* 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.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@123670 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 13 insertions, 1 deletions

diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c
index 777685af652..86b26562754 100644
--- a/gcc/tree-ssa-threadedge.c
+++ b/gcc/tree-ssa-threadedge.c
@@ -488,7 +488,19 @@ simplify_control_stmt_condition (edge e,
    Note it is quite common for the first block inside a loop to
    end with a conditional which is either always true or always
    false when reached via the loop backedge.  Thus we do not want
-   to blindly disable threading across a loop backedge.  */
+   to blindly disable threading across a loop backedge.
+ 
+   DUMMY_COND is a shared cond_expr used by condition simplification as scratch,
+   to avoid allocating memory.
+ 
+   HANDLE_DOMINATING_ASSERTS is true if we should try to replace operands of
+   the simplified condition with left-hand sides of ASSERT_EXPRs they are
+   used in.
+ 
+   STACK is used to undo temporary equivalences created during the walk of
+   E->dest.
+
+   SIMPLIFY is a pass-specific function used to simplify statements.  */
 
 void
 thread_across_edge (tree dummy_cond,