Tree Versioning Question

[Matt Davis]

On Mon, Aug 6, 2012 at 1:43 PM, Matt Davis <mattdavis9@gmail.com> wrote:
> Hello,
> I am using cgraph_function_versioning() to create a duplicate
> function, e.g. a clone.  This usually has worked well for me in the
> past, but I have run into an interesting case where the
> tree_function_versioning() code is performing a split_edge() on the
> successor of the entry basic block.  What I am left with is a gimple

<snip>

> The code is just a test routine I am using for testing how my plugin
> for region-based memory handles packages.  Anyways, the important part
> (I think) is that <bb 4> is the result of the split_edge call
> mentioned earlier when I clone NewThing2, and that BB is just empty, a
> fall-thru.  When the gimple_cfg_expand() pass kicks-in
> find_bb_boundaries() is called in find_many_sub_basic_blocks() and <bb
> 5>'s loop father is referenced.  Well, that loop_father instance is
> NULL.  And gcc is dying in add_bb_to_loop().  I think I can avoid this
> if I were to remove <bb 4>  But I am not entirely sure.  I am not even
> sure why BB5 is even created as 0 is the Entry and 1 is the exit
> block.  I am running gcc 4.7.1 and am a bit lost as to what to do.

I have "solved" this problem.  I am not entirely sure what was
happening, but I was modifying the cloned function, which had an
effect that caused a basic block to be split, primarily because of a
label/note rtx in the call graph.

-Matt