re PR tree-optimization/66388 (Test gcc.target/i386/pr49781-1.c failed because of...

re PR tree-optimization/66388 (Test gcc.target/i386/pr49781-1.c failed because of recent scev overflow patches.)

	PR tree-optimization/66388
	* tree-ssa-loop-ivopts.c (struct iv, iv_cand, ivopts_data): New
	fields.
	(dump_iv): Dump no_overflow information.
	(alloc_iv): Initialize new field for struct iv.
	(mark_bivs): Count number of no_overflow bivs.
	(find_deriving_biv_for_expr, record_biv_for_address_use): New
	functions.
	(idx_find_step): Call new functions above.
	(add_candidate_1, add_candidate): New paramter.
	(add_iv_candidate_for_biv): Add sizetype cand for BIV.
	(get_computation_aff): Simplify convertion of cand for BIV.
	(get_computation_cost_at): Step cand's base if necessary.

From-SVN: r227844