identifying a BB representing a self-loop

[Zdenek Dvorak]

Hello,

> >> If we compile this by "#gcc -c -O -da demo.c, we can see there are only
> >> three BBs. Actually, BB1 is a self-looped basic block. But this loop
> >> information is not explicitly expressed.
> >>
> >
> >What do you mean "not explicitly expressed".
> >
> >If you call the loop finding routines (flow_loops_find), and look in the
> >result loop information, does it not give you a loop with a single node?
> 
> I meant that there is no edge like BB1-->BB1, if BB1 itself is a loop. For 
> example,

but in your original example, this edge *is* present:

> Basic block 1
> Successors:  1 2

Zdenek