From: Eli Zaretskii <eliz@gnu.org>
To: Dan Nicolaescu <dann@gnu.org>
Cc: 10164@debbugs.gnu.org, tim.crews@code-affinity.com
Subject: bug#10164: 24.0.91; Instant crash enabling linum-mode
Date: Wed, 30 Nov 2011 08:54:41 -0500 [thread overview]
Message-ID: <E1RVkcT-0005os-HE@fencepost.gnu.org> (raw)
In-Reply-To: <yxqliqx3h7r.fsf@fencepost.gnu.org> (message from Dan Nicolaescu on Wed, 30 Nov 2011 07:52:40 -0500)
> From: Dan Nicolaescu <dann@gnu.org>
> Cc: Tim Crews <tim.crews@code-affinity.com>, 10164@debbugs.gnu.org
> Date: Wed, 30 Nov 2011 07:52:40 -0500
>
> Eli Zaretskii <eliz@gnu.org> writes:
>
> >> Date: Tue, 29 Nov 2011 19:05:20 -0700
> >> From: Tim Crews <tim.crews@code-affinity.com>
> >>
> >> Start Emacs with runemacs -Q --no-init-file
> >> C-x C-f foo.txt
> >> M-x linum-mode
> >> (Emacs doesn't crash yet)
> >> Type anything. Emacs instantly crashes.
> >
> > Arrgh! This is GCC 4.6.x "as-is" code reordering in action. Emacs
> > crashes here:
> >
> > xassert (!row->enabled_p
> > || row->mode_line_p
> > || verify_row_hash (row));
> >
> > Evidently, it calls verify_row_hash before it tests row->mode_line_p.
>
> Are you sure?
How else can I explain this display from GDB:
(gdb) prow
y=0 x=0 pwid=673 a+d=12+4=16 phys=12+4=16 vis=16
used=(LMargin=0,Text=84,RMargin=0) Hash=263825844
start=0 end=0 ENA MODEL
? MODEL says that this row has its mode_line_p flag set.
Just to be sure, I ran the recipe again under GDB, setting a
breakpoint inside verify_row_hash thusly:
(gdb) break verify_row_hash if row->mode_line_p != 0
and sure enough, it breaks as soon as I turn on linum-mode, with ROW
that shows the glyphs in the mode line.
> Without interprocedural analysis the compiler cannot know
> that `verify_row_hash' does not alter row->enabled_p, so it cannot
> change the evaluation order.
I don't know. Maybe GCC does perform such an analysis. Or maybe it
decides that the result of this comparison in verify_row_hash:
row->hash == row_hash (row)
will not change even if row_hash does modify its argument ROW. Or
maybe it's a bug in GCC.
next prev parent reply other threads:[~2011-11-30 13:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-30 2:05 bug#10164: 24.0.91; Instant crash enabling linum-mode Tim Crews
2011-11-30 12:19 ` Eli Zaretskii
2011-11-30 12:52 ` Dan Nicolaescu
2011-11-30 13:54 ` Eli Zaretskii [this message]
2011-11-30 15:51 ` Dan Nicolaescu
2011-11-30 15:01 ` Andy Moreton
2011-11-30 15:10 ` Juanma Barranquero
2011-11-30 12:29 ` Eli Zaretskii
2011-11-30 12:38 ` Juanma Barranquero
2011-11-30 13:40 ` Eli Zaretskii
[not found] ` <CAAeL0SS_ydvYGqw0rOd3UR6RoYzJWkEkFhaYX5kZ2m+vTx-Q0w@mail.gmail.com>
[not found] ` <E1RVkfB-00062i-AB@fencepost.gnu.org>
[not found] ` <CAAeL0SRW1A7-vOzNGxFvGtbv=zVSo2ji+_HB7R8rFtq15ufhPg@mail.gmail.com>
2011-11-30 16:24 ` Eli Zaretskii
2011-11-30 16:29 ` Chong Yidong
2011-11-30 16:35 ` Chong Yidong
2011-11-30 16:39 ` Juanma Barranquero
2011-11-30 16:42 ` Chong Yidong
2011-11-30 16:56 ` Eli Zaretskii
2011-11-30 17:37 ` Chong Yidong
2011-11-30 18:10 ` Dan Nicolaescu
2011-11-30 18:29 ` Eli Zaretskii
2011-11-30 18:55 ` Dan Nicolaescu
[not found] ` <handler.10164.D10164.132267227016711.notifdone@debbugs.gnu.org>
2011-11-30 17:29 ` bug#10164: closed (Instant crash enabling linum-mode) Tim Crews
2011-11-30 18:06 ` Eli Zaretskii
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