bb-reorder.c (partition_hot_cold_basic_blocks): Do not enter/exit cfglayout mode.

2009-03-30  Paolo Bonzini  <bonzini@gnu.org>

	* bb-reorder.c (partition_hot_cold_basic_blocks): Do not
	enter/exit cfglayout mode.
	(pass_partition_block): Require it.
	* combine.c (find_single_use, reg_dead_at_p): Use CFG.
	(combine_instructions): Track basic blocks instead of labels.
	(update_cfg_for_uncondjump): New.
	(try_combine): Use it.  Update jumps after rescanning.
	(pass_combine): Require PROP_cfglayout.
	* passes.c (pass_outof_cfg_layout_mode): Move after regmove.

From-SVN: r145283