[patch 6/8 tree-optimization]: Bitwise and logic for fold_binary_loc.

Kai Tietz ktietz70@googlemail.com
Wed Jul 13 07:38:00 GMT 2011


Hello,

This patch adds support to fold_binary_loc for one-bit precision
typed bitwise-and expression.

ChangeLog

2011-07-13  Kai Tietz  <ktietz@redhat.com>

	* fold-const.c (fold_binary_loc): Add
	support for one-bit bitwise-and optimizeation.

Bootstrapped and regression tested with prior patches of this series
for x86_64-pc-linux-gnu.
Ok for apply?

Regards,
Kai

Index: gcc/gcc/fold-const.c
===================================================================
--- gcc.orig/gcc/fold-const.c	2011-07-13 08:43:37.000000000 +0200
+++ gcc/gcc/fold-const.c	2011-07-13 08:58:38.692620200 +0200
@@ -11062,6 +11062,48 @@ fold_binary_loc (location_t loc,
       if (operand_equal_p (arg0, arg1, 0))
 	return non_lvalue_loc (loc, fold_convert_loc (loc, type, arg0));

+      if (TYPE_PRECISION (type) == 1 && INTEGRAL_TYPE_P (type))
+        {
+	  if (TREE_CODE (arg0) == INTEGER_CST && ! integer_zerop (arg0))
+	    return non_lvalue_loc (loc, fold_convert_loc (loc, type, arg1));
+	  if (TREE_CODE (arg1) == INTEGER_CST && ! integer_zerop (arg1))
+	    return non_lvalue_loc (loc, fold_convert_loc (loc, type, arg0));
+	  /* Likewise for first arg.  */
+	  if (integer_zerop (arg0))
+	    return omit_one_operand_loc (loc, type, arg0, arg1);
+
+	  /* !X & X is always false.  ~X & X is always false.  */
+	  if ((TREE_CODE (arg0) == TRUTH_NOT_EXPR
+	       || TREE_CODE (arg0) == BIT_NOT_EXPR)
+	      && operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
+	    return omit_one_operand_loc (loc, type, integer_zero_node, arg1);
+	  /* X & !X is always false.  X & ~X is always false.  */
+	  if ((TREE_CODE (arg1) == TRUTH_NOT_EXPR
+	       || TREE_CODE (arg1) == BIT_NOT_EXPR)
+	      && operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
+	    return omit_one_operand_loc (loc, type, integer_zero_node, arg0);
+
+	  /* (A < X) & (A + 1 > Y) ==> (A < X) & (A >= Y).  Normally
+	     A + 1 > Y means (A >= Y) & (A != MAX), but in this case
+	     we know that A < X <= MAX.  */
+
+	  if (!TREE_SIDE_EFFECTS (arg0) && !TREE_SIDE_EFFECTS (arg1))
+	    {
+	      tem = fold_to_nonsharp_ineq_using_bound (loc, arg0, arg1);
+	      if (tem && !operand_equal_p (tem, arg0, 0))
+		return fold_build2_loc (loc, code, type, tem, arg1);
+
+	      tem = fold_to_nonsharp_ineq_using_bound (loc, arg1, arg0);
+	      if (tem && !operand_equal_p (tem, arg1, 0))
+		return fold_build2_loc (loc, code, type, arg0, tem);
+	    }
+
+	  tem = fold_truth_andor (loc, code, type, arg0, arg1, op0, op1);
+	  if (tem)
+	    return tem;
+
+	}
+
       /* ~X & X, (X == 0) & X, and !X & X are always zero.  */
       if ((TREE_CODE (arg0) == BIT_NOT_EXPR
 	   || TREE_CODE (arg0) == TRUTH_NOT_EXPR



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