re PR tree-optimization/81488 (gcc goes off the limits allocating memory in gimple...

re PR tree-optimization/81488 (gcc goes off the limits allocating memory in gimple-ssa-strength-reduction.c)

2017-08-22  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/81488
	* gimple-ssa-strength-reduction (struct slsr_cand_d): Add visited
	and cached_basis fields.
	(MAX_SPREAD): New constant.
	(alloc_cand_and_find_basis): Initialize new fields.
	(clear_visited): New function.
	(create_phi_basis_1): Rename from create_phi_basis, set visited
	and cached_basis fields.
	(create_phi_basis): New wrapper function.
	(phi_add_costs_1): Rename from phi_add_costs, add spread
	parameter, set visited field, short-circuit when limits reached.
	(phi_add_costs): New wrapper function.
	(record_phi_increments_1): Rename from record_phi_increments, set
	visited field.
	(record_phi_increments): New wrapper function.
	(phi_incr_cost_1): Rename from phi_incr_cost, set visited field.
	(phi_incr_cost): New wrapper function.
	(all_phi_incrs_profitable_1): Rename from
	all_phi_incrs_profitable, set visited field.
	(all_phi_incrs_profitable): New wrapper function.

From-SVN: r251286