re PR tree-optimization/70623 (ICE in compute_antic at -O2)

re PR tree-optimization/70623 (ICE in compute_antic at -O2)

2016-04-14  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/70623
	* tree-ssa-pre.c (changed_blocks): Make global ...
	(compute_antic): ... local here.  Move and fix worklist
	handling here.  Do not clear EDGE_DFS_BACK or call mark_dfs_back_edges.
	(compute_antic_aux): Add dumping for MAX assumed succs.  Remove
	worklist handling, dump when ANTIC_IN changed.
	(compute_partial_antic_aux): Remove worklist handling.
	(init_pre): Do not compute post dominators.  Add a comment about
	the CFG order chosen.
	(fini_pre): Do not free post dominators.

	* gcc.dg/torture/pr70623.c: New testcase.
	* gcc.dg/torture/pr70623-2.c: Likewise.

From-SVN: r234970