On 14/01/20 22:25 +0100, François Dumont wrote:
On 1/13/20 10:53 PM, Jonathan Wakely wrote:
On 13/01/20 22:41 +0100, François Dumont wrote:
For the multi-keys we could still avoid redundant comparisons when
_Equal is just doing == on the key type. On unordered_multiset we
could just avoids the call to is_permuation and on the
unordered_multimap we could check the is_permutation only on the
associated value rather than on the std::pair.
I don't think that's necessary, or helpful.
The idea of https://gcc.gnu.org/ml/libstdc++/2020-01/msg00070.html is
that you shouldn't be using _Equal at all, and therefore it doesn't
matter whether it's std::equal_to or not.
And it was indeed possible.
Nice!
PR libstdc++/91223
* include/bits/hashtable.h (_Hashtable<>): Make _Equality<> friend.
* include/bits/hashtable_policy.h: Include <bits/stl_algo.h>.
(_Equality_base): Remove.
(_Equality<>::_M_equal): Review implementation. Use
std::is_permutation.
* testsuite/23_containers/unordered_multiset/operators/1.cc
(Hash, Equal, test02, test03): New.
* testsuite/23_containers/unordered_set/operators/1.cc
(Hash, Equal, test02, test03): New.
Tested under Linux x86_64.
Ok to commit ?
Yes, OK for trunk (we're in stage4 but your patch was posted in stage3
and fixes a pretty nasty performance bug, so is OK now).
N.B. GCC has moved to Git instead of Subversion. If you don't have Git
access set up let me know and I can commit the patch for you.
