re PR tree-optimization/79740 (ICE on -Os and above in both 32-bit and 64-bit modes...

re PR tree-optimization/79740 (ICE on -Os and above in both 32-bit and 64-bit modes on x86_64-linux-gnu (internal compiler error: in VN_INFO_GET, at tree-ssa-sccvn.c:407  }))

2017-02-28  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/79740
	* tree-ssa-sccvn.c (vn_nary_op_insert_into): Allow redundant
	inserts.
	(visit_nary_op): Insert the nary into the hashtable if we
	pattern-matched sth.
	* tree-ssa-pre.c (eliminate_insert): Robustify.

	* gcc.dg/torture/pr79740.c: New testcase.

From-SVN: r245780