On 11/28/2012 09:20 AM, Michael Zolotukhin wrote:
>> Where was the null condition created in the first place?
> The reason it's happening is following. Before introduction of
> define_subst, function apply_iterators had the following loop:
> condition = NULL;
> FOR_EACH_VEC_ELT (iterator_uses, i, iuse)
> {
> v = iuse->iterator->current_value;
> iuse->iterator->group->apply_iterator (iuse->ptr, v->number);
> condition = join_c_conditions (condition, v->string);
> }
> apply_attribute_uses ();
> x = copy_rtx_for_iterators (original);
> add_condition_to_rtx (x, condition);
>
> This loop always iterated at least once, so 'condition' always became
> not-null (though, it could become empty-string ""). So, function
> add_condition_to_rtx always had not-null string in the arguments.
>
> With subst-iterators this loop is looking like this:
> condition = NULL;
> FOR_EACH_VEC_ELT (iterator_uses, i, iuse)
> {
> if (iuse->iterator->group == &substs)
> continue;
> v = iuse->iterator->current_value;
> iuse->iterator->group->apply_iterator (iuse->ptr, v->number);
> condition = join_c_conditions (condition, v->string);
> }
> So, it's possible that join_c_condition wouldn't be called at all, and
> 'condition' will remain NULL. Then it goes to add_condition_to_rtx and
> we get the fail we've seen.
>
> There is no mistake in such behaviour, but now we should be aware of
> possible NULL-string. It should be handled properly, and I see two
> places where we could do that - in join_c_conditions or in add_c_tests
> and maybe_eval_c_test.
>
Well, there does seem to be a mistake -- the use of NULL in the first
place. It seems to me that the easiest fix is
condition = "";
right at the beginning.
r~
