[libcxx-commits] [PATCH] D80057: [libc++][NFCI] Optimization to std::~unique_ptr

[Zoe Carver via Phabricator via libcxx-commits]

zoecarver added a comment.

@ldionne

> In your example, I don't see what __p is.

`__p` is `nullptr`. I still think this might be a good solution. Essentially exiting `reset` early if `__ptr` is null. It eliminates the store without adding any compares and it will set the pointer to null the exact same number of times (so we don't add any unsafe memory issues).

@jfb It looks like <https://godbolt.org/z/UeVN2j> (in clang, at least) as long as everything can be inlined it can get rid of the store but, if the unique_ptr escapes, it can't. I would be really surprised if this change made a meaningful impact on performance, though. I think you'd need to create a lot of null unique_ptrs.


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https://reviews.llvm.org/D80057