shrink-wrap: Rewrite

shrink-wrap: Rewrite

This patch rewrites the shrink-wrapping algorithm, allowing non-linear
pieces of CFG to be duplicated for use without prologue instead of just
linear pieces.

	* shrink-wrap.c (requires_stack_frame_p): Fix formatting.
	(dup_block_and_redirect): Delete function.
	(can_dup_for_shrink_wrapping): New function.
	(fix_fake_fallthrough_edge): New function.
	(try_shrink_wrapping): Rewrite function.
	(convert_to_simple_return): Call fix_fake_fallthrough_edge.

From-SVN: r227775