re PR tree-optimization/72772 (Missed SCEV after pass reordering@236440)

PR tree-optimization/72772
	* tree-ssa-loop-niter.h (simplify_using_initial_conditions): Delete
	parameter STOP.
	* tree-ssa-loop-niter.c (tree_simplify_using_condition_1): Delete
	parameter STOP and update calls.  Move expand_simple_operations
	function call from here...
	(simplify_using_initial_conditions): ...to here.  Delete parameter
	STOP.
	(tree_simplify_using_condition): Delete parameter STOP.
	* tree-scalar-evolution.c (simple_iv_with_niters): Update call to
	simplify_using_initial_conditions.

From-SVN: r239290

gcc/ChangeLog

@@ -1,3 +1,17 @@
+2016-08-09  Bin Cheng  <bin.cheng@arm.com>
+
+	PR tree-optimization/72772
+	* tree-ssa-loop-niter.h (simplify_using_initial_conditions): Delete
+	parameter STOP.
+	* tree-ssa-loop-niter.c (tree_simplify_using_condition_1): Delete
+	parameter STOP and update calls.  Move expand_simple_operations
+	function call from here...
+	(simplify_using_initial_conditions): ...to here.  Delete parameter
+	STOP.
+	(tree_simplify_using_condition): Delete parameter STOP.
+	* tree-scalar-evolution.c (simple_iv_with_niters): Update call to
+	simplify_using_initial_conditions.
+
 2016-08-09  Matthew Fortune  <matthew.fortune@imgtec.com>
 
 	PR c/65345

gcc/tree-scalar-evolution.c

@@ -3484,7 +3484,7 @@ simple_iv_with_niters (struct loop *wrto_loop, struct loop *use_loop,
 		       bool allow_nonconstant_step)
 {
   enum tree_code code;
-  tree type, ev, base, e, stop;
+  tree type, ev, base, e;
   wide_int extreme;
   bool folded_casts, overflow;
 
@@ -3601,8 +3601,7 @@ simple_iv_with_niters (struct loop *wrto_loop, struct loop *use_loop,
     return true;
   e = fold_build2 (code, boolean_type_node, base,
 		   wide_int_to_tree (type, extreme));
-  stop = (TREE_CODE (base) == SSA_NAME) ? base : NULL;
+  e = simplify_using_initial_conditions (use_loop, e);
-  e = simplify_using_initial_conditions (use_loop, e, stop);
   if (!integer_zerop (e))
     return true;
 

gcc/tree-ssa-loop-niter.c

@@ -1939,10 +1939,10 @@ expand_simple_operations (tree expr, tree stop)
    expression (or EXPR unchanged, if no simplification was possible).  */
 
 static tree
-tree_simplify_using_condition_1 (tree cond, tree expr, tree stop)
+tree_simplify_using_condition_1 (tree cond, tree expr)
 {
   bool changed;
-  tree e, te, e0, e1, e2, notcond;
+  tree e, e0, e1, e2, notcond;
   enum tree_code code = TREE_CODE (expr);
 
   if (code == INTEGER_CST)
@@ -1954,17 +1954,17 @@ tree_simplify_using_condition_1 (tree cond, tree expr, tree stop)
     {
       changed = false;
 
-      e0 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 0), stop);
+      e0 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 0));
       if (TREE_OPERAND (expr, 0) != e0)
 	changed = true;
 
-      e1 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 1), stop);
+      e1 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 1));
       if (TREE_OPERAND (expr, 1) != e1)
 	changed = true;
 
       if (code == COND_EXPR)
 	{
-	  e2 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 2), stop);
+	  e2 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 2));
 	  if (TREE_OPERAND (expr, 2) != e2)
 	    changed = true;
 	}
@@ -2027,16 +2027,14 @@ tree_simplify_using_condition_1 (tree cond, tree expr, tree stop)
 	return boolean_true_node;
     }
 
-  te = expand_simple_operations (expr, stop);
-
   /* Check whether COND ==> EXPR.  */
   notcond = invert_truthvalue (cond);
-  e = fold_binary (TRUTH_OR_EXPR, boolean_type_node, notcond, te);
+  e = fold_binary (TRUTH_OR_EXPR, boolean_type_node, notcond, expr);
   if (e && integer_nonzerop (e))
     return e;
 
   /* Check whether COND ==> not EXPR.  */
-  e = fold_binary (TRUTH_AND_EXPR, boolean_type_node, cond, te);
+  e = fold_binary (TRUTH_AND_EXPR, boolean_type_node, cond, expr);
   if (e && integer_zerop (e))
     return e;
 
@@ -2051,11 +2049,11 @@ tree_simplify_using_condition_1 (tree cond, tree expr, tree stop)
    the loop do not cause us to fail.  */
 
 static tree
-tree_simplify_using_condition (tree cond, tree expr, tree stop)
+tree_simplify_using_condition (tree cond, tree expr)
 {
-  cond = expand_simple_operations (cond, stop);
+  cond = expand_simple_operations (cond);
 
-  return tree_simplify_using_condition_1 (cond, expr, stop);
+  return tree_simplify_using_condition_1 (cond, expr);
 }
 
 /* Tries to simplify EXPR using the conditions on entry to LOOP.
@@ -2063,17 +2061,19 @@ tree_simplify_using_condition (tree cond, tree expr, tree stop)
    simplification was possible).  */
 
 tree
-simplify_using_initial_conditions (struct loop *loop, tree expr, tree stop)
+simplify_using_initial_conditions (struct loop *loop, tree expr)
 {
   edge e;
   basic_block bb;
   gimple *stmt;
-  tree cond;
+  tree cond, expanded, backup;
   int cnt = 0;
 
   if (TREE_CODE (expr) == INTEGER_CST)
     return expr;
 
+  backup = expanded = expand_simple_operations (expr);
+
   /* Limit walking the dominators to avoid quadraticness in
      the number of BBs times the number of loops in degenerate
      cases.  */
@@ -2095,15 +2095,17 @@ simplify_using_initial_conditions (struct loop *loop, tree expr, tree stop)
 			  gimple_cond_rhs (stmt));
       if (e->flags & EDGE_FALSE_VALUE)
 	cond = invert_truthvalue (cond);
-      expr = tree_simplify_using_condition (cond, expr, stop);
+      expanded = tree_simplify_using_condition (cond, expanded);
       /* Break if EXPR is simplified to const values.  */
-      if (expr && (integer_zerop (expr) || integer_nonzerop (expr)))
+      if (expanded
-	break;
+	  && (integer_zerop (expanded) || integer_nonzerop (expanded)))
+	return expanded;
 
       ++cnt;
     }
 
-  return expr;
+  /* Return the original expression if no simplification is done.  */
+  return operand_equal_p (backup, expanded, 0) ? expr : expanded;
 }
 
 /* Tries to simplify EXPR using the evolutions of the loop invariants
@@ -4209,8 +4211,6 @@ loop_exits_before_overflow (tree base, tree step,
      constant step because otherwise we don't have the information.  */
   if (TREE_CODE (step) == INTEGER_CST)
     {
-      tree stop = (TREE_CODE (base) == SSA_NAME) ? base : NULL;
-
       for (civ = loop->control_ivs; civ; civ = civ->next)
 	{
 	  enum tree_code code;
@@ -4268,7 +4268,7 @@ loop_exits_before_overflow (tree base, tree step,
 		}
 	      extreme = fold_build2 (MINUS_EXPR, type, extreme, step);
 	      e = fold_build2 (code, boolean_type_node, base, extreme);
-	      e = simplify_using_initial_conditions (loop, e, stop);
+	      e = simplify_using_initial_conditions (loop, e);
 	      if (integer_zerop (e))
 		return true;
 	    }

gcc/tree-ssa-loop-niter.h

@@ -21,8 +21,7 @@ along with GCC; see the file COPYING3.  If not see
 #define GCC_TREE_SSA_LOOP_NITER_H
 
 extern tree expand_simple_operations (tree, tree = NULL);
-extern tree simplify_using_initial_conditions (struct loop *,
+extern tree simplify_using_initial_conditions (struct loop *, tree);
-					       tree, tree = NULL);
 extern bool loop_only_exit_p (const struct loop *, const_edge);
 extern bool number_of_iterations_exit (struct loop *, edge,
 				       struct tree_niter_desc *niter, bool,