2010-06-14  Changpeng Fang  <changpeng.fang@amd.com>

	* tree-ssa-loop-prefetch.c (nothing_to_prefetch_p): New.  Return
	true if no prefetch is going to be generated for a given group.
	(estimate_prefetch_count): Use prefetch_mod and unroll_factor to
	estimate the prefetch_count.
	(loop_prefetch_arrays): Call nothing_to_prefetch_p; estimate the
	prefetch count by considering the unroll_factor and prefetch_mod
	for is_loop_prefetching_profitable.

From-SVN: r160766