Note that this was reverted due to post-commit review, but Phab forked it into a different thread. Here it is: http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20160118/147795.html
> On 2016-Jan-22, at 14:48, Duncan P. N. Exon Smith via cfe-commits > <cfe-commits@lists.llvm.org> wrote: > > Author: dexonsmith > Date: Fri Jan 22 16:48:02 2016 > New Revision: 258575 > > URL: http://llvm.org/viewvc/llvm-project?rev=258575&view=rev > Log: > unordered_map: Reuse insert logic in emplace when possible, NFC > > An upcoming commit will add an optimization to insert() that avoids > unnecessary mallocs when we can safely extract the key type. This > commit shares code between emplace() and insert(): > - if emplace() is given a single argument, and > - value_type is constructible from that argument > so that we have a single code path for the two. > > I also updated the debug version of emplace_hint() to defer to > emplace(), like the non-debug version does. > > In both cases, there should be NFC here. > > Modified: > libcxx/trunk/include/unordered_map > > Modified: libcxx/trunk/include/unordered_map > URL: > http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/unordered_map?rev=258575&r1=258574&r2=258575&view=diff > ============================================================================== > --- libcxx/trunk/include/unordered_map (original) > +++ libcxx/trunk/include/unordered_map Fri Jan 22 16:48:02 2016 > @@ -922,8 +922,32 @@ public: > #ifndef _LIBCPP_HAS_NO_VARIADICS > > template <class... _Args> > - pair<iterator, bool> emplace(_Args&&... __args); > + pair<iterator, bool> emplace(_Args&&... __args) > + {return __emplace_dispatch(std::forward<_Args>(__args)...);} > > +private: > + template <class _Arg> > + pair<iterator, bool> __emplace_dispatch(_Arg&& __arg) > + { > + typedef is_constructible<value_type, _Arg> __constructible; > + return > __emplace_insert_if_constructible(std::forward<_Arg>(__arg), > + __constructible()); > + } > + template <class _Arg1, class... _Args> > + pair<iterator, bool> __emplace_dispatch(_Arg1&& __arg1, _Args&&... > __args) > + {return __emplace_impl(std::forward<_Arg1>(__arg1), > std::forward<_Args>(__args)...);} > + > + template <class _Arg> > + pair<iterator, bool> __emplace_insert_if_constructible(_Arg&& __arg, > false_type) > + {return __emplace_impl(std::forward<_Arg>(__arg));} > + template <class _Arg> > + pair<iterator, bool> __emplace_insert_if_constructible(_Arg&& __arg, > true_type) > + {return insert(std::forward<_Arg>(__arg));} > + > + template <class... _Args> > + pair<iterator, bool> __emplace_impl(_Args&&... __args); > + > +public: > template <class... _Args> > _LIBCPP_INLINE_VISIBILITY > #if _LIBCPP_DEBUG_LEVEL >= 2 > @@ -932,7 +956,7 @@ public: > _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__p) == this, > "unordered_map::emplace_hint(const_iterator, args...) called > with an iterator not" > " referring to this unordered_map"); > - return > __table_.__emplace_unique(_VSTD::forward<_Args>(__args)...).first; > + return emplace(_VSTD::forward<_Args>(__args)...).first; > } > #else > iterator emplace_hint(const_iterator, _Args&&... __args) > @@ -1477,7 +1501,7 @@ unordered_map<_Key, _Tp, _Hash, _Pred, _ > template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc> > template <class... _Args> > pair<typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::iterator, bool> > -unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::emplace(_Args&&... __args) > +unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__emplace_impl(_Args&&... > __args) > { > __node_holder __h = __construct_node(_VSTD::forward<_Args>(__args)...); > pair<iterator, bool> __r = __table_.__node_insert_unique(__h.get()); > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
