Add -ftree-loop-distribute-patterns enabled at -O3.

Add -ftree-loop-distribute-patterns enabled at -O3.

2010-08-02  Sebastian Pop  <sebastian.pop@amd.com>

	* common.opt (ftree-loop-distribute-patterns): New.
	* invoke.texi (-ftree-loop-distribute-patterns): Documented.
	* opts.c (decode_options): Enable flag_tree_loop_distribute_patterns
	at -O3.
	* tree-data-ref.c (stores_zero_from_loop): New.
	* tree-data-ref.h (stores_zero_from_loop): Declared.
	* tree-loop-distribution.c (tree_loop_distribution): Call
	stores_zero_from_loop.
	(tree_loop_distribution): Check flag_tree_loop_distribute_patterns.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@162822 138bc75d-0d04-0410-961f-82ee72b054a4