[patch 5/8 tree-optimization]: Bitwise xor logic for fold_binary_loc.
Kai Tietz
ktietz70@googlemail.com
Wed Jul 13 07:36:00 GMT 2011
Hello,
This patch adds support to fold_binary_loc for one-bit precision
typed bitwise-xor expression.
ChangeLog
2011-07-13 Kai Tietz <ktietz@redhat.com>
* fold-const.c (fold_binary_loc): Add
support for one-bit bitwise-xor 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 08:38:06.000000000 +0200
+++ gcc/gcc/fold-const.c 2011-07-13 08:58:52.686620200 +0200
@@ -10872,11 +10872,35 @@ fold_binary_loc (location_t loc,
case BIT_XOR_EXPR:
if (integer_zerop (arg1))
return non_lvalue_loc (loc, fold_convert_loc (loc, type, arg0));
- if (integer_all_onesp (arg1))
- return fold_build1_loc (loc, BIT_NOT_EXPR, type, op0);
if (operand_equal_p (arg0, arg1, 0))
return omit_one_operand_loc (loc, type, integer_zero_node, arg0);
+ if (TYPE_PRECISION (type) == 1 && INTEGRAL_TYPE_P (type))
+ {
+ /* If the second arg is constant true, this is a logical inversion. */
+ if (integer_onep (arg1))
+ {
+ tem = invert_truthvalue_loc (loc, arg0);
+ return non_lvalue_loc (loc, fold_convert_loc (loc, type, tem));
+ }
+ }
+ else if (integer_all_onesp (arg1))
+ return fold_build1_loc (loc, BIT_NOT_EXPR, type, op0);
+
+ if (TYPE_PRECISION (type) == 1 && INTEGRAL_TYPE_P (type))
+ {
+ /* !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 ^ X is -1. */
if (TREE_CODE (arg0) == BIT_NOT_EXPR
&& operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
@@ -10911,7 +10935,7 @@ fold_binary_loc (location_t loc,
goto bit_ior;
}
- /* (X | Y) ^ X -> Y & ~ X*/
+ /* (X | Y) ^ X -> Y & ~ X. */
if (TREE_CODE (arg0) == BIT_IOR_EXPR
&& operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
{
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