Fix PR45199: do not aggregate memory accesses to the same array for -ftree-loop-distr...

2010-11-30  Sebastian Pop  <sebastian.pop@amd.com>

	PR tree-optimization/45199
	* tree-data-ref.c (mem_write_stride_of_same_size_as_unit_type_p): New.
	(stores_zero_from_loop): Call
	mem_write_stride_of_same_size_as_unit_type_p.
	* tree-data-ref.h (stride_of_unit_type_p): New.
	* tree-loop-distribution.c (generate_memset_zero): Simplified.
	Call stride_of_unit_type_p.
	(build_rdg_partition_for_component): Do not call
	rdg_flag_similar_memory_accesses when
	flag_tree_loop_distribute_patterns is set.

	* gcc.dg/tree-ssa/ldist-15.c: New.
	* gcc.dg/tree-ssa/ldist-16.c: New.
	* gfortran.dg/ldist-pr45199.f: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@167380 138bc75d-0d04-0410-961f-82ee72b054a4