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Re: [patch 5/8 tree-optimization]: Bitwise xor logic for fold_binary_loc.
- From: Richard Guenther <richard dot guenther at gmail dot com>
- To: Kai Tietz <ktietz70 at googlemail dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 13 Jul 2011 12:29:58 +0200
- Subject: Re: [patch 5/8 tree-optimization]: Bitwise xor logic for fold_binary_loc.
- References: <CAEwic4YZbE-C2Jci-miVQLM30GqxLEb4mgvsmVQ0KY3uXo6dag@mail.gmail.com>
On Wed, Jul 13, 2011 at 9:34 AM, Kai Tietz <ktietz70@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 ?<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))
> ? ? ? ? {
>