On Wed, Jul 13, 2011 at 9:34 AM, Kai Tietz <ktiet...@googlemail.com> wrote:
> Hello,
>
> This patch adds support to fold_binary_loc for one-bit precision
> typed bitwise-xor expression.
Similar - we don't want to build a TRUTH_NOT_EXPR from a BIT_XOR_EXPR.
> ChangeLog
>
> 2011-07-13 Kai Tietz <kti...@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))
> {
>
