AIX/xlc test failures for gmp-5.0.1

[Torbjorn Granlund]

Torbjorn Granlund <tg at gmplib.org> writes:

  OK, now I am able to see the same error as you do.  I have not attempted
  to track this down, and I will probably not have time do do that in a
  while.
  
I gave it a go this evening.

Unfortunately, this environment is too buggy for me to make any
progress.

1. A build without optimisation is miscompiled in several places.  I
   don't think it is possible to use such a build.  One problem is that
   it in effect folds x & 0 -> x.  This is an extremely basic compiler
   bug.

2. Debugging the t-toom32 problem with -O is completely hopeless since
   the debugging information and gdb does not agree about almost
   anything.  Single stepping doesn't work, variable printing doesn't
   work.

3. Tracking down the problem with t-toom32 will with very high
   probability just lead to another compiler bug.  The code works on a
   large number of systems, and is quite solid.  Therefore, I am not
   willing to try to fight with print statements or whatnot.

If somebody wants to help isolating this problem, it might be best done
by adding lots of print statements, hoping that they will not make the
compiler work better (which unfortunately is not unlikely).  Then
compile the code on a non-problem system (or with gcc on the same
system) and run them side-by-side, comparing the printed results.

I don't plan to work more on this.

-- 
Torbjörn