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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/109442] Dead local copy of std::vector not removed from function
Date: Sat, 11 May 2024 16:44:12 +0000	[thread overview]
Message-ID: <bug-109442-4-WSnfsCWiQt@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-109442-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109442

--- Comment #20 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jan Hubicka from comment #19)
> Similar argument can IMO be used for eliding unused memory allocations. It
> is kind of up to std::vector implementation on how many
> allocations/deallocations it does, right?

It's up to std::allocator, which is not required to call operator new every
time memory is needed. 


> So we need a way to annotate the new/delete calls in the standard library as
> safe for such optimizations (i.e. implement clang's
> __bulitin_operator_new/delete?)

Yes, see PR 110137.

> How clang manages to optimize this out without additional hinting?

It supports __builtin_operator_{new,delete} and libstdc++ uses that when
compiled with clang.

  parent reply	other threads:[~2024-05-11 16:44 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-06 19:00 [Bug tree-optimization/109442] New: " hiraditya at msn dot com
2023-04-11 13:28 ` [Bug tree-optimization/109442] " rguenth at gcc dot gnu.org
2023-04-11 13:33 ` redi at gcc dot gnu.org
2023-04-11 13:38 ` redi at gcc dot gnu.org
2023-04-12  7:40 ` [Bug libstdc++/109442] " rguenth at gcc dot gnu.org
2023-04-12  9:29 ` redi at gcc dot gnu.org
2023-04-12  9:45 ` rguenth at gcc dot gnu.org
2023-04-12 10:01 ` redi at gcc dot gnu.org
2023-04-12 10:13 ` redi at gcc dot gnu.org
2023-04-12 10:22 ` rguenth at gcc dot gnu.org
2023-04-12 10:29 ` redi at gcc dot gnu.org
2023-04-12 10:35 ` redi at gcc dot gnu.org
2023-04-12 11:52 ` rguenther at suse dot de
2023-04-12 11:55 ` redi at gcc dot gnu.org
2023-04-16 18:38 ` richard-gccbugzilla at metafoo dot co.uk
2023-04-17  6:49 ` rguenth at gcc dot gnu.org
2023-04-18  2:15 ` richard-gccbugzilla at metafoo dot co.uk
2023-06-15 18:38 ` hiraditya at msn dot com
2024-05-11  0:07 ` xry111 at gcc dot gnu.org
2024-05-11 16:05 ` hubicka at gcc dot gnu.org
2024-05-14 13:47   ` Jan Hubicka
2024-05-11 16:44 ` redi at gcc dot gnu.org [this message]
2024-05-14 13:47 ` hubicka at ucw dot cz

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