* lower-subreg.c: Include except.h.
	(decompose_multiword_subregs): Verify that the only control flow
	insns we can split are loads to multi-words pseudos.
	Handle breaking such blocks after splitting, instead of calling
	find_many_sub_basic_blocks.

	* loop-unroll.c (split_edge_and_insert): Don't set BB_SUPERBLOCK
	on the new basic block.  Add a lengthy comment explaining why we
	thought this was necessary.
	* cfglayout.c (cfg_layout_finalize): Don't break superblocks.

From-SVN: r122807