[PATCH] D52697: Bug 39129: Speeding up partition_point/lower_bound/upper_bound by using unsigned difference_type when possible.
Denis Yaroshevskiy via Phabricator
reviews at reviews.llvm.org
Sat Sep 29 16:28:06 PDT 2018
dyaroshev added a comment.
Thanks for the quick review! I will address you comments tomorrow.
- In general, this is the kind of optimization that I would rather see the compiler do (everywhere, automatically) than libc++ (here and there, manually).
I don't think it can, can it? The optimization comes from knowing the last - first will never be < 0. How would the compiler know that?
Comment at: include/algorithm:4162
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(_Reference __u)
> Why constexpr after C++11?
Mostly to be constexpr in c++17. Do I say 17 instead? Can be contstexpr in 11 no problem
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