re PR tree-optimization/19401 (Trivial loop not unrolled)

re PR tree-optimization/19401 (Trivial loop not unrolled)

	PR tree-optimization/19401
	* tree-flow.h (tree_unroll_loops_completely): Declaration changed.
	* tree-ssa-loop-ivcanon.c (enum unroll_level): New.
	(estimated_unrolled_size): New function.
	(try_unroll_loop_completely, canonicalize_loop_induction_variables,
	tree_unroll_loops_completely): Always unroll loops if the code size
	does not increase.
	* tree-ssa-loop.c (tree_complete_unroll): Indicate whether all
	loops should be unrolled completely.
	(gate_tree_complete_unroll): Run complete unrolling unconditionally.

From-SVN: r99334