re PR tree-optimization/45397 (Issues with integer narrowing conversions)

2017-02-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/45397
	* tree-ssa-pre.c (eliminate_insert): Handle BIT_AND_EXPR.
	* tree-ssa-sccvn.c (valueized_wider_op): New helper.
	(visit_nary_op): Add pattern matching for CSEing sign-changed
	or truncated operations with wider ones.

	* gcc.dg/tree-ssa/pr45397.c: New testcase.

From-SVN: r245752

1 files changed, 109 insertions, 7 deletions

diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 7953228..4f5e852 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -3447,23 +3447,125 @@ visit_copy (tree lhs, tree rhs)
   return set_ssa_val_to (lhs, rhs);
 }
 
+/* Lookup a value for OP in type WIDE_TYPE where the value in type of OP
+   is the same.  */
+
+static tree
+valueized_wider_op (tree wide_type, tree op)
+{
+  if (TREE_CODE (op) == SSA_NAME)
+    op = SSA_VAL (op);
+
+  /* Either we have the op widened available.  */
+  tree ops[3] = {};
+  ops[0] = op;
+  tree tem = vn_nary_op_lookup_pieces (1, NOP_EXPR,
+				       wide_type, ops, NULL);
+  if (tem)
+    return tem;
+
+  /* Or the op is truncated from some existing value.  */
+  if (TREE_CODE (op) == SSA_NAME)
+    {
+      gimple *def = SSA_NAME_DEF_STMT (op);
+      if (is_gimple_assign (def)
+	  && CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def)))
+	{
+	  tem = gimple_assign_rhs1 (def);
+	  if (useless_type_conversion_p (wide_type, TREE_TYPE (tem)))
+	    {
+	      if (TREE_CODE (tem) == SSA_NAME)
+		tem = SSA_VAL (tem);
+	      return tem;
+	    }
+	}
+    }
+
+  /* For constants simply extend it.  */
+  if (TREE_CODE (op) == INTEGER_CST)
+    return wide_int_to_tree (wide_type, op);
+
+  return NULL_TREE;
+}
+
 /* Visit a nary operator RHS, value number it, and return true if the
    value number of LHS has changed as a result.  */
 
 static bool
-visit_nary_op (tree lhs, gimple *stmt)
+visit_nary_op (tree lhs, gassign *stmt)
 {
-  bool changed = false;
   tree result = vn_nary_op_lookup_stmt (stmt, NULL);
-
   if (result)
-    changed = set_ssa_val_to (lhs, result);
-  else
+    return set_ssa_val_to (lhs, result);
+
+  /* Do some special pattern matching for redundancies of operations
+     in different types.  */
+  enum tree_code code = gimple_assign_rhs_code (stmt);
+  tree type = TREE_TYPE (lhs);
+  tree rhs1 = gimple_assign_rhs1 (stmt);
+  switch (code)
     {
-      changed = set_ssa_val_to (lhs, lhs);
-      vn_nary_op_insert_stmt (stmt, lhs);
+    CASE_CONVERT:
+      /* Match arithmetic done in a different type where we can easily
+         substitute the result from some earlier sign-changed or widened
+	 operation.  */
+      if (INTEGRAL_TYPE_P (type)
+	  && TREE_CODE (rhs1) == SSA_NAME
+	  /* We only handle sign-changes or zero-extension -> & mask.  */
+	  && ((TYPE_UNSIGNED (TREE_TYPE (rhs1))
+	       && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (rhs1)))
+	      || TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (rhs1))))
+	{
+	  gassign *def = dyn_cast <gassign *> (SSA_NAME_DEF_STMT (rhs1));
+	  if (def
+	      && (gimple_assign_rhs_code (def) == PLUS_EXPR
+		  || gimple_assign_rhs_code (def) == MINUS_EXPR
+		  || gimple_assign_rhs_code (def) == MULT_EXPR))
+	    {
+	      tree ops[3] = {};
+	      /* Either we have the op widened available.  */
+	      ops[0] = valueized_wider_op (type,
+					   gimple_assign_rhs1 (def));
+	      if (ops[0])
+		ops[1] = valueized_wider_op (type,
+					     gimple_assign_rhs2 (def));
+	      if (ops[0] && ops[1])
+		{
+		  ops[0] = vn_nary_op_lookup_pieces
+		      (2, gimple_assign_rhs_code (def), type, ops, NULL);
+		  /* We have wider operation available.  */
+		  if (ops[0])
+		    {
+		      unsigned lhs_prec = TYPE_PRECISION (type);
+		      unsigned rhs_prec = TYPE_PRECISION (TREE_TYPE (rhs1));
+		      if (lhs_prec == rhs_prec)
+			{
+			  ops[1] = NULL_TREE;
+			  result = vn_nary_build_or_lookup (NOP_EXPR,
+							    type, ops);
+			  if (result)
+			    return set_ssa_val_to (lhs, result);
+			}
+		      else
+			{
+			  ops[1] = wide_int_to_tree (type,
+						     wi::mask (rhs_prec, false,
+							       lhs_prec));
+			  result = vn_nary_build_or_lookup (BIT_AND_EXPR,
+							    TREE_TYPE (lhs),
+							    ops);
+			  if (result)
+			    return set_ssa_val_to (lhs, result);
+			}
+		    }
+		}
+	    }
+	}
+    default:;
     }
 
+  bool changed = set_ssa_val_to (lhs, lhs);
+  vn_nary_op_insert_stmt (stmt, lhs);
   return changed;
 }