| Summary: | [3.3 regression] miscompiles XDM-AUTHORIZATION-1 key generation and/or validation in XFree86 at -O2 | ||
|---|---|---|---|
| Product: | gcc | Reporter: | Debian GCC Maintainers <debian-gcc> |
| Component: | rtl-optimization | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED DUPLICATE | ||
| Severity: | critical | CC: | gcc-bugs, pme |
| Priority: | P2 | Keywords: | wrong-code |
| Version: | 3.3 | ||
| Target Milestone: | 3.3.2 | ||
| Host: | i386-linux / powerpc-linux | Target: | i386-linux / powerpc-linux |
| Build: | i386-linux / powerpc-linux | Known to work: | |
| Known to fail: | Last reconfirmed: | ||
|
Description
Debian GCC Maintainers
2003-06-29 09:19:22 UTC
Subject: Re: [3.3 regression] miscompiles XDM-AUTHORIZATION-1 key generation and/or validation in XFree86 at -O2
reichelt at gcc dot gnu dot org writes:
> Might be related to PR 11198.
No. Rechecked with 3.3 CVS 20030708.
Out of interest, since you are still using XFree86-4.2.1, have you made sure you compiled XFree86 with -fno-strict-aliasing, a thing that is done automatically since 4.3.0? Subject: Re: [3.3 regression] miscompiles XDM-AUTHORIZATION-1 key generation and/or validation in XFree86 at -O2 "sirl at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> writes: > ------- Additional Comments From sirl at gcc dot gnu dot org 2003-07-14 18:17 ------- > Out of interest, since you are still using XFree86-4.2.1, have you made sure > you compiled XFree86 with -fno-strict-aliasing, a thing that is done > automatically since 4.3.0? Yes, I tried this; it doesn't help. I have no other idea then, 4.2 already had -fno-merge-constants and I can't think of another promising option to try. Maybe -fno-strength-reduce? Otherwise you have to narrow down the bugreport to a single miscompiled file, we won't be able to help you otherwise. Subject: Re: [3.3 regression] miscompiles XDM-AUTHORIZATION-1 key generation and/or validation in XFree86 at -O2
sirl at gcc dot gnu dot org writes:
> I have no other idea then, 4.2 already had -fno-merge-constants and
> I can't think of another promising option to try. Maybe
> -fno-strength-reduce? Otherwise you have to narrow down the
> bugreport to a single miscompiled file, we won't be able to help you
> otherwise.
Daniel, Branden,
I see, that on Debian only -O2 is used, not any of the mentioned
flags.
Can you also try with -fno-gcse, since there was a bug in gcse where it would miscompile a bitfields. Ideally, what we'd really need from the Debian team are: 1) the file that gets miscompiled, and 2) the -f flag which causes it (1) is essential. (2) would be nice but not crucial. The "easy" way to find (2) is to compile with "-fFOO" where FOO is one of the flags turned on by -O2, as listed in the manual. Iterate over the list until you find the FOO that causes the breakage. Building with "-O2 -fno-FOO" should give you all the /other/ benefits as well as working code. This goes much faster, of course, if you can identify (1), then you only have to recompile that file. I would also use -W -Wall and see if there is any warnings that could be causing this. Until we have a test case for this PR, there is nothing that we can do. Therefore, I've postponed it until GCC 3.3.2. Subject: Re: [3.3 regression] miscompiles XDM-AUTHORIZATION-1 key generation and/or validation in XFree86 at -O2
On Tue, Jul 15, 2003 at 07:45:02AM +0200, Matthias Klose wrote:
> sirl at gcc dot gnu dot org writes:
> > I have no other idea then, 4.2 already had -fno-merge-constants and
> > I can't think of another promising option to try. Maybe
> > -fno-strength-reduce? Otherwise you have to narrow down the
> > bugreport to a single miscompiled file, we won't be able to help you
> > otherwise.
>
> Daniel, Branden,
>
> I see, that on Debian only -O2 is used, not any of the mentioned
> flags.
Can someone give me an idea of what the proper followup to this message
might be? Is more information required?
> Can someone give me an idea of what the proper followup to this message > might be? Is more information required? Yes, more information is required. See comment #8 and comment #9. The "other mentioned flags" are the flags mentioned in comments 3, 4, 5, and 7. I believe those are a subset of the possible ones mentioned in comment 8. It looks like this is fixed with Jim Wilson's alias.c patch(?), at least I am unable to reproduce the failure on the 20030812 3.3 branch. Checked on i386-linux, need to recheck on powerpc. Any news about this on powerpc? Thanks. Subject: Re: [3.3 regression] miscompiles XDM-AUTHORIZATION-1 key generation and/or validation in XFree86 at -O2
This problem appears to have been fixed by:
gcc-3.3 (1:3.3.2ds0-0pre0) unstable; urgency=medium
* Update to gcc-3.3.2 CVS 20030812.
- Fixes generation of wrong code for XDM-AUTHORIZATION-1 key generation
and/or validation. Closes: #196090.
* Update NEWS files.
* Change ix86 default CPU type for code generation:
- i386-linux -> i486-linux
- i386-gnu -> i586-gnu
- i386-freebsd-gnu -> i486-freebsd-gnu
Use -march=i386 to target i386 CPUs.
-- Matthias Klose <doko@debian.org> Tue, 12 Aug 2003 10:31:28 +0200
Thanks for fixing it.
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