re PR middle-end/30322 (((-i-1) + i) +1) is turned into ~i + (i+1) and never into 0 on the tree level)

	PR tree-optimization/30322
	* tree-ssa-loop-ivopts.c (fold_affine_expr, iv_value): Removed.
	(cand_value_at): Return the value as aff_tree.
	(may_eliminate_iv): Convert the bound from aff_tree to tree.
	* tree-affine.c (aff_combination_add_cst, aff_combination_add_product,
	aff_combination_mult): New functions.
	(aff_combination_add): Use aff_combination_add_cst.
	(aff_combination_convert): Allow conversions to a wider type.
	(tree_to_aff_combination): Handle BIT_NOT_EXPR.
	* tree-affine.h (aff_combination_mult): Declare.

	* gcc.dg/tree-ssa/loop-21.c: New test.

From-SVN: r120630