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 2:22 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
> Ok, I see. ?This might be profitable to do that. ?So fold_truth_op
> hunk looks like this
>
> @@ -5149,13 +5176,6 @@ fold_truthop (location_t loc, enum tree_
> ? ? ? ? ? ? ? ? ? ? ? ? ? build2 (BIT_IOR_EXPR, TREE_TYPE (ll_arg),
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ll_arg, rl_arg),
> ? ? ? ? ? ? ? ? ? ? ? ? ? build_int_cst (TREE_TYPE (ll_arg), 0));
> -
> - ? ? ?if (LOGICAL_OP_NON_SHORT_CIRCUIT)
> - ? ? ? {
> - ? ? ? ? if (code != orig_code || lhs != orig_lhs || rhs != orig_rhs)
> - ? ? ? ? ? return build2_loc (loc, code, truth_type, lhs, rhs);
> - ? ? ? ? return NULL_TREE;
> - ? ? ? }
> ? ? }
>
> ? /* See if the comparisons can be merged. ?Then get all the parameters for
> @@ -8380,13 +8400,77 @@ 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
> + ? ? ?&& simple_operand_p_2 (arg1))
> + ? ?{
> + ? ? ?enum tree_code ncode;
> +
> + ? ? ?if (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
> + ? ? ? ?{
> + ? ? ? ? ncode = (code == TRUTH_ANDIF_EXPR ? TRUTH_AND_EXPR : TRUTH_OR_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 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) == code
> + ? ? ? ? ? ? /* 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, code, type, TREE_OPERAND (arg0, 0),
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? tem);
> + ? ? ? ? ? }
> + ? ? ? ? /* 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 (simple_operand_p_2 (arg0))
> + ? ? ? ? ? return fold_build2_loc (loc, ncode, type, arg0, arg1);
> + ? ? ? }
> + ? ? ?else
> + ? ? ? ?{
> + ? ? ? ? ncode = (code == TRUTH_AND_EXPR ? TRUTH_ANDIF_EXPR
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? : TRUTH_ORIF_EXPR);
> + ? ? ? ? /* Transform ((A AND-IF B) AND C) into (A AND-IF (B AND C)),
> + ? ? ? ? ? ?or ((A OR-IF B) OR 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 NCODE, 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) == ncode
> + ? ? ? ? ? ? /* Needed for sequence points to handle trappings, and
> + ? ? ? ? ? ? ? ?side-effects. ?*/
> + ? ? ? ? ? ? && simple_operand_p_2 (TREE_OPERAND (arg0, 1)))
> + ? ? ? ? ? {
> + ? ? ? ? ? ? tem = fold_build2_loc (loc, code, type, TREE_OPERAND (arg0, 1),
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?arg1);
> + ? ? ? ? ? ? return fold_build2_loc (loc, ncode, type,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TREE_OPERAND (arg0, 0), tem);
> + ? ? ? ? ? }
> + ? ? ? }
> +
> + ? ?}
> +
> ? return NULL_TREE;
> ?}
>
> Ok, with other changes you mentioned?

This can be done without so much code duplication.

> Regards,
> Kai
>