cfgloopmanip.c (create_preheader): Do not use loop_preheader_edge.
* cfgloopmanip.c (create_preheader): Do not use loop_preheader_edge.
(create_preheaders): Check that loops are available.
(fix_loop_structure): Clean up, improve comments.
* tree-ssa-loop-manip.c (rewrite_into_loop_closed_ssa):
Check that loops are available. Set LOOP_CLOSED_SSA to the loops
state flags.
* tree-scalar-evolution.c (scev_finalize): Clear scalar_evolution_info.
* predict.c (tree_estimate_probability): Do not call
calculate_dominance_info. Call create_preheaders.
* tree-cfgcleanup.c (cleanup_tree_cfg_loop): Only call
rewrite_into_loop_closed_ssa if LOOP_CLOSED_SSA is set in loops state
flags.
* cfgloop.c (loop_preheader_edge): Assert that loops have preheaders.
* cfgloop.h (LOOP_CLOSED_SSA): New constant.
* tree-cfg.c (tree_split_edge): Make an assert more precise.
* tree-ssa-threadedge.c (thread_across_edge): Comment the function
arguments.