On Fri, Oct 14, 2011 at 9:43 PM, Kai Tietz <[email protected]> wrote:
> Hello,
>
> So I committed the gimplify patch separate. And here is the remaining
> fold-const patch.
> The important tests here are in gcc.dg/tree-ssa/builtin-expect[1-4].c, which
> cover the one special-case for branching. Also tree-ssa/20040204-1.c covers
> tests for branching code (on targets having high-engough BRANCH_COST and no
> special-casing - like MIPS, S/390, and AVR.
>
> ChangeLog
>
> 2011-10-14 Kai Tietz <[email protected]>
>
> * 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.
>
> Bootstrapped and regression-tested for all languages plus Ada and
> Obj-C++ on x86_64-pc-linux-gnu.
> Ok for apply?
Ok with ...
> 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)));
recurse with simple_operand_p.
> +
> + if (TREE_SIDE_EFFECTS (exp)
> + || tree_could_trap_p (exp))
Move this check before the tcc_comparison check and remove the
then redundant tree_could_trap_p check there.
> + return false;
> +
> + switch (code)
> + {
> + case SSA_NAME:
> + return true;
Do not handle here, it's handled in simple_operand_p.
> + 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;
Remove the BIT_NOT_EXPR handling. Thus, simply change this switch
to
if (code == TRUTH_NOT_EXPR)
return simple_operand_p_2 (TREE_OPERAND (exp, 0));
return simple_operand_p (exp);
> + 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);
> + }
I see you insist on this change. Let me explain again. You do this
for ((A AND-IF B) AND-IF C) but you don't do this for
((A AND-IF B) AND C). Why? That is what doesn't make sense ot me.
Thus omit this hunk.
Ok with the above changes.
Thanks,
Richard.
> + /* 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;
> }
>
