[m-rev.] for review: Fix compiler abort during liveness detection.

[Julien Fischer]

On Mon, 9 Sep 2013, Peter Wang wrote:

> On Mon, 9 Sep 2013 13:43:28 +1000 (EST), Julien Fischer <jfischer at opturion.com> wrote:
>>
>> Hi Peter,
>>
>> On Wed, 4 Sep 2013, Peter Wang wrote:
>>
>>> [I'm not certain of the fix]
>>
>> Neither am I.
>>
>> Do you know where the call to goal_info_get_post_births that is causing
>> the aborts is?  In particular, is it whne detect_deadness (i.e. stage 2
>> of of liveness analysis) is processing an if-then-else?
>
> It happens immediately afterwards in the call to add_liveness_after_goal.

So even sooner in fact.  I think you should go ahead and commit your
fix since it's an improvement on the status quo.  I suggest you change
the comment that you added to something like:

     % XXX Initialize liveness-related fields, since some Other code in
     % this module assumes that they are initialized.

(There are at least two spots, the call to add_liveness_after_goal
and also in detect_deadness_in_goal.  Presumably, another fix would be
to replicate the check for condition that cannot fail at all of those
points?)

Cheers,
Julien.