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

1 files changed, 38 insertions, 0 deletions

diff --git a/gcc/tree.c b/gcc/tree.c
index 4e7f7bfcf9b..186594375c7 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -6311,4 +6311,42 @@ operand_equal_for_phi_arg_p (tree arg0, tree arg1)
   return operand_equal_p (arg0, arg1, 0);
 }
 
+/* Returns number of zeros at the end of binary representation of X.
+   
+   ??? Use ffs if available?  */
+
+tree
+num_ending_zeros (tree x)
+{
+  unsigned HOST_WIDE_INT fr, nfr;
+  unsigned num, abits;
+  tree type = TREE_TYPE (x);
+
+  if (TREE_INT_CST_LOW (x) == 0)
+    {
+      num = HOST_BITS_PER_WIDE_INT;
+      fr = TREE_INT_CST_HIGH (x);
+    }
+  else
+    {
+      num = 0;
+      fr = TREE_INT_CST_LOW (x);
+    }
+
+  for (abits = HOST_BITS_PER_WIDE_INT / 2; abits; abits /= 2)
+    {
+      nfr = fr >> abits;
+      if (nfr << abits == fr)
+	{
+	  num += abits;
+	  fr = nfr;
+	}
+    }
+
+  if (num > TYPE_PRECISION (type))
+    num = TYPE_PRECISION (type);
+
+  return build_int_cst_type (type, num);
+}
+
 #include "gt-tree.h"