From: James Dennett <jdennett@acm.org>
Subject: Re: Compiler Bug or what I'm doing wrong?
Date: Wed, 21 Jun 2006 19:07:31 -0700
Date: 2006-06-21T19:07:31-07:00 [thread overview]
Message-ID: <EXmmg.5733$6w.1813@fed1read11> (raw)
In-Reply-To: <4fstb4F1kgmekU1@individual.net>
Alex R. Mosteo wrote:
> M E Leypold wrote:
>
>> "Ludovic Brenta" <ludovic@ludovic-brenta.org> writes:
>>
>>> M E Leypold writes :
>>>> I've generated a core and also can reproduce the SIGSEGV in this
>>>> configuration 100% of the time. Don't hesitate to ask for more
>>>> debugger output or more code.
>>> I'd ask for *less* code :-)
>>>
>>> It would be nice if you could write a minimal test case that reproduces
>>> the problem. Yes, it takes time. I cannot do that for you, for various
>> I've already done that (it took me 10 hours so far to isolate the
>> problem from a larger program): The original program was much
>> larger. I'll be trying to even strip the example furter, but the
>> problem with the bug seems to be that it's a Heisenbug which vanishes
>> when you delete some fields in the datastructure, then turns up again
>> if you delete more fields and so on. The malloc() implementation of
>> libc which the GNAt runtime uses is unchecked so obviously one gets
>> sometimes away when freeing unvalid pointers and (as we know from C
>> programming).
>
> Indeed, for me the most frustrating part of bug reporting is obtaining a
> sufficiently small test case. I usually hit bugs in a large project I'm
> involved. Once you start to chop off, you know that the bug will disappear
> along the way. When you're not even sure if you're the culprit and not the
> compiler, the frustration is even bigger.
The "delta" tool can largely automate the task of reducing
a test case to something closer to minimal, though some
manual intervention helps:
http://gcc.gnu.org/wiki/A%20guide%20to%20testcase%20reduction
I've used it only a couple of times, but it saved me a *lot*
of effort. (On the other hand, it might need tweaking to
support Ada; I don't know, I used it on C++ code.)
-- James
next prev parent reply other threads:[~2006-06-22 2:07 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-20 16:56 Compiler Bug or what I'm doing wrong? M E Leypold
2006-06-21 7:44 ` Ludovic Brenta
2006-06-21 12:29 ` M E Leypold
2006-06-21 12:46 ` Alex R. Mosteo
2006-06-21 13:23 ` M E Leypold
2006-06-22 19:10 ` Simon Wright
2006-06-23 8:24 ` Ludovic Brenta
2006-06-23 13:14 ` Alex R. Mosteo
2006-06-23 13:24 ` Alex R. Mosteo
2006-06-24 20:33 ` Simon Wright
2006-06-24 20:56 ` M E Leypold
2006-06-26 7:32 ` Ludovic Brenta
2006-06-26 11:16 ` M E Leypold
2006-06-26 12:13 ` [Ada in Debian] GtkAda and GNAT versions Ludovic Brenta
2006-06-26 12:25 ` M E Leypold
2006-06-27 20:55 ` Compiler Bug or what I'm doing wrong? Simon Wright
2006-06-27 22:26 ` Ludovic Brenta
2006-06-22 2:07 ` James Dennett [this message]
2006-06-22 6:37 ` Duncan Sands
2006-06-22 16:53 ` M E Leypold
2006-06-22 19:01 ` Pascal Obry
2006-06-23 8:37 ` M E Leypold
2006-06-22 19:05 ` Dmitry A. Kazakov
2006-06-23 4:47 ` Jeffrey R. Carter
2006-06-23 12:26 ` Stephen Leake
2006-06-23 13:11 ` Dmitry A. Kazakov
2006-06-23 13:15 ` Alex R. Mosteo
2006-06-23 9:55 ` A smaller self contained test case. Was: " M E Leypold
2006-06-23 10:03 ` M E Leypold
2006-06-23 11:04 ` And a Workaround: Was: A smaller test case / Compiler Bug M E Leypold
2006-06-23 11:12 ` Possible memory leaks when reading/writing variant records M E Leypold
2006-06-24 11:46 ` A smaller self contained test case. Was: Compiler Bug or what I'm doing wrong? Dmitry A. Kazakov
2006-06-24 12:27 ` M E Leypold
2006-06-24 12:52 ` Dmitry A. Kazakov
2006-06-24 13:53 ` M E Leypold
2006-06-24 19:58 ` Dmitry A. Kazakov
2006-06-24 20:22 ` M E Leypold
2006-06-25 7:59 ` Dmitry A. Kazakov
2006-06-25 10:51 ` M E Leypold
2006-06-26 6:22 ` Martin Dowie
2006-06-24 21:21 ` M E Leypold
2006-06-25 21:36 ` M E Leypold
2006-06-26 21:53 ` Possibly fixed in gcc 4.1.1, but bug box -- Was: Re: A smaller self contained test case M E Leypold
2006-06-27 18:24 ` Alex R. Mosteo
2006-06-27 22:58 ` M E Leypold
2006-06-28 10:32 ` Alex R. Mosteo
2006-07-03 1:38 ` Steve Whalen
2006-07-03 10:36 ` M E Leypold
2006-06-28 8:41 ` Ludovic Brenta
2006-06-28 8:51 ` Georg Bauhaus
2006-06-28 10:43 ` Alex R. Mosteo
2006-06-23 10:00 ` Compiler Bug or what I'm doing wrong? M E Leypold
-- strict thread matches above, loose matches on Subject: below --
2006-06-23 17:42 Anh Vo
2006-06-26 6:59 ` Alex R. Mosteo
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