https://bugs.llvm.org/show_bug.cgi?id=45848
Bug ID: 45848
Summary: std::~unique_ptr is inefficient
Product: libc++
Version: unspecified
Hardware: Macintosh
OS: MacOS X
Status: NEW
Severity: normal
Priority: P
Component: All Bugs
Assignee: unassignedclangb...@nondot.org
Reporter: jsba...@adobe.com
CC: llvm-bugs@lists.llvm.org, mclow.li...@gmail.com
The dtor of unique_ptr is implemented in terms of reset (which defaults to a
set of a nullptr).
~unique_ptr() { reset(); }
This is inefficient as the effect is that the dtor modifies the address held by
its ptr
__ptr_.first() = __p;
This causes address invalidation (and a related cacheline invalidation).
Since this is in the dtor, noone should read that value again.
~unique_ptr should be implemented in terms of the contained destructor only:
~unique_ptr() {
const pointer ptr = __ptr_.first();
if (ptr)
__ptr_.second()(ptr);
}
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