Re: [patch tree-optimization]: Improve handling of conditional-branches on targets with high branch costs

[Richard Guenther <richard dot guenther at gmail dot com>]

On Mon, Oct 17, 2011 at 3:36 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
> Sure,
>
> Is simplier and also handles (A T[-IF] (B T-IF C) -> (A T B) T-IF C
> case, which can happen by framing in conditions.
>
> @@ -8380,13 +8400,65 @@ fold_truth_andor (location_t loc, enum t
> ? ? ?lhs is another similar operation, try to merge its rhs with our
> ? ? ?rhs. ?Then try to merge our lhs and rhs. ?*/
> ? if (TREE_CODE (arg0) == code
> - ? ? ?&& 0 != (tem = fold_truthop (loc, code, type,
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?TREE_OPERAND (arg0, 1), arg1)))
> + ? ? ?&& 0 != (tem = fold_truth_andor_1 (loc, code, type,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?TREE_OPERAND (arg0, 1), arg1)))
> ? ? return fold_build2_loc (loc, code, type, TREE_OPERAND (arg0, 0), tem);
>
> - ?if ((tem = fold_truthop (loc, code, type, arg0, arg1)) != 0)
> + ?if ((tem = fold_truth_andor_1 (loc, code, type, arg0, arg1)) != 0)
> ? ? return tem;
>
> + ?if ((BRANCH_COST (optimize_function_for_speed_p (cfun),
> + ? ? ? ? ? ? ? ? ? false) >= 2)
> + ? ? ?&& LOGICAL_OP_NON_SHORT_CIRCUIT)
> + ? ?{
> + ? ? ?enum tree_code ncode, icode;
> +
> + ? ? ?ncode = (code == TRUTH_ANDIF_EXPR || code == TRUTH_AND_EXPR)
> + ? ? ? ? ? ? ? TRUTH_AND_EXPR : TRUTH_OR_EXPR;
> + ? ? ?icode = ncode == TRUTH_AND_EXPR ? TRUTH_ANDIF_EXPR : TRUTH_ORIF_EXPR;
> +
> + ? ? ?/* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
> + ? ? ? ?or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
> + ? ? ? ?We don't want to pack more than two leafs to a non-IF AND/OR
> + ? ? ? ?expression.
> + ? ? ? ?If tree-code of left-hand operand isn't an AND/OR-IF code and not
> + ? ? ? ?equal to IF-CODE, then we don't want to add right-hand operand.
> + ? ? ? ?If the inner right-hand side of left-hand operand has
> + ? ? ? ?side-effects, or isn't simple, then we can't add to it,
> + ? ? ? ?as otherwise we might destroy if-sequence. ?*/
> + ? ? ?if (TREE_CODE (arg0) == icode
> + ? ? ? ? && simple_operand_p_2 (arg1)
> + ? ? ? ? /* Needed for sequence points to handle trappings, and
> + ? ? ? ? ? ?side-effects. ?*/
> + ? ? ? ? && simple_operand_p_2 (TREE_OPERAND (arg0, 1)))
> + ? ? ? {
> + ? ? ? ? tem = fold_build2_loc (loc, ncode, type, TREE_OPERAND (arg0, 1),
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?arg1);
> + ? ? ? ? return fold_build2_loc (loc, icode, type, TREE_OPERAND (arg0, 0),
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? tem);
> + ? ? ? }
> + ? ? ? /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
> + ? ? ? ? ?or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). ?*/
> + ? ? ?else if (TREE_CODE (arg1) == icode
> + ? ? ? ? && simple_operand_p_2 (arg0)
> + ? ? ? ? /* Needed for sequence points to handle trappings, and
> + ? ? ? ? ? ?side-effects. ?*/
> + ? ? ? ? && simple_operand_p_2 (TREE_OPERAND (arg1, 0)))
> + ? ? ? {
> + ? ? ? ? tem = fold_build2_loc (loc, ncode, type,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?arg0, TREE_OPERAND (arg1, 0));
> + ? ? ? ? return fold_build2_loc (loc, icode, type, tem,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TREE_OPERAND (arg1, 1));
> + ? ? ? }
> + ? ? ?/* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
> + ? ? ? ?into (A OR B).
> + ? ? ? ?For sequence point consistancy, we need to check for trapping,
> + ? ? ? ?and side-effects. ?*/
> + ? ? ?else if (code == icode && simple_operand_p_2 (arg0)
> + ? ? ? ? ? ? ? && simple_operand_p_2 (arg1))
> + ? ? ? return fold_build2_loc (loc, ncode, type, arg0, arg1);
> + ? ?}
> +
> ? return NULL_TREE;
> ?}

Ok with the rest of the changes I requested.

Richard.

> Regards,
> Kai
>