re PR middle-end/86554 (Incorrect code generation with signed/unsigned comparison)

2019-01-08  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/86554
	* tree-ssa-sccvn.c (eliminate_dom_walker, rpo_elim,
	rpo_avail): Move earlier.
	(visit_nary_op): When value-numbering to expressions
	with different overflow behavior make sure there's an
	available expression on the path.

	* gcc.dg/torture/pr86554-1.c: New testcase.
	* gcc.dg/torture/pr86554-2.c: Likewise.

From-SVN: r267725