Move min(max...) and max(min...) folds to match.pd

[Richard Biener]

On Mon, Oct 26, 2015 at 11:00 AM, Richard Sandiford
<richard.sandiford@arm.com> wrote:
> This handles both integer and floating-point arguments.  It's needed
> for the follow-on patch to move fmin and fmax to match.pd.
>
> Tested on x86_64-linux-gnu, aarch64-linux-gnu and arm-linux-gnueabi.
> OK to install?

Ok.

Thanks,
Richard.

> Thanks,
> Richard
>
>
> gcc/
>         * fold-const.c (fold_minmax): Delete.
>         (fold_binary_loc): Don't call it.
>         * match.pd: Add rules previously handled by fold_minmax.
>
> diff --git a/gcc/fold-const.c b/gcc/fold-const.c
> index ffad732..e8ff1de 100644
> --- a/gcc/fold-const.c
> +++ b/gcc/fold-const.c
> @@ -8073,49 +8073,6 @@ fold_truth_andor (location_t loc, enum tree_code code, tree type,
>    return NULL_TREE;
>  }
>
> -/* Fold a binary expression of code CODE and type TYPE with operands
> -   OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
> -   Return the folded expression if folding is successful.  Otherwise,
> -   return NULL_TREE.  */
> -
> -static tree
> -fold_minmax (location_t loc, enum tree_code code, tree type, tree op0, tree op1)
> -{
> -  enum tree_code compl_code;
> -
> -  if (code == MIN_EXPR)
> -    compl_code = MAX_EXPR;
> -  else if (code == MAX_EXPR)
> -    compl_code = MIN_EXPR;
> -  else
> -    gcc_unreachable ();
> -
> -  /* MIN (MAX (a, b), b) == b.  */
> -  if (TREE_CODE (op0) == compl_code
> -      && operand_equal_p (TREE_OPERAND (op0, 1), op1, 0))
> -    return omit_one_operand_loc (loc, type, op1, TREE_OPERAND (op0, 0));
> -
> -  /* MIN (MAX (b, a), b) == b.  */
> -  if (TREE_CODE (op0) == compl_code
> -      && operand_equal_p (TREE_OPERAND (op0, 0), op1, 0)
> -      && reorder_operands_p (TREE_OPERAND (op0, 1), op1))
> -    return omit_one_operand_loc (loc, type, op1, TREE_OPERAND (op0, 1));
> -
> -  /* MIN (a, MAX (a, b)) == a.  */
> -  if (TREE_CODE (op1) == compl_code
> -      && operand_equal_p (op0, TREE_OPERAND (op1, 0), 0)
> -      && reorder_operands_p (op0, TREE_OPERAND (op1, 1)))
> -    return omit_one_operand_loc (loc, type, op0, TREE_OPERAND (op1, 1));
> -
> -  /* MIN (a, MAX (b, a)) == a.  */
> -  if (TREE_CODE (op1) == compl_code
> -      && operand_equal_p (op0, TREE_OPERAND (op1, 1), 0)
> -      && reorder_operands_p (op0, TREE_OPERAND (op1, 0)))
> -    return omit_one_operand_loc (loc, type, op0, TREE_OPERAND (op1, 0));
> -
> -  return NULL_TREE;
> -}
> -
>  /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
>     by changing CODE to reduce the magnitude of constants involved in
>     ARG0 of the comparison.
> @@ -10426,15 +10383,7 @@ fold_binary_loc (location_t loc,
>        return NULL_TREE;
>
>      case MIN_EXPR:
> -      tem = fold_minmax (loc, MIN_EXPR, type, arg0, arg1);
> -      if (tem)
> -       return tem;
> -      goto associate;
> -
>      case MAX_EXPR:
> -      tem = fold_minmax (loc, MAX_EXPR, type, arg0, arg1);
> -      if (tem)
> -       return tem;
>        goto associate;
>
>      case TRUTH_ANDIF_EXPR:
> diff --git a/gcc/match.pd b/gcc/match.pd
> index e02379f..338644c 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -1176,6 +1176,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>   (simplify
>    (minmax @0 @0)
>    @0))
> +/* min(max(x,y),y) -> y.  */
> +(simplify
> + (min:c (max:c @0 @1) @1)
> + @1)
> +/* max(min(x,y),y) -> y.  */
> +(simplify
> + (max:c (min:c @0 @1) @1)
> + @1)
>  (simplify
>   (min @0 @1)
>   (if (INTEGRAL_TYPE_P (type)
>