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From: "cuzdav at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/106275] unordered_map with std::string key, std::hash<std::string>, and custom equality predicate weirdness
Date: Wed, 13 Jul 2022 16:28:27 +0000	[thread overview]
Message-ID: <bug-106275-4-gfRXaRPiDH@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-106275-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106275

--- Comment #6 from Chris Uzdavinis <cuzdav at gmail dot com> ---
Thank you for the information.  If the equality comparison function is slow
enough, the large number of extra calls may not be an optimization.  

While looking into it, the vastly different runtime behavior of it jumped out
to me as an indication of a problem, and seemed to be the answer to why
internal tests drew my attention to this in the first place.  (Behavior is
normal without this optimization, but tests complained with it.)  But now I
understand it better, being a combination of the new behavior and
characteristics of the custom predicate in "real code" of which this is a
minimization.  The extra calls are a symptom, not a cause.

  parent reply	other threads:[~2022-07-13 16:28 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-12 22:18 [Bug libstdc++/106275] New: " cuzdav at gmail dot com
2022-07-12 22:19 ` [Bug libstdc++/106275] " cuzdav at gmail dot com
2022-07-12 22:49 ` redi at gcc dot gnu.org
2022-07-12 22:51 ` redi at gcc dot gnu.org
2022-07-12 22:53 ` redi at gcc dot gnu.org
2022-07-12 23:00 ` redi at gcc dot gnu.org
2022-07-13 16:28 ` cuzdav at gmail dot com [this message]
2022-07-13 20:14 ` redi at gcc dot gnu.org

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