[PPL-devel] ppl-0.10.2 check thorough test fail

[Enea Zaffanella]

Il 29/03/2011 02:39, David Fang ha scritto:
> Hello,
>     With ppl-0.10.2, several Mac OS X fink users (including myself) have
> observed the following single test failure on 10.5 and 10.6, using
> Apple's gcc-4.2, arch i686-apple-darwin{9,10}, with thorough tests enabled:
> 
> /usr/bin/grep -E "^Optimum value: " ../../../demos/ppl_lpsol/expected_mpz
>> expected_optima && /usr/bin/grep -E "^Optimum value: " obtained
>> obtained_optima && diff -u expected_optima obtained_optima
> --- expected_optima     2011-03-22 21:05:58.000000000 -0400
> +++ obtained_optima     2011-03-22 21:05:58.000000000 -0400
> @@ -1,9 +1,10 @@
> -Optimum value: -3
> -Optimum value: 2
> +Optimum value: -2
> +Optimum value: 1

I agree with Roberto that all of the symptoms suggest that Apple gcc-4.2
is miscompiling something (and we would really appreciate if someone can
try out using a newer gcc).

The first differences above are related to a very simple MIP problem
test. Can you please provide us with the output of the following command:

$ cd <PATH_TO_PPL_BUILD>/demos/ppl_lpsol
$ ./ppl_lpsol -s -p1 -v 4 -c -M
<PATH_TO_PPL_SRC>/demos/ppl_lpsol/examples/ex1.mps

This will also show the problem as read from the input, which should be
something like:
=============
Integer variables:
x1 x2
Constraints:
-2*x1 - x2 >= -5
4*x1 - 4*x2 >= -5
x1 >= 0
x2 >= 0
Objective function:
x1 - 2*x2
Maximizing.
=============
We would like to be sure that we are not stumbling on (a miscompilation
causing) an input-parsing bug well before entering the optimization code.

Also note that the same command above can be used (in this specific case
only!) as a quick replacement for the lengthy 'make check' for those
building the ppl with a newer gcc. If the bug is still there, you will
obtain something different wrt the following:
=============
Optimum value: 2
Optimum location:
x1 = 2
x2 = 0
=============

Thanks,
Enea.