re PR middle-end/28683 (ICE (segfault in add_reg_br_prob_note) when comparing pointers with -O (and higher))

	PR middle-end/28683
	* cfgexpand.c (add_reg_br_prob_note): Check if last has exactly
	3 following insns.

	* gcc.c-torture/compile/20060823-1.c: New test.

From-SVN: r116467