re PR tree-optimization/82060 (ICE in refs_may_alias_p_1 with devirtualization enabled)

re PR tree-optimization/82060 (ICE in refs_may_alias_p_1 with devirtualization enabled)

2017-09-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/82060
	* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
	Move devirtualization after stmt folding and before EH/AB/noreturn
	cleanup to get the stmt refs canonicalized.  Use a bool instead
	of gimple_modified_p since that doesn't work for NOPs.  Schedule
	NOPs generated by folding for removal.

	* g++.dg/torture/pr82060.C: New testcase.

From-SVN: r251650