[tree-ssa] Loop detection broken by the last merges

[Pop Sébastian]

Hi Diego, hi Jan,

The loop detection is broken mainly from the fact that mainline 
is using the BB.aux field in the following macro:

#define HEADER_BLOCK(B) (* (int *) (B)->aux)

This results in a conflict since this field is already used for 
other purposes in the tree-ssa branch.  

I have proposed to use a varray in stead of this field, but this 
part of the patch was not included in mainline, and now it has 
been completely removed by the merge.  

Jan, 
is the cfg_layout supposed to work on tree level too?
My impression is that cfg_layout is RTL specific.

I will post a patch for making the loop detection work again.

Sebastian.