From: Segher Boessenkool <segher@kernel.crashing.org>
To: Martin Oberzalek <kingleo@gmx.at>
Cc: gcc-help@gcc.gnu.org
Subject: Re: Guaranteed copy elision
Date: Fri, 18 Nov 2022 15:58:04 -0600 [thread overview]
Message-ID: <20221118215804.GC25951@gate.crashing.org> (raw)
In-Reply-To: <32119174b061d5bf07e3d39063709f852ff5ca5f.camel@gmx.at>
On Fri, Nov 18, 2022 at 10:35:20PM +0100, Martin Oberzalek via Gcc-help wrote:
> Am Freitag, dem 18.11.2022 um 16:05 +0100 schrieb Stefan Ring via Gcc-
> help:
> > On Tue, Nov 15, 2022 at 6:48 AM Yubin Ruan via Gcc-help
> > <gcc-help@gcc.gnu.org> wrote:
> > > Is there any language facility to help us guarantee that at compile
> > > time
> > > (such as some kind of static_assert() ) so that we can be confident
> > > writing
> > > those one-liner ?
> With c++ language features this may is a solution:
Nope. Try with -O0 for example.
There is no way to guarantee copy elision. It isn't even clear what
*exactly* you want guaranteed, what "copy elision" means *exactly*, what
"guaranteeing copy elision" means, etc.
If you write clear and simple (which means: not artificially made
complex) and correct source code, you can trust the compiler will
generate good machine code for you (if you use -O2 or such). If not,
bug reports are welcome!
A C compiler is not a "portable assembler", you have no direct control
over generated code. This is a good thing: the compiler is much better
at writing fast machine code than users are.
Segher
next prev parent reply other threads:[~2022-11-18 21:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-15 5:47 Yubin Ruan
2022-11-18 15:05 ` Stefan Ring
2022-11-18 21:35 ` Martin Oberzalek
2022-11-18 21:58 ` Segher Boessenkool [this message]
2022-11-19 10:07 ` Jonathan Wakely
2022-11-19 10:12 ` Jonathan Wakely
2022-11-21 14:17 ` Yubin Ruan
2022-11-21 14:20 ` Jonathan Wakely
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