We've tracked down an "array reference count is negative!" problem,
and think it's in the generated C code.
The error occurs in a procedure that picks random elements from
two arrays as seeds to determine how well two images match up.
It looks like:
proc pick_seeds(const corners1 : [] corner,
const corners2 : [] corner, rand : RandomStream,
inout try : tryinfo) : bool {
var matches : [corners2.domain] int;
var nmatch : int;
var pick : int;
var ind31, ind32 : int;
/* Pick random seeds, verify they are similar, store in try.
The list of possible matches is kept in the array, and nmatch
contains the number of seeds we've stored. If it's 0, then
there are no seeds and we can return. If it's not, then we
need to pick one by choosing a random number between 1 and
nmatch. ind31 is the first half of the pair that's already
been determined; ind32 is the second half.
*/
if (0 == nmatch) then return false;
pick = random_bound(rand, 1, nmatch);
ind32 = matches(pick);
try.seed3 = (ind31, ind32);
return true;
}
The problem is that the program crashes in the line with the
(0 == nmatch) test; the error message is "halt reached - array
reference count is negative!"
We scattered writeln's through the procedure so we could see in
the generated C code where these lines were. At the (0 == nmatch)
test:
call_tmp_chpl299 = (INT64(0) == nmatch_chpl);
if (call_tmp_chpl299) {
ret_chpl = false;
chpl__autoDestroy5(matches_chpl, INT64(224), "ransac_rst.chpl");
chpl__autoDestroy2(call_tmp_chpl6, INT64(227), "ransac_rst.chpl");
chpl__autoDestroy2(call_tmp_chpl7, INT64(228), "ransac_rst.chpl");
goto _end_pick_seeds_chpl;
}
call_tmp_chpl300 = random_bound_chpl(rand_chpl, INT64(1), nmatch_chpl);
and at the end of the procedure:
/* code between the call to random_bound and the try.seed3
assignment is skipped */
ret_chpl = true;
_end_pick_seeds_chpl:;
chpl___ASSIGN_17(try_chpl, &_formal_tmp_try_chpl);
chpl__autoDestroy2(call_tmp_chpl7, INT64(228), "ransac_rst.chpl");
chpl__autoDestroy2(call_tmp_chpl6, INT64(227), "ransac_rst.chpl");
chpl__autoDestroy5(matches_chpl, INT64(224), "ransac_rst.chpl");
return ret_chpl;
It looks like matches_chpl is being destroyed twice, once at the
if .. then site, and once at the end. Which would explain the
reference count problem.
Hopefully this code snippet is enough to track down the problem;
the full program and test case is fairly big ... Please let me
know if there's any other information you need.
Greg
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