rs6000.c (rs6000_builtin_vectorization_cost): Revise costs for vec_perm and vec_promo...

rs6000.c (rs6000_builtin_vectorization_cost): Revise costs for vec_perm and vec_promote_demote down to more natural values.

2012-07-31  Bill Schmidt  <wschmidt@linux.ibm.com>

	* config/rs6000/rs6000.c (rs6000_builtin_vectorization_cost): Revise
	costs for vec_perm and vec_promote_demote down to more natural values.
	(struct _rs6000_cost_data): New data structure.
	(rs6000_density_test): New function.
	(rs6000_init_cost): Change to use rs6000_cost_data.
	(rs6000_add_stmt_cost): Likewise.
	(rs6000_finish_cost): Perform density test when vectorizing a loop.

From-SVN: r190019