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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug pch/108732] Pre-compiled headers cannot be output to /dev/null
Date: Wed, 08 Feb 2023 22:45:48 +0000	[thread overview]
Message-ID: <bug-108732-4-BaHqt7a8ZF@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-108732-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108732

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Matt Hellige from comment #3)
> As long as I'm updating builds, I'll switch to that invocation, thanks.
> 
> I still do think it's a little odd that in this case (and *only* in this
> case?) output needs to be written to a mappable file. 

The way PCH works is mapping files in and out for speed reasons. So it is not
really that odd. Even though it is not expliclty mentioned in the manual:
https://gcc.gnu.org/onlinedocs/gcc-12.2.0/gcc/Precompiled-Headers.html#Precompiled-Headers

The whole idea of PCH is that the file is mapped in with almost no changes done
afterwards so an exact dump of the memory from compiler can be loaded back in
without doing anything special; rather the OS handles the loading into memory
from the file.

  parent reply	other threads:[~2023-02-08 22:45 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-08 21:59 [Bug c/108732] New: " matt at immute dot net
2023-02-08 22:09 ` [Bug pch/108732] " pinskia at gcc dot gnu.org
2023-02-08 22:11 ` pinskia at gcc dot gnu.org
2023-02-08 22:23 ` matt at immute dot net
2023-02-08 22:45 ` pinskia at gcc dot gnu.org [this message]
2023-02-08 22:56 ` matt at immute dot net
2023-02-08 23:01 ` pinskia at gcc dot gnu.org
2023-02-08 23:15 ` matt at immute dot net
2023-05-22 23:16 ` justinpopo6 at gmail dot com

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