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[libc++] Optimize vector<bool>(const vector<bool>&) #161672

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Merged
merged 1 commit into from
Oct 7, 2025
+17 −3
Merged

[libc++] Optimize vector<bool>(const vector<bool>&) #161672

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9 changes: 6 additions & 3 deletions libcxx/include/__vector/vector_bool.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@

#include <__algorithm/copy.h>
#include <__algorithm/copy_backward.h>
#include <__algorithm/copy_n.h>
#include <__algorithm/fill_n.h>
#include <__algorithm/iterator_operations.h>
#include <__algorithm/max.h>
Expand Down Expand Up @@ -701,7 +702,8 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 vector<bool, _Allocator>::vector(const vector& __v
__alloc_(__storage_traits::select_on_container_copy_construction(__v.__alloc_)) {
if (__v.size() > 0) {
__vallocate(__v.size());
__construct_at_end(__v.begin(), __v.end(), __v.size());
std::copy_n(__v.__begin_, __external_cap_to_internal(__v.size()), __begin_);
__size_ = __v.size();
}
}

Expand All @@ -710,7 +712,8 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 vector<bool, _Allocator>::vector(const vector& __v
: __begin_(nullptr), __size_(0), __cap_(0), __alloc_(__a) {
if (__v.size() > 0) {
__vallocate(__v.size());
__construct_at_end(__v.begin(), __v.end(), __v.size());
std::copy_n(__v.__begin_, __external_cap_to_internal(__v.size()), __begin_);
__size_ = __v.size();
}
}

Expand All @@ -723,7 +726,7 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 vector<bool, _Allocator>& vector<bool, _Allocator>
__vdeallocate();
__vallocate(__v.__size_);
}
std::copy(__v.__begin_, __v.__begin_ + __external_cap_to_internal(__v.__size_), __begin_);
std::copy_n(__v.__begin_, __external_cap_to_internal(__v.size()), __begin_);
}
__size_ = __v.__size_;
}
Expand Down
11 changes: 11 additions & 0 deletions libcxx/test/benchmarks/containers/sequence/vector_bool.bench.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,17 @@
#include <benchmark/benchmark.h>
#include <vector>

static void BM_vector_bool_copy_ctor(benchmark::State& state) {
std::vector<bool> vec(100, true);

for (auto _ : state) {
benchmark::DoNotOptimize(vec);
std::vector<bool> vec2(vec);
benchmark::DoNotOptimize(vec2);
}
}
BENCHMARK(BM_vector_bool_copy_ctor);

static void BM_vector_bool_size_ctor(benchmark::State& state) {
for (auto _ : state) {
std::vector<bool> vec(100, true);
Expand Down
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