[libcxx-commits] [libcxx] [libc++] Simplify vector<bool>::__construct_at_end (Reopend) (PR #119632)
Peng Liu via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Jan 24 08:17:43 PST 2025
https://github.com/winner245 updated https://github.com/llvm/llvm-project/pull/119632
>From 010d34ffa5a9d70c9c4ca0d914f21d7cd80096dc Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Wed, 11 Dec 2024 18:21:46 -0500
Subject: [PATCH 1/4] Simplify vector<bool>::__construct_at_end
---
libcxx/include/__vector/vector_bool.h | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)
diff --git a/libcxx/include/__vector/vector_bool.h b/libcxx/include/__vector/vector_bool.h
index 4f1c442ce0be8d..3f4d443d386fe6 100644
--- a/libcxx/include/__vector/vector_bool.h
+++ b/libcxx/include/__vector/vector_bool.h
@@ -558,30 +558,20 @@ vector<bool, _Allocator>::__recommend(size_type __new_size) const {
template <class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
vector<bool, _Allocator>::__construct_at_end(size_type __n, bool __x) {
- size_type __old_size = this->__size_;
+ iterator __old_end = end();
this->__size_ += __n;
- if (__old_size == 0 || ((__old_size - 1) / __bits_per_word) != ((this->__size_ - 1) / __bits_per_word)) {
- if (this->__size_ <= __bits_per_word)
- this->__begin_[0] = __storage_type(0);
- else
- this->__begin_[(this->__size_ - 1) / __bits_per_word] = __storage_type(0);
- }
- std::fill_n(__make_iter(__old_size), __n, __x);
+ this->__begin_[(this->__size_ - 1) / __bits_per_word] = __storage_type(0);
+ std::fill_n(__old_end, __n, __x);
}
template <class _Allocator>
template <class _InputIterator, class _Sentinel>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void
vector<bool, _Allocator>::__construct_at_end(_InputIterator __first, _Sentinel __last, size_type __n) {
- size_type __old_size = this->__size_;
+ iterator __old_end = end();
this->__size_ += __n;
- if (__old_size == 0 || ((__old_size - 1) / __bits_per_word) != ((this->__size_ - 1) / __bits_per_word)) {
- if (this->__size_ <= __bits_per_word)
- this->__begin_[0] = __storage_type(0);
- else
- this->__begin_[(this->__size_ - 1) / __bits_per_word] = __storage_type(0);
- }
- std::__copy(std::move(__first), std::move(__last), __make_iter(__old_size));
+ this->__begin_[(this->__size_ - 1) / __bits_per_word] = __storage_type(0);
+ std::__copy(std::move(__first), std::move(__last), __old_end);
}
template <class _Allocator>
@@ -855,7 +845,9 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 void vector<bool, _Allocator>::reserve(size_type _
this->__throw_length_error();
vector __v(this->get_allocator());
__v.__vallocate(__n);
- __v.__construct_at_end(this->begin(), this->end(), this->size());
+ // Ensure that the call to __construct_at_end(first, last, n) meets the precondition of n > 0
+ if (this->size() > 0)
+ __v.__construct_at_end(this->begin(), this->end(), this->size());
swap(__v);
}
}
>From bc9dad15ba528c0adbf1ac98cb78f2312d48c58c Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Mon, 13 Jan 2025 20:33:52 -0500
Subject: [PATCH 2/4] Add _LIBCPP_ASSERT_INTERNAL
---
libcxx/include/__vector/vector_bool.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/libcxx/include/__vector/vector_bool.h b/libcxx/include/__vector/vector_bool.h
index 3f4d443d386fe6..494f91e781166a 100644
--- a/libcxx/include/__vector/vector_bool.h
+++ b/libcxx/include/__vector/vector_bool.h
@@ -558,6 +558,7 @@ vector<bool, _Allocator>::__recommend(size_type __new_size) const {
template <class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
vector<bool, _Allocator>::__construct_at_end(size_type __n, bool __x) {
+ _LIBCPP_ASSERT_INTERNAL(__n > 0, "This function expects __n > 0");
iterator __old_end = end();
this->__size_ += __n;
this->__begin_[(this->__size_ - 1) / __bits_per_word] = __storage_type(0);
@@ -568,6 +569,7 @@ template <class _Allocator>
template <class _InputIterator, class _Sentinel>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void
vector<bool, _Allocator>::__construct_at_end(_InputIterator __first, _Sentinel __last, size_type __n) {
+ _LIBCPP_ASSERT_INTERNAL(__n > 0, "This function expects __n > 0");
iterator __old_end = end();
this->__size_ += __n;
this->__begin_[(this->__size_ - 1) / __bits_per_word] = __storage_type(0);
>From 16a92bc120f94524fd399b296746249e8964c3fe Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Mon, 20 Jan 2025 14:45:49 -0500
Subject: [PATCH 3/4] Add explicit precondition check
---
libcxx/include/__vector/vector_bool.h | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
diff --git a/libcxx/include/__vector/vector_bool.h b/libcxx/include/__vector/vector_bool.h
index 494f91e781166a..698f6c2658d100 100644
--- a/libcxx/include/__vector/vector_bool.h
+++ b/libcxx/include/__vector/vector_bool.h
@@ -552,28 +552,29 @@ vector<bool, _Allocator>::__recommend(size_type __new_size) const {
}
// Default constructs __n objects starting at __end_
-// Precondition: __n > 0
// Precondition: size() + __n <= capacity()
// Postcondition: size() == size() + __n
template <class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
vector<bool, _Allocator>::__construct_at_end(size_type __n, bool __x) {
- _LIBCPP_ASSERT_INTERNAL(__n > 0, "This function expects __n > 0");
- iterator __old_end = end();
+ _LIBCPP_ASSERT_INTERNAL(
+ capacity() >= size() + __n, "vector<bool>::__construct_at_end called with insufficient capacity");
+ std::fill_n(end(), __n, __x);
this->__size_ += __n;
- this->__begin_[(this->__size_ - 1) / __bits_per_word] = __storage_type(0);
- std::fill_n(__old_end, __n, __x);
+ if (end().__ctz_ != 0) // has uninitialized trailing bits in the last word
+ std::fill_n(end(), __bits_per_word - end().__ctz_, 0);
}
template <class _Allocator>
template <class _InputIterator, class _Sentinel>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void
vector<bool, _Allocator>::__construct_at_end(_InputIterator __first, _Sentinel __last, size_type __n) {
- _LIBCPP_ASSERT_INTERNAL(__n > 0, "This function expects __n > 0");
- iterator __old_end = end();
+ _LIBCPP_ASSERT_INTERNAL(
+ capacity() >= size() + __n, "vector<bool>::__construct_at_end called with insufficient capacity");
+ std::__copy(std::move(__first), std::move(__last), end());
this->__size_ += __n;
- this->__begin_[(this->__size_ - 1) / __bits_per_word] = __storage_type(0);
- std::__copy(std::move(__first), std::move(__last), __old_end);
+ if (end().__ctz_ != 0) // has uninitialized trailing bits in the last word
+ std::fill_n(end(), __bits_per_word - end().__ctz_, 0);
}
template <class _Allocator>
>From e3a0995566c287de12ca744bb082ec4998e8a717 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Mon, 20 Jan 2025 15:16:22 -0500
Subject: [PATCH 4/4] Remove unnecessary if condition and comment
---
libcxx/include/__vector/vector_bool.h | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/libcxx/include/__vector/vector_bool.h b/libcxx/include/__vector/vector_bool.h
index 698f6c2658d100..8d9257eddfcd2d 100644
--- a/libcxx/include/__vector/vector_bool.h
+++ b/libcxx/include/__vector/vector_bool.h
@@ -561,7 +561,7 @@ vector<bool, _Allocator>::__construct_at_end(size_type __n, bool __x) {
capacity() >= size() + __n, "vector<bool>::__construct_at_end called with insufficient capacity");
std::fill_n(end(), __n, __x);
this->__size_ += __n;
- if (end().__ctz_ != 0) // has uninitialized trailing bits in the last word
+ if (end().__ctz_ != 0) // Ensure uninitialized leading bits in the last word are set to zero
std::fill_n(end(), __bits_per_word - end().__ctz_, 0);
}
@@ -573,7 +573,7 @@ vector<bool, _Allocator>::__construct_at_end(_InputIterator __first, _Sentinel _
capacity() >= size() + __n, "vector<bool>::__construct_at_end called with insufficient capacity");
std::__copy(std::move(__first), std::move(__last), end());
this->__size_ += __n;
- if (end().__ctz_ != 0) // has uninitialized trailing bits in the last word
+ if (end().__ctz_ != 0) // Ensure uninitialized leading bits in the last word are set to zero
std::fill_n(end(), __bits_per_word - end().__ctz_, 0);
}
@@ -848,9 +848,7 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 void vector<bool, _Allocator>::reserve(size_type _
this->__throw_length_error();
vector __v(this->get_allocator());
__v.__vallocate(__n);
- // Ensure that the call to __construct_at_end(first, last, n) meets the precondition of n > 0
- if (this->size() > 0)
- __v.__construct_at_end(this->begin(), this->end(), this->size());
+ __v.__construct_at_end(this->begin(), this->end(), this->size());
swap(__v);
}
}
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