re PR tree-optimization/18527 (cannot determine number of iterations for loops with <=)

	PR tree-optimization/18527
	* tree-ssa-loop-niter.c (number_of_iterations_cond,
	number_of_iterations_special, number_of_iterations_exit):
	Move base and step of an iv to a single structure.  Add
	no_overflow flag, and use it in # of iterations analysis.
	* tree-scalar-evolution.c (analyze_scalar_evolution_in_loop): Add
	folded_casts argument.
	(simple_iv): Pass base and step in a structure.  Set no_overflow
	flag.
	(scev_const_prop): Add argument to analyze_scalar_evolution_in_loop.
	Evaluate expensiveness of computing # of iterations instead of
	the final expression.
	* tree-scalar-evolution.h (affine_iv): New structure.
	(simple_iv): Declaration changed.
	* tree-chrec.c (chrec_apply): Handle chrecs containing symbols.
	* tree-ssa-loop-ivopts.c (determine_biv_step, find_givs_in_stmt_scev,
	find_givs_in_stmt): Changed due to simple_iv change.

	* gcc.dg/tree-ssa/loop-15.c: New test.

From-SVN: r109427

1 files changed, 15 insertions, 18 deletions

diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
index 1e6d17ed6a0..8e1c53ad174 100644
--- a/gcc/tree-ssa-loop-ivopts.c
+++ b/gcc/tree-ssa-loop-ivopts.c
@@ -881,18 +881,16 @@ static tree
 determine_biv_step (tree phi)
 {
   struct loop *loop = bb_for_stmt (phi)->loop_father;
-  tree name = PHI_RESULT (phi), base, step;
+  tree name = PHI_RESULT (phi);
+  affine_iv iv;
 
   if (!is_gimple_reg (name))
     return NULL_TREE;
 
-  if (!simple_iv (loop, phi, name, &base, &step, true))
+  if (!simple_iv (loop, phi, name, &iv, true))
     return NULL_TREE;
 
-  if (zero_p (step))
-    return NULL_TREE;
-
-  return step;
+  return (zero_p (iv.step) ? NULL_TREE : iv.step);
 }
 
 /* Returns true if EXP is a ssa name that occurs in an abnormal phi node.  */
@@ -1044,17 +1042,16 @@ mark_bivs (struct ivopts_data *data)
 }
 
 /* Checks whether STMT defines a linear induction variable and stores its
-   parameters to BASE and STEP.  */
+   parameters to IV.  */
 
 static bool
-find_givs_in_stmt_scev (struct ivopts_data *data, tree stmt,
-			tree *base, tree *step)
+find_givs_in_stmt_scev (struct ivopts_data *data, tree stmt, affine_iv *iv)
 {
   tree lhs;
   struct loop *loop = data->current_loop;
 
-  *base = NULL_TREE;
-  *step = NULL_TREE;
+  iv->base = NULL_TREE;
+  iv->step = NULL_TREE;
 
   if (TREE_CODE (stmt) != MODIFY_EXPR)
     return false;
@@ -1063,12 +1060,12 @@ find_givs_in_stmt_scev (struct ivopts_data *data, tree stmt,
   if (TREE_CODE (lhs) != SSA_NAME)
     return false;
 
-  if (!simple_iv (loop, stmt, TREE_OPERAND (stmt, 1), base, step, true))
+  if (!simple_iv (loop, stmt, TREE_OPERAND (stmt, 1), iv, true))
     return false;
-  *base = expand_simple_operations (*base);
+  iv->base = expand_simple_operations (iv->base);
 
-  if (contains_abnormal_ssa_name_p (*base)
-      || contains_abnormal_ssa_name_p (*step))
+  if (contains_abnormal_ssa_name_p (iv->base)
+      || contains_abnormal_ssa_name_p (iv->step))
     return false;
 
   return true;
@@ -1079,12 +1076,12 @@ find_givs_in_stmt_scev (struct ivopts_data *data, tree stmt,
 static void
 find_givs_in_stmt (struct ivopts_data *data, tree stmt)
 {
-  tree base, step;
+  affine_iv iv;
 
-  if (!find_givs_in_stmt_scev (data, stmt, &base, &step))
+  if (!find_givs_in_stmt_scev (data, stmt, &iv))
     return;
 
-  set_iv (data, TREE_OPERAND (stmt, 0), base, step);
+  set_iv (data, TREE_OPERAND (stmt, 0), iv.base, iv.step);
 }
 
 /* Finds general ivs in basic block BB.  */