Debian Bug report logs - #393275
-O2 on Alpha makes code crash

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Package: g++; Maintainer for g++ is Debian GCC Maintainers <debian-gcc@lists.debian.org>; Source for g++ is src:gcc-defaults.

Reported by: Enrico Zini <enrico@debian.org>

Date: Sun, 15 Oct 2006 20:48:10 UTC

Severity: normal

Found in version gcc-defaults/1.46

Done: Steve Langasek <vorlon@debian.org>

Bug is archived. No further changes may be made.

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Report forwarded to debian-bugs-dist@lists.debian.org, debian-alpha@lists.debian.org, Debian GCC Maintainers <debian-gcc@lists.debian.org>:
Bug#393275; Package g++. Full text and rfc822 format available.

Acknowledgement sent to Enrico Zini <enrico@debian.org>:
New Bug report received and forwarded. Copy sent to debian-alpha@lists.debian.org, Debian GCC Maintainers <debian-gcc@lists.debian.org>. Full text and rfc822 format available.

Message #5 received at submit@bugs.debian.org (full text, mbox):

From: Enrico Zini <enrico@debian.org>
To: Debian Bug Tracking System <submit@bugs.debian.org>
Subject: -O2 on Alpha makes code crash
Date: Sun, 15 Oct 2006 21:17:01 +0100
[Message part 1 (text/plain, inline)]
Package: g++
Version: 4:4.1.1-11
Severity: normal

Hello,

I'm trying to debug http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=393194
and I found out that the test suite passes with -O0, -O1 and -O3 but fails
with -O2.  g++ is gcc version 4.1.2 20061007 (prerelease) (Debian 4.1.1-16)

g++-4.0 (gcc version 4.0.4 20060904 (prerelease) (Debian 4.0.3-7))
builds tagcoll fine with -O2.

I'm attaching the minimal test case I've been able to conjure that still
reproduces the bug.  I can't seem to be able to remove further code from
it and have the bug still reproduce.

To reproduce the problm, unpack the tarball then do:

  make CXXFLAGS+=-O2
  make clean
  make CXXFLAGS+=-O0

You can speed up the process by adding "-gstabs+" to CXXFLAGS.


Ciao,

Enrico


-- System Information:
Debian Release: testing/unstable
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-1-686
Locale: LANG=it_IT.UTF-8, LC_CTYPE=it_IT.UTF-8 (charmap=UTF-8)
[tagcoll2-gccbug.tar.gz (application/octet-stream, attachment)]

Information forwarded to debian-bugs-dist@lists.debian.org, Debian GCC Maintainers <debian-gcc@lists.debian.org>:
Bug#393275; Package g++. Full text and rfc822 format available.

Acknowledgement sent to Matthias Klose <doko@cs.tu-berlin.de>:
Extra info received and forwarded to list. Copy sent to Debian GCC Maintainers <debian-gcc@lists.debian.org>. Full text and rfc822 format available.

Message #10 received at 393275@bugs.debian.org (full text, mbox):

From: Matthias Klose <doko@cs.tu-berlin.de>
To: Enrico Zini <enrico@debian.org>, 393275@bugs.debian.org
Subject: Re: -O2 on Alpha makes code crash
Date: Mon, 23 Jul 2007 10:54:35 +0200
tag 393275 + moreinfo
thanks

Please recheck with g++-4.1, g++-4.2 and gcc-snapshot from unstable.



Information forwarded to debian-bugs-dist@lists.debian.org, Debian GCC Maintainers <debian-gcc@lists.debian.org>:
Bug#393275; Package g++. Full text and rfc822 format available.

Acknowledgement sent to Enrico Zini <enrico@debian.org>:
Extra info received and forwarded to list. Copy sent to Debian GCC Maintainers <debian-gcc@lists.debian.org>. Full text and rfc822 format available.

Message #15 received at 393275@bugs.debian.org (full text, mbox):

From: Enrico Zini <enrico@debian.org>
To: 393275@bugs.debian.org
Cc: falk@debian.org
Subject: Re: -O2 on Alpha makes code crash
Date: Fri, 24 Aug 2007 01:37:11 +0100
[Message part 1 (text/plain, inline)]
On Mon, Jul 23, 2007 at 10:54:35AM +0200, Matthias Klose wrote:

> tag 393275 + moreinfo
> thanks
> Please recheck with g++-4.1, g++-4.2 and gcc-snapshot from unstable.

We're talking about spending a couple of days full time installing
snapshots and supervising compiler runs: I'm sorry I'm quite sure it
won't come to the top of my TODO list in any near future.

I welcome anyone to try: debian/rules contains this work-around, it's
just a matter of removing these lines, running "fakeroot debian/rules
build" and after many hours, seeing that all the tests pass in the test
case:

  DEB_HOST_ARCH := $(shell dpkg-architecture -qDEB_HOST_ARCH)
  ifeq ($(DEB_HOST_ARCH),alpha)
  ifeq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
  	DEB_OPT_FLAG = -O1
  endif
  endif


Ciao,

Enrico

-- 
GPG key: 1024D/797EBFAB 2000-12-05 Enrico Zini <enrico@debian.org>
[signature.asc (application/pgp-signature, inline)]

Reply sent to Steve Langasek <vorlon@debian.org>:
You have taken responsibility. Full text and rfc822 format available.

Notification sent to Enrico Zini <enrico@debian.org>:
Bug acknowledged by developer. Full text and rfc822 format available.

Message #20 received at 393275-done@bugs.debian.org (full text, mbox):

From: Steve Langasek <vorlon@debian.org>
To: 393275-done@bugs.debian.org
Subject: Re: -O2 on Alpha makes code crash
Date: Thu, 23 Aug 2007 17:55:02 -0700
Test case builds and runs fine for me here on alpha with g++-4.1 4.1.2-14.

I'm not sure what kind of system is supposed to take "several days" to test
this, it built in a minute for me even on my slow alpha.

BTW, the provided Makefile is broken and tries to link a C++ app using $(CC)
instead of $(CXX).

So I have some doubt that I'm making use of the test case correctly, but in
any case I don't see any reason to keep this report open since the bug is
indeed not reproducible with the provided test case.

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
vorlon@debian.org                                   http://www.debian.org/



Information forwarded to debian-bugs-dist@lists.debian.org, Debian GCC Maintainers <debian-gcc@lists.debian.org>:
Bug#393275; Package g++. Full text and rfc822 format available.

Acknowledgement sent to Enrico Zini <enrico@debian.org>:
Extra info received and forwarded to list. Copy sent to Debian GCC Maintainers <debian-gcc@lists.debian.org>. Full text and rfc822 format available.

Message #25 received at 393275@bugs.debian.org (full text, mbox):

From: Enrico Zini <enrico@debian.org>
To: 393275@bugs.debian.org
Subject: Re: Bug#393275 closed by Steve Langasek <vorlon@debian.org> (Re: -O2 on Alpha makes code crash)
Date: Fri, 24 Aug 2007 10:02:29 +0100
[Message part 1 (text/plain, inline)]
On Fri, Aug 24, 2007 at 12:57:03AM +0000, Debian Bug Tracking System wrote:

> Test case builds and runs fine for me here on alpha with g++-4.1 4.1.2-14.
> 
> I'm not sure what kind of system is supposed to take "several days" to test
> this, it built in a minute for me even on my slow alpha.
> 
> BTW, the provided Makefile is broken and tries to link a C++ app using $(CC)
> instead of $(CXX).
> 
> So I have some doubt that I'm making use of the test case correctly, but in
> any case I don't see any reason to keep this report open since the bug is
> indeed not reproducible with the provided test case.

Agreed.

For the records, my answer last night was wrong: I had forgotten that I
had provided a much reduced test case, and I thought I had to rebuild
the entire tagcoll2 on alpha many times in order to see wether the bug
is still reproducible: that is what would have taken several days.


Ciao,

Enrico

-- 
GPG key: 1024D/797EBFAB 2000-12-05 Enrico Zini <enrico@debian.org>
[signature.asc (application/pgp-signature, inline)]

Bug archived. Request was from Debbugs Internal Request <owner@bugs.debian.org> to internal_control@bugs.debian.org. (Sat, 22 Sep 2007 07:29:34 GMT) Full text and rfc822 format available.

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