[libc++] Remove unnecessary assignments #78678
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This commit removes unnecessary assignments, which already happen in called functions.
AdvenamTacet
added
the
libc++
|
@llvm/pr-subscribers-libcxx Author: Tacet (AdvenamTacet) ChangesThis commit removes unnecessary assignments, which already happen in called functions. This PR is untested, I just spotted it trying to understand why #75882 is causing problems with buildbots. Full diff: https://github.com/llvm/llvm-project/pull/78678.diff 1 Files Affected:
diff --git a/libcxx/include/vector b/libcxx/include/vector
index e9dd57055cb112d..81c70394fd8ec37 100644
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -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()) {
__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>
@@ -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
}
|
ldionne
requested changes
Jan 22, 2024
| @@ -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()) { | |||
There was a problem hiding this comment.
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.
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@ldionne Interesting, thx for the feedback, do we want to keep updating the same value in Transactions? Same work is done twice here, maybe we should remove analogical code in transaction class? |
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This commit removes unnecessary assignments, which already happen in called functions.
This PR is untested, I just spotted it trying to understand why #75882 is causing problems with buildbots.