Hello,
This patch adds support to fold_binary_loc for one-bit precision
typed bitwise-and expression.
ChangeLog
2011-07-13 Kai Tietz <kti...@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
