re PR tree-optimization/54489 (tree FRE uses an excessive amount of memory)

re PR tree-optimization/54489 (tree FRE uses an excessive amount of memory)

2012-09-12  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/54489
	* tree-ssa-pre.c: Include domwalk.h.
	(in_fre): Remove.
	(sccvn_valnum_from_value_id): New function.
	(debug_bitmap_sets_for): Simplify.
	(get_representative_for): Properly initialize the SCCVN valnum.
	(create_expression_by_pieces): Likewise.
	(insert_into_preds_of_block): Likewise.
	(can_PRE_operation): Remove.
	(make_values_for_phi): Simplify.
	(compute_avail): Likewise.
	(do_SCCVN_insertion): Remove.
	(eliminate_avail, eliminate_push_avail, eliminate_insert):
	New functions.
	(eliminate): Split and perform a domwalk.
	(eliminate_bb): Former eliminate part that is now dom-enter.
	(eliminate_leave_block): New function.
	(fini_eliminate): Likewise.
	(init_pre): Simplify.
	(fini_pre): Likewise.
	(execute_pre): Fold into do_pre and do_fre.
	(do_pre): Consume execute_pre.
	(do_fre): Likewise.
	* Makefile.in (tree-ssa-pre.o): Add domwalk.h dependency.

From-SVN: r191225