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[libc++] Remove unnecessary assignments #78678

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[libc++] Remove unnecessary assignments #78678

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23 changes: 7 additions & 16 deletions libcxx/include/vector
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Original file line number Diff line number Diff line change
Expand Up @@ -1459,26 +1459,20 @@ vector<_Tp, _Allocator>::__push_back_slow_path(_Up&& __x) {
template <class _Tp, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 inline _LIBCPP_HIDE_FROM_ABI void
vector<_Tp, _Allocator>::push_back(const_reference __x) {
pointer __end = this->__end_;
if (__end < this->__end_cap()) {
if (this->__end_ < this->__end_cap()) {
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This was added in 6fe4e03, which optimized std::vector. Removing those would be a performance regression. Unfortunately we have benchmarks but no automated performance regression tests right now.

__construct_one_at_end(__x);
++__end;
} else {
__end = __push_back_slow_path(__x);
__push_back_slow_path(__x);
}
this->__end_ = __end;
}

template <class _Tp, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 inline _LIBCPP_HIDE_FROM_ABI void vector<_Tp, _Allocator>::push_back(value_type&& __x) {
pointer __end = this->__end_;
if (__end < this->__end_cap()) {
if (this->__end_ < this->__end_cap()) {
__construct_one_at_end(std::move(__x));
++__end;
} else {
__end = __push_back_slow_path(std::move(__x));
__push_back_slow_path(std::move(__x));
}
this->__end_ = __end;
}

template <class _Tp, class _Allocator>
Expand All @@ -1503,16 +1497,13 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 inline
void
#endif
vector<_Tp, _Allocator>::emplace_back(_Args&&... __args) {
pointer __end = this->__end_;
if (__end < this->__end_cap()) {
if (this->__end_ < this->__end_cap()) {
__construct_one_at_end(std::forward<_Args>(__args)...);
++__end;
} else {
__end = __emplace_back_slow_path(std::forward<_Args>(__args)...);
__emplace_back_slow_path(std::forward<_Args>(__args)...);
}
this->__end_ = __end;
#if _LIBCPP_STD_VER >= 17
return *(__end - 1);
return *(this->__end_ - 1);
#endif
}

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