re PR tree-optimization/55107 (GCC in an infinite loop in PRE)

re PR tree-optimization/55107 (GCC in an infinite loop in PRE)

2012-12-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/55107
	* tree-ssa-pre.c (struct pre_stats): Remove constified field.
	(bitmap_set_replace_value): Add gcc_unreachable.
	(do_regular_insertion): Re-write all_same handling.  Insert
	an assignment instead of a PHI in this case.
	(eliminate_bb): Record availability also for SSA names defined
	by a constant.
	(do_pre): Do not record constified events.
	(execute_fre): Likewise.

	* gcc.dg/torture/pr55107.c: New testcase.
	* gcc.dg/tree-ssa/ssa-pre-5.c: Adjust.

From-SVN: r194358