Hello,
This patch adds support to fold_binary_loc for one-bit precision
typed bitwise-or expression.
ChangeLog
2011-07-13 Kai Tietz <kti...@redhat.com>
* fold-const.c (fold_binary_loc): Add
support for one-bit bitwise-or 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 08:23:29.000000000 +0200
+++ gcc/gcc/fold-const.c 2011-07-13 08:59:04.011620200 +0200
@@ -10688,6 +10688,52 @@ fold_binary_loc (location_t loc,
return omit_one_operand_loc (loc, type, t1, arg0);
}
+ if (TYPE_PRECISION (type) == 1 && INTEGRAL_TYPE_P (type))
+ {
+ /* If arg0 is constant zero, drop it. */
+ if (TREE_CODE (arg0) == INTEGER_CST && integer_zerop (arg0))
+ return non_lvalue_loc (loc, fold_convert_loc (loc, type, arg1));
+ if (TREE_CODE (arg0) == INTEGER_CST && ! integer_zerop (arg0))
+ return omit_one_operand_loc (loc, type, arg0, arg1);
+
+ /* !X | X is always true. ~X | X is always true. */
+ 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_one_node, arg1);
+ /* X | !X is always true. X | ~X is always true. */
+ 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_one_node, arg0);
+
+ /* (X & !Y) | (!X & Y) is X ^ Y */
+ if (TREE_CODE (arg0) == BIT_AND_EXPR
+ && TREE_CODE (arg1) == BIT_AND_EXPR)
+ {
+ tree a0, a1, l0, l1, n0, n1;
+
+ a0 = fold_convert_loc (loc, type, TREE_OPERAND (arg1, 0));
+ a1 = fold_convert_loc (loc, type, TREE_OPERAND (arg1, 1));
+
+ l0 = fold_convert_loc (loc, type, TREE_OPERAND (arg0, 0));
+ l1 = fold_convert_loc (loc, type, TREE_OPERAND (arg0, 1));
+
+ n0 = fold_build1_loc (loc, TRUTH_NOT_EXPR, type, l0);
+ n1 = fold_build1_loc (loc, TRUTH_NOT_EXPR, type, l1);
+
+ if ((operand_equal_p (n0, a0, 0)
+ && operand_equal_p (n1, a1, 0))
+ || (operand_equal_p (n0, a1, 0)
+ && operand_equal_p (n1, a0, 0)))
+ return fold_build2_loc (loc, BIT_XOR_EXPR, type, l0, n1);
+ }
+
+ tem = fold_truth_andor (loc, code, type, arg0, arg1, op0, op1);
+ if (tem)
+ return tem;
+ }
+
/* Canonicalize (X & C1) | C2. */
if (TREE_CODE (arg0) == BIT_AND_EXPR
&& TREE_CODE (arg1) == INTEGER_CST
