re PR tree-optimization/84929 (ICE at -O3 on valid code on x86_64-linux-gnu: tree check: expected polynomial_chrec, have nop_expr in analyze_siv_subscript_cst_affine, at tree-data-ref.c:3018)

2018-03-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/84929
	* tree-data-ref.c (analyze_siv_subscript_cst_affine): Guard
	chrec_is_positive against non-chrec arg.

	* gcc.dg/torture/pr84929.c: New testcase.

From-SVN: r258643