Re: [PATCH] range-op-float: Improve binary reverse operations

[Andrew MacLeod <amacleod@redhat.com>]

On 12/5/22 17:38, Jakub Jelinek wrote:
> On Mon, Dec 05, 2022 at 09:54:09PM +0100, Jakub Jelinek via Gcc-patches wrote:
>> On Mon, Dec 05, 2022 at 03:43:16PM -0500, Andrew MacLeod wrote:
>>> Id actually prefer to avoid passing the tree code around... we're trying to
>>> avoid that sort of thing even though Aldy temporarily introduced them to
>>> range-ops. Hes suppose to remove that next stage 1 :-P   Ideally anything
>>> "special" is locally contained to the specific routine.
>> Would a bool divide_op2 argument be better (perhaps defaulted to false)?
>> Inlining float_binary_op_range_finish by hand doesn't seem to be a good
>> idea, if it needs to be changed, it would need to be changed in multiple
>> places...

Yeah thats also fine.

Andrew


> In patch form on top of PR107975 patch.
>
> 2022-12-05  Jakub Jelinek  <jakub@redhat.com>
>
> 	PR tree-optimization/107972
> 	* range-op-float.cc (frange_drop_infs): New function.
> 	(float_binary_op_range_finish): Add DIV_OP2 argument.  If DIV_OP2 is
> 	false and lhs is finite or if DIV_OP2 is true and lhs is non-zero and
> 	not NAN, r must be finite too.
> 	(foperator_div::op2_range): Pass true to DIV_OP2 of
> 	float_binary_op_range_finish.
>
> --- gcc/range-op-float.cc.jj	2022-12-05 11:17:34.900573272 +0100
> +++ gcc/range-op-float.cc	2022-12-05 16:13:54.414845672 +0100
> @@ -330,6 +330,18 @@ frange_drop_ninf (frange &r, tree type)
>     r.intersect (tmp);
>   }
>   
> +// Crop R to [MIN, MAX] where MAX is the maximum representable number
> +// for TYPE and MIN the minimum representable number for TYPE.
> +
> +static inline void
> +frange_drop_infs (frange &r, tree type)
> +{
> +  REAL_VALUE_TYPE max = real_max_representable (type);
> +  REAL_VALUE_TYPE min = real_min_representable (type);
> +  frange tmp (type, min, max);
> +  r.intersect (tmp);
> +}
> +
>   // If zero is in R, make sure both -0.0 and +0.0 are in the range.
>   
>   static inline void
> @@ -1883,7 +1895,7 @@ foperator_unordered_equal::op1_range (fr
>   
>   static bool
>   float_binary_op_range_finish (bool ret, frange &r, tree type,
> -			      const frange &lhs)
> +			      const frange &lhs, bool div_op2 = false)
>   {
>     if (!ret)
>       return false;
> @@ -1904,7 +1916,20 @@ float_binary_op_range_finish (bool ret,
>     // If lhs isn't NAN, then neither operand could be NAN,
>     // even if the reverse operation does introduce a maybe_nan.
>     if (!lhs.maybe_isnan ())
> -    r.clear_nan ();
> +    {
> +      r.clear_nan ();
> +      if (div_op2
> +	  ? !(real_compare (LE_EXPR, &lhs.lower_bound (), &dconst0)
> +	      && real_compare (GE_EXPR, &lhs.upper_bound (), &dconst0))
> +	  : !(real_isinf (&lhs.lower_bound ())
> +	      || real_isinf (&lhs.upper_bound ())))
> +	// For reverse + or - or * or op1 of /, if result is finite, then
> +	// r must be finite too, as X + INF or X - INF or X * INF or
> +	// INF / X is always +-INF or NAN.  For op2 of /, if result is
> +	// non-zero and not NAN, r must be finite, as X / INF is always
> +	// 0 or NAN.
> +	frange_drop_infs (r, type);
> +    }
>     // If lhs is a maybe or known NAN, the operand could be
>     // NAN.
>     else
> @@ -2330,7 +2355,7 @@ public:
>       if (!ret)
>         return ret;
>       if (lhs.known_isnan () || op1.known_isnan () || op1.undefined_p ())
> -      return float_binary_op_range_finish (ret, r, type, lhs);
> +      return float_binary_op_range_finish (ret, r, type, lhs, true);
>       const REAL_VALUE_TYPE &lhs_lb = lhs.lower_bound ();
>       const REAL_VALUE_TYPE &lhs_ub = lhs.upper_bound ();
>       const REAL_VALUE_TYPE &op1_lb = op1.lower_bound ();
> @@ -2347,7 +2372,7 @@ public:
>   	zero_to_inf_range (lb, ub, signbit_known);
>   	r.set (type, lb, ub);
>         }
> -    return float_binary_op_range_finish (ret, r, type, lhs);
> +    return float_binary_op_range_finish (ret, r, type, lhs, true);
>     }
>   private:
>     void rv_fold (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub, bool &maybe_nan,
>
>
> 	Jakub
>