PR tree-optimization/18687

	* tree-flow.h (find_loop_niter): Declare.
	* tree-ssa-loop-ivcanon.c (canonicalize_loop_induction_variables):
	Try using scev even for loops with more than one exit.
	* tree-ssa-loop-ivopts.c (struct loop_data): Removed niter field.
	(struct ivopts_data): Added niters field.
	(struct nfe_cache_elt): New.
	(nfe_hash, nfe_eq, niter_for_exit, niter_for_single_dom_exit): New
	functions.
	(tree_ssa_iv_optimize_init): Initialize niters cache.
	(determine_number_of_iterations): Removed.
	(find_induction_variables): Do not call determine_number_of_iterations.
	Access niters for single exit through niter_for_single_dom_exit.
	(add_iv_outer_candidates): Access niters for single exit through
	niter_for_single_dom_exit.
	(may_eliminate_iv): Take data argument.  Use niter_for_exit.  Do not use
	number_of_iterations_cond.
	(iv_period): New function.
	(determine_use_iv_cost_condition): Pass data to may_eliminate_iv.
	(may_replace_final_value): Take data argument.  Use
	niter_for_single_dom_exit.
	(determine_use_iv_cost_outer): Pass data to may_replace_final_value.
	(rewrite_use_compare): Pass data to may_eliminate_iv.
	(rewrite_use_outer): Pass data to may_replace_final_value.
	(free_loop_data): Clean up the niters cache.
	(tree_ssa_iv_optimize_finalize): Free the niters cache.
	(tree_ssa_iv_optimize_loop): Do not call loop_commit_inserts.
	* tree-ssa-loop-niter.c (find_loop_niter): New function.
	(find_loop_niter_by_eval): Use tree_int_cst_lt.
	(num_ending_zeros): Moved to tree.c.
	* tree.h (num_ending_zeros): Declare.
	* tree.c (num_ending_zeros): Moved from tree.c.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@94787 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 17 insertions, 6 deletions

diff --git a/gcc/tree-ssa-loop-ivcanon.c b/gcc/tree-ssa-loop-ivcanon.c
index 4635a023962..a2930166908 100644
--- a/gcc/tree-ssa-loop-ivcanon.c
+++ b/gcc/tree-ssa-loop-ivcanon.c
@@ -220,12 +220,23 @@ canonicalize_loop_induction_variables (struct loops *loops, struct loop *loop,
       niter = fold (build2 (MINUS_EXPR, TREE_TYPE (niter), niter,
 			    build_int_cst (TREE_TYPE (niter), 1)));
     }
-  else if (try_eval)
-    niter = find_loop_niter_by_eval (loop, &exit);
-
-  if (chrec_contains_undetermined (niter)
-      || TREE_CODE (niter) != INTEGER_CST)
-    return false;
+  else
+    {
+      /* If the loop has more than one exit, try checking all of them
+	 for # of iterations determinable through scev.  */
+      if (!loop->single_exit)
+	niter = find_loop_niter (loop, &exit);
+
+      /* Finally if everything else fails, try brute force evaluation.  */
+      if (try_eval
+	  && (chrec_contains_undetermined (niter)
+	      || TREE_CODE (niter) != INTEGER_CST))
+	niter = find_loop_niter_by_eval (loop, &exit);
+
+      if (chrec_contains_undetermined (niter)
+	  || TREE_CODE (niter) != INTEGER_CST)
+	return false;
+    }
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {