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


On Thu, Oct 13, 2011 at 1:25 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
> Hello,
>
> this new version addresses the comments from Michael and additional fixes
> an latent issue shown up by this rewrite in fold-const.
> On gimplify.c's gimple_boolify we didn't handled the case that operands
> for TRUTH-expressions need to have same operand-size for transformation to
> bitwise operation. ?This shows up for Fortran, as here are more then one
> boolean-kind type with different mode-sizes. ?I added a testcase for this,
>
> ChangeLog
>
> 2011-10-13 ?Kai Tietz ?<ktietz@redhat.com>
>
> ? ? ? ?* fold-const.c (simple_operand_p_2): New function.
> ? ? ? ?(fold_truthop): Rename to
> ? ? ? ?(fold_truth_andor_1): function name.
> ? ? ? ?Additionally remove branching creation for logical and/or.
> ? ? ? ?(fold_truth_andor): Handle branching creation for logical and/or here.
> ? ? ? ?* gimplify.c (gimple_boolify): Take care that for bitwise-binary
> ? ? ? ?transformation the operands have compatible types.
>
> 2011-10-13 ?Kai Tietz ?<ktietz@redhat.com>
>
> ? ? ? ?* gfortran.fortran-torture/compile/logical-2.f90: New test.
>
> Bootstrapped and regression-tested for all languages plus Ada and
> Obj-C++ on x86_64-pc-linux-gnu.
> Ok for apply?
>
> Regards,
> Kai
>
> Index: gcc/gcc/fold-const.c
> ===================================================================
> --- gcc.orig/gcc/fold-const.c
> +++ gcc/gcc/fold-const.c
> @@ -112,13 +112,13 @@ static tree decode_field_reference (loca
> ?static int all_ones_mask_p (const_tree, int);
> ?static tree sign_bit_p (tree, const_tree);
> ?static int simple_operand_p (const_tree);
> +static bool simple_operand_p_2 (tree);
> ?static tree range_binop (enum tree_code, tree, tree, int, tree, int);
> ?static tree range_predecessor (tree);
> ?static tree range_successor (tree);
> ?static tree fold_range_test (location_t, enum tree_code, tree, tree, tree);
> ?static tree fold_cond_expr_with_comparison (location_t, tree, tree,
> tree, tree);
> ?static tree unextend (tree, int, int, tree);
> -static tree fold_truthop (location_t, enum tree_code, tree, tree, tree);
> ?static tree optimize_minmax_comparison (location_t, enum tree_code,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?tree, tree, tree);
> ?static tree extract_muldiv (tree, tree, enum tree_code, tree, bool *);
> @@ -3500,7 +3500,7 @@ optimize_bit_field_compare (location_t l
> ? return lhs;
> ?}
>
> -/* Subroutine for fold_truthop: decode a field reference.
> +/* Subroutine for fold_truth_andor_1: decode a field reference.
>
> ? ?If EXP is a comparison reference, we return the innermost reference.
>
> @@ -3668,7 +3668,7 @@ sign_bit_p (tree exp, const_tree val)
> ? return NULL_TREE;
> ?}
>
> -/* Subroutine for fold_truthop: determine if an operand is simple enough
> +/* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
> ? ?to be evaluated unconditionally. ?*/
>
> ?static int
> @@ -3678,7 +3678,7 @@ simple_operand_p (const_tree exp)
> ? STRIP_NOPS (exp);
>
> ? return (CONSTANT_CLASS_P (exp)
> - ? ? ? ? || TREE_CODE (exp) == SSA_NAME
> + ? ? ? ? || TREE_CODE (exp) == SSA_NAME
> ? ? ? ? ?|| (DECL_P (exp)
> ? ? ? ? ? ? ?&& ! TREE_ADDRESSABLE (exp)
> ? ? ? ? ? ? ?&& ! TREE_THIS_VOLATILE (exp)
> @@ -3692,6 +3692,46 @@ simple_operand_p (const_tree exp)
> ? ? ? ? ? ? ? ? registers aren't expensive. ?*/
> ? ? ? ? ? ? ?&& (! TREE_STATIC (exp) || DECL_REGISTER (exp))));
> ?}
> +
> +/* Subroutine for fold_truth_andor: determine if an operand is simple enough
> + ? to be evaluated unconditionally.
> + ? I addition to simple_operand_p, we assume that comparisons and logic-not
> + ? operations are simple, if their operands are simple, too. ?*/
> +
> +static bool
> +simple_operand_p_2 (tree exp)
> +{
> + ?enum tree_code code;
> +
> + ?/* Strip any conversions that don't change the machine mode. ?*/
> + ?STRIP_NOPS (exp);
> +
> + ?code = TREE_CODE (exp);
> +
> + ?if (TREE_CODE_CLASS (code) == tcc_comparison)
> + ? ?return (!tree_could_trap_p (exp)
> + ? ? ? ? ? && simple_operand_p_2 (TREE_OPERAND (exp, 0))
> + ? ? ? ? ? && simple_operand_p_2 (TREE_OPERAND (exp, 1)));
> +
> + ?if (TREE_SIDE_EFFECTS (exp)
> + ? ? ?|| tree_could_trap_p (exp))
> + ? ?return false;
> +
> + ?switch (code)
> + ? ?{
> + ? ?case SSA_NAME:
> + ? ? ?return true;
> + ? ?case TRUTH_NOT_EXPR:
> + ? ? ?return simple_operand_p_2 (TREE_OPERAND (exp, 0));
> + ? ?case BIT_NOT_EXPR:
> + ? ? ?if (TREE_CODE (TREE_TYPE (exp)) != BOOLEAN_TYPE)
> + ? ? ? return false;
> + ? ? ?return simple_operand_p_2 (TREE_OPERAND (exp, 0));
> + ? ?default:
> + ? ? ?return simple_operand_p (exp);
> + ? ?}
> +}
> +
>
> ?/* The following functions are subroutines to fold_range_test and allow it to
> ? ?try to change a logical combination of comparisons into a range test.
> @@ -4888,7 +4928,7 @@ fold_range_test (location_t loc, enum tr
> ? return 0;
> ?}
>
> -/* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
> +/* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
> ? ?bit value. ?Arrange things so the extra bits will be set to zero if and
> ? ?only if C is signed-extended to its full width. ?If MASK is nonzero,
> ? ?it is an INTEGER_CST that should be AND'ed with the extra bits. ?*/
> @@ -5025,8 +5065,8 @@ merge_truthop_with_opposite_arm (locatio
> ? ?We return the simplified tree or 0 if no optimization is possible. ?*/
>
> ?static tree
> -fold_truthop (location_t loc, enum tree_code code, tree truth_type,
> - ? ? ? ? ? ? tree lhs, tree rhs)
> +fold_truth_andor_1 (location_t loc, enum tree_code code, tree truth_type,
> + ? ? ? ? ? ? ? ? ? tree lhs, tree rhs)
> ?{
> ? /* If this is the "or" of two comparisons, we can do something if
> ? ? ?the comparisons are NE_EXPR. ?If this is the "and", we can do something
> @@ -5054,8 +5094,6 @@ fold_truthop (location_t loc, enum tree_
> ? tree lntype, rntype, result;
> ? HOST_WIDE_INT first_bit, end_bit;
> ? int volatilep;
> - ?tree orig_lhs = lhs, orig_rhs = rhs;
> - ?enum tree_code orig_code = code;
>
> ? /* Start by getting the comparison codes. ?Fail if anything is volatile.
> ? ? ?If one operand is a BIT_AND_EXPR with the constant one, treat it as if
> @@ -5119,8 +5157,7 @@ fold_truthop (location_t loc, enum tree_
> ? /* If the RHS can be evaluated unconditionally and its operands are
> ? ? ?simple, it wins to evaluate the RHS unconditionally on machines
> ? ? ?with expensive branches. ?In this case, this isn't a comparison
> - ? ? that can be merged. ?Avoid doing this if the RHS is a floating-point
> - ? ? comparison since those can trap. ?*/
> + ? ? that can be merged. ?*/
>
> ? if (BRANCH_COST (optimize_function_for_speed_p (cfun),
> ? ? ? ? ? ? ? ? ? false) >= 2
> @@ -5149,13 +5186,6 @@ 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 +8410,49 @@ 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 ((code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
> + ? ? ?&& (BRANCH_COST (optimize_function_for_speed_p (cfun),
> + ? ? ? ? ? ? ? ? ? ? ?false) >= 2)
> + ? ? ?&& LOGICAL_OP_NON_SHORT_CIRCUIT
> + ? ? ?&& simple_operand_p_2 (arg1))
> + ? ?{
> + ? ? ?enum tree_code 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);
> + ? ?}
> +
> ? return NULL_TREE;
> ?}
>
> Index: gcc/gcc/gimplify.c
> ===================================================================
> --- gcc.orig/gcc/gimplify.c
> +++ gcc/gcc/gimplify.c
> @@ -2804,8 +2804,13 @@ tree
> ?gimple_boolify (tree expr)
> ?{
> ? tree type = TREE_TYPE (expr);
> + ?tree new_expr_type;
> ? location_t loc = EXPR_LOCATION (expr);
>
> + ?new_expr_type = type;
> + ?if (TREE_CODE (type) != BOOLEAN_TYPE)
> + ? ?new_expr_type = boolean_type_node;
> +
> ? if (TREE_CODE (expr) == NE_EXPR
> ? ? ? && TREE_CODE (TREE_OPERAND (expr, 0)) == CALL_EXPR
> ? ? ? && integer_zerop (TREE_OPERAND (expr, 1)))
> @@ -2845,11 +2850,26 @@ gimple_boolify (tree expr)
> ? ? case TRUTH_ORIF_EXPR:
> ? ? ? /* Also boolify the arguments of truth exprs. ?*/
> ? ? ? TREE_OPERAND (expr, 1) = gimple_boolify (TREE_OPERAND (expr, 1));
> - ? ? ?/* FALLTHRU */
> +
> + ? ? ?/* Make sure that operand type is compatible to final
> + ? ? ? ? expression's type. ?*/
> + ? ? ?if (!useless_type_conversion_p (new_expr_type,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TREE_TYPE (TREE_OPERAND (expr, 1))))
> + ? ? ? ?TREE_OPERAND (expr, 1) =
> + ? ? ? ? ?fold_convert_loc (loc, new_expr_type, TREE_OPERAND (expr, 1));
> +
> + ? ? ?/* Fall through. ?*/
>
> ? ? case TRUTH_NOT_EXPR:
> ? ? ? TREE_OPERAND (expr, 0) = gimple_boolify (TREE_OPERAND (expr, 0));
>
> + ? ? ?/* Make sure that operand type is compatible to final
> + ? ? ? ? expression's type. ?*/
> + ? ? ?if (!useless_type_conversion_p (new_expr_type,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TREE_TYPE (TREE_OPERAND (expr, 0))))
> + ? ? ? ?TREE_OPERAND (expr, 0) =
> + ? ? ? ? ?fold_convert_loc (loc, new_expr_type, TREE_OPERAND (expr, 0));
> +
> ? ? ? /* These expressions always produce boolean results. ?*/
> ? ? ? if (TREE_CODE (type) != BOOLEAN_TYPE)
> ? ? ? ?TREE_TYPE (expr) = boolean_type_node;

No, the callers are responsible for this.

> Index: gcc/gcc/testsuite/gfortran.fortran-torture/compile/logical-2.f90
> ===================================================================
> --- /dev/null
> +++ gcc/gcc/testsuite/gfortran.fortran-torture/compile/logical-2.f90
> @@ -0,0 +1,10 @@
> +! Check for operand type validity after gimplification
> +
> +subroutine whatever()
> +logical(kind=1) :: l1
> +logical(kind=2) :: l2
> +logical(kind=4) :: l3
> +if ((l1 .and. l2) .neqv. l3) then
> + ? l1 = .true.
> +endif
> +end
>


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