* tree-loop-distribution.c (struct builtin_info): New struct.
	(struct partition): Refactor fields into struct builtin_info.
	(partition_free): Free struct builtin_info.
	(build_size_arg_loc, build_addr_arg_loc): Delete.
	(generate_memset_builtin, generate_memcpy_builtin): Get memory range
	information from struct builtin_info.
	(find_single_drs): New function refactored from classify_partition.
	Also moved builtin validity checks to this function.
	(compute_access_range, alloc_builtin): New functions.
	(classify_builtin_st, classify_builtin_ldst): New functions.
	(classify_partition): Refactor code into functions find_single_drs,
	classify_builtin_st and classify_builtin_ldst.
	(distribute_loop): Don't do runtime alias check when distributing
	loop nest.
	(find_seed_stmts_for_distribution): New function.
	(pass_loop_distribution::execute): Refactor code finding seed
	stmts into above function.  Support distribution for the innermost
	two-level loop nest.  Adjust dump information.

	gcc/testsuite
	* gcc.dg/tree-ssa/ldist-28.c: New test.
	* gcc.dg/tree-ssa/ldist-29.c: New test.
	* gcc.dg/tree-ssa/ldist-30.c: New test.
	* gcc.dg/tree-ssa/ldist-31.c: New test.

From-SVN: r253680