imcc -O2 question

[Matt Fowles]

All~

I have been playing with imcc's optimization and have a question about 
it.  With -O2 we get the following results for various inputs:

----------------------------(results 1, invariant removed from loop)
.sub _main
       set I0, 5
loop:
       set I1, 2
       add I0, I1
       lt I0, 20, loop
       print I0
       end
.end
vvvvvvvvvvvvvvvvvvvvvvvvv
_main:
        set I0, 5
        set I1, 2
loop:
        add I0, I1
        lt I0, 20, loop
        print I0
        end
---------------------------------(results 2, invariant not removed)
.sub _main
       set I0, 5
loop:
       set I1, 2
       add I0, I1
       lt I0, 20, loop
       print I0
       print I1
       end
.end
vvvvvvvvvvvvvvvvvvvvvvvvvvv
_main:
        set I0, 5
loop:
        set I1, 2
        add I0, I1
        lt I0, 20, loop
        print I0
        print I1
        end
The debug data helpfully tells me that it is because of reason 10, which 
means less than nothing to me, but gave me a place to look in the source.

Changing line 1096 from

return what == CHK_CLONE ? 1 : (reason=10,0);

to

return 1;

works, but that seems like it is probably the wrong answer.  Anyone want 
to give me a hint why this is happening and possibly add the above as a 
test?

Thanks,
Matt