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

gcc/ChangeLog

+2015-09-14  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	* 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.
+
 2015-09-14  Rich Felker  <dalias@libc.org>
 
 	* configure.ac: Change target pattern for sh TLS support