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

Hello,

this new version addresses the comments from you.
On gimplify.c's gimplify_expr we didn't handled the case that operands
for TRUTH-AND/OR/XOR expressions need to have same operand-size in
case  of transformation to bitwise-binary operation.  This shows up
for Fortran, as there are more than one boolean-kind type with

On Thu, Oct 13, 2011 at 3:25 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
> Hello,
>
> this new version addresses the comments from you.
> On gimplify.c's gimplify_expr we didn't handled the case that operands
> for TRUTH-AND/OR/XOR expressions need to have same operand-size in
> case  of transformation to bitwise-binary operation.  This shows up
> for Fortran, as there are more than one boolean-kind type with
> different mode-sizes.  I added a testcase for this,

The gimplify.c bits and the new testcase is ok.  They should have been
submitted separately.

Please re-submit the fold-const.c part.

Thanks,
Richard.

> 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 (gimplify_expr): 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
> @@ -7256,8 +7257,10 @@ gimplify_expr (tree *expr_p, gimple_seq
>        case TRUTH_XOR_EXPR:
>          {
>            tree orig_type = TREE_TYPE (*expr_p);
> +           tree new_type, xop0, xop1;
>            *expr_p = gimple_boolify (*expr_p);
> -           if (!useless_type_conversion_p (orig_type, TREE_TYPE (*expr_p)))
> +           new_type = TREE_TYPE (*expr_p);
> +           if (!useless_type_conversion_p (orig_type, new_type))
>              {
>                *expr_p = fold_convert_loc (input_location, orig_type, *expr_p);
>                ret = GS_OK;
> @@ -7281,7 +7284,18 @@ gimplify_expr (tree *expr_p, gimple_seq
>              default:
>                break;
>              }
> -
> +           /* Now make sure that operands have compatible type to
> +              expression's new_type.  */
> +           xop0 = TREE_OPERAND (*expr_p, 0);
> +           xop1 = TREE_OPERAND (*expr_p, 1);
> +           if (!useless_type_conversion_p (new_type, TREE_TYPE (xop0)))
> +             TREE_OPERAND (*expr_p, 0) = fold_convert_loc (input_location,
> +                                                           new_type,
> +                                                           xop0);
> +           if (!useless_type_conversion_p (new_type, TREE_TYPE (xop1)))
> +             TREE_OPERAND (*expr_p, 1) = fold_convert_loc (input_location,
> +                                                           new_type,
> +                                                           xop1);
>            /* Continue classified as tcc_binary.  */
>            goto expr_2;
>          }
> 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
>