http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54128
--- Comment #11 from Steve Ellcey <sje at gcc dot gnu.org> 2012-08-28 23:07:25 UTC --- I think the problem is the use of INSN_P instead of NONDEBUG_INSN_P in build_insn_chain (ira.c). Changing this fixes the small test case and I will do a full bootstrap build and test to verify it fixes the overall problem.