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Groups > muc.lists.netbsd.tech.toolchain > #3600
| From | Robert Elz <kre@munnari.OZ.AU> |
|---|---|
| Newsgroups | muc.lists.netbsd.tech.toolchain |
| Subject | Re: netbsd-11 gcc bug |
| Date | 2026-05-24 02:29 +0700 |
| Organization | Newsgate at muc.de e.V. |
| Message-ID | <9186.1779564551@jacaranda.noi.kre.to> (permalink) |
| References | <ahH2NFJ58JQpjOBi@antioche.eu.org> <> |
Date: Sat, 23 May 2026 20:47:16 +0200
From: Manuel Bouyer <bouyer@antioche.eu.org>
Message-ID: <ahH2NFJ58JQpjOBi@antioche.eu.org>
| We're just taking computing the address here, we're not telling anything
| about its validity.
I believe the argument is that you're computing an address based upon
a NULL pointer, which has unspecified representation, hence the result
is undefined (we know NULL is 0, but C doesn't). One of the many
stupidities inflicted upon the C language by the compiler people who
want to be able to use every trick they can to be able to generate
faster code.
| I guess there's still variants of offsetof() around which uses this.
Perhaps.
| So what are you suggesting ? changing line 1214 to
| if ((fdp != &fr->fr_dif || fr == NULL) && (fin->fin_out == 0)) {
It would need to be
if ((fr == NULL || fdp != &fr->fr_dif) && fin->fin_out == 0) {
(removing the parens around the == test is just style). The way you
wrote it the compiler would just omit the fr == NULL test, as by doing
the addr comparison first you've already promised that fr != NULL).
kre
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netbsd-11 gcc bug Manuel Bouyer <bouyer@antioche.eu.org> - 2026-05-23 10:59 +0200
Re: netbsd-11 gcc bug Manuel Bouyer <bouyer@antioche.eu.org> - 2026-05-23 12:55 +0200
Re: netbsd-11 gcc bug Manuel Bouyer <bouyer@antioche.eu.org> - 2026-05-23 20:45 +0200
Re: netbsd-11 gcc bug Valery Ushakov <uwe@stderr.spb.ru> - 2026-05-23 14:22 +0300
Re: netbsd-11 gcc bug Manuel Bouyer <bouyer@antioche.eu.org> - 2026-05-23 13:28 +0200
Re: netbsd-11 gcc bug Roland Illig <roland.illig@gmx.de> - 2026-05-23 20:38 +0200
Re: netbsd-11 gcc bug Manuel Bouyer <bouyer@antioche.eu.org> - 2026-05-23 20:47 +0200
Re: netbsd-11 gcc bug Robert Elz <kre@munnari.OZ.AU> - 2026-05-24 02:29 +0700
Re: netbsd-11 gcc bug Mouse <mouse@Rodents-Montreal.ORG> - 2026-05-23 19:11 -0400
Re: netbsd-11 gcc bug Martin Husemann <martin@duskware.de> - 2026-05-24 10:44 +0200
Re: netbsd-11 gcc bug Mouse <mouse@Rodents-Montreal.ORG> - 2026-05-24 08:33 -0400
Re: netbsd-11 gcc bug Jason Thorpe <thorpej@me.com> - 2026-05-24 11:38 -0400
Re: netbsd-11 gcc bug "Greg A. Woods" <woods@planix.ca> - 2026-05-24 16:53 -0700
Re: netbsd-11 gcc bug David Holland <dholland-tech@netbsd.org> - 2026-05-25 00:02 +0000
Re: netbsd-11 gcc bug Mouse <mouse@Rodents-Montreal.ORG> - 2026-05-25 08:23 -0400
C compiler (over-)optimization (was: netbsd-11 gcc bug) Edgar Fuß <ef@math.uni-bonn.de> - 2026-05-29 19:12 +0200
Re: C compiler (over-)optimization (was: netbsd-11 gcc bug) Mouse <mouse@Rodents-Montreal.ORG> - 2026-05-29 14:21 -0400
Re: C compiler (over-)optimization (was: netbsd-11 gcc bug) "Greg A. Woods" <woods@planix.ca> - 2026-05-29 14:27 -0700
Re: C compiler (over-)optimization Anders Magnusson <ragge@tethuvudet.se> - 2026-05-30 12:30 +0200
Re: C compiler (over-)optimization (was: netbsd-11 gcc bug) Andrew Cagney <andrew.cagney@gmail.com> - 2026-05-31 13:02 -0400
Re: C compiler (over-)optimization (was: netbsd-11 gcc bug) Jason Thorpe <thorpej@me.com> - 2026-05-31 14:29 -0500
Re: netbsd-11 gcc bug "Greg A. Woods" <woods@planix.ca> - 2026-05-28 14:40 -0700
Re: netbsd-11 gcc bug Mouse <mouse@Rodents-Montreal.ORG> - 2026-05-28 18:36 -0400
Re: netbsd-11 gcc bug Jason Thorpe <thorpej@me.com> - 2026-05-28 19:04 -0400
Re: netbsd-11 gcc bug "Greg A. Woods" <woods@planix.ca> - 2026-05-29 14:31 -0700
Re: netbsd-11 gcc bug Jörg Sonnenberger <joerg@bec.de> - 2026-05-26 13:52 +0200
Re: netbsd-11 gcc bug Jason Thorpe <thorpej@me.com> - 2026-05-26 10:02 -0400
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