[Bug optimization/11386] GNU Emacs 21.3 failed to install using GCC 3.3, but GCC 3.2.3 works.

["simon dot marshall at misys dot com" <gcc-bugzilla at gcc dot gnu dot org>]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11386



------- Additional Comments From simon dot marshall at misys dot com  2003-07-11 10:09 -------
Here's an email from an Emacs list.  It looks interesting, and I guess everyone 
on this list working on this problem should know what is happening on the Emacs 
list.  If you think I'm spamming this list, let me know.

From: Paul Eggert [mailto:eggert@twinsun.com]
Sent: 11 July 2003 10:55
To: rms@gnu.org
Cc: simon.marshall@misys.com; emacs-devel@gnu.org;
emacs-pretesters@gnu.org
Subject: Re: Anyone built Emacs with gcc-3.3?


> From: Richard Stallman <rms@gnu.org>
> Date: Sat, 05 Jul 2003 18:25:56 -0400
> 
> The way to debug this is to treat it as an Emacs bug.  When you
> find the bug, it will actually be a miscompiled function (if this
> is GCC's fault).  Then you can send a useful GCC bug report.

I looked into this a bit, and there seem to be at least two problems.
One is an Emacs portability problem; the rest I don't know yet.

Emacs assumes that a top-level declaration like "int pure[1000] = {0};"
puts "pure" into the data area.  However, this assumption is no longer
true with GCC 3.3 on Solaris 8, which notices that "pure" has an
initializer that is all zeros, and puts "pure" into BSS instead.
This is a valid optimization, so I guess Emacs should deal with it.

I checked for all static variables that Emacs 21.3 defines to be zero
in Solaris 8, and which become readonly after dumping with GCC 3.2.3
but not with GCC 3.3, and I came up with the following patch to fix
this portability problem.  This fixes part of the bug, but not all;
Emacs still dumps core.  I'll see if I can investigate this further if
I find more time but that won't be before this weekend.