cdce3.C execution fault

[Richard Sandiford]

Michael Hope <michael.hope at linaro.org> writes:
> On Tue, Dec 20, 2011 at 10:00 PM, Richard Sandiford
> <richard.sandiford at linaro.org> wrote:
>> Michael Hope <michael.hope at linaro.org> writes:
>>> Hi there.  I've looked further into the intermittent
>>> gcc/testsuite/g++.dg/cdce3.C test failures.  Taking Ira's
>>> vectoriser-only fix-pr51301-4.6 branch and comparing it with it's
>>> predecessor r106845:
>>>  * cdce3.o itself is identical across compilers
>>>  * Fault occurs in a parallel test run as part of the normal auto build
>>>  * Fault occurs every time
>>>  * Fault occurs with a manual 'make check-gcc RUNTESTFLAGS="dg.exp=cdce*'
>>>  * Fault doesn't occur when building from the command line
>>>  * Fault doesn't occur after updating binutils
>>>
>>> I'm suspicious of the linker.  The auto builders are Natty based and
>>> come with ld 2.21.0.20110327.  Updating them to Oneiric's
>>> 2.21.53.20110810 clears the problem.
>>
>> Hmm, FWIW, this reminds me of the problems that I had reproducing the
>> chromium linker bug from way back (which I think was also on Natty).
>> The bug only triggered for me when building under dpkg-buildpackage.
>> If I ran (seemingly) the same command by hand, it worked OK.
>
> What was the fix in the end?

I never did get to the bottom of the (seemingly) environment-dependent
linker behaviour, unfortunately.  Just the link took in the order of hours,
and it ended up being a time sink.

There's a good possibility it was just pilot error, although I did try
several times.

The bug itself was about an internal linker error, and in the end
Matthias gave me a nice self-contained testcase that reproduced cross,
so I fixed it that way instead.

Richard