re PR tree-optimization/85615 (ICE at -O2 and above on valid code on x86_64-linux-gnu: in dfs_enumerate_from, at cfganal.c:1197)

2018-05-03  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/85615
	* tree-ssa-threadupdate.c (thread_block_1): Only allow exits
	to loops not nested in BBs loop father to avoid creating multi-entry
	loops.

	* gcc.dg/torture/pr85615.c: New testcase.

From-SVN: r259891