmentedIterator>;
+ typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
+ _IntegralSize __n = __orig_n;
+ auto __seg = _Traits::__segment(__first);
+ auto __sfirst = _Traits::__begin(__seg);
+ auto __slast = _Traits::__end(__seg);
+ auto __lfirst = _Traits::__local(__first);
+ auto __seg_size = static_cast<_IntegralSize>(std::distance(__lfirst, __slast));
+
+ // We have only one single segment, which might not start or end at the boundaries of the segment
+ if (__n <= __seg_size) {
+ auto __llast = std::next(__lfirst, __n);
+ __func(__lfirst, __llast);
+ return _Traits::__compose(__seg, __llast);
+ }
+
+ // We have more than one segment. Iterate over the first segment which might not start at the beginning
+ __func(__lfirst, std::next(__lfirst, __seg_size));
+ ++__seg;
+ __n -= __seg_size;
+
+ // Iterate over the 2nd to last segments which are guaranteed to start at the beginning of each segment
+ while (true) {
+ __sfirst = _Traits::__begin(__seg);
+ __slast = _Traits::__end(__seg);
+ __seg_size = std::distance(__sfirst, __slast);
+
+ // We are in the last segment
+ if (__n <= __seg_size) {
+ auto __llast = std::next(__sfirst, __n);
+ __func(__sfirst, __llast);
+ return _Traits::__compose(__seg, __llast);
+ }
+
+ // We are in middle segments that are completely in the range
+ __func(__sfirst, __slast);
+ ++__seg;
+ __n -= __seg_size;
+ }
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___ALGORITHM_FOR_EACH_N_SEGMENT_H
diff --git a/libcxx/include/__algorithm/ranges_for_each_n.h b/libcxx/include/__algorithm/ranges_for_each_n.h
index 9c6c2b97a2ad1..b92eeb6fa8d7c 100644
--- a/libcxx/include/__algorithm/ranges_for_each_n.h
+++ b/libcxx/include/__algorithm/ranges_for_each_n.h
@@ -9,7 +9,7 @@
#ifndef _LIBCPP___ALGORITHM_RANGES_FOR_EACH_N_H
#define _LIBCPP___ALGORITHM_RANGES_FOR_EACH_N_H
-#include <__algorithm/for_each.h>
+#include <__algorithm/for_each_n.h>
#include <__algorithm/in_fun_result.h>
#include <__config>
#include <__functional/identity.h>
@@ -43,9 +43,8 @@ struct __for_each_n {
_LIBCPP_HIDE_FROM_ABI constexpr for_each_n_result<_Iter, _Func>
operator()(_Iter __first, iter_difference_t<_Iter> __count, _Func __func, _Proj __proj = {}) const {
if constexpr (forward_iterator<_Iter>) {
- auto __last = std::ranges::next(__first, __count);
auto __f = [&](auto&& __val) { std::invoke(__func, std::invoke(__proj, __val)); };
- std::__for_each(__first, __last, __f);
+ auto __last = std::for_each_n(__first, __count, __f);
return {std::move(__last), std::move(__func)};
} else {
while (__count-- > 0) {
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
index 0ce42fc4d3633..da7034f7c081d 100644
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -436,6 +436,7 @@ module std [system] {
module find_segment_if { header "__algorithm/find_segment_if.h" }
module find { header "__algorithm/find.h" }
module for_each_n { header "__algorithm/for_each_n.h" }
+ module for_each_n_segment { header "__algorithm/for_each_n_segment.h" }
module for_each_segment { header "__algorithm/for_each_segment.h" }
module for_each { header "__algorithm/for_each.h" }
module generate_n { header "__algorithm/generate_n.h" }
diff --git a/libcxx/test/benchmarks/algorithms/nonmodifying/for_each.bench.cpp b/libcxx/test/benchmarks/algorithms/nonmodifying/for_each.bench.cpp
index 760accbe4d929..1e33cf70f8487 100644
--- a/libcxx/test/benchmarks/algorithms/nonmodifying/for_each.bench.cpp
+++ b/libcxx/test/benchmarks/algorithms/nonmodifying/for_each.bench.cpp
@@ -23,6 +23,7 @@ int main(int argc, char** argv) {
// {std,ranges}::for_each
{
auto bm = []<class Container>(std::string name, auto for_each) {
+ using ElemType = typename Container::value_type;
benchmark::RegisterBenchmark(
name,
[for_each](auto& st) {
@@ -33,16 +34,34 @@ int main(int argc, char** argv) {
for ([[maybe_unused]] auto _ : st) {
benchmark::DoNotOptimize(c);
- auto result = for_each(first, last, [](int& x) { x = std::clamp(x, 10, 100); });
+ auto result = for_each(first, last, [](ElemType& x) { x = std::clamp<ElemType>(x, 10, 100); });
benchmark::DoNotOptimize(result);
}
})
->Arg(8)
->Arg(32)
->Arg(50) // non power-of-two
+ ->Arg(1024)
+ ->Arg(4096)
->Arg(8192)
- ->Arg(1 << 20);
+ ->Arg(1 << 14)
+ ->Arg(1 << 16)
+ ->Arg(1 << 18);
};
+ bm.operator()<std::vector<char>>("std::for_each(vector<char>)", std_for_each);
+ bm.operator()<std::deque<char>>("std::for_each(deque<char>)", std_for_each);
+ bm.operator()<std::list<char>>("std::for_each(list<char>)", std_for_each);
+ bm.operator()<std::vector<char>>("rng::for_each(vector<char>)", std::ranges::for_each);
+ bm.operator()<std::deque<char>>("rng::for_each(deque<char>)", std::ranges::for_each);
+ bm.operator()<std::list<char>>("rng::for_each(list<char>)", std::ranges::for_each);
+
+ bm.operator()<std::vector<short>>("std::for_each(vector<short>)", std_for_each);
+ bm.operator()<std::deque<short>>("std::for_each(deque<short>)", std_for_each);
+ bm.operator()<std::list<short>>("std::for_each(list<short>)", std_for_each);
+ bm.operator()<std::vector<short>>("rng::for_each(vector<short>)", std::ranges::for_each);
+ bm.operator()<std::deque<short>>("rng::for_each(deque<short>)", std::ranges::for_each);
+ bm.operator()<std::list<short>>("rng::for_each(list<short>)", std::ranges::for_each);
+
bm.operator()<std::vector<int>>("std::for_each(vector<int>)", std_for_each);
bm.operator()<std::deque<int>>("std::for_each(deque<int>)", std_for_each);
bm.operator()<std::list<int>>("std::for_each(list<int>)", std_for_each);
diff --git a/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_join_view.bench.cpp b/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_join_view.bench.cpp
new file mode 100644
index 0000000000000..28398ac988bf7
--- /dev/null
+++ b/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_join_view.bench.cpp
@@ -0,0 +1,122 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+#include <algorithm>
+#include <cstddef>
+#include <deque>
+#include <list>
+#include <ranges>
+#include <string>
+#include <vector>
+
+#include <benchmark/benchmark.h>
+
+int main(int argc, char** argv) {
+ auto std_for_each = [](auto first, auto last, auto f) { return std::for_each(first, last, f); };
+ auto std_for_each_n = [](auto first, auto n, auto f) { return std::for_each_n(first, n, f); };
+
+ // {std,ranges}::for_each
+ {
+ auto bm = []<class Container>(std::string name, auto for_each) {
+ using C1 = typename Container::value_type;
+ using ElemType = typename C1::value_type;
+
+ benchmark::RegisterBenchmark(
+ name,
+ [for_each](auto& st) {
+ std::size_t const size = st.range(0);
+ std::size_t const seg_size = 256;
+ std::size_t const segments = (size + seg_size - 1) / seg_size;
+ Container c(segments);
+ for (std::size_t i = 0, n = size; i < segments; ++i, n -= seg_size) {
+ c[i].resize(std::min(seg_size, n), ElemType(1));
+ }
+
+ auto view = c | std::views::join;
+ auto first = view.begin();
+ auto last = view.end();
+
+ for ([[maybe_unused]] auto _ : st) {
+ benchmark::DoNotOptimize(c);
+ auto result = for_each(first, last, [](ElemType& x) { x = std::clamp<ElemType>(x, 10, 100); });
+ benchmark::DoNotOptimize(result);
+ }
+ })
+ ->Arg(8)
+ ->Arg(32)
+ ->Arg(50) // non power-of-two
+ ->Arg(1024)
+ ->Arg(4096)
+ ->Arg(8192)
+ ->Arg(1 << 14)
+ ->Arg(1 << 16)
+ ->Arg(1 << 18);
+ };
+ bm.operator()<std::vector<std::vector<char>>>("std::for_each(join_view(vector<vector<char>>))", std_for_each);
+ bm.operator()<std::vector<std::vector<short>>>("std::for_each(join_view(vector<vector<short>>))", std_for_each);
+ bm.operator()<std::vector<std::vector<int>>>("std::for_each(join_view(vector<vector<int>>))", std_for_each);
+ bm.operator()<std::vector<std::vector<char>>>(
+ "rng::for_each(join_view(vector<vector<char>>)", std::ranges::for_each);
+ bm.operator()<std::vector<std::vector<short>>>(
+ "rng::for_each(join_view(vector<vector<short>>)", std::ranges::for_each);
+ bm.operator()<std::vector<std::vector<int>>>("rng::for_each(join_view(vector<vector<int>>)", std::ranges::for_each);
+ }
+
+ // {std,ranges}::for_each_n
+ {
+ auto bm = []<class Container>(std::string name, auto for_each_n) {
+ using C1 = typename Container::value_type;
+ using ElemType = typename C1::value_type;
+ benchmark::RegisterBenchmark(
+ name,
+ [for_each_n](auto& st) {
+ std::size_t const size = st.range(0);
+ std::size_t const seg_size = 256;
+ std::size_t const segments = (size + seg_size - 1) / seg_size;
+ Container c(segments);
+ for (std::size_t i = 0, n = size; i < segments; ++i, n -= seg_size) {
+ c[i].resize(std::min(seg_size, n), ElemType(1));
+ }
+
+ auto view = c | std::views::join;
+ auto first = view.begin();
+
+ for ([[maybe_unused]] auto _ : st) {
+ benchmark::DoNotOptimize(c);
+ auto result = for_each_n(first, size, [](ElemType& x) { x = std::clamp<ElemType>(x, 10, 100); });
+ benchmark::DoNotOptimize(result);
+ }
+ })
+ ->Arg(8)
+ ->Arg(32)
+ ->Arg(50) // non power-of-two
+ ->Arg(1024)
+ ->Arg(4096)
+ ->Arg(8192)
+ ->Arg(1 << 14)
+ ->Arg(1 << 16)
+ ->Arg(1 << 18);
+ };
+ bm.operator()<std::vector<std::vector<char>>>("std::for_each_n(join_view(vector<vector<char>>))", std_for_each_n);
+ bm.operator()<std::vector<std::vector<short>>>("std::for_each_n(join_view(vector<vector<short>>))", std_for_each_n);
+ bm.operator()<std::vector<std::vector<int>>>("std::for_each_n(join_view(vector<vector<int>>))", std_for_each_n);
+ bm.operator()<std::vector<std::vector<char>>>(
+ "rng::for_each_n(join_view(vector<vector<char>>)", std::ranges::for_each_n);
+ bm.operator()<std::vector<std::vector<short>>>(
+ "rng::for_each_n(join_view(vector<vector<short>>)", std::ranges::for_each_n);
+ bm.operator()<std::vector<std::vector<int>>>(
+ "rng::for_each_n(join_view(vector<vector<int>>)", std::ranges::for_each_n);
+ }
+
+ benchmark::Initialize(&argc, argv);
+ benchmark::RunSpecifiedBenchmarks();
+ benchmark::Shutdown();
+ return 0;
+}
diff --git a/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_n.bench.cpp b/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_n.bench.cpp
index af46371881577..9e77f51db10cc 100644
--- a/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_n.bench.cpp
+++ b/libcxx/test/benchmarks/algorithms/nonmodifying/for_each_n.bench.cpp
@@ -23,6 +23,7 @@ int main(int argc, char** argv) {
// {std,ranges}::for_each_n
{
auto bm = []<class Container>(std::string name, auto for_each_n) {
+ using ElemType = typename Container::value_type;
benchmark::RegisterBenchmark(
name,
[for_each_n](auto& st) {
@@ -32,16 +33,34 @@ int main(int argc, char** argv) {
for ([[maybe_unused]] auto _ : st) {
benchmark::DoNotOptimize(c);
- auto result = for_each_n(first, n, [](int& x) { x = std::clamp(x, 10, 100); });
+ auto result = for_each_n(first, n, [](ElemType& x) { x = std::clamp<ElemType>(x, 10, 100); });
benchmark::DoNotOptimize(result);
}
})
->Arg(8)
->Arg(32)
->Arg(50) // non power-of-two
+ ->Arg(1024)
+ ->Arg(4096)
->Arg(8192)
- ->Arg(1 << 20);
+ ->Arg(1 << 14)
+ ->Arg(1 << 16)
+ ->Arg(1 << 18);
};
+ bm.operator()<std::vector<char>>("std::for_each_n(vector<char>)", std_for_each_n);
+ bm.operator()<std::deque<char>>("std::for_each_n(deque<char>)", std_for_each_n);
+ bm.operator()<std::list<char>>("std::for_each_n(list<char>)", std_for_each_n);
+ bm.operator()<std::vector<char>>("rng::for_each_n(vector<char>)", std::ranges::for_each_n);
+ bm.operator()<std::deque<char>>("rng::for_each_n(deque<char>)", std::ranges::for_each_n);
+ bm.operator()<std::list<char>>("rng::for_each_n(list<char>)", std::ranges::for_each_n);
+
+ bm.operator()<std::vector<short>>("std::for_each_n(vector<short>)", std_for_each_n);
+ bm.operator()<std::deque<short>>("std::for_each_n(deque<short>)", std_for_each_n);
+ bm.operator()<std::list<short>>("std::for_each_n(list<short>)", std_for_each_n);
+ bm.operator()<std::vector<short>>("rng::for_each_n(vector<short>)", std::ranges::for_each_n);
+ bm.operator()<std::deque<short>>("rng::for_each_n(deque<short>)", std::ranges::for_each_n);
+ bm.operator()<std::list<short>>("rng::for_each_n(list<short>)", std::ranges::for_each_n);
+
bm.operator()<std::vector<int>>("std::for_each_n(vector<int>)", std_for_each_n);
bm.operator()<std::deque<int>>("std::for_each_n(deque<int>)", std_for_each_n);
bm.operator()<std::list<int>>("std::for_each_n(list<int>)", std_for_each_n);
More information about the libcxx-commits
mailing list